SMD capacitors

[Ralph Mowery]

I started working with the SMD parts a year or so ago. I decided to
stock up on some from ebay where you get strips of 10 each of about 50
valuse for a couple of bucks.

In this assortment were some 2.2 and 10 uF capacitors. For the most
part capacitors I am used to working with valuse round 1 uF and up are
usually polarity sensitive. Are the the large values non polar like the
smaler values ?

I have not had time to look at them under my microscope to see if they
look different.

[gghe...@gmail.com]

I'm not sure I understand your question. Whether a cap is polarized or not
depends on the type cap. Tant's and Al are polarized (in general) and ceramics aren't.

George H.

[N_Cook]

If they are MLCC, the capacity can be quite high maybe even 10uF these
days, but very low V and a susceptibility to metal migration it PbF
soldering temp requirement fracture the ceramic at laying

[Ralph Mowery]

In article <oo1tsf$emk$1...@dont-email.me>, div...@tcp.co.uk says...

>
>
>
> If they are MLCC, the capacity can be quite high maybe even 10uF these
> days, but very low V and a susceptibility to metal migration it PbF
> soldering temp requirement fracture the ceramic at laying

I have read about the need to slowly heat the capacitors to keep them
from fracturing. I doubt I will use any of the lead free solder, being
in the US and this is just a hobby for me. I have a spool of some .25
and .15 solder that is 63/37 so should be good for life with that.

The listing does not say what kind of capacitors they are, just the size
and SMD capacitors.

The 2.2 uF is rated for 25 V and the 10 uF is rated for 10 V,, most of
the others are for 25 or 50 V which is more than most circuits I will be
dealing with.

They probably come out of China and may not be very good quality, but
for the price and my hobby usage I thought it may be a way to have a
stock on hand. I try to keep many small parts on hand if they are not
too expensive. Never can tell when I may want one and don't want to
wait on the mail from Digikey or Mouser, evenif it is only a few days.
Wouldn't surprise me if many of the electronic items don't come from
over seas. Some very good,, some not so good.

I remeber around 1970 while in school we took a tour of a TV studio and
they were telling us how the Japan cameras were better than any other at
that time.
That was still back when many people thought anything comming out of
Japan was no good. Maybe some of the China items will be the same way.

[Ralph Mowery]

In article <0819aeb5-c464-4d0c...@googlegroups.com>,
gghe...@gmail.com says...

>
>
>
> I'm not sure I understand your question. Whether a cap is polarized or not
> depends on the type cap. Tant's and Al are polarized (in general) and ceramics aren't.
>

That may be the key. The listing did not say what kind of capacitors
they are, just SMD and the value and voltage rating. Whatever they are,
they are probably the same material, so the larger ones won't be
ploarized either. I did notice the voltage on them is only 10 volts
instead of 25 and 50 like the others.

[tabb...@gmail.com]

Last I looked the planet's number 1 supercomputer is or was Chinese. Tianhe-2 iirc.


NT

[Look165]

X7E caps are not recommended.

Ralph Mowery a écrit :

[Ian Field]

"Ralph Mowery" <rmower...@earthlink.net> wrote in message
news:MPG.340e4bcbb...@news.east.earthlink.net...

The lower voltage ratings are probably tantalum, polarity is *VERY*
important.

Don't be fooled by large capacitance values - I've seen a brochure for MLCC
capacitors up to 180uF.

SMD tantalum caps are usually encapsulated (after a fashion) and usually
have markings.

SMD ceramics are rarely encapsulated and rarely have any markings. Sometimes
I've encountered MELF round glass encapsulated MLCC caps on high end
equipment.

[Ralph Mowery]

In article <kXkpB.728842$YV4.5...@fx18.am4>, gangprobing.alien1
@virginmedia.com says...

>
>
> The lower voltage ratings are probably tantalum, polarity is *VERY*
> important.
>
> Don't be fooled by large capacitance values - I've seen a brochure for MLCC
> capacitors up to 180uF.
>
> SMD tantalum caps are usually encapsulated (after a fashion) and usually
> have markings.
>
> SMD ceramics are rarely encapsulated and rarely have any markings. Sometimes
> I've encountered MELF round glass encapsulated MLCC caps on high end
> equipment.

Yes, the polarity is very important if the capacitor has one. I have
not installed any of thse backwards to see what happens as of yet. I
have seen the old aluminum and tantalum one blow over the years.

I am not used to seeing capacitors ( other than large AC and speaker
crossover) much over 1 uF.

I can see why they don't mark most of the SMD, just no room but with
micro printing there may be a way but it would cost. Even buying them
from Digikey and Mouser they are very inexpensive compaired to the old
point to point components.

As mentioned, been working with components for over 50 years,but just
started with the SMD in the last year. Could not justify the items it
took to do that for just a hobby. Now they have came down a lot. Like
the China hot air rework station for about $ 60 and a $ 200 microscope.
The hot air station is probably no where near good enough for regular
shop work,but good enough for hobby,and if it breaks, the replacement is
not that much.

I am learning a lot about the capacitors with the help here.

[tabb...@gmail.com]

I've seen SMDs where one end is a bit pointed to indicate polarity.

If there's really nothing to indicate polarity it's most likely nonpolar. Hook one up & see, not that hard.


NT

[rickman]

Ralph Mowery wrote on 8/29/2017 5:55 PM:
> In article <kXkpB.728842$YV4.5...@fx18.am4>, gangprobing.alien1
> @virginmedia.com says...
>>
>>
>> The lower voltage ratings are probably tantalum, polarity is *VERY*
>> important.
>>
>> Don't be fooled by large capacitance values - I've seen a brochure for MLCC
>> capacitors up to 180uF.
>>
>> SMD tantalum caps are usually encapsulated (after a fashion) and usually
>> have markings.
>>
>> SMD ceramics are rarely encapsulated and rarely have any markings. Sometimes
>> I've encountered MELF round glass encapsulated MLCC caps on high end
>> equipment.
>
> Yes, the polarity is very important if the capacitor has one. I have
> not installed any of thse backwards to see what happens as of yet. I
> have seen the old aluminum and tantalum one blow over the years.

I think you just answered your question. If the caps have polarity markings
they are polarized. If they don't have polarity markings, how do you know
you have any installed correctly?

> I am not used to seeing capacitors ( other than large AC and speaker
> crossover) much over 1 uF.

MLCCs (which are ceramic) can be found above 1 uF. I often use them at 10
uF and I know they are available at higher values. The product of
capacitance and voltage determines the size, so in a given size the voltage
will drop as the capacitance approaches the max value. There are also
different material ceramic caps with widely different tolerances and
voltage/temperature responses. X5R is a good general purpose type of
ceramic cap.

> I can see why they don't mark most of the SMD, just no room but with
> micro printing there may be a way but it would cost. Even buying them
> from Digikey and Mouser they are very inexpensive compaired to the old
> point to point components.
>
> As mentioned, been working with components for over 50 years,but just
> started with the SMD in the last year. Could not justify the items it
> took to do that for just a hobby. Now they have came down a lot. Like
> the China hot air rework station for about $ 60 and a $ 200 microscope.
> The hot air station is probably no where near good enough for regular
> shop work,but good enough for hobby,and if it breaks, the replacement is
> not that much.
>
> I am learning a lot about the capacitors with the help here.

While the idea of a cap is pretty simple, the realities can get pretty
complex.

--

Rick C

Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998

[Ralph Mowery]

In article <oo85si$sgh$1...@dont-email.me>, gnu...@gmail.com says...

>
>
> I think you just answered your question. If the caps have polarity markings
> they are polarized. If they don't have polarity markings, how do you know
> you have any installed correctly?
>
>

Someone sent a pix with several kinds of the SMD capacitors. A couple
of them had a pointed tit on one end. I did not know that,so would have
missed that as a polariaty mark. If I had just looked at the capacitor,
I probably would have dismissed it as just a blob of material instead of
a polarity mark.

Sometimes it helps to know all the small details of the components. I
don't know, but guess that some could not have any marking and it could
depend on how they are placed in the reel they come in.

[rickman]

Ralph Mowery wrote on 8/31/2017 10:27 AM:
> In article <oo85si$sgh$1...@dont-email.me>, gnu...@gmail.com says...
>>
>>
>> I think you just answered your question. If the caps have polarity markings
>> they are polarized. If they don't have polarity markings, how do you know
>> you have any installed correctly?
>>
>>
> Someone sent a pix with several kinds of the SMD capacitors. A couple
> of them had a pointed tit on one end. I did not know that,so would have
> missed that as a polariaty mark. If I had just looked at the capacitor,
> I probably would have dismissed it as just a blob of material instead of
> a polarity mark.

I don't know if that *is* a polarity mark. I'm not sure what you are
describing, but I don't recall seeing any SMD polarized capacitors that
don't have *clear* markings of polarity. Do you have an image or can you
find a similar cap on the Internet?

> Sometimes it helps to know all the small details of the components. I
> don't know, but guess that some could not have any marking and it could
> depend on how they are placed in the reel they come in.

I've never seen polarized caps that weren't marked. I've never seen
polarized caps that relied solely on the reel orientation to indicate
polarity.

[Ralph Mowery]

In article <oo9b8b$hvt$1...@dont-email.me>, gnu...@gmail.com says...

>
>
> I've never seen polarized caps that weren't marked. I've never seen
> polarized caps that relied solely on the reel orientation to indicate
> polarity.

Here is a link to a px of some SMD capacitors. The two on the right
have that little tit I mentioned. It could be mistaken by someone like
me that has never seen one as just some excess solder when it was made.

https://drive.google.com/drive/folders/0B7wJcih38lRAMl9MRk1sdnA3ajA

There probably are not any that are not marked in some way. I was just
guessing at the reel thing.

As mentioned it is a hobby now and upto a short while ago I had not
messed with any of the SMD. There have been lots of advances and
changes in the components over the years. Just more to learn. I still
have trouble with the values of some components being packaged in a
small package.

Just hope I am not sounding like some of the other older people on here
with the SMDs.

[rickman]

Ralph Mowery wrote on 8/31/2017 1:11 PM:
> In article <oo9b8b$hvt$1...@dont-email.me>, gnu...@gmail.com says...
>>
>>
>> I've never seen polarized caps that weren't marked. I've never seen
>> polarized caps that relied solely on the reel orientation to indicate
>> polarity.
>
>
> Here is a link to a px of some SMD capacitors. The two on the right
> have that little tit I mentioned. It could be mistaken by someone like
> me that has never seen one as just some excess solder when it was made.
>
> https://drive.google.com/drive/folders/0B7wJcih38lRAMl9MRk1sdnA3ajA

Ok, these are un-encapsulated tantalum caps and that pin is a part of the
device internal connections. They are the same part as the yellow ones to
the left (and maybe the black ones too, but not the round ones which are
electrolytic), but without the plastic coating to make them smaller. Yes,
the point might look like excess solder, but if you use a part without
looking at the data sheet you are screwing up.

> There probably are not any that are not marked in some way. I was just
> guessing at the reel thing.
>
> As mentioned it is a hobby now and upto a short while ago I had not
> messed with any of the SMD. There have been lots of advances and
> changes in the components over the years. Just more to learn. I still
> have trouble with the values of some components being packaged in a
> small package.

Trouble? You mean you have trouble accepting the small sizes?

> Just hope I am not sounding like some of the other older people on here
> with the SMDs.

Only a little... ;) Wanting to learn new stuff is what is setting you
apart. It is hard to go with new ideas when you've been doing the same
thing for a long time, especially when the eyesight makes it hard. But it's
not impossible. I have essential tremor but I still make stuff from time to
time. When it's work I let an assembly house deal with it.

[Ralph Mowery]

In article <oo9hia$9nf$1...@dont-email.me>, gnu...@gmail.com says...

>
> Ralph Mowery wrote on 8/31/2017 1:11 PM:
> > In article <oo9b8b$hvt$1...@dont-email.me>, gnu...@gmail.com says...
> >>
> >>
> >

> > As mentioned it is a hobby now and upto a short while ago I had not
> > messed with any of the SMD. There have been lots of advances and
> > changes in the components over the years. Just more to learn. I still
> > have trouble with the values of some components being packaged in a
> > small package.
>
> Trouble? You mean you have trouble accepting the small sizes?
>
>

Not really trouble, but just have not worked with the SMD enough to
learn all the small details. Like learning that they can make a
capacitor of over 1 uF the size of fly poop and not big enough to have
any markings on them.

The first computers I dealt with had the memory chips that would thake 8
chips to make about 1 K of memory, maybe not even that much. Just the
memory board alone for 8 K of memory was larger than several of the
smart phones now. Now they over 100 GB of memory in the space of one of
those chips. I can accept them, just have not seen enough of them to
know they are in use.

I just have to keep up with the times. Like the cars. I remember
changing oil from 30 W to 20 W and back when the temperature changed
from summer to winter, and change every 3000 miles, or was it less.
Then came the 10W 40 types and no change was needed for summer to winter
and 5000 or 7500 mile change.. Just bought a new car and the
recommendation is 0 w 20 and only change at 10 K miles. They give 2
years free maintence. Going by the book, that is only 2 oil changes the
way I drive. Nothing else to be done but look it over.

[bruce2...@gmail.com]

On Monday, August 28, 2017 9:44PM , Ralph Mowery <rmower...@earthlink.net> wrote:
> In article <oo1tsf$emk$1...@dont-email.me>, div...@tcp.co.uk says...
> >
> > If they are MLCC, the capacity can be quite high maybe even 10uF these
> > days, but very low V and a susceptibility to metal migration it PbF
> > soldering temp requirement fracture the ceramic at laying
>
> I have read about the need to slowly heat the capacitors to keep
> them from fracturing.

I don't mean to go further on a tangent and I have no experience with the A+++ related computer hardware construction and repair, but I know fans keep computer hardware cool. But with cold capacitor heat rising to fast, should something like incandescent light bulb first turn-on before cooling fans kick-in in a CPU tower-area to keep hardware temperature more at an exact setting?

[tabb...@gmail.com]

can you put that in english?