Soldering surface mount components
Daniel Kelly (AKA Jack)
I am planning a job where I need to manually solder surface mount ICs. Some
of these ICs have pins that are only 0.5mm apart! I'm worried that this
will be impossible to solder manually.
I've looked on the web - people tell me it is possible to solder SMDs but
I'm worried their talking about older SMDs with pin-to-pin distances of more
like 1mm.
I'm a relatively skilled soldering iron user.
Is it possible to manually solder ICs with pins only 0.5mm apart?
Thanks,
Jack
Charles Schuler
"Daniel Kelly (AKA Jack)" <d.kell...@NOSPAM.ucl.ac.uk> wrote in message
news:ca57k1$1mja$1...@uns-a.ucl.ac.uk...
1/ Magnification
2/ Liquid flux and solder paste
3/ Hot air soldering device
4/ Practice and patience
Mariano
"Charles Schuler" <charle...@comcast.net> wrote in message
news:PPWdnXrQkMH...@comcast.com...
> 1/ Magnification
> 2/ Liquid flux and solder paste
How do you apply the solder paste manually to the IC pins or pads ? I've
tried and the paste does not stick anywhere (before soldering). I even tried
with a syringe and ended up clogging the needle.
IMO this is the most critical part in SMD. It doesn't matter if your
placement is poor, since the solder will try to align the components with
the pads (when soldering). But you need to apply an even coat (and right
quantity) of paste to each pad. This is were I fail.
Ian Stirling
> Hi,
>
> I am planning a job where I need to manually solder surface mount ICs. Some
> of these ICs have pins that are only 0.5mm apart! I'm worried that this
> will be impossible to solder manually.
To add to this, is it possible to buy smaller diameter than normal solder?
I've found I can make my own, with a drawplate, but it is a tedious process.
I ahven't found anywhere that stocks under .5mm multicore.
Repzak
> Is it possible to manually solder ICs with pins only 0.5mm apart?
Hey
Yearh.. i did it last week with a Tusb6250, on a home etched pcb...
u just used some quite thin solder and a lot of flux....
i thing my tip on the solder iron is 0,5 times 1mm ... but as long as there
is a lot of flux and you dosent use much solder i runs nice... and maybe use
"solder remover litze" with added flux to remove some of the solder there is
to much...
normally i just put litle solder on the solderiron tip and flux on the IC
legs, and then the flux will attrack the solder to the legs...
you could find some old computer stuff and remove some of the ic's with hot
air and use then as test, before using an expensive ic
Kasper
Mjolinor
"Ian Stirling" <ro...@mauve.demon.co.uk> wrote in message
news:40c63159$0$551$ed26...@ptn-nntp-reader02.plus.net...
Mark (UK)
How I do it, is once the chip is removed, and you've got the bare pads,
I then use a regular iron set to a low temp, 275-300, to go over the
pads with fresh LMP solder and lots of flux, that tinns them up,the flux
helps stop them joining together, and leaves solder on each pad to help
solder the new IC legs to. Then use a hot air pencil to finally solder
the chip in place.
Yours, Mark.
John Larkin
wrote:
>
>"Charles Schuler" <charle...@comcast.net> wrote in message
>news:PPWdnXrQkMH...@comcast.com...
>
>> 1/ Magnification
>> 2/ Liquid flux and solder paste
>
>How do you apply the solder paste manually to the IC pins or pads ? I've
>tried and the paste does not stick anywhere (before soldering). I even tried
>with a syringe and ended up clogging the needle.
>
Paste isn't necessary. Flux the pins (liquid, maybe diluted RMA rosin
flux) and apply a small glob of solder to the tip of the iron. Run the
tip down the pins, at the pin/pad junctions; solder will magically
wick off the tip onto the pins. There are special "hoof" tips with a
beveled flat that holds a nice little pool of solder to make this work
better.
Tack two corner pins first, then just run down the line. Works great.
John
Impmon
<d.kell...@NOSPAM.ucl.ac.uk> wrote:
>Is it possible to manually solder ICs with pins only 0.5mm apart?
Yes it can be done, just use fine point, magnifying glass, and use
little solder.
It'd be easier to leave such tiny work to machines. Why do you need
to solder them manually?
--
To reply, replace digi.mon with tds.net
Chuck Olson
"Daniel Kelly (AKA Jack)" <d.kell...@NOSPAM.ucl.ac.uk> wrote in message
news:ca57k1$1mja$1...@uns-a.ucl.ac.uk...
is a binocular microscope with variable power from 7 to 30 diameters and a
socket for a spotlight. If you can see it, you can do it. You should be
able to find a used one for about $200, (try Ebay) (and another $25 for the
spotlight) and it will last your whole life. You will be astounded at what
you can see with that microscope - - from examining today's almost invisible
electronic components to removing slivers and hangnails, and learning about
tiny creatures. Nobody should be without one.
The next thing you need is a soldering iron that allows your fingers to get
within about 1.25" of where the soldering is happening so that you have as
good control of the soldering tip as you have of the tip of a pencil when
you write. I find the Metcal stuff works very well, and older used systems
are available for under $100 on Ebay. Finally, you should be able to find
some 0.020" diameter solder (try Ebay or a big electronics flea market).
I made a surface-mount component clamp for my microscope consisting of a
strip of springy phosphor-bronze or beryllium-copper between two standoffs
about 3 inches apart and a piece of #12 wire soldered at the middle of the
strip to form a "T" so it pokes almost into the field of view of the
microscope, and finally a piece of #20 solid wire soldered at the end of the
#12 arm and bent down so the tip of the wire presses on the component you
want to solder right in the middle of the field of view. Just pull up on
the spring-supported #12 arm when you want to move the assembly or lift it
up onto another component.
Good luck,
Chuck
Daniel Kelly (AKA Jack)
> It'd be easier to leave such tiny work to machines. Why do you need
> to solder them manually?
I'm building a one-off design for a psychology PhD experiment. I do have
access to University College London's Electrical Engineering department but
I doubt they have robots for building surface mount systems.
Oh, and I have looked long and hard for 'normal' sized chips but they just
don't exist for the sort of application I need.
Thanks,
Jack
"Impmon" <imp...@digi.mon> wrote in message
news:u6gcc0594a15b7ii0...@4ax.com...
Daniel Kelly (AKA Jack)
Jack
"Chuck Olson" <chucko...@REMOVETHIScomcast.net> wrote in message
news:p8uxc.5829$0y.3064@attbi_s03...
Tim Auton
>
>> It'd be easier to leave such tiny work to machines. Why do you need
>> to solder them manually?
>
>I'm building a one-off design for a psychology PhD experiment. I do have
>access to University College London's Electrical Engineering department but
>I doubt they have robots for building surface mount systems.
They will have technicians, lecturers and students who should know
what to do though. Ask nicely and someone might give you a
demonstration and show you the tools they have available.
Tim
--
Love is a travelator.
Product developer
Antex low watt iron with fine tip. Use a flux pen to paint flux onto
pads. Using tweezers hold the I.C. in place and tack the corner pins.
Apply just enough solder to iron tip to wet it and flick off excess.
Apply the tip very briefly to the pin end and pad and the solder will
wick into and between the pin and pad. When removing a chip without
heat simply take a sharp Xacto blade and carefully apply pressure to
the blade onto the pins as near to the chip body as possible. This
will sever the pins from the chip body making them easier for removal
without lifting a pad. Be careful to not exceed the pin / chip body
with the knife or you will risk opening a trace. I have been doing
this for years and have lost a trace or pad in over twenty years.
Daniel Kelly (AKA Jack)
Jack
"Tim Auton" <tim.auton@uton.[groupSexWithoutTheY]> wrote in message
news:8c9ec0pugtdofn6mc...@4ax.com...
Gordon Youd
They make SMT rework by hand look so simple, like John Larkin said "tack the
ends and run down the line".
Try CPC Ltd for a copy of the video, it's free.
If you cannot get a copy I can copy mine for you.
The site for Metcal is www.metcal.com, I could not find the video there
but electronic wholesalers have it.
Regards, Gordon.
Remove the Z from my address to reply.
----------------------------------------------------------------------------
-----------
"Daniel Kelly (AKA Jack)" <d.kell...@NOSPAM.ucl.ac.uk> wrote in message
news:ca57k1$1mja$1...@uns-a.ucl.ac.uk...
Rene Tschaggelar
> "Charles Schuler" <charle...@comcast.net> wrote in message
> news:PPWdnXrQkMH...@comcast.com...
>
>
>>1/ Magnification
>>2/ Liquid flux and solder paste
>
>
> How do you apply the solder paste manually to the IC pins or pads ? I've
> tried and the paste does not stick anywhere (before soldering). I even tried
> with a syringe and ended up clogging the needle.
I have Flux inside a syringe with a 1mm needle. Before application i
heat the syringe and the flux with the heatgun to 80 degC or so.
The solder past also comes in a syringe that needs to be heated before
use. I prefer the 1mm tin wire though. Tin paste is a mess.
Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net
Rene Tschaggelar
Yes. Sure.
For magnification I recommend strong reading glasses. I use 4 dioptries.
That let me have it as close as 15cm from my eyes.
Then I use fluxpaste from a syringe, heated with the heatgun to make it
more liquid.
And medium tip iron plus 1 mm or 0.8mm tim wire.
First come the fixng phase where two diagonal corner pins are soldered
down. It doesn't matter whether the adjacent pins are soldered too.
Don't even try to solder a single pins. A few of them at one is ok. The
flux separates the tin on the pins.
Oh, yes, having a soldermask helps.
Mariano
Newark products and they are quite expensive. And since I have no experience
with flux/paste, I don't want to screw up buying something useless.
Thanks.
Mariano
"Rene Tschaggelar" <no...@none.net> wrote in message
news:40c776b4$0$21346$5402...@news.sunrise.ch...
Paul Guy
The pads MUST NOT have any applied solder on them. If they do,
remove it all with solderwick. (the bumps from the solder will not
allow the chip to lie flat.)
Align the IC, solder one corner pin to hold it down. Solder the
opposite corner down. Don't worry if the solder joins several pins.
Make absolutely sure it's aligned properly, and all the pins are
resting on the pads. Now apply enough solder that all the pins are
covered, even if they are all shorted together.
Here's the neat part: Take some "solderwick" (the braided stuff you
use for removing solder) and remove all the solder! It doesn't really
take it all off, it leaves the required amount underneath the "feet"
of the pins. If you look in a microscope, you'll find that you have
almost perfectly soldered pins. There will be trouble if the pins
didn't all touch the pads prior to soldering. Chips intended for
surface mount must have good co-planarity, so be very gentle handling
them. If you bend the leads for than a few thousands of an inch, you
can expect trouble.
If you have a good touch with an iron, and are using good liquid
flux (RMA type, you must remove the residual flux afterward using a
solvent like isopropyl alcohol), you can zoom thin solder along the
pins, and it will not short them out. I believe it's absolutely
necessary to use the proper liquid flux in order to pull this off, and
it does need a bit of practice. You'll need the solderwick to remove
shorted pins. I figure if you're using solderwick anyhow, then do the
first method and not lose any sleep over it.
I have successfully soldered QFP80's this way, the most difficult
part is the alignment to the pads.
This is not a fast way to solder, but it doesn't need any fancy
equipment.
To show how crude you can get, instead of using our hot air reflow
stations (several thousand $ each), I demonstrated soldering a QFP80
using an old crappy soldering GUN, along with the solderwick removal.
The final results were just as good, under close inspection with a
microscope, and they easily met the IPC/EIA J-STD-001C soldering
standards. (Don't do this with a good chip! The soldering guns can
damage chips because of electrostatic discharge (ESD) from the
capacitive coupling to the power line.)
-Paul
..............................................................
Paul
Somewhere in the Nova Scotia fog
ANTISPAM - Please remove the m's in my email address
John Popelish
>
> Can anybody point me to any flux and paste product in the US ? I checked
> Newark products and they are quite expensive. And since I have no experience
> with flux/paste, I don't want to screw up buying something useless.
>
several different fluxes in a felt tip pen dispensers.
--
John Popelish
John Larkin
<mpaul...@meastlinkm.ca> wrote:
>On Tue, 8 Jun 2004 21:31:28 +0100, "Daniel Kelly \(AKA Jack\)"
><d.kell...@NOSPAM.ucl.ac.uk> wrote:
>
>>Hi,
>>
>>I am planning a job where I need to manually solder surface mount ICs. Some
>>of these ICs have pins that are only 0.5mm apart! I'm worried that this
>>will be impossible to solder manually.
>>
>>I've looked on the web - people tell me it is possible to solder SMDs but
>>I'm worried their talking about older SMDs with pin-to-pin distances of more
>>like 1mm.
>>
>>I'm a relatively skilled soldering iron user.
>>
>>Is it possible to manually solder ICs with pins only 0.5mm apart?
>>
>>Thanks,
>>Jack
>>
> The pads MUST NOT have any applied solder on them. If they do,
>remove it all with solderwick. (the bumps from the solder will not
>allow the chip to lie flat.)
We sent out some BGA chips (560 or so balls) to be soldered. The guy
who did it for us applied no solder, just used the solder coating that
came on the board. He said you have to apply the flux with a bare
finger, nothing else will do. He did xray every joint, and all the
boards worked fine.
John
Andre
Thats pretty neat :) I have some dead cameras here with fried BGA
controller chips.
BGA chips are a total pain to solder- you need a proper infra-red
reflow unit and X-ray scanner which your average hobbyist (except
maybe Sam G and/or Chip Shultz) won't have access to.
:)
-A
-A
>
> John
Daniel Kelly (AKA Jack)
Many many thanks for your reply.
I've had a search for the video and can't find it anywhere.
Do you know for sure where I could get hold of it in the UK?
If not, I would be most indepted if I could get a copy from you. Could you
e-mail me a DivX or something?
Many many thanks,
Jack
"Gordon Youd" <gor...@Zgyoud.demon.co.uk> wrote in message
news:ca7fq2$1on$1$8300...@news.demon.co.uk...
Daniel Kelly (AKA Jack)
Actually, don't worry - I've just phoned up Eagle, METCAL's UK supplier, and
they're sending a CD-ROM to me in the post right now! How cool is that?!?
Thanks so much!
Jack
"Daniel Kelly (AKA Jack)" <d.kell...@NOSPAM.ucl.ac.uk> wrote in message
news:ca9e2a$305q$1...@uns-a.ucl.ac.uk...
Cyclonus
<d.kell...@NOSPAM.ucl.ac.uk> wrote:
>Dear Gordon,
>
>Actually, don't worry - I've just phoned up Eagle, METCAL's UK supplier, and
>they're sending a CD-ROM to me in the post right now! How cool is that?!?
>Thanks so much!
>
>Jack
>
Wow, thats really great, I suppose you wouldnt know whom I could
contact in Canada to get a copy of that CD??
Maurice
Gordon Youd
CANADA
EMX
(Manufacturers Rep)
227 Idema Road
Marhkam, ON, L3R 1B1, CANADA
Phone: 905-475-8000
Fax: 905-475-2300
Email: sa...@emx.ca
--------------------------------------------------------------------------
EMX
(Manufacturers Rep)
5950 Frued #23
Montreal, PQ, H4S 1T1, CANADA
Phone: 514-484-6565
Fax: 514-482-2221
Email: sa...@emx.ca
--------------------------------------------------------------------------
Adtool
(Distributor)
10 Ronald Drive
Montreal, Quebec, H4X 1M8, CANADA
Phone: 514-482-2548
Fax:
Email:
--------------------------------------------------------------------------
Adtool
(Distributor)
141 6200 MacKay Ave.
Burnaby, B. C., V5H 4M9, CANADA
Phone: 604-618-2924
Fax:
Email:
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Regards, Gordon.
----------------------------------------------------------------
"Cyclonus" <xycycl...@NOSPAMhotmail.com> wrote in message
news:s6khc0d3rolbebe4j...@4ax.com...
Michael Schwingen
Rene Tschaggelar <no...@none.net> wrote:
>
>Then I use fluxpaste from a syringe, heated with the heatgun to make it
>more liquid.
Metcal has a nice Fluxpen ("FP-1") with a brush-like tip and
squeeze-dispenser that works very well when filled with liquid flux - I use
no-clean flux, which is non-sticky, but it should also work with rosin flux.
cu
Michael
Cyclonus
<gor...@Zgyoud.demon.co.uk> wrote:
Thanks!, I sent a request off the the local Canadian office.
Maurice
Hans Summers
You people are all talking about flux, solder flows, PCB's, but you've got
it all wrong!
You should take a look at my page
http://www.hanssummers.com/electronics/equipment/spectrumanalyser2/index.htm
. About 2/3 the way down you'll see a closeup photo on the left hand side,
showing a 24-pin TSSOP packaged ADC chip. The pin spacing is 0.65mm (Ok, so
not quite your 0.5mm). You can click the picture for a larger version.
I did this with:
NO magnifying glass
NO special lighting
NO hot air etc
NO special soldering iron, just my old 18W Antex CS
NO special bit, just my Antex 1mm bit type 1106
NO special solder or flux, just ordinary 22swg 60/40 multicore fluxed solder
NO pre-etched PCB, just a piece of PCB stock I cut some pads in with a cheap
plastic craft knife
NO fancy rigs to hold the work, just loose on the bench, with the IC glued
to the board
And it worked first time.
I've soldered other SMD IC's too, but this one was the most extreme. You'll
also find less tiny spacing'ed SMD IC's soldered on these pages of my site:
http://www.hanssummers.com/radio/polyphase/index.htm
http://www.hanssummers.com/radio/ozon/index.htm
http://www.hanssummers.com/computers/newz80/intro.htm
http://www.hanssummers.com/electronics/equipment/riskometer/index.htm
Anything's possible ;-)
Hans
http://www.HansSummers.com
Chuck Olson
"Hans Summers" <hans.s...@tudor.com> wrote in message
news:2j5kp9F...@uni-berlin.de...
Spehro Pefhany
<chucko...@REMOVETHIScomcast.net> wrote:
>
>"Hans Summers" <hans.s...@tudor.com> wrote in message
>news:2j5kp9F...@uni-berlin.de...
>>
>> You people are all talking about flux, solder flows, PCB's, but you've got
>> it all wrong!
>>
>> You should take a look at my page
>>
>http://www.hanssummers.com/electronics/equipment/spectrumanalyser2/index.htm
That old Heathkit signal generator is a hoot. Tubes (err, "valves"),
right?
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
sp...@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
Mariano
So how did you do it then? you forgot to tell us how
- solder tip size?
- solder type?
- ...
"Hans Summers" <hans.s...@tudor.com> wrote in message
news:2j5kp9F...@uni-berlin.de...
>
Hans Summers
"Mariano" <mfilippaR...@uol.com.ar> wrote in message
news:Crlzc.90$gs....@news.itd.umich.edu...
>
> So how did you do it then? you forgot to tell us how
No, I did tell you (at least, I did tell you those things)... here's my
original relevant sections pasted in again:
>
> - solder tip size?
> > NO special soldering iron, just my old 18W Antex CS
> > NO special bit, just my Antex 1mm bit type 1106
> - solder type?
> > NO special solder or flux, just ordinary 22swg 60/40 multicore fluxed
solder
As for process:
This TSSOP had 24 pins (unfortunately the catalogue had claimed in was DIL,
but in reality it was SMD. Pity I didn't read the datasheet carefully enough
and match up the part numbers).
So anyway, I carved two columns of small pads on the surface of the unetched
PCB using a knife (one of those ubiquitous dirt cheap orange "craft"
knives). 2 columns of 6 on each side of the chip, makes 24. I couldn't do 12
per side because they would have been too narrow for me to cut with that
knife. I left a space in between the pairs of columns either side, for the
IC.
The IC was glued in position. Now alternate pins on the TSSOP are bent
upwards. So considering the left hand side, pins 1, 3, 5, 7, 9, 11 continue
resting on the newly carved first column of 5 pads. Pins 2, 4, 6, 8, 10, 12
are bent upwards away from the board. Then I took ordinary multi-core wire,
and took single copper strands from it. These pins 2, 4, 6 etc were
connected to the outer column of 6 pads using these thin copper strands.
Bending alternate pins of the IC in opposite directions makes it possible to
solder to the pins even with this 1mm iron bit.
Have another look at the picture,
http://www.hanssummers.com/electronics/equipment/spectrumanalyser2/index.htm
and you will be able to see some of the things I'm talking about (the
columns of carved pads etc).
Hans
http://www.HansSummers.com
Hans Summers
> You must be very near-sighted.
>
Hans
http://www.HansSummers.com
Hans Summers
"Spehro Pefhany" <spef...@interlogDOTyou.knowwhat> wrote in message
news:idnrc0prkf0k6co7b...@4ax.com...
> On Mon, 14 Jun 2004 16:41:47 GMT, the renowned "Chuck Olson"
> <chucko...@REMOVETHIScomcast.net> wrote:
>
> >
> >"Hans Summers" <hans.s...@tudor.com> wrote in message
> >news:2j5kp9F...@uni-berlin.de...
> >>
> >> You people are all talking about flux, solder flows, PCB's, but you've
got
> >> it all wrong!
> >>
> >> You should take a look at my page
> >>
>
>http://www.hanssummers.com/electronics/equipment/spectrumanalyser2/index.ht
m
>
>
> That old Heathkit signal generator is a hoot. Tubes (err, "valves"),
> right?
Right, valves ;-) I forget the valve types. If I recall it contains only
two valves, but I might be remembering wrongly. You can find a large picture
of it here:
http://www.hanssummers.com/electronics/equipment/signalgenerator/sig.htm . I
did open it and take some photos of the insides, but I got the focus all
wrong and didn't bother to re-open it again. I've even got a copy of most of
the manual, sent to me by an Irish radio amateur who has the same generator.
Hans
http://www.HansSummers.com
Steven McGahey
I've read this thread with a lot of interest, as I have a small bit of
surface-mount work to do, but no experience working with these tiny
components.
I would have thought that when working with these components, you would have
to use a different approach, and try to keep the component cool (as it'll
fry otherwise), but this thread seems to suggest otherwise.
Can someone straighten me out on this subject, as I have a feeling that
Nokia will want me to purchase a new phone circuit-board (~£70) if I ask
them to repair it, when it's only a minor soldering job that is required.
Thanks in advance,
- Steve
Roger Johansson
the obvious bits)> wrote:
> I've read this thread with a lot of interest, as I have a small bit of
> surface-mount work to do, but no experience working with these tiny
> components.
>
> I would have thought that when working with these components, you would
> have to use a different approach, and try to keep the component cool
> (as it'll fry otherwise), but this thread seems to suggest otherwise.
Modern components are very seldom destroyed by heat.
Components are made to withstand soldering heat for 10 seconds, or so.
If you fail to make a good soldering joint in 5 seconds, wait for a few
minutes before you make a new try, to let the component cool down.
--
Roger J.
John Larkin
>Hi all,
>
>I've read this thread with a lot of interest, as I have a small bit of
>surface-mount work to do, but no experience working with these tiny
>components.
>
>I would have thought that when working with these components, you would have
>to use a different approach, and try to keep the component cool (as it'll
>fry otherwise), but this thread seems to suggest otherwise.
>
>Can someone straighten me out on this subject, as I have a feeling that
>Nokia will want me to purchase a new phone circuit-board (~£70) if I ask
>them to repair it, when it's only a minor soldering job that is required.
>
>Thanks in advance,
>- Steve
>
Surface-mount parts are designed to be soldered in a reflow oven,
where the entire loaded board gets heated above solder-melt
temperature for a minute or so. Most parts don't mind. I just solder
them by hand, and it pretty much always works.
I have seen some surfmount LEDs turn to putty when hand soldered. The
transparent plastics seem to be fragile.
John
Larry Brasfield
wrote in message news:a7lpq05v0jvt6vqbg...@4ax.com...
> Surface-mount parts are designed to be soldered in a reflow oven,
> where the entire loaded board gets heated above solder-melt
> temperature for a minute or so. Most parts don't mind. I just solder
> them by hand, and it pretty much always works.
Hand soldering can be very hard on SMD ceramic capacitors.
The high temperature gradiant created by applying heat suddenly
at one end can fracture the ceramic. This can lead to excess noise
or a tendency to break down at a lower than rated voltage as
moisure gets into the crack(s). The insidious aspect of this kind
of damage is that it can show up in the field, quite some time
after the parts perform alright in initial testing.
At Siemens Ultrasound, we learned this the hard way, then had it
confirmed by at least one vendor's examination of abused parts.
...
> John
--
--Larry Brasfield
email: donotspam_la...@hotmail.com
Above views may belong only to me.
Clarence
"Larry Brasfield" <donotspam_la...@hotmail.com> wrote in message
news:nQcrd.395$O54....@news.uswest.net...
> "John Larkin" <jjla...@highSNIPlandTHIStechPLEASEnology.com>
> wrote in message news:a7lpq05v0jvt6vqbg...@4ax.com...
> > Surface-mount parts are designed to be soldered in a reflow oven,
> > where the entire loaded board gets heated above solder-melt
> > temperature for a minute or so. Most parts don't mind. I just solder
> > them by hand, and it pretty much always works.
>
> Hand soldering can be very hard on SMD ceramic capacitors.
> The high temperature gradiant created by applying heat suddenly
> at one end can fracture the ceramic. This can lead to excess noise
> or a tendency to break down at a lower than rated voltage as
> moisure gets into the crack(s). The insidious aspect of this kind
> of damage is that it can show up in the field, quite some time
> after the parts perform alright in initial testing.
>
> At Siemens Ultrasound, we learned this the hard way, then had it
> confirmed by at least one vendor's examination of abused parts.
>
Of course this may have actually happened, and Boy, you had some pretty lousy
assembly people. I've seen the pre-prod units used for test assembled and
soldered by hand and subjected to extensive testing. Never saw a solder
related failure of a component. We tested for very long periods on many
boards. Of course we also inspected the boards before applying power and
checking for damage. Rarely had to retouch a board after the first three.
Terry Given
This is a VERY good point. Reflow ovens have very well controlled
thermal profiles, slowly ramping temperature to a plateau, holding,
slowly ramping up to final tmep, holding etc. Mostly to avoid this
thermal shock related mechanical failure mechanism. High voltage
ceramics are especially prone to this - hand soldering them is a risky
process.
I once used 2 x 15nF 1000V smt X7R caps in series across an 80-800Vdc
supply for a smps application. During testing one smps failed
catastrophically (two others ran fine). Detailed examination of the
corpse showed a blast pattern radiating outward from one of the caps,
which had ruptured. The resulting mess sprayed directly across the legs
of one of the FETs, thereby toasting the unit. At the time it was
operating at a DC bus voltage of around 400V, so the cap was nowhere
near its rated voltage, more like 20%. One of the guys I worked with had
extensive experience in this area (hi-rel smps hybrids for
il/aerospace), and showed us what went wrong. We immediately replaced
the capacitors, carefully using a manual hot air station, to both
preheat and solder. The units operated continuously into a dead short at
800Vdc, no problems - there were other issues of course, it was a
pre-production protoype, but none of the explosive kind.
Cheers
Terry
John Larkin
<donotspam_la...@hotmail.com> wrote:
>"John Larkin" <jjla...@highSNIPlandTHIStechPLEASEnology.com>
>wrote in message news:a7lpq05v0jvt6vqbg...@4ax.com...
>> Surface-mount parts are designed to be soldered in a reflow oven,
>> where the entire loaded board gets heated above solder-melt
>> temperature for a minute or so. Most parts don't mind. I just solder
>> them by hand, and it pretty much always works.
>
>Hand soldering can be very hard on SMD ceramic capacitors.
>The high temperature gradiant created by applying heat suddenly
>at one end can fracture the ceramic. This can lead to excess noise
>or a tendency to break down at a lower than rated voltage as
>moisure gets into the crack(s). The insidious aspect of this kind
>of damage is that it can show up in the field, quite some time
>after the parts perform alright in initial testing.
>
>At Siemens Ultrasound, we learned this the hard way, then had it
>confirmed by at least one vendor's examination of abused parts.
>
Maybe the parts are getting better, but I've never seen that happen,
and some of our boards have lots of parts on the bottom,
hand-soldered. I hand-solder all kinds of parts in the lab, and can't
recall ever damaging one, unless it wasn't on a PCB, like soldered
directly to a connector or on a copperclad breadboard, where it is
possible to apply some bending forces and rip off the end caps.
We have virtually zero returns from the field due to damaged passives.
John
Howard Long
the obvious bits)> wrote in message
news:IW3rd.1515$ck3....@newsfe6-gui.ntli.net...
> Hi all,
>
> I've read this thread with a lot of interest, as I have a small bit of
> surface-mount work to do, but no experience working with these tiny
> components.
>
> I would have thought that when working with these components, you would
have > to use a different approach, and try to keep the component cool (as
it'll
> fry otherwise), but this thread seems to suggest otherwise.
FWIW, I use a standard temperature controlled iron with a small tip (I think
it cost about $50), with very thin solder, desolder braid.
I do everyting on a plain white tray with lips around the edge - there's
nothing worse than losing that last 3.3k resistor you had on the carpet...
I do have a small magnifying glass, but that's just to help me identify the
components that actually have markings - I don't use it for anything else.
For the chips with loads of pins at tiny spacing (including 0.5mm), I use a
really tiny piece of bluetak (a bit like plasticine or playdoh, but sticks
paper to walls) to fix the component into place, then I solder the
component. I don't worry too much about solder bridges over the leads for
now, but I am rather careful to use small amounts of solder, in case it
creeps under the chip.
Then I use the desolder braid to mop up the excess solder. After a visual
inspection, I do a continuity check of each of the leads to ensure there's
connection to the pcb as well as no shorts between adjacent leads of the
chip. A pain, and almost every time it shows nothing untoward.
Rework involving removal of chips takes a number of tricks, but primarily
remember that you're much more interested in maintaining the PCB in good
shape, at the expense of a trashed component.
Good luck. Howard.
Larry Brasfield
news:mTfrd.36936$6q2....@newssvr14.news.prodigy.com...
> "Larry Brasfield" <donotspam_la...@hotmail.com> wrote in message
> news:nQcrd.395$O54....@news.uswest.net...
>> "John Larkin" <jjla...@highSNIPlandTHIStechPLEASEnology.com>
>> wrote in message news:a7lpq05v0jvt6vqbg...@4ax.com...
>> > Surface-mount parts are designed to be soldered in a reflow oven,
>> > where the entire loaded board gets heated above solder-melt
>> > temperature for a minute or so. Most parts don't mind. I just solder
>> > them by hand, and it pretty much always works.
>>
>> Hand soldering can be very hard on SMD ceramic capacitors.
>> The high temperature gradiant created by applying heat suddenly
>> at one end can fracture the ceramic. This can lead to excess noise
>> or a tendency to break down at a lower than rated voltage as
>> moisure gets into the crack(s). The insidious aspect of this kind
>> of damage is that it can show up in the field, quite some time
>> after the parts perform alright in initial testing.
>>
>> At Siemens Ultrasound, we learned this the hard way, then had it
>> confirmed by at least one vendor's examination of abused parts.
>>
>> --Larry Brasfield
>
> Of course this may have actually happened,
Yes, of course.
> and Boy, you had some pretty lousy assembly people.
They were quite skilled and competent, generally. If you knew
the circumstances under which the hand soldering occured, you
might not be so willing to denigrate them. (But who knows?)
> I've seen the pre-prod units used for test assembled and
> soldered by hand and subjected to extensive testing. Never saw a solder
> related failure of a component.
To see the excess noise phenomenon, you would have to be
looking at a circuit handling low level signals which would be
affected by random parametric shifts. To see the drop in
voltage withstand, you would have to be using parts at an
appreciable fraction of their rated voltage, or subject them
to conditions under which moisture would enter the cracks.
So the fact that you never saw that is not much reassurance.
> We tested for very long periods on many boards.
But what were you testing for? Did the environment
promote moisture ingression into the cracks? Was there
thermal cycling? I must say, your failure to see that
phenomenon is weak evidence against its reality.
> Of course we also inspected the boards before applying power and
> checking for damage. Rarely had to retouch a board after the first three.
The damage I mentioned is nearly impossible to see without
a microscope. Typically, the micro-cracks do not extend
clear thru the part, and they tend to be closed, being held
together by the unbroken material. I doubt your inspection
would have caught that damage.
The facts I have related regarding the failure mechansim,
and the strong disrecommendation against hand soldering
ceramic SMD capacitors, came to me directly from a well
known and reputable supplier of such parts. You, or other
"we got away with something, so it must be fine" kind of
folks can disregard it and often not pay the price. Those
who desire reliability will more likely heed it.
Terry Given
its the rate-of-change of temperature thats the real killer. Larger caps
are worse, as the resulting dimensional changes are bigger.
>
>
>>I've seen the pre-prod units used for test assembled and
>>soldered by hand and subjected to extensive testing. Never saw a solder
>>related failure of a component.
>
>
> To see the excess noise phenomenon, you would have to be
> looking at a circuit handling low level signals which would be
> affected by random parametric shifts. To see the drop in
> voltage withstand, you would have to be using parts at an
> appreciable fraction of their rated voltage, or subject them
> to conditions under which moisture would enter the cracks.
> So the fact that you never saw that is not much reassurance.
>
>
>>We tested for very long periods on many boards.
>
>
> But what were you testing for? Did the environment
> promote moisture ingression into the cracks? Was there
> thermal cycling? I must say, your failure to see that
> phenomenon is weak evidence against its reality.
>
ROTFLMAO!
>
>>Of course we also inspected the boards before applying power and
>>checking for damage. Rarely had to retouch a board after the first three.
>
>
> The damage I mentioned is nearly impossible to see without
> a microscope. Typically, the micro-cracks do not extend
> clear thru the part, and they tend to be closed, being held
> together by the unbroken material. I doubt your inspection
> would have caught that damage.
doesnt everyone have a binocular microscope? how quaint.
>
> The facts I have related regarding the failure mechansim,
> and the strong disrecommendation against hand soldering
> ceramic SMD capacitors, came to me directly from a well
> known and reputable supplier of such parts. You, or other
> "we got away with something, so it must be fine" kind of
> folks can disregard it and often not pay the price. Those
> who desire reliability will more likely heed it.
There are also mechanical resonance related with the larger ceramic smt
parts (Marcon have poublished several papers on this effect).
Recently I have hand-soldered about 2000 0603 caps (prototypes). Perhaps
2-3 caps failed immediately; as its a prorotype I dont care about
medium-long term reliability, but no way would I give it to a customer :)
Cheers
Terry
Clarence
"Terry Given" <my_...@ieee.org> wrote in message
news:QEord.20625$9A.3...@news.xtra.co.nz...
> > might not be so willing to denigrate them. (But who knows?)
>
> are worse, as the resulting dimensional changes are bigger.
> >
> >>I've seen the pre-prod units used for test assembled and
> >>soldered by hand and subjected to extensive testing. Never saw a solder
> >>related failure of a component.
> >
> > To see the excess noise phenomenon, you would have to be
> > looking at a circuit handling low level signals which would be
> > affected by random parametric shifts. To see the drop in
> > voltage withstand, you would have to be using parts at an
> > appreciable fraction of their rated voltage, or subject them
> > to conditions under which moisture would enter the cracks.
> > So the fact that you never saw that is not much reassurance.
> >
> >>We tested for very long periods on many boards.
> >
> > But what were you testing for? Did the environment
> > promote moisture ingression into the cracks? Was there
> > thermal cycling? I must say, your failure to see that
> > phenomenon is weak evidence against its reality.
> >
> ROTFLMAO!
Not much moisture in a near vacuum!
> >
> >>Of course we also inspected the boards before applying power and
> >>checking for damage. Rarely had to retouch a board after the first three.
> >
> > The damage I mentioned is nearly impossible to see without
> > a microscope. Typically, the micro-cracks do not extend
> > clear thru the part, and they tend to be closed, being held
> > together by the unbroken material. I doubt your inspection
> > would have caught that damage.
>
> doesn't everyone have a binocular microscope? how quaint.
>
> >
> > The facts I have related regarding the failure mechanism,
> > and the strong disrecommendation against hand soldering
> > ceramic SMD capacitors, came to me directly from a well
> > known and reputable supplier of such parts. You, or other
> > "we got away with something, so it must be fine" kind of
> > folks can disregard it and often not pay the price. Those
> > who desire reliability will more likely heed it.
I'll take the 'disrecommendation' with a box of salt!
> There are also mechanical resonance related with the larger ceramic SMT
> parts (Marcon have published several papers on this effect).
>
> Recently I have hand-soldered about 2000 0603 caps (prototypes). Perhaps
> 2-3 caps failed immediately; as its a prototype I don't care about
> medium-long term reliability, but no way would I give it to a customer :)
>
> Cheers
> Terry
I am delighted to hear you wouldn't give your work to a customer. Many
prototypes are unsuited for the customer to see anyway due to the rework and
handling in engineering test. I NEVER ship a 'prototype' to anyone. That is
what a "first Article" is for!
As for the work I cited! These were weather Satellite boards, RF, motor
control, CPU, and digital communications, plus low level analog video, with
analog to digital conversion. There will only be 18 final units built, and
testing (with temperature cycling from -40 to + 80 Degrees C four times a day
at 5 degrees C per minute) was eight times a day, total time of a complete test
was 2,000 hours. MTTF predicted is 18 years. Also they must survive 50,000
Kilorads exposure.
Yes, Inspection under a microscope, 20 and 50 diameters magnification. Before
and after tests. Yes All boards were also tested on a shake table, they must
survive launch.
The Customer is NASA, they are very particular, and will launch the first of
these in 2006.
Shooting one's mouth off when someone tries to help causes a loss of
credibility!
Since your really an amateur, live with your poor workmanship and cry about it!
Jim Adney
<steven.doesntn...@virgin.theISP.net (remove the obvious
bits)> wrote:
>I would have thought that when working with these components, you would have
>to use a different approach, and try to keep the component cool (as it'll
>fry otherwise), but this thread seems to suggest otherwise.
I was on the Vishay web site recently and came across a writeup they
have on hand soldering surface mount electrolytics. If you do any of
this I believe it's worth looking up. They are rather cautious and
suggest that if you spend more than 3 seconds on a junction that's too
long and you should start over with a new part.
Seems extreme to me, but they're the ones who are actually in a
position to know.
-
-----------------------------------------------
Jim Adney jad...@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------
Terry Given
Clarence wrote:
Hear Hear!
Reflow machines are best suited to soldering smt. If you have to do it
by hand, use hot air. A bloody great soldering is the worst way.
>
> As for the work I cited! These were weather Satellite boards, RF, motor
> control, CPU, and digital communications, plus low level analog video, with
> analog to digital conversion. There will only be 18 final units built, and
> testing (with temperature cycling from -40 to + 80 Degrees C four times a day
> at 5 degrees C per minute) was eight times a day, total time of a complete test
> was 2,000 hours. MTTF predicted is 18 years. Also they must survive 50,000
> Kilorads exposure.
ouch.
>
> Yes, Inspection under a microscope, 20 and 50 diameters magnification. Before
> and after tests. Yes All boards were also tested on a shake table, they must
> survive launch.
>
> The Customer is NASA, they are very particular, and will launch the first of
> these in 2006.
>
> Shooting one's mouth off when someone tries to help causes a loss of
> credibility!
> Since your really an amateur, live with your poor workmanship and cry about it!
What makes you think I'm an amateur? I just dont want to hire a tech
(labour laws become a real pain in the ass when you have staff).
Cheers
Terry
remove two items of clothing
Thanks for your response, guys - much appreciated.
I'll give this a go with the blutack (we had the same thing in Australia -
wonder what the UK equivalent is...) and desoldering braid.
I think I also need a smaller soldering iron tip - the last one was still
too big and bulky with a 1 or 2 mm point.
Cheers,
-Steve.
Clarence
> Hi Clarence,
> Clarence wrote:
> > "Terry Given" <my_...@ieee.org> wrote in message
> > news:QEord.20625$9A.3...@news.xtra.co.nz...
> >>Larry Brasfield wrote:
> >>>"Clarence" <n...@No.com> wrote in message
> >>> news:mTfrd.36936$6q2....@newssvr14.news.prodigy.com...
<snip>
> > I am delighted to hear you wouldn't give your work to a customer. Many
> > prototypes are unsuited for the customer to see anyway due to the rework
and
> > handling in engineering test. I NEVER ship a 'prototype' to anyone. That
is
> > what a "first Article" is for!
>
> Hear Hear!
>
> Reflow machines are best suited to soldering smt. If you have to do it
> by hand, use hot air. A bloody great soldering is the worst way.
Since that is what they were designed for, and that is what I use them for when
it is appropriate.
> > As for the work I cited! These were weather Satellite boards, RF, motor
> > control, CPU, and digital communications, plus low level analog video, with
> > analog to digital conversion. There will only be 18 final units built, and
> > testing (with temperature cycling from -40 to + 80 Degrees C four times a
day
> > at 5 degrees C per minute) was eight times a day, total time of a complete
test
> > was 2,000 hours. MTTF predicted is 18 years. Also they must survive 50
(Op's)
> > Kilorads exposure.
>
> ouch.
>
> > Yes, Inspection under a microscope, 20 and 50 diameters magnification.
Before
> > and after tests. Yes All boards were also tested on a shake table, they
must
> > survive launch.
> >
> > The Customer is NASA, they are very particular, and will launch the first
of
> > these in 2006.
By the way, all these boards MAY be hand soldered in the limited production.
There are components which can be reliably flow soldered, but these boards are
populated on both sides, and depending upon weight MAY not remain in place
going through the reflow process with an already soldered side down. Ordinary
FR4 will usually work this way, but the aluminum cored boards get too hot on
the bottom when the core conducts the heat through the board. (There is no
"convection cooling" in space. Only radiation and conduction.)
> > Shooting one's mouth off when someone tries to help causes a loss of
> > credibility!
> > Since your really an amateur, live with your poor workmanship and cry about
it!
>
> What makes you think I'm an amateur? I just don't want to hire a tech
> (labor laws become a real pain in the ass when you have staff).
> Cheers
> Terry
Your statements were a strong clue, then the lack of experience added fuel. I
would hope I was wrong! I only maintain five consultants (1099) on call, all
specialists! I do the initial design, and work along side of experienced
specialists for a quality result.
Sometimes I take my entire team into a customers facility, it helps to have
people with all those training certifications and credentials.
Thanks for the warning about Macon. I'll avoid them!
Paul Burke
> I'll give this a go with the blutack (we had the same thing in Australia -
> wonder what the UK equivalent is...)
Parkin
Howard Long
> wonder what the UK equivalent is...) and desoldering braid.
It's the tiniest piece of blutak - too much and the chip's leads don't rest
in contact with the PCB solder pads. This allows you to position the chip
accurately by sight over the solder pads. The blutak then remains there ad
infinitum (or until you have to rework the chip!).
In the US blutak's like this
http://www.staples.com/Catalog/Browse/sku.asp?PageType=1&Sku=334690&bcFlag=True&bcSCatId=1&bcSCatName=Office+Supplies&bcCatId=28&bcCatName=Tape%2C+Glue+%26+Adhesives&bcClassId=10000&bcClassName=Glue+%26+Adhesive+Products
> I think I also need a smaller soldering iron tip - the last one was still
> too big and bulky with a 1 or 2 mm point.
Here's the iron I use
http://www.maplin.co.uk/Module.aspx?ModuleNo=10271&TabID=1&source=15&WorldID=9&doy=2m12
I use the same sized tip that was supplied with the iron - it's pointy but
not miniscule.
Cheers, Howard
Watson A.Name - "Watt Sun, the Dark Remover"
"Howard Long" <how...@howardlongxxx.com> wrote in message
news:comr7t$441$1...@sparta.btinternet.com...
[snip]
> > I think I also need a smaller soldering iron tip - the last one was
still
> > too big and bulky with a 1 or 2 mm point.
>
> Here's the iron I use
>
http://www.maplin.co.uk/Module.aspx?ModuleNo=10271&TabID=1&source=15&Wor
ldID=9&doy=2m12
I read the text in that ad three times, and I still couldn't find
anything that said what the wattage was. Why would they leave out
someething so important?
Clarence
"Terry Given" wrote> > <snip>
> > Thanks for the warning about Macon. I'll avoid them!
>
> Actually its not Marcon per se, its just that the larger ceramic caps
> have mechanical resonance's that can be excited electrically. square-loop
> ferrite has the same problem - witness the warnings in the Ferroxcube
> databook.
>
> Cheers
> Terry
Like the 2.2mF to 100mF units I normally use?
Never seen any warnings. They are not piezoelectric.
Ian
"Watson A.Name - "Watt Sun, the Dark Remover"" <NOS...@dslextreme.com> wrote
in message news:10qu79b...@corp.supernews.com...
>
> "Howard Long" <how...@howardlongxxx.com> wrote in message
> news:comr7t$441$1...@sparta.btinternet.com...
> [snip]
>
> > > I think I also need a smaller soldering iron tip - the last one was
> still
> > > too big and bulky with a 1 or 2 mm point.
> >
> > Here's the iron I use
> >
> http://www.maplin.co.uk/Module.aspx?ModuleNo=10271&TabID=1&source=15&Wor
> ldID=9&doy=2m12
>
> I read the text in that ad three times, and I still couldn't find
> anything that said what the wattage was. Why would they leave out
> someething so important?
>
Regards
Ian
Larry Brasfield
> Electrical excitation to mechanical resonance is the DEFINITION of
> "piezoelectric."
No, that is not right at all. A material can be piezoelectric
even when configured such that no resonance can occur.
Mechanical resonance is an extensive property, applicable
to a specific object with particular boundaries. In contrast,
a material itself, (regardless of its shape), has piezoelectic
parameters defining an intensive property, applicable to
infinitessimal volumes.
Perhaps, if you are going to "correct" people and set out
to "educate" them, you should be careful that you are not
simply throwing out some vague notions that you have
inadvertantly collected.
Terry Given
Actually its not Marcon per se, its just that the larger ceramic caps
have mechanical resonances that can be excited electrically. square-loop
Clarence
C4532X7R2A225M By TDK 2.2uF 100V (since your into SI (stupid interference))
Up to and including C4532Y5V1A107Z 100uF 10V
And NOJC107M004RWJ 100uF 4V Y5V
These are all 1812 SMT parts.
>
> you use 0.1 farad ceramic caps? those I'd like to see. What's the
> dielectric? (or perhaps you use "mF" to mean micro-Farads - quaint but
> confusing, given the preponderance of SI units nowadays). I did once see
> a 100uF 200V (IIRC) NPO cap (mil smps). very very expensive - US$300 IIRC.
>
> AFAICR the piezoelectric behavior was not the issue - just electrically
> exciting them at their mechanical resonant frequencies.
Terry Given
you use 0.1 farad ceramic caps? those I'd like to see. Whats the
dielectric? (or perhaps you use "mF" to mean micro-Farads - quaint but
confusing, given the preponderance of SI units nowadays). I did once see
a 100uF 200V (IIRC) NPO cap (mil smps). very very expensive - US$300 IIRC.
AFAICR the piezoelectric behaviour was not the issue - just electrically
exciting them at their mechanical resonant frequencies.
Cheers
Terry
Terry Given
> On Thu, 02 Dec 2004 23:06:21 GMT, "Clarence" <n...@No.com> wrote:
>
>
>
>>Like the 2.2mF to 100mF units I normally use?
>
>
> ---
> Pretty large value for ceramics, eh?
> ---
>
>
>>Never seen any warnings. They are not piezoelectric.
>
>
> ---
> It's not necessary for a capacitor to be piezoelectric to exhibit a
> mechanical resonance or to be microphonic. All that's required is for
> the dielectric to be mechanically deformable by the forces exerted by
> the electric field across it or for the dielectric to be deformed by
> external mechanical forces.
>
And if the mechanical resonant frequency is the same as the electrical
excitation, significant (wrt the cap) forces can build up over time.
2220 and bigger were noted in the Marcon paper.
Cheers
Terry
Clarence
> "Clarence" <n...@No.com> wrote in message
news:JfQrd.27826$zx1....@newssvr13.news.prodigy.com...
> > Electrical excitation to mechanical resonance is the DEFINITION of
> > "piezoelectric."
>
> No, that is not right at all. A material can be piezoelectric
> even when configured such that no resonance can occur.
> Mechanical resonance is an extensive property, applicable
> to a specific object with particular boundaries. In contrast,
> parameters defining an intensive property, applicable to
>
> Perhaps, if you are going to "correct" people and set out
> to "educate" them, you should be careful that you are not
> simply throwing out some vague notions that you have
> --
> --Larry Brasfield
> email: larry_b...@hotmail.com
> Above views may belong only to me.
I am not sure I understand what your trying to say. It appears to be
speculation.
I was about to reply, then I read your disavowal. I see you are aware that you
are only vaguely familiar with the phenomena. A piezoelectric material which
has not been shaped, or which has no electrodes attached to excite the
piezoelectric properties is not affected in a predictable manner. So if a
material with those piezoelectric is applied in a product it "MAY" behave in a
way which creates stress. However AFAIK piezoelectric quartz, barium titanate,
or other piezoelectric materials are NOT routinely used in the production of
capacitors. It takes relatively high voltages to get much movement in
piezoelectric materials. Lose molecules would not have any effect at all since
it is the matrix of crystal formation which exhibits the property.
I designed equipment to solder leads on crystals and we measured the flexure in
tens of micro inches. Placing material in a position where movement was
inhibited, as in a potting compound, reduced movement to fractions of a micro
inches. Resonance would vanish with inhibiting pressure applied.
Unlike a ferrite, or crystal quartz, alumna used for SMT components do not
exhibit piezoelectric properties.
If your aware of any other piezoelectric materials please list them. I can
think of many applications for a low cost piezoelectric operated mechanical
device.
BTW: The soldering process should Twine the piezoelectric material if it was
present. Heat destroys the piezoelectric properties in the same manner as
magnets are demagnetized.
John Fields
>Like the 2.2mF to 100mF units I normally use?
---
Pretty large value for ceramics, eh?
---
>Never seen any warnings. They are not piezoelectric.
---
It's not necessary for a capacitor to be piezoelectric to exhibit a
mechanical resonance or to be microphonic. All that's required is for
the dielectric to be mechanically deformable by the forces exerted by
the electric field across it or for the dielectric to be deformed by
external mechanical forces.
--
John Fields
Leif Erickson
Check out http://protoboards.theshoppe.com/articles.html
for some soldering advice. There is a basic soldering and SMD article on
there, and SMD breadboards.
You should be able to put the chip on by hand. I do.
1.You need a good HANDS FREE magnifier, one of them geeky head set
flip-up magnifiers. OPTI-VISOR is one I use, and can get different
lenses for them and has a little monacle magnifier that you push over 1
eye to see even closer. A bench mounted, spring folding magnifier and
lamp combo can work, or a goose neck one with a heavy base. You got to
have both hands free to see, and work. Do not try them stupid little
tweezer/magnifier combo deals for $3-5, they are worthless. And you
usually are not lined up to see into it while soldering.
2. Get a low wattage iron, 10-20 Watts, or so. Don't need a lot of heat
for the chips. Ebay has Metcal MPX style soldering iron sets with a iron
and a stand. They are first or 2nd generation now, but still way better
than ANYTHING on the market for soldering. 5-10 second warm up times.
2nd generation power supply unit has 2 iron connectors! 1st gen. has
only 1 iron connector on it. They all use the same type of tips, and can
get IC size tips, 0603-1210 size tips, many other special ones. What you
need for IC's is a HOOF tip. Its an angled tip, with a depression in the
end, to hold some solder.
3. Tack solder the chip on 1 corner. Put TINY bit of solder on a corner
pad. Get chip in right PIN #1 Position FIRST. AFTER getting the chip in
place, REGISTER the corners and sides so ALL the pins line up. If some
are bent, use the tweezers you have to move them. OF COURSE YOU ARE
WEARING A WRIST STRAP ON AN ESD MAT!!!!!
Solder 1 corner, and make it quick, no more than 5-7 seconds on a pad.
RE-REGISTER THE OPPOSITE CORNER, and solder it down. CHECK ALL PINS
BEFORE COMMITTING YOURSELF!! Then use a lot of flux, preferably from a
flux pen, and coat the pads and pins good. Then with a WELL TINNED TIP,
put a small bit on the tip, put it on one side of the pins, and
LIGHTLY!! DRAG IT ACROSS PADS/PINS to the end. If not enough solder on
the side, do it again, AFTER fluxing a little more. Flux should keep the
shorts from happening, if you go fast enough, too slow and it may leave
a blob on 2-3 pins. Not to worry. Finish up all sides of chip.
4. FLUX again - Then go back with fine tip and try to drag the blob over
2-4 pins or so, to get rid of short(s). With FINE PITCH 0.8/0.5 mm QFPs
and such, just be a little more careful with pressure on pins. For the
0.5 mm you will need a good magnifier. You can also use the desoldering
braid, SODER-WICK, or some type of braid to pull solder shorts off pins.
5. You WILL need a good magnifier, a DECENT iron and different types of
tips, 1-2 different type of tweezers, and a flux pen for all SMD type
soldering. I have a bent fine point pair of tweezers, for the tiny stiff
and picking up QFP's by 1 pin! And a thicker, straight utility pair,
with square tips for bending the wires, or getting a better grip, and
general use, as its a heavy pair. Contact East, Techni-tool, or any
electronics catalog should have what you need. Some tools may cost, like
the tweezers, but they are for life, unless you drop the fine tip one on
the floor!
Hope this helps out.
Leif Erickson
Ken Smith
Clarence <n...@No.com> wrote:
[...]
>If your aware of any other piezoelectric materials please list them. I can
>think of many applications for a low cost piezoelectric operated mechanical
>device.
Both X7R and X5R are slightly piezoelectric. Neither is good enough to be
put to practical use as an actuator. If you put about 500mA at 2KHz
through a 2.2uF X7R cap mounted on a PCB you get just enough motion that
you can hear it.
Somewhere around here, I have a paper by Advanced Technical Ceramics which
talks about this subject. They had quite a nice collection of reference
material related to the use of ceramic capacitors in RF power
applications.
--
--
kens...@rahul.net forging knowledge
John Fields
>
>"Terry Given" <my_...@ieee.org> wrote in message
>news:ZZOrd.21704$9A.3...@news.xtra.co.nz...
>> AFAICR the piezoelectric behavior was not the issue - just electrically
>> exciting them at their mechanical resonant frequencies.
>
>Electrical excitation to mechanical resonance is the DEFINITION of
>"piezoelectric."
---
Frayed knot, Clarence.
Also wrong:
1. Your statement, in another post, that piezoelectric materials
aren't use in the manufacture of ceramic capacitors. Check it out
and you'll find that barium titanate is quite often used as a
dielectric.
2. From another post, you imply that "alumna" is used for the
dielectric in surface-mount caps. I don't believe that's true, and
I believe that what you're referring to is "alumina",
(aluminum oxide) the material which is used for the substrate of
surface mount _resistors_. Take a look at the dielectric constant
of alumina VS that of barium titanate for a clue.
You also seem to be laboring under the misapprehension that merely
shaping a material like barium titanate will imbue it with
piezoelectric characteristics. It will not; poling is a necessary
step in the process and, while it can occur spontaneously under
certain circumstances, it's usually forced.
All of this information is available by Googling for it and you do
yourself a great disservice by not availaing yourself of it before you
"Open mouth, insert foot".
--
John Fields
Clarence
"Ken Smith" <kens...@green.rahul.net> wrote in message
news:coq4c5$s69$3...@blue.rahul.net...
> In article <JDUrd.53480$QJ3....@newssvr21.news.prodigy.com>,
> Clarence <n...@No.com> wrote:
> [...]
> >If your aware of any other piezoelectric materials please list them. I can
> >think of many applications for a low cost piezoelectric operated mechanical
> >device.
>
> Both X7R and X5R are slightly piezoelectric. Neither is good enough to be
> put to practical use as an actuator. If you put about 500mA at 2KHz
> through a 2.2uF X7R cap mounted on a PCB you get just enough motion that
> you can hear it.
500mA is a rather substantial level of power for that value. It takes 39.3
Volts sinusoidal directly across the cap. I could find no part which is rated
to withstand that level of ripple current at these frequencies. All were rated
for .03 to .09 ohms ESR for frequencies over 100KHz.
> Somewhere around here, I have a paper by Advanced Technical Ceramics which
> talks about this subject. They had quite a nice collection of reference
> material related to the use of ceramic capacitors in RF power
> applications.
As little as a reliable motion of 0.002 for a 100V bias would be useful.
Assume a bar shape for maximum deflection.
So how much motion do you get at 100KHz? The entire unit is 0.180 long, 0.120
wide, and 0.080 high (max) with tolerances of +/- 0.010 Inches. The cap
element is coated with a resilient encapsulate.
The AC component is 30VRMS max and the DC is 80V.
I find nothing that confirms the property, nor the magnitude of the motion.
BTW, NASA, and FAA do not provide any warnings on these devices.
How about the X5V material?
John Fields
>
>"Ken Smith" <kens...@green.rahul.net> wrote in message
>news:coq4c5$s69$3...@blue.rahul.net...
>> In article <JDUrd.53480$QJ3....@newssvr21.news.prodigy.com>,
>> Clarence <n...@No.com> wrote:
>> [...]
>> >If your aware of any other piezoelectric materials please list them. I can
>> >think of many applications for a low cost piezoelectric operated mechanical
>> >device.
>>
>> Both X7R and X5R are slightly piezoelectric. Neither is good enough to be
>> put to practical use as an actuator. If you put about 500mA at 2KHz
>> through a 2.2uF X7R cap mounted on a PCB you get just enough motion that
>> you can hear it.
>
>500mA is a rather substantial level of power for that value.
---
mA is current. mW is power.
---
>It takes 39.3 Volts sinusoidal directly across the cap.
---
???
1 1
Xc = ------- = -------------------- ~ 36 ohms
2pifC 6.28*2000Hz*2.2E-6
E = I Xc = 0.5A * 36 ohms = 18VRMS ~ 50.9VPP
---
>I could find no part which is rated
>to withstand that level of ripple current at these frequencies. All were rated
>for .03 to .09 ohms ESR for frequencies over 100KHz.
---
What levels of ripple current were you able to find which these parts
could withstand at 2.2kHz?
---
>As little as a reliable motion of 0.002 for a 100V bias would be useful.
>Assume a bar shape for maximum deflection.
>
>So how much motion do you get at 100KHz? The entire unit is 0.180 long, 0.120
>wide, and 0.080 high (max) with tolerances of +/- 0.010 Inches. The cap
>element is coated with a resilient encapsulate.
>
>The AC component is 30VRMS max and the DC is 80V.
>I find nothing that confirms the property, nor the magnitude of the motion.
>BTW, NASA, and FAA do not provide any warnings on these devices.
---
If you search the literature, you may find that piezoelectric
actuators lie typically in the microinch of length change per inch of
material per volt of excitation. I think even Edmund might have some.
If not, Google "piezoelectric actuators" for a clue.
---
>
>How about the X5V material?
>
---
How _about_ the X5V material?
--
John Fields
Ken Smith
Clarence <n...@No.com> wrote:
>
>"Ken Smith" <kens...@green.rahul.net> wrote in message
>news:coq4c5$s69$3...@blue.rahul.net...
>> In article <JDUrd.53480$QJ3....@newssvr21.news.prodigy.com>,
>> Clarence <n...@No.com> wrote:
>> [...]
>> >If your aware of any other piezoelectric materials please list them. I can
>> >think of many applications for a low cost piezoelectric operated mechanical
>> >device.
>>
>> Both X7R and X5R are slightly piezoelectric. Neither is good enough to be
>> put to practical use as an actuator. If you put about 500mA at 2KHz
>> through a 2.2uF X7R cap mounted on a PCB you get just enough motion that
>> you can hear it.
>
>500mA is a rather substantial level of power for that value. It takes 39.3
>Volts sinusoidal directly across the cap.
I didn't suggest it was a good idea to put that much AC through the poor
thing. I just said that it screems if you do.
BTW: 1/( 2 * PI * F * C ) = 36.17 on my slide rule
0.5 * 36.17 = 18.08 Then we have to add a little for the ESR.
Also the ATC capacitors are rated for several Amps at 30MHz.
[...]
>As little as a reliable motion of 0.002 for a 100V bias would be useful.
>Assume a bar shape for maximum deflection.
A lot depends on what you call reliable. If you want cheap use a plastic
piezoelectric element. There are many makers of piezielectric ceramic
elements. If you are doing something like pushing a grating to tune a
laser, don't use the plastic stuff. It is a good thermometer.
>So how much motion do you get at 100KHz? The entire unit is 0.180 long, 0.120
>wide, and 0.080 high (max) with tolerances of +/- 0.010 Inches. The cap
>element is coated with a resilient encapsulate.
I've never been interested enough to measure it.
>The AC component is 30VRMS max and the DC is 80V.
>I find nothing that confirms the property, nor the magnitude of the motion.
Try google. I'll bet you will find something from AVX's web site that
confirms the effect and says words like "but our do it less".
>BTW, NASA, and FAA do not provide any warnings on these devices.
Im not surprised about the FAA.
NASA does surprise me a bit. They wouldn't allow PVC parts to be used in
the U2/ER2 because of the fume risk to the pilot. This even applies to
the parts that are at outdoors pressure.
>
>How about the X5V material?
>
I think all high K materials do it to some degree.
John Popelish
>
> In article <JDUrd.53480$QJ3....@newssvr21.news.prodigy.com>,
> Clarence <n...@No.com> wrote:
> [...]
> >If your aware of any other piezoelectric materials please list them. I can
> >think of many applications for a low cost piezoelectric operated mechanical
> >device.
>
> Both X7R and X5R are slightly piezoelectric. Neither is good enough to be
> put to practical use as an actuator. If you put about 500mA at 2KHz
> through a 2.2uF X7R cap mounted on a PCB you get just enough motion that
> you can hear it.
Agreed. I have a little pump and dump LED pulser that charges a 1 uf
100 VDC X7R 1210 smt capacitor. I gcharge it up to 50 volts over 900
us and dump it through the LEDs with a peak current of almost 1 amp in
100 us with the current peak controlled by a series inductance. I can
always tell when the circuit is working by the thin whine emitted.
Mylar caps in the same circuit made no noise.
--
John Popelish
John Fields
wrote:
>Agreed. I have a little pump and dump LED pulser that charges a 1 uf
>100 VDC X7R 1210 smt capacitor. I gcharge it up to 50 volts over 900
>us and dump it through the LEDs with a peak current of almost 1 amp in
>100 us with the current peak controlled by a series inductance. I can
>always tell when the circuit is working by the thin whine emitted.
>Mylar caps in the same circuit made no noise.
---
"Thin whine"?
If only more of us could write like you do maybe we'd have fewer
disagreements...
--
John Fields
John Popelish
Thanks?
--
John Popelish
Clarence
"John Popelish" <jpop...@rica.net> wrote
> John Fields wrote:
> > John Popelish wrote:
> > >I can
> > >always tell when the circuit is working by the thin whine emitted.
> > >Mylar caps in the same circuit made no noise.
> > ---
> > "Thin whine"?
> > > > If only more of us could write like you do maybe we'd have fewer
> > disagreements...
> Thanks?
Before it was stated that they would be cracked by the piezoelectric effect!
I buy caps by the roll, and they are installed by many different people, some
by flow soldering, some manually soldered by a convention Iron. Never heard a
peep, nor had a failure due to a crack from soldering. Thermal cycling has
causes a few failures, but only a few. Less than 0.1%!
Clarence
"Ken Smith" wrote
> Clarence wrote
> >> [...]
> >> >If your aware of any other piezoelectric materials please list them. I
can
> >> >think of many applications for a low cost piezoelectric operated
mechanical
> >> >device.
> >>
> >> Both X7R and X5R are slightly piezoelectric. Neither is good enough to be
> >> put to practical use as an actuator. If you put about 500mA at 2KHz
> >> through a 2.2uF X7R cap mounted on a PCB you get just enough motion that
> >> you can hear it.
> >
> >500mA is a rather substantial level of power for that value. It takes 39.3
> >Volts sinusoidal directly across the cap.
>
> I didn't suggest it was a good idea to put that much AC through the poor
>
> BTW: 1/( 2 * PI * F * C ) = 36.17 on my slide rule
Did you allow for ESR? I did!
> 0.5 * 36.17 = 18.08 Then we have to add a little for the ESR.
>
> Also the ATC capacitors are rated for several Amps at 30MHz.
Which is NOT 2Khz!
> [...]
> >As little as a reliable motion of 0.002 for a 100V bias would be useful.
> >Assume a bar shape for maximum deflection.
>
> A lot depends on what you call reliable. If you want cheap use a plastic
> piezoelectric element. There are many makers of piezoelectric ceramic
> elements. If you are doing something like pushing a grating to tune a
> laser, don't use the plastic stuff. It is a good thermometer.
I'm looking for a pump impeller an implanted medical application.
> >So how much motion do you get at 100KHz? The entire unit is 0.180 long,
0.120
> >wide, and 0.080 high (max) with tolerances of +/- 0.010 Inches. The cap
> >element is coated with a resilient encapsulate.
>
> I've never been interested enough to measure it.
I Goggled, and found no published studies which gave numbers. Only that the
motion was detected.
> >The AC component is 30VRMS max and the DC is 80V.
> >I find nothing that confirms the property, nor the magnitude of the motion.
I
> Try google. I'll bet you will find something from AVX's web site that
> confirms the effect and says words like "but our do it less".
>
> >BTW, NASA, and FAA do not provide any warnings on these devices.
>
> I'm not surprised about the FAA.
The FAA is very stringent about any condition which might cause a fair or spark
on a board. For instance "Gold caps" often used to maintain a RTD are not
acceptable since they fail (rarely) by out gassing with a flame.
> NASA does surprise me a bit. They wouldn't allow PVC parts to be used in
> the U2/ER2 because of the fume risk to the pilot. This even applies to
> the parts that are at outdoors pressure.
I used many of these in a satellite program.
> >How about the X5V material?
> I think all high K materials do it to some degree.
Very small Degree!
These got clipped from my last mail:
Per AVX:
Effects of Mechanical Stress – High "K" dielectric ceramic capacitors
exhibit 'some' 'low level' piezoelectric reactions under 'mechanical
stress.' As a general statement, the piezoelectric output is higher,
the higher the dielectric constant of the ceramic. 'It is desirable to
investigate this effect before using high "K" dielectrics as coupling
capacitors in extremely low level applications.'
Also found:
Piezoelectric Effect. One minor drawback for X7R dielectrics has been
their sceptibility to 'piezoelectric-induced stresses.' Although this
effect is 'marginal' and 'may be neglected for case sizes smaller than
the 2220,' for larger capacitors it can lead to catastrophic failures
caused by cracking. Modifying the dielectric composition to avoid any
piezoelectric effects within the range of operating frequencies may
skirt this problem.
Whereas the standard X7R material shows piezoelectric noise, this is
almost absent from the new ceramic. These measurements were made
under a 300-V bias at 90°C. Note this effect is not present in film
or aluminum-electrolytic capacitors. With this new development,
ceramics now offer a viable alternative to film and electrolytic
capacitors in the large case sizes.
Ken Smith
Clarence <n...@No.com> wrote:
>
>"Ken Smith" wrote
>> Clarence wrote
>> >"Ken Smith" <kens...@green.rahul.net> wrote in message
>> >> Clarence <n...@No.com> wrote:
>> >> [...]
>> >> >If your aware of any other piezoelectric materials please list them. I
>can
>> >> >think of many applications for a low cost piezoelectric operated
>mechanical
>> >> >device.
>> >>
>> >> Both X7R and X5R are slightly piezoelectric. Neither is good enough to be
>> >> put to practical use as an actuator. If you put about 500mA at 2KHz
>> >> through a 2.2uF X7R cap mounted on a PCB you get just enough motion that
>> >> you can hear it.
>> >
>> >500mA is a rather substantial level of power for that value. It takes 39.3
>> >Volts sinusoidal directly across the cap.
>>
>> I didn't suggest it was a good idea to put that much AC through the poor
>> thing. I just said that it screams if you do.
>>
>> BTW: 1/( 2 * PI * F * C ) = 36.17 on my slide rule
>
>Did you allow for ESR? I did!
So:
ESR = sqrt( (39.3/0.5)^2 - 36.17^2) = 69.78 Ohms
Holy smoking capacitors Batman were do you buy these caps so I can avoid
them!
>> 0.5 * 36.17 = 18.08 Then we have to add a little for the ESR.
>>
>> Also the ATC capacitors are rated for several Amps at 30MHz.
>
>Which is NOT 2Khz!
Yes I noticed. The spec. is based on the heating. It doesn't vary that
much with frequency.
>I'm looking for a pump impeller an implanted medical application.
You have bio compatibility issues then too don'y you? The plastic stuff
is based on Kynar and nickel plated IIRC. Does the Kynar cause trouble?
Will you keep it out of contact with the host? The Kynar causes larger
motion than the ceramic. The force it can produce is much less and the
losses are greater.
[...]
>> NASA does surprise me a bit. They wouldn't allow PVC parts to be used in
>> the U2/ER2 because of the fume risk to the pilot. This even applies to
>> the parts that are at outdoors pressure.
>
>
>I used many of these in a satellite program.
There are not many pilots on these satellites are there?
>These got clipped from my last mail:
>
>Per AVX:
>Effects of Mechanical Stress – High "K" dielectric ceramic capacitors
>exhibit 'some' 'low level' piezoelectric reactions under 'mechanical
>stress.' As a general statement, the piezoelectric output is higher,
>the higher the dielectric constant of the ceramic. 'It is desirable to
>investigate this effect before using high "K" dielectrics as coupling
>capacitors in extremely low level applications.'
AVX is trying to sell you these capacitors. The fact that the makers seem
so unwilling to put a number on it makes me suspect that they are trying
to downplay it. I know that the piezoelectric effect can be real trouble
in low signal level analog circuits. they make microphones out of the
coupling capacitors.
Clarence
> In article <Kw9sd.53752$QJ3....@newssvr21.news.prodigy.com>,
> Clarence <n...@No.com> wrote:
> >
> >"Ken Smith" wrote
> >> Clarence wrote
> >> >"Ken Smith" <kens...@green.rahul.net> wrote in message
> >> >> Clarence <n...@No.com> wrote:
> >>
> >> BTW: 1/( 2 * PI * F * C ) = 36.17 on my slide rule
> >
> >Did you allow for ESR? I did!
>
> So:
>
> ESR = sqrt( (39.3/0.5)^2 - 36.17^2) = 69.78 Ohms
>
> Holy smoking capacitors Batman were do you buy these caps so I can avoid
> them!
>
John Fields
wrote:
>John Fields wrote:
>>
>> On Fri, 03 Dec 2004 19:45:53 -0500, John Popelish <jpop...@rica.net>
>> wrote:
>> >I can
>> >always tell when the circuit is working by the thin whine emitted.
>> >Mylar caps in the same circuit made no noise.
>>
>> ---
>> "Thin whine"?
>>
>> If only more of us could write like you do maybe we'd have fewer
>> disagreements...
>
>Thanks?
---
You're welcome. :-)
--
John Fields
Terry Given
> "Terry Given" <my_...@ieee.org> wrote in message
> news:ZZOrd.21704$9A.3...@news.xtra.co.nz...
>
>>Clarence wrote:
>>
>>
>>>"Terry Given" wrote
>>>
>>>
>>>>Clarence wrote:
>>>>
>>>>
>>>>>"Terry Given" <my_...@ieee.org> wrote in message
>>>>><snip>
>>>
>>>
>>>>>Thanks for the warning about Macon. I'll avoid them!
>>>>
>>>>Actually its not Marcon per se, its just that the larger ceramic caps
>>>>have mechanical resonance's that can be excited electrically. square-loop
>>>>ferrite has the same problem - witness the warnings in the Ferroxcube
>>>>databook.
>>>>Cheers > >>Terry
>>>
>>>Like the 2.2mF to 100mF units I normally use?
>>>
>>>Never seen any warnings. They are not piezoelectric.
>
>
> C4532X7R2A225M By TDK 2.2uF 100V (since your into SI (stupid interference))
> Up to and including C4532Y5V1A107Z 100uF 10V
> And NOJC107M004RWJ 100uF 4V Y5V
>
> These are all 1812 SMT parts.
I'm curious about using Y5V - you have a 100uF 10V cap. TDK spec Y5V as
+22%/-85% over -30C - +85C range. Using the AVX data (TDK dont seem to
mention this) the voltage coefficient is -90% at 60% rated Vcc, -80% at
40% Vcc. Assuming Vcc = 4V = 40% of rated voltage, you therefore only
have 20uF of overall capacitance. You probably use a 10V cap at more
like 6-7V, so its more like 10uF. Add in the temperature effects, and
its looking more like 1.5uF.
X7R = +/- 15% over -55C - +125C. AVX give -10% at 100% rated voltage. A
22uF 10V X7R cap comes in a 1210 package from TDK, and will have MORE
CAPACITANCE than the 100uF part you are currently using. Unless of
course you are using it at very low voltage (< 20% rated), with
temperature between 0-45C. Given that this is a space application, I
doubt the temperature is that well controlled.
Mind you you might be using the cap as a DC bias/temperature/vibration
detector, in which case Y5V would be a very good choice.
>
>>you use 0.1 farad ceramic caps? those I'd like to see. What's the
>>dielectric? (or perhaps you use "mF" to mean micro-Farads - quaint but
>>confusing, given the preponderance of SI units nowadays). I did once see
>>a 100uF 200V (IIRC) NPO cap (mil smps). very very expensive - US$300 IIRC.
>>
>>AFAICR the piezoelectric behavior was not the issue - just electrically
>>exciting them at their mechanical resonant frequencies.
>
>
> Electrical excitation to mechanical resonance is the DEFINITION of
> "piezoelectric."
No its not. The IEEE standard dictionary of electrical and electronics
terms, 6th ed. defines piezoelectric effect as:
"Some materials become electrically polarized when they are mechanically
strained. The direction and magnitude of polarization depend upon the
nature and amount of the strain, and upon the direction of the strain.
In such materials the converse effect is observed, namely, that a strain
results from the application of an electric field."
Note the complete and utter lack of the word "resonance" or any of its
variants.
It also appears you are suggesting there are no forces whatsoever inside
a capacitor, other than those caused by the piezoelectric effect. That
would be a fairly neat trick if it were true, and would doubtless be a
major concern to the manufacturers of electrostatic loudspeakers, which
by now ought to have all stopped working in light of this revelation.
Cheers
Terry
Clarence
> > On Thu, 02 Dec 2004 23:06:21 GMT, "Clarence" <n...@No.com> wrote:
> >>Like the 2.2mF to 100mF units I normally use?
> > ---
> > Pretty large value for ceramics, eh?
> > ---
Actually,NO! But the higher values are generally too expensive.
> >>Never seen any warnings. They are not piezoelectric.
> > ---
> > It's not necessary for a capacitor to be piezoelectric to exhibit a
> > mechanical resonance or to be microphonic. All that's required is for
> > the dielectric to be mechanically deformable by the forces exerted by
> > the electric field across it or for the dielectric to be deformed by
> > external mechanical forces.
This has nothing to do with part damage due to a piezoelectric property. Many
types of Capacitors including AIR dielectric are subject to "PURELY MECHANICAL"
variation.
I used to use WOBULATORS to modulate a VFO for a particular type of FM. Driving
a split stator ball bearing variable capacitor with a motor to generate a wide
frequency variation at a controlled rate. So what has this kind of mechanical
change of capacity have to do with piezoelectric damage to a part?
> And if the mechanical resonant frequency is the same as the electrical
> excitation, significant (wrt the cap) forces can build up over time.
> 2220 and bigger were noted in the Marcon paper.
>
> Cheers
> Terry
Since I do not use the larger package size, I see no relevance.
Clarence
"Terry Given" <my_...@ieee.org> wrote
Rest assured that the components we used were applied properly and with the
approval of the design staff, and NASA, who along with myself, recommended this
approach to solve another problem.
<snip>
> >>
> >>AFAICR the piezoelectric behavior was not the issue - just electrically
> >>exciting them at their mechanical resonant frequencies.
This appears to be a change of subject from the effect being due to forces from
piezoelectric characteristics. I see nothing relevant to discussing this!
> > Electrical excitation to mechanical resonance is the DEFINITION of
> > "piezoelectric."
>
> No its not. The IEEE standard dictionary of electrical and electronics
> terms, 6th ed. defines piezoelectric effect as:
>
> "Some materials become electrically polarized when they are mechanically
> strained. The direction and magnitude of polarization depend upon the
> nature and amount of the strain, and upon the direction of the strain.
> In such materials the converse effect is observed, namely, that a strain
> results from the application of an electric field."
>
> Note the complete and utter lack of the word "resonance" or any of its
> variants.
I'll concede the IEEE is correct, I should have quoted precisely.
> It also appears you are suggesting there are no forces whatsoever inside
> a capacitor, other than those caused by the piezoelectric effect. That
> would be a fairly neat trick if it were true, and would doubtless be a
> major concern to the manufacturers of electrostatic loudspeakers, which
> by now ought to have all stopped working in light of this revelation.
Again, your attempting to change the subject, unless you are asserting that
electrostatic loudspeakers operate on and are damaged by piezoelectric forces.
I have not addressed such speakers, and INDEED have no interest in them.
I think this is no longer a matter of sharing different experiences, rather is
appears to be you trying unsuccessfully to prove you knowledge is greater and
more correct than someone else's. I don't care to play. I designed weapons
system components for use in Vietnam which are still working and in use. I
have nothing I care to prove to you. Your entitled to your opine. So am I!
Terry Given
I have yet to see an area where Y5V caps are actually worth using.
Absence of proof is not however proof of absence; I assume there are in
fact very good reasons why you chose Y5V, and was kind of hoping you
would share those reasons, so that I and others could learn from your
experience.
I am however constantly surprised by how few engineers seem to know
about the voltage characteristics of Y5V, or for that matter the
temperature characteristics - odd when you consider most manufacturers
supply that information (although TDK seems to want to hide the voltage
coefficient, Philips (or whatever they are now called), AVX and others
do not).
>
> <snip>
>
>>>>AFAICR the piezoelectric behavior was not the issue - just electrically
>>>>exciting them at their mechanical resonant frequencies.
>
>
> This appears to be a change of subject from the effect being due to forces from
> piezoelectric characteristics. I see nothing relevant to discussing this!
**YOU** brought up the piezoelectric effect, then incorrectly defined
it, and erroneously said X7R and Y5V are not piezoelectric.
>
>
>>>Electrical excitation to mechanical resonance is the DEFINITION of
>>>"piezoelectric."
>>
>>No its not. The IEEE standard dictionary of electrical and electronics
>>terms, 6th ed. defines piezoelectric effect as:
>>
>>"Some materials become electrically polarized when they are mechanically
>>strained. The direction and magnitude of polarization depend upon the
>>nature and amount of the strain, and upon the direction of the strain.
>>In such materials the converse effect is observed, namely, that a strain
>>results from the application of an electric field."
>>
>>Note the complete and utter lack of the word "resonance" or any of its
>>variants.
>
>
> I'll concede the IEEE is correct, I should have quoted precisely.
I'll concede I'm a pedant :)
(but the resonance was enough of a red herring to warrant correction)
>
>
>>It also appears you are suggesting there are no forces whatsoever inside
>>a capacitor, other than those caused by the piezoelectric effect. That
>>would be a fairly neat trick if it were true, and would doubtless be a
>>major concern to the manufacturers of electrostatic loudspeakers, which
>>by now ought to have all stopped working in light of this revelation.
>
>
> Again, your attempting to change the subject, unless you are asserting that
> electrostatic loudspeakers operate on and are damaged by piezoelectric forces.
I originally stated:
"AFAICR the piezoelectric behaviour was not the issue - just
electrically exciting them at their mechanical resonant frequencies."
I am merely asserting that forces act on capacitors, regardless of any
piezoelectric effect. I had a look, but cant dig up the Marcon paper; I
suspect that you are probably right about the piezoelectric effect being
the predominant issue though.
>
> I have not addressed such speakers, and INDEED have no interest in them.
Nor do I, except they provide a fairly graphic demonstration that forces
act on capacitors.
>
> I think this is no longer a matter of sharing different experiences, rather is
> appears to be you trying unsuccessfully to prove you knowledge is greater and
> more correct than someone else's. I don't care to play. I designed weapons
> system components for use in Vietnam which are still working and in use. I
> have nothing I care to prove to you. Your entitled to your opine. So am I!
Not at all. I greatly enjoy technical discussions, I often learn a lot
from them - for example I didnt really know much at all about
microphonics until following discussions here - in smps use the
piezoelectric effect of caps is pretty much negligible (unless, of
course, your large caps break due to exciting the mechanical resonance).
The OP is of course about soldering smt parts. The TDK app notes here:
http://www.component.tdk.com/ceramic.asp
are quite useful. "Common cracking modes" is particularly pertinent. TDK
state that the main causes of cracking are mechanical damage - impact
damage or pcb flexure. But they also talk about how uneven soldering
causes stress concentrations that exacerbate flexure related cracking
(probably a lot less of an issue on Aluminium cored boards than FR4).
They very briefly (one sentence) mention thermal stress, in-circuit
testers (impact I presume) and H2 absorption as possible failure modes.
Something I did not know about high-K caps was the ageing effect - the
"what is the capacitance of this capacitor" document talks about it.
Another thing due to the use of Barium Titanate. And the ageing is a
reversible process! See, lots of interesting things to learn.
I can share a funny story about pcb flexure - our production dept.
wanted to reduce the build time on a gatedriver pcb (6 per product) so
smt'd it, and panelised about 20 onto an A4 sized FR4 pcb. Rather than
routing the pcb and using breakouts as advised, they V-grooved it and
got the mechanical workshop to produce a guillotine-like device to cut
the individual PCBs out. As the guillotine sliced the PCB it bent
significantly, and all the caps and resistors disappeared off the PCBs,
leaving only their endcaps behind. The really sad part is that
production abandoned the product, rather than simply routing the
panelised PCB. ISTR the original PCB hand assembly cost about the same
as the parts themselves, and the smt pcb was almost half the price.
Adding in the extra money for routing would have added around 10% to the
cost of the smt pcb, so it was still a lot cheaper.
The same guys also built a Jig to insert a pcb into a press-fit plastic
enclosure, by pressing on the top of a 1206 resistor. We had a 100%
failure rate on the first couple of hundred PCBs, but the tech never
mentioned that every single resistor broke in half when he desoldered
them. The real funny bit was there was huge amounts of space, the mech
guys never looked but miraculously picked the one spot there was a
resistor - that Murphy fellow again....
Cheers
Terry
Boris Mohar
<donotspam_la...@hotmail.com> wrote:
>"Clarence" <n...@No.com> wrote in message
> news:mTfrd.36936$6q2....@newssvr14.news.prodigy.com...
>> "Larry Brasfield" <donotspam_la...@hotmail.com> wrote in message
>> news:nQcrd.395$O54....@news.uswest.net...
>>> "John Larkin" <jjla...@highSNIPlandTHIStechPLEASEnology.com>
>>> wrote in message news:a7lpq05v0jvt6vqbg...@4ax.com...
>>> > Surface-mount parts are designed to be soldered in a reflow oven,
>>> > where the entire loaded board gets heated above solder-melt
>>> > temperature for a minute or so. Most parts don't mind. I just solder
>>> > them by hand, and it pretty much always works.
>>>
>>> Hand soldering can be very hard on SMD ceramic capacitors.
>>> The high temperature gradiant created by applying heat suddenly
>>> at one end can fracture the ceramic. This can lead to excess noise
>>> or a tendency to break down at a lower than rated voltage as
>>> moisure gets into the crack(s). The insidious aspect of this kind
>>> of damage is that it can show up in the field, quite some time
>>> after the parts perform alright in initial testing.
>>>
>>> At Siemens Ultrasound, we learned this the hard way, then had it
>>> confirmed by at least one vendor's examination of abused parts.
>>>
>>> --Larry Brasfield
>>
>> Of course this may have actually happened,
>
>Yes, of course.
>
>> and Boy, you had some pretty lousy assembly people.
>
>They were quite skilled and competent, generally. If you knew
>the circumstances under which the hand soldering occured, you
>might not be so willing to denigrate them. (But who knows?)
>
>> I've seen the pre-prod units used for test assembled and
>> soldered by hand and subjected to extensive testing. Never saw a solder
>> related failure of a component.
>
>To see the excess noise phenomenon, you would have to be
>looking at a circuit handling low level signals which would be
>affected by random parametric shifts. To see the drop in
>voltage withstand, you would have to be using parts at an
>appreciable fraction of their rated voltage, or subject them
>to conditions under which moisture would enter the cracks.
>So the fact that you never saw that is not much reassurance.
>
>> We tested for very long periods on many boards.
>
>But what were you testing for? Did the environment
>promote moisture ingression into the cracks? Was there
>thermal cycling? I must say, your failure to see that
>phenomenon is weak evidence against its reality.
>
>> Of course we also inspected the boards before applying power and
>> checking for damage. Rarely had to retouch a board after the first three.
>
>The damage I mentioned is nearly impossible to see without
>a microscope. Typically, the micro-cracks do not extend
>clear thru the part, and they tend to be closed, being held
>together by the unbroken material. I doubt your inspection
>would have caught that damage.
>
>The facts I have related regarding the failure mechansim,
>and the strong disrecommendation against hand soldering
>ceramic SMD capacitors, came to me directly from a well
>known and reputable supplier of such parts. You, or other
>"we got away with something, so it must be fine" kind of
>folks can disregard it and often not pay the price. Those
>who desire reliability will more likely heed it.
Any particular brand of capacitors? Any particular dielectric? Over years
we hand assembled a number of prototypes and small production runs that used
plenty of ceramic capacitors. These included high voltage, tuned and timing
circuits where a partial value failure would show up. At up to 30 power
magnification there were no visible cracks. The dielectric materials varied
from NPO to Y5V. We use Metcal MX with 700˜ tips and organic flux. The
environment is geophysical instrumentation which can be pretty demanding.
We had two component failures directly attributable to hand soldering. One
was stacked film chip capacitor where there was a drastic drop in value due
to internal stack disconnects from the end termination. The other was a
resetable fuse where the end termination cracked. The fuse was still
operational.
Regards,
Boris Mohar
Got Knock? - see:
Viatrack Printed Circuit Designs http://www3.sympatico.ca/borism/
void _-void-_ in the obvious place
Regards,
Boris Mohar
Got Knock? - see:
Viatrack Printed Circuit Designs http://www3.sympatico.ca/borism/
Larry Brasfield
>>>> Hand soldering can be very hard on SMD ceramic capacitors.
>>>> The high temperature gradiant created by applying heat suddenly
>>>> at one end can fracture the ceramic. This can lead to excess noise
>>>> or a tendency to break down at a lower than rated voltage as
>>>> moisure gets into the crack(s). The insidious aspect of this kind
>>>> of damage is that it can show up in the field, quite some time
>>>> after the parts perform alright in initial testing.
>>>>
>>>> At Siemens Ultrasound, we learned this the hard way, then had it
>>>> confirmed by at least one vendor's examination of abused parts.
>>To see the excess noise phenomenon, you would have to be
>>looking at a circuit handling low level signals which would be
>>affected by random parametric shifts. To see the drop in
>>voltage withstand, you would have to be using parts at an
>>appreciable fraction of their rated voltage, or subject them
>>to conditions under which moisture would enter the cracks.
>>The damage I mentioned is nearly impossible to see without
>>a microscope. Typically, the micro-cracks do not extend
>>clear thru the part, and they tend to be closed, being held
>>together by the unbroken material.
>>The facts I have related regarding the failure mechansim,
>>and the strong disrecommendation against hand soldering
>>ceramic SMD capacitors, came to me directly from a well
>>known and reputable supplier of such parts.
>
> Any particular brand of capacitors?
I'm sorry that I cannot recall, precisely. It was one of the
Japanese producers. A representative of theirs gave a
presentation to (some of) our engineers (including myself)
where the effects of that abuse where shown in micro-
photographs. From my visual memory of it, I suspect
the magnification was well in excess of 30, and the cracks
were somewhat subtle in appearance because they were
closed and on the corners.
> Any particular dielectric?
I am sure it was NPO. I expect all the vendors are using
similar ceramics, at least with respect to the mechanical and
thermal properties that relate to thermally induced microcracking.
> Over years
> we hand assembled a number of prototypes and small production runs that used
> plenty of ceramic capacitors. These included high voltage, tuned and timing
> circuits where a partial value failure would show up. At up to 30 power
> magnification there were no visible cracks. The dielectric materials varied
> from NPO to Y5V. We use Metcal MX with 700~ tips and organic flux. The
> environment is geophysical instrumentation which can be pretty demanding.
We were doing Doppler processing where minute phase
or amplitude shifts would be interpreted as meaningful.
The cracked capacitors would create artifacts. These
were not much above the noise floor, so they would
have been 50 to 70 dB below the signal that had been
modulated by the parametric noise to make the artifact.
(This, too, is a demanding application.)
> We had two component failures directly attributable to hand soldering. One
> was stacked film chip capacitor where there was a drastic drop in value due
> to internal stack disconnects from the end termination. The other was a
> resetable fuse where the end termination cracked. The fuse was still
> operational.
We would see this failure maybe in 1 out of 5000 parts.
Perhaps the parts in your prototypes that had to be very
stable were lucky, or the person doing the soldering was
applying the iron to the pad, which is gentler thermally.
Even after seeing that effect, I hand solder SMD ceramic
capacitors for initial prototypes. But I take care (or have
care taken by the assembler) to not apply the iron to the
endcaps. And the finished article is not fielded. I cannot
consider them reliable because of potential cracking.
> Regards,
>
> Boris Mohar
--
--Larry Brasfield
email: donotspam_la...@hotmail.com
John Fields
>
>"Terry Given" <my_...@ieee.org> wrote in message
>> John Fields wrote:
>> > On Thu, 02 Dec 2004 23:06:21 GMT, "Clarence" <n...@No.com> wrote:
>
>> >>Like the 2.2mF to 100mF units I normally use?
>> > ---
>> > Pretty large value for ceramics, eh?
>> > ---
>Actually,NO! But the higher values are generally too expensive.
---
I would think so, especially that 100milliFarad unit you normally use?
---
>> >>Never seen any warnings. They are not piezoelectric.
---
The piezoelectric characteristics of the part are not normally
something which warrants a "warning", since operation within the
specified electrical and mechanical limits for the part will not cause
a failure because of the piezoelectric nature of the dielectric.
Rather it's an inherent characteristic of the device which must be
taken into account when using the part and its contribution "designed
out" if necessary.
---
>> > ---
>> > It's not necessary for a capacitor to be piezoelectric to exhibit a
>> > mechanical resonance or to be microphonic. All that's required is for
>> > the dielectric to be mechanically deformable by the forces exerted by
>> > the electric field across it or for the dielectric to be deformed by
>> > external mechanical forces.
>
>This has nothing to do with part damage due to a piezoelectric property.
---
????? I don't believe I said that it did.
---
> Many types of Capacitors including AIR dielectric are subject to
> "PURELY MECHANICAL" variation.
---
Yeah, I see you have a remarkable grasp of the obvious, but so what?
I mean, what point are you trying to make?
You've already demonstrated that you know nothing about the
manufacture of ceramic dielectric capacitors as evidenced by your
ignorance of the fact that barium titanate is a commonly used
dielectric, yet here you are throwing around platitudes as if they
were rare gems. In all fairness though, perhaps they are... to you.
---
>I used to use WOBULATORS to modulate a VFO for a particular type of FM. Driving
>a split stator ball bearing variable capacitor with a motor to generate a wide
>frequency variation at a controlled rate. So what has this kind of mechanical
>change of capacity have to do with piezoelectric damage to a part?
---
Absolutely nothing, so why are you even bringing it up?
---
>> And if the mechanical resonant frequency is the same as the electrical
>> excitation, significant (wrt the cap) forces can build up over time.
>> 2220 and bigger were noted in the Marcon paper.
>>
>> Cheers
>> Terry
>
>Since I do not use the larger package size, I see no relevance.
---
Duck, or bob and weave?
--
John Fields
Terry Given
Ditto. And I *NEVER* re-use ceramic smt parts. I just buy values 1,000
at a time. But me and my METCAL MX2 (and my binocular microscope) have
soldered many, many thousands of 0603 parts (when a prototype uses 1400
parts, and you re-build it 5 times, thats a lot of dead parts) over the
last month or so, and no parts have failed (yet). But of course it aint
going to a customer.
I mostly break 0603 parts by moving the tweezers after soldering one end
only; both Cs and Rs are susceptible to this, but its fairly obvious
when you do it. perhaps 1% break like this.
1206 quad pack resistors are a pain to solder, especially when I lay out
my pcb so closely the tweezers are obstructed :( Self inflicted, so no
sympathy I guess :)
>
>
>>Regards,
>>
>>Boris Mohar
Cheers
Terry
Clarence
> >>>>Clarence wrote:
> >>>>>"Terry Given" wrote
> >>>>>>Clarence wrote:
> >>>>>>>"Terry Given" <my_...@ieee.org> wrote in message
<snip>
> >
> >>>>AFAICR the piezoelectric behavior was not the issue - just electrically
> >>>>exciting them at their mechanical resonant frequencies.
> >
> > This appears to be a change of subject from the effect being due to forces
from
> > piezoelectric characteristics. I see nothing relevant to discussing this!
>
> **YOU** brought up the piezoelectric effect, then incorrectly defined
> it, and erroneously said X7R and Y5V are not piezoelectric.
No, I said they were not damaged by a piezoelectric effect while hand
soldering.
I only miss quoted the definition. So what?
As I said:
> > I'll concede the IEEE is correct, I should have quoted precisely.
<snip>
> Not at all. I greatly enjoy technical discussions,
You are also something of a pest. I got nothing from this except going over
very old ground which was not the topic.
Larry Brasfield
[huge snip]
> I have yet to see an area where Y5V caps are actually worth using. Absence of proof is not however proof of absence; I assume
> there are in fact very good reasons why you chose Y5V, and was kind of hoping you would share those reasons, so that I and others
> could learn from your experience.
>
> I am however constantly surprised by how few engineers seem to know about the voltage characteristics of Y5V, or for that matter
> the temperature characteristics - odd when you consider most manufacturers supply that information (although TDK seems to want to
> hide the voltage coefficient, Philips (or whatever they are now called), AVX and others do not).
I once had a knarly argument with a guy who thought I
was irresponsible for using a high K capacitor in a circuit
whose accuracy relied on charge balancing rather than
the particular capacitance or even its linearity. He had
adopted a rule resembling "Y5U's are crap". (I think he
may have eschewed them even for bypass applications.)
[snip]
> **YOU** brought up the piezoelectric effect, then incorrectly defined it, and erroneously said X7R and Y5V are not piezoelectric.
...
>>>No its not. The IEEE standard dictionary of electrical and electronics
>>>terms, 6th ed. defines piezoelectric effect as:
>>>
>>>"Some materials become electrically polarized when they are mechanically
>>>strained. The direction and magnitude of polarization depend upon the
>>>nature and amount of the strain, and upon the direction of the strain.
>>>In such materials the converse effect is observed, namely, that a strain
>>>results from the application of an electric field."
Methinks that common ceramic capacitors are not
actually piezoelectric. The forces that occur with
applied voltage are different in character from what
is defined as piezoelectric effect. Consider that the
dielectric of a charged capacitor is compressed
regardless of the polarity of the charge. This differs
from what happens with (properly poled) piezoelectric
ceramics, where one polarity compresses and the other
decompresses. For similar reasons, a capacitor with
no charge on it will not transduce mechanical strain
into an electrical output, while a piezoelectric device
will transduce without an ostensible external charge.
(The poling produces a situation similar to applied
charge, but it is not available at the terminals unless
the device temperature is elevated.) So, to sum up,
a material that *can be used* to obtain piezoelectric
effects (when poled) is not necessarily piezoelectric.
Commonly sold ceramic caps are not piezoelectric.
> Cheers
> Terry
Regards,
Terry Given
> "Terry Given" <my_...@ieee.org> wrote in message
> news:dfDsd.22266$9A.3...@news.xtra.co.nz...
>
>>Clarence wrote:
>>
>>>"Terry Given" <my_...@ieee.org> wrote
>>>
>>>>Clarence wrote:
>>>>
>>>>>"Terry Given" <Terry Gi...@ieee.org> wrote in message
>>>>>
>>>>>>Clarence wrote:
>>>>>>
>>>>>>>"Terry Given" wrote
>>>>>>>
>>>>>>>>Clarence wrote:
>>>>>>>>
>>>>>>>>>"Terry Given" <my_...@ieee.org> wrote in message
>
>
> <snip>
>
>>>>>>AFAICR the piezoelectric behavior was not the issue - just electrically
>>>>>>exciting them at their mechanical resonant frequencies.
>>>
>>>This appears to be a change of subject from the effect being due to forces
>
> from
>
>>>piezoelectric characteristics. I see nothing relevant to discussing this!
>>
>>**YOU** brought up the piezoelectric effect, then incorrectly defined
>>it, and erroneously said X7R and Y5V are not piezoelectric.
>
>
>
>
> No, I said they were not damaged by a piezoelectric effect while hand
> soldering.
No you didnt - read your own posts. The discussion was about reliability
of hand soldering smt caps. I pointed out that mechanical resonance
related issues can also arise with large smt caps (although I omitted
the word "issues"). You come back with:
"Like the 2.2mF to 100mF units I normally use?
Never seen any warnings. They are not piezoelectric."
when in fact you meant 2.2uF - 100uF that ARE piezoelectric. mF instead
of uF indicates vintage, the "not piezoelectric" indicates lack of
knowledge re. Barium Titanate, of which you later state:
"However AFAIK piezoelectric quartz, barium titanate,
or other piezoelectric materials are NOT routinely used in the
production of capacitors."
So I go to the TDK website, click on ceramic caps and what pops up - PDF
documents stating they are made from Barium Titanate. Have you even
looked at the manufacturers datasheets for the components you use?!
Your knowledge is clearly, demonstrably incorrect, as evinced by your
own statements.
Without any accompanying verbiage it is reasonable to assume you are
blaming the mechanical resonance problems on the piezoelectric behaviour
of the caps - so a couple of people point out that forces act on all
capacitors, and that X7R, Y5V, Z5U are piezoelectric.
>
> I only miss quoted the definition. So what?
by "miss quoted" (sic) you actually mean "got it completely, totally and
utterly wrong, whilst simultaneously missing the point entirely"
>
> As I said:
>
>>>I'll concede the IEEE is correct, I should have quoted precisely.
>
> <snip>
>
>>Not at all. I greatly enjoy technical discussions,
>
>
> You are also something of a pest. I got nothing from this except going over
> very old ground which was not the topic.
I presume the pesky parts relate to pointing out technical errors. Dont
be so hard on yourself - everyone makes mistakes.
I find it very interesting that you never seem to respond to technical
comments - for example why use Y5V caps. Although my X7R argument is
sufficiently persuasive (and demonstrably factual) that I am not
surprised you cannot refute it.
It would also appear that your grasp of written english is less than
profound. We could all take lessons from John Popelish - his
pump-and-dump LED pulser paragraph was a marvel of clarity and brevity,
and contains all of the pertinent technical data.
Cheers
Terry
Terry Given
Larry Brasfield wrote:
> "Terry Given" <my_...@ieee.org> wrote in message news:dfDsd.22266$9A.3...@news.xtra.co.nz...
> [huge snip]
>
>>I have yet to see an area where Y5V caps are actually worth using. Absence of proof is not however proof of absence; I assume
>>there are in fact very good reasons why you chose Y5V, and was kind of hoping you would share those reasons, so that I and others
>>could learn from your experience.
>>
>>I am however constantly surprised by how few engineers seem to know about the voltage characteristics of Y5V, or for that matter
>>the temperature characteristics - odd when you consider most manufacturers supply that information (although TDK seems to want to
>>hide the voltage coefficient, Philips (or whatever they are now called), AVX and others do not).
>
>
> I once had a knarly argument with a guy who thought I
> was irresponsible for using a high K capacitor in a circuit
> whose accuracy relied on charge balancing rather than
> the particular capacitance or even its linearity. He had
> adopted a rule resembling "Y5U's are crap". (I think he
> may have eschewed them even for bypass applications.)
To be honest I just avoid Z5U/Y5V (and in fact seek them out for
criticism/removal during design reviews), but in theory I would be quite
happy with using one in a charge-balancing circuit. In practice I would
be concerned about having them on the shelf, because some bright spark
in production is bound to use them in the wrong place (hey, lets put
them in this active filter...).
And when it comes to bypass applications, I still havent seen a valid
reason for using them - by the time you work out what the actual
capacitance is under DC bias and operating temperature range, its so low
that you can invariably get an X7R cap for the same price that has about
the same (if not much more) overall capacitance, and its usually the DC
bias that is the strongest factor - who runs caps at 10% of rated
voltage? thats just wasteful.
But, if you have a good reason, I'd love to hear it.
Something to think about. Thanks.
Cheers
Terry
Ken Smith
Larry Brasfield <donotspam_la...@hotmail.com> wrote:
[...]
>Methinks that common ceramic capacitors are not
>actually piezoelectric.
I think, you think wrongly here. Ceramic capacitors with high K materials
are often enough piezoelectric to make them a bad idea for small signal
work. They make a voltage if you thump on them. This makes your circuit
into a bad microphone.
Terry Given
This is where it gets interesting. Testing the microphonics is
relatively straightforward, but would need to be done for a variety of
DC bias conditions and temperatures, and of course differing dielectrics.
How to test the forces generated though...and the mechanical resonant
frequency (that might be easier by calculation given the fairly simple
geometry) of the device under consideration. What about some form of
model using relatively easily measured data to predict the mechanical
effects?
Cheers
Terry
Ken Smith
Terry Given <my_...@ieee.org> wrote:
>Ken Smith wrote:
>> In article <toMsd.18$li7....@news.uswest.net>,
>> Larry Brasfield <donotspam_la...@hotmail.com> wrote:
>> [...]
>>
>>>Methinks that common ceramic capacitors are not
>>>actually piezoelectric.
>>
>>
>> I think, you think wrongly here. Ceramic capacitors with high K materials
>> are often enough piezoelectric to make them a bad idea for small signal
>> work. They make a voltage if you thump on them. This makes your circuit
>> into a bad microphone.
>
>This is where it gets interesting.
.. or boring depending on your point of view. Or this may even a way to
start another flame war on the subject.
> Testing the microphonics is
>relatively straightforward, but would need to be done for a variety of
>DC bias conditions and temperatures, and of course differing dielectrics.
It is easier to put in NPO capacitors or design the need for capacitors
out than it is to ensure that the high K ones are not microphonic. The
high K capacitors I had trouble with had no bias voltage on them and were
microphonic at room temperature. I could get a few tens of microvolts
signal from them by dragging my fingernail over the PCB near them.
Even if we tested 100 capacitors of a certain type, we could not really be
sure. What would happen if the next batch were made during a thunderstorm
or just after the crew ate lunch?
>How to test the forces generated though...and the mechanical resonant
>frequency (that might be easier by calculation given the fairly simple
>geometry) of the device under consideration. What about some form of
>model using relatively easily measured data to predict the mechanical
>effects?
I think the problem will be the loading of the capacitor. Ceramics have a
high "Q" mechanically. It is likely that the PCB loads the mechanical
vibration enough to be the controlling factor in the amplitude of the
stress.
An interesting thought: Tin-lead solder is very lossy mechanically. This
no no-lead stuff may not be as lossy. The no-lead folks may have created
another problem.
Larry Brasfield
If you define "piezoelectric" loosely enough, then your "bad
microphone" is relying on piezoelectric effect. By such a
loose definition, even vacuum is piezoelectric. But by the
more discriminating definition Terry quoted, and according
to the usage among people who exploit the piezoelectric
effect, ordinary interactions among separated charges, such
as occur in a charged capacitor when thumped, should not
be deemed "piezoelectric".
What do you think happens when you thump a capacitor
that is not biased? If it was piezoelectric, (and read Terry's
quoted definition carefully), it would produce an electrical
signal. But it does not.
I do not deny that there are electric/mechanical interactions
in capacitors, or that high K capacitors can be misused.
But nothing you have said goes to show that I am wrong.
> kens...@rahul.net forging knowledge
Terry Given
> In article <96Osd.22640$9A.3...@news.xtra.co.nz>,
> Terry Given <my_...@ieee.org> wrote:
>
>>Ken Smith wrote:
>>
>>>In article <toMsd.18$li7....@news.uswest.net>,
>>>Larry Brasfield <donotspam_la...@hotmail.com> wrote:
>>>[...]
>>>
>>>
>>>>Methinks that common ceramic capacitors are not
>>>>actually piezoelectric.
>>>
>>>
>>>I think, you think wrongly here. Ceramic capacitors with high K materials
>>>are often enough piezoelectric to make them a bad idea for small signal
>>>work. They make a voltage if you thump on them. This makes your circuit
>>>into a bad microphone.
>>
>>This is where it gets interesting.
>
>
> .. or boring depending on your point of view. Or this may even a way to
> start another flame war on the subject.
>
>
>>Testing the microphonics is
>>relatively straightforward, but would need to be done for a variety of
>>DC bias conditions and temperatures, and of course differing dielectrics.
>
>
> It is easier to put in NPO capacitors or design the need for capacitors
> out than it is to ensure that the high K ones are not microphonic.
Absolutely. Although for most of the stuff I do its the tempco and DC
bias that cause the biggest problems. I use a fair bit of X7R, but avoid
Z5U/Y5V, and recently re-worked an actve filter design to drop an X7R
cap down to an NPO.
> The
> high K capacitors I had trouble with had no bias voltage on them and were
> microphonic at room temperature. I could get a few tens of microvolts
> signal from them by dragging my fingernail over the PCB near them.
It probably depends on the rate of change of force, too. Thanks for the
data though - sounds like (sorry, couldnt resist) mV signals ought to be
quite feasible..
>
> Even if we tested 100 capacitors of a certain type, we could not really be
> sure. What would happen if the next batch were made during a thunderstorm
> or just after the crew ate lunch?
>
>
>>How to test the forces generated though...and the mechanical resonant
>>frequency (that might be easier by calculation given the fairly simple
>>geometry) of the device under consideration. What about some form of
>>model using relatively easily measured data to predict the mechanical
>>effects?
>
>
> I think the problem will be the loading of the capacitor. Ceramics have a
> high "Q" mechanically. It is likely that the PCB loads the mechanical
> vibration enough to be the controlling factor in the amplitude of the
> stress.
yes. I am constantly impressed at how damn hard mechanical engineering
really is (if you do it properly). Electronics is often easy by
comparison, and usually devolves into mechanics anyway (thermal etc).
>
> An interesting thought: Tin-lead solder is very lossy mechanically. This
> no no-lead stuff may not be as lossy. The no-lead folks may have created
> another problem.
doh. This sort of metallurgy is way beyond me - but I guess it boils
down to the malleability of the resultant alloy?
Cheers
Terry
Terry Given
> "Ken Smith" <kens...@green.rahul.net> wrote in message news:cp0a8c$qke$1...@blue.rahul.net...
>
>>In article <toMsd.18$li7....@news.uswest.net>,
>>Larry Brasfield <donotspam_la...@hotmail.com> wrote:
>>[...]
>>
>>>Methinks that common ceramic capacitors are not
>>>actually piezoelectric.
>>
>>I think, you think wrongly here. Ceramic capacitors with high K materials
>>are often enough piezoelectric to make them a bad idea for small signal
>>work. They make a voltage if you thump on them. This makes your circuit
>>into a bad microphone.
>
>
> If you define "piezoelectric" loosely enough, then your "bad
> microphone" is relying on piezoelectric effect. By such a
> loose definition, even vacuum is piezoelectric. But by the
> more discriminating definition Terry quoted, and according
> to the usage among people who exploit the piezoelectric
> effect, ordinary interactions among separated charges, such
> as occur in a charged capacitor when thumped, should not
> be deemed "piezoelectric".
>
> What do you think happens when you thump a capacitor
> that is not biased? If it was piezoelectric, (and read Terry's
> quoted definition carefully), it would produce an electrical
> signal. But it does not.
I'm gonna get a steak and cheese pie, then whack up a little test
circuit - inverting amp, cap from -ve i/p to 0V, 100k feedback and bias
comp resistors, +/-5V supplies, and do a few tests. I have some nice
10uF X7R caps, and some 1nF NPOs. I think I have a few Y5Vs too...
anything wrong with this setup? other than the fact I amp applying a
VERY small bias to the cap, around the offset voltage of the opamp - in
this case about 4mV. How can I reduce this further?
And the corollary here is of course thumping a biased cap WILL produce a
signal, as the pressure wave propagates through the cap there will be
deflection of the plates, therefore VdC/dt current must flow. Stiffer
caps have smaller dC/dt, so generate smaller signals - eg film or npo
caps versus air caps (eg trimmers) or electrolytics (there are probably
other things going on inside electrolytics, but I imagine the pressure
wave will actually move the electrolyte much, much more than the atoms
of say NPO will move when thumped).
>
> I do not deny that there are electric/mechanical interactions
> in capacitors, or that high K capacitors can be misused.
> But nothing you have said goes to show that I am wrong.
>
>
>>kens...@rahul.net forging knowledge
>
>
Cheers
Terry
Ken Smith
[...]
>
>
>> The
>> high K capacitors I had trouble with had no bias voltage on them and were
>> microphonic at room temperature. I could get a few tens of microvolts
>> signal from them by dragging my fingernail over the PCB near them.
>
>It probably depends on the rate of change of force, too. Thanks for the
>data though - sounds like (sorry, couldnt resist) mV signals ought to be
>quite feasible..
It depends on the operating environment. Does your product have to detect
mV signals while being dragged down a dirt road, from the back of a pick
up truck? If not, your life may be easy.
[...]
>> I think the problem will be the loading of the capacitor. Ceramics have a
>> high "Q" mechanically. It is likely that the PCB loads the mechanical
>> vibration enough to be the controlling factor in the amplitude of the
>> stress.
>
>yes. I am constantly impressed at how damn hard mechanical engineering
>really is (if you do it properly). Electronics is often easy by
>comparison, and usually devolves into mechanics anyway (thermal etc).
I have met at least 5 people who's busines card said "mechanical
engineer". As far as I can remember, I have actually only met one
mechanical engineer and that is not what his business card reads. The
others were mechanical dunder-heads. I've very often ended up doing my
own mechanical design. It is not the fastest way to get the job done.
Ken Smith
Larry Brasfield <donotspam_la...@hotmail.com> wrote:
>"Ken Smith" <kens...@green.rahul.net> wrote in message
>news:cp0a8c$qke$1...@blue.rahul.net...
>> In article <toMsd.18$li7....@news.uswest.net>,
>> Larry Brasfield <donotspam_la...@hotmail.com> wrote:
>> [...]
>>>Methinks that common ceramic capacitors are not
>>>actually piezoelectric.
>>
>> I think, you think wrongly here. Ceramic capacitors with high K materials
>> are often enough piezoelectric to make them a bad idea for small signal
>> work. They make a voltage if you thump on them. This makes your circuit
>> into a bad microphone.
>
>If you define "piezoelectric" loosely enough, then your "bad
>microphone" is relying on piezoelectric effect. By such a
>loose definition, even vacuum is piezoelectric.
True but I was not defining it loosely as indicated below.
[...]
>What do you think happens when you thump a capacitor
>that is not biased?
As stated elsewhere, I got tens of uV of signal from a non-biased
capacitor by dragging my fingernail along the PCB material near it.
>But nothing you have said goes to show that I am wrong.
How about now?
Ken Smith
Terry Given <my_...@ieee.org> wrote:
[....]
>I'm gonna get a steak and cheese pie, then whack up a little test
>circuit - inverting amp, cap from -ve i/p to 0V, 100k feedback and bias
>comp resistors, +/-5V supplies, and do a few tests. I have some nice
>10uF X7R caps, and some 1nF NPOs. I think I have a few Y5Vs too...
>
>anything wrong with this setup? other than the fact I amp applying a
>VERY small bias to the cap, around the offset voltage of the opamp - in
>this case about 4mV. How can I reduce this further?
2SK170
30mH 0.1u !--- ect
--------+----------- -------->!
( ! )( !--- ect
( --- )(
( --- )(
( ! )(
--------+----!!----- ----------- ect
C2 SP-4
Triad
1K:200K
The 30mH has a SRF above 10KHz, is air cored, and has a resistance of
about 13 ohms. It is made from 2 15mH coils pointing in opposite and
matched so that their distance source pickup is under 1 turn on a 3
sqr-inch area worth. The coil is then placed in a 3 layer shield can.
Terry Given
I think the problem with mechanics is that it initially is more
accessible than electronics. By that I mean it is easy to get a handle
on say torque - lean on a bar, whereas getting a handle on an electron
is a bit trickier - you cant see it, feel it etc. most of the
electronics people I meet have a fair understanding of second order
systems, stuff like that. but few so-called mechanical engineers do. I
have been fortunate enough to work with some brilliant mechanical
engineers, people who are every bit as clever and creative as the
smartest electronics guys I know (some guys I very briefly worked with
at Penn State were incredible), but most seem a bit thick. Hell, try
getting a sheet metal shop to fold up a box accurately.
Then when you really get into it, mechanics is a lot more complex than
(most) electronics - nothing is isotropic, or homogeneous, or perhaps
even well characterised. Everything is as non-linear as all hell, and
the measurements are a lot harder. I suspect all the clever mech
engineers go work on the really tricky stuff, and leave the rest of the
work to the metal-shop dropouts.
Cheers
Terry
Ken Smith
>accessible than electronics.
Yes I agree. People should be able to get a feel for the basic lever
problem just from living in the universe. You don't see electrons in the
play yard much.
[...]
>at Penn State were incredible), but most seem a bit thick. Hell, try
>getting a sheet metal shop to fold up a box accurately.
Or put the PEMs in the right way.
>Then when you really get into it, mechanics is a lot more complex than
>(most) electronics - nothing is isotropic, or homogeneous, or perhaps
>even well characterised. Everything is as non-linear as all hell, and
>the measurements are a lot harder.
And the units of measure are all weird. "Shore D" indeed.
I think I'll use a 3/8th cable over a 10 CM pully.