Reflow soldering for dummies

[mkr5000]

In all my years as an electronics "hobbyist", I've never bothered to experiment with SMD and reflow soldering.

I have a project now that is a very simple board and may even try some of those DIY techniques I've seen posted but also may send the board out to be populated.

BUT --

inevitably I'll use a combination of SMD and some through hole, (for a pin header, transformer, terminal blocks etc).

My question is --

if I send the board out and ask them to do JUST the SMD components (and I do all the through hole when I get them back) -- will I be able to do the through hole?

will the plated holes clog up ? (even without the flux?) or should I allow for larger diameters etc?

like I say -- complete novice at this. -- thanks

[Lasse Langwadt Christensen]

the solder paste is put on with a stencil, so you control where the solder
goes in your CAD

-Lasse

[Tim Wescott]

And if you have a decent CAD program with decent libraries, stencil
generation is automatic and correct.

You will, of course, want to double-check the gerbers.

--
Tim Wescott
Control systems, embedded software and circuit design
I'm looking for work! See my website if you're interested
http://www.wescottdesign.com

[Tim Wescott]

Once you find out how much it'll cost, consider that a toaster or a
skillet from Goodwill costs $5 to $10, and will do a great job.

[Lasse Langwadt Christensen]

Den fredag den 27. maj 2016 kl. 23.10.00 UTC+2 skrev Tim Wescott:
> On Fri, 27 May 2016 13:23:29 -0700, Lasse Langwadt Christensen wrote:
>
> > Den fredag den 27. maj 2016 kl. 22.20.22 UTC+2 skrev mkr5000:
> >> In all my years as an electronics "hobbyist", I've never bothered to
> >> experiment with SMD and reflow soldering.
> >>
> >> I have a project now that is a very simple board and may even try some
> >> of those DIY techniques I've seen posted but also may send the board
> >> out to be populated.
> >>
> >> BUT --
> >>
> >> inevitably I'll use a combination of SMD and some through hole, (for a
> >> pin header, transformer, terminal blocks etc).
> >>
> >> My question is --
> >>
> >> if I send the board out and ask them to do JUST the SMD components (and
> >> I do all the through hole when I get them back) -- will I be able to do
> >> the through hole?
> >>
> >> will the plated holes clog up ? (even without the flux?) or should I
> >> allow for larger diameters etc?
> >>
> >> like I say -- complete novice at this. -- thanks
> >
> > the solder paste is put on with a stencil, so you control where the
> > solder goes in your CAD
> >
> > -Lasse
>
> And if you have a decent CAD program with decent libraries, stencil
> generation is automatic and correct.
>
> You will, of course, want to double-check the gerbers.

and depending on the stencil thickness maybe reduce the openings,
common default is same size as pad which in my experience is a bit too much

-Lasse

[Jon Elson]

mkr5000 wrote:

> In all my years as an electronics "hobbyist", I've never bothered to
> experiment with SMD and reflow soldering.
>

Yes, I was in that camp until 2007.

> My question is --
>
> if I send the board out and ask them to do JUST the SMD components (and I
> do all the through hole when I get them back) -- will I be able to do the
> through hole?
>
> will the plated holes clog up ? (even without the flux?) or should I allow
> for larger diameters etc?

Many PCB fabricators now offer stencil services as part of the deal (for
additional cost). One thing to know is that you want to reduce the size of
the stencil apertures to, maybe, 60% of the pad area. As components get
smaller, the apertures need to get even smaller than that, to avoid
bridging.

Anyway, if you have a stencil, wiping solder paste on the board and
reflowing in a toaster oven or fry pan is surprisingly easy. In fact, it is
so simple and works so well, it is quite close to MAGIC!

I bought a P&P machine in 2007 and hacked a thermocouple ramp & soak
temperature programmer into it, and it works like a charm. I've done about
a thousand boards this way.

If there is no solder paste on the through hole pads, they will stay
perfectly clear, for your later manual installation of those parts. I do
this all the time, I have through-hole connectors on everything I make.

For one board, I do dip soldering of the many through-hole connectors, there
are too many for manual soldering. I slather liquid flux on the bottom of
the board, drop all the components into place and then dip into a large
solder pot to solder all the parts at once. This process is just a bit
tricky, but this board has over 40 through-hole parts, so it is worth it.

Jon

[Tim Wescott]

Inneresting. I've only bought one mask -- I usually do prototypes, for
which I just apply a dot of solder to each pad, then rosin with a pin.
This works well for everything except the various styles that have just a
pad on the bottom of the part -- those parts need either more precision
in getting the dots right than I can attain, or they need something more
forgiving (like paste).

Come to think of it, I could put on BIG dots and file them flat -- I
think I'll stick with solder paste, though.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

I'm looking for work -- see my website!

[mkr5000]

Ok great -- as I thought. So if I send it out I'll just note the SMD pads for flux -- actually, will have to check my PCB program (Sprint layout) if it even does that, I know it has copper, silk screen and solder mask layers.

Do they generate where to put the flux from those? How would I designate -- ok no flux on the pt holes?

Do you use the silk screen layer and edit it? But isn't that for printed text etc?

When I get the CAD figured out I do want to do the oven thing.

[Lasse Langwadt Christensen]

there should be a layer for paste

-Lasse

[Tim Wescott]

Lasse Langwadt Christensen <lang...@fonz.dk> Wrote in message:

And if there isn't, use a better program!
--
www.wescottdesign.com


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

[mkr5000]

ok -- haven't updated this program in many years -- maybe there's a paste layer now.

[Reinhardt Behm]

I put a little bit of solder on those pads and take away most of it with
solder wick, then I solder them with a hot air gun and put some pressure on
them with tweezers. This usually works for parts with legs.

--
Reinhardt

[Tim Wescott]

That works great for parts with legs -- you usually don't even need the
"take away" step if you apply it right.

But more and more of the parts coming across my desk just have pads on
the bottom (I can NOT remember the package names off the top of my head!
), and it doesn't work very reliably at all for those.

[Jasen Betts]

If they do the SMD with stencilled paste and reflow the holes will be
left untouched. if the do it glued-on parts and with wave solder they'll be plugged.

--
\_(ツ)_

[Jasen Betts]

On 2016-05-27, mkr5000 <mike...@gmail.com> wrote:

The solder paste is a mix of solder powder and flux, so both are a
single layer.

--
\_(ツ)_

[John S]

See:

<https://www.youtube.com/watch?v=JA-vi2iQ5vA>

for Dave Jones' video using a toaster oven. You can watch his failures
as well as his successes.

[John S]

On 5/27/2016 3:20 PM, mkr5000 wrote:

Sorry. You might want to start with this one:
<https://www.youtube.com/watch?v=FNNRoXZom30>

[Klaus Kragelund]

This is so cheap it make no sense working on an oven with a timer:

http://www.ebay.com/itm/281884523260

I think I need to try this in my home lab :-)

Cheers

Klaus

[Reinhardt Behm]

I meant exactly those parts with a (thermal) pad on the bottom. I would not
do this for series production but for prototyping or replacing a blown part
it works quite well for me.
Like recently replacing that step-up LED driver that committed suicide by
generating an output voltage way above its maximum ratings. It just better
not to forget to connect the voltage feed back pin :-(

What I have problems with are the DFN types. They usually also have a big
pad at the bottom and no legs, only metal that ends flush with the plastic
case.

And you are correct that for normal parts with legs and no bottom pad (like
so-NN) the "take away" step is not needed. It was only meant for the bottom
pad to prevent or remove any bumps of solder.

--
Reinhardt

[Tim Wescott]

DFN, that's what I was trying to remember -- and those are the ones where
you just need to use paste.

[John Larkin]

On Fri, 27 May 2016 13:20:17 -0700 (PDT), mkr5000 <mike...@gmail.com>
wrote:

>In all my years as an electronics "hobbyist", I've never bothered to experiment with SMD and reflow soldering.
>
>I have a project now that is a very simple board and may even try some of those DIY techniques I've seen posted but also may send the board out to be populated.
>
>BUT --
>
>inevitably I'll use a combination of SMD and some through hole, (for a pin header, transformer, terminal blocks etc).
>
>My question is --
>
>if I send the board out and ask them to do JUST the SMD components (and I do all the through hole when I get them back) -- will I be able to do the through hole?

Yes. We do surface mount on an auto pick-and-place, solder and
inspect, and then add the thru-hole parts by hand. Make sure the
solder paste stencil doesn't paste the thru hole pads.

>
>will the plated holes clog up ? (even without the flux?) or should I allow for larger diameters etc?

They will if you paste them. Don't. The flux should be cleaned up by
the assembler so the holes will be clean.

ENIG (gold over nickel) PCB finish is fabulous, beautiful to solder
after years of storage. Solder coating can get a bit oxidized by the
reflow oven.

>
>like I say -- complete novice at this. -- thanks

It's not hard. People will make laser-cut mylar paste stencils cheap,
sometimes free. They won't last as long as stainless but they are fine
for small quantity production.



--

John Larkin Highland Technology, Inc

lunatic fringe electronics

[John Larkin]

On Fri, 27 May 2016 21:23:51 -0500, Tim Wescott <t...@seemywebsite.com>
wrote:

I have a post-it on the door of my office.

NO QFNS

[John Larkin]

On Fri, 27 May 2016 16:51:22 -0500, Jon Elson <jme...@wustl.edu>
wrote:

>mkr5000 wrote:
>
>> In all my years as an electronics "hobbyist", I've never bothered to
>> experiment with SMD and reflow soldering.
>>
>Yes, I was in that camp until 2007.
>
>> My question is --
>>
>> if I send the board out and ask them to do JUST the SMD components (and I
>> do all the through hole when I get them back) -- will I be able to do the
>> through hole?
>>
>> will the plated holes clog up ? (even without the flux?) or should I allow
>> for larger diameters etc?
>Many PCB fabricators now offer stencil services as part of the deal (for
>additional cost). One thing to know is that you want to reduce the size of
>the stencil apertures to, maybe, 60% of the pad area. As components get
>smaller, the apertures need to get even smaller than that, to avoid
>bridging.
>
>Anyway, if you have a stencil, wiping solder paste on the board and
>reflowing in a toaster oven or fry pan is surprisingly easy. In fact, it is
>so simple and works so well, it is quite close to MAGIC!

I was once wary of 1206's. Then 0805s and 0603s and then BGAs. They
all work fine. BGAs are more reliable than leaded parts.

[John Larkin]

On Fri, 27 May 2016 15:55:33 -0700 (PDT), mkr5000 <mike...@gmail.com>
wrote:

We delete the thru holes from the solder paste stencil. There is no
flux as such, just solder paste that includes flux in the goo.

You should receive the boards with the surface-mount parts soldered
and clean. The thruhole pads and drills should be perfectly clean,
solder-free and flux-free.

[krw]

I love QFNs and DFNs. They're easier if they have the wettable
flanks. When asked, I tell the manufacturers I'll use their Q/DFNs if
they include the wettable flanks. Evidently I'm not the only one
because most are including the detail.

[George Herold]

On Friday, May 27, 2016 at 5:51:26 PM UTC-4, Jon Elson wrote:
> mkr5000 wrote:
>
> > In all my years as an electronics "hobbyist", I've never bothered to
> > experiment with SMD and reflow soldering.
> >
> Yes, I was in that camp until 2007.
>
> > My question is --
> >
> > if I send the board out and ask them to do JUST the SMD components (and I
> > do all the through hole when I get them back) -- will I be able to do the
> > through hole?
> >
> > will the plated holes clog up ? (even without the flux?) or should I allow
> > for larger diameters etc?
> Many PCB fabricators now offer stencil services as part of the deal (for
> additional cost). One thing to know is that you want to reduce the size of
> the stencil apertures to, maybe, 60% of the pad area. As components get
> smaller, the apertures need to get even smaller than that, to avoid
> bridging.
>
> Anyway, if you have a stencil, wiping solder paste on the board and
> reflowing in a toaster oven or fry pan is surprisingly easy. In fact, it is
> so simple and works so well, it is quite close to MAGIC!

Thanks, I've been thinking of a toaster oven for doing some smd parts on boards.
Right now we do them "by hand", each one soldered in place under a microscope.
But these are when there are only a few smd parts... for more we send them out
to a board house.. which means a relatively big buy in terms of numbers... 100's.

I've watched some videos where people put down blobs of solder paste by hand...
out of a plunger thing. That looks almost as painful as out "by hand" method.

So can you give me some guesstiamte on the price of a stencil? ~$100?
Do you then panelize the boards and do several at once...
Do you use SS for the stencil?

George H.

[George Herold]

Tim, do you mean a dot of solder, or a dot of solder paste?
(assuming just solder, does the rosin flux then hold the part
to the board?)

George H.

[Phil Hobbs]

There are lots cheaper stencils than that. For small volume, Kapton is
okay, but mylar is garbage because it doesn't laser-cut cleanly and
snags easily.

Stainless is better for medium volume, obviously, but don't dent it!

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

[Carl Ijames]

"Phil Hobbs" wrote in message news:574DA53...@electrooptical.net...

==================================================================

Maybe this could be a niche for one of those cricut.com cutters that came up
for cutting thin copper foil, making your own stencils from mylar?

-----
Regards,
Carl Ijames

[krw]

I do prototype/development work. My run is generally fifteen to
thirty boards. Our CMs don't have a problem with this quantity but
they also charge us for it. It's almost as much work to make 10 as it
is 100, so we expect to pay.

>
>I've watched some videos where people put down blobs of solder paste by hand...
>out of a plunger thing. That looks almost as painful as out "by hand" method.
>
>So can you give me some guesstiamte on the price of a stencil? ~$100?
>Do you then panelize the boards and do several at once...
>Do you use SS for the stencil?

That's what our CM charges us for a stainless stencil (one per side).
He says they just pass through the cost.
>

[Lasse Langwadt Christensen]

Den tirsdag den 31. maj 2016 kl. 16.44.35 UTC+2 skrev George Herold:
> On Friday, May 27, 2016 at 5:51:26 PM UTC-4, Jon Elson wrote:
> > mkr5000 wrote:
> >
> > > In all my years as an electronics "hobbyist", I've never bothered to
> > > experiment with SMD and reflow soldering.
> > >
> > Yes, I was in that camp until 2007.
> >
> > > My question is --
> > >
> > > if I send the board out and ask them to do JUST the SMD components (and I
> > > do all the through hole when I get them back) -- will I be able to do the
> > > through hole?
> > >
> > > will the plated holes clog up ? (even without the flux?) or should I allow
> > > for larger diameters etc?
> > Many PCB fabricators now offer stencil services as part of the deal (for
> > additional cost). One thing to know is that you want to reduce the size of
> > the stencil apertures to, maybe, 60% of the pad area. As components get
> > smaller, the apertures need to get even smaller than that, to avoid
> > bridging.
> >
> > Anyway, if you have a stencil, wiping solder paste on the board and
> > reflowing in a toaster oven or fry pan is surprisingly easy. In fact, it is
> > so simple and works so well, it is quite close to MAGIC!
>
> Thanks, I've been thinking of a toaster oven for doing some smd parts on boards.
> Right now we do them "by hand", each one soldered in place under a microscope.
> But these are when there are only a few smd parts... for more we send them out
> to a board house.. which means a relatively big buy in terms of numbers... 100's.
>

We've had good luck with a hot plate, one of those magnetic stirrers for
lab use with the magnet removed

> I've watched some videos where people put down blobs of solder paste by hand...
> out of a plunger thing. That looks almost as painful as out "by hand" method.
>
> So can you give me some guesstiamte on the price of a stencil? ~$100?
> Do you then panelize the boards and do several at once...
> Do you use SS for the stencil?
>

http://smart-prototyping.com/PCB-Solder-Paste-Stencil.html

$17.70 for a 13x21cm aluminium stencil

-Lasse

[Tim Wescott]

There's too many things I need to do for which only QFNs are available.
So I've acquiesced.

[Reinhardt Behm]

George Herold wrote:

>> Inneresting. I've only bought one mask -- I usually do prototypes, for
>> which I just apply a dot of solder to each pad, then rosin with a pin.
>
> Tim, do you mean a dot of solder, or a dot of solder paste?
> (assuming just solder, does the rosin flux then hold the part
> to the board?)
>
> George H.

For SO or QFP housings I just put a bump of solder on all pads by having a
thick drop of solder on the tip and move that fast over all pads. Normally
surface tension prevents shorts here. If it still happens it is easy to fix
in this stage.
Then I place the part on these solder bumps and just fix two corners with
the tip. The rest is the done with a hot air gun with a 1-2mm nozzle. During
that I put light pressure on the chip with tweezers.
Look nearly like soldered in the oven.

I even solder Rs and Cs this. I just do not fix them but heat the pads with
hot air and put the part into the molten solder.

--
Reinhardt

[Tim Wescott]

Solder, with an iron. Nice shiny (if I'm doing it right) dot of solid
medal. Then I use a rosin pen (NOT "pin", dammit!) to apply rosin. The
rosin from that pen, once the solvent flashes off, is gummy.

The rosin flux holds the parts weakly to the board -- not as good as the
solder paste that I have, but then with the solder paste I have you still
want to walk carefully to the reflow skillet if you want everything in
place when you get there.

Just using stencils would be better -- I just need to remember that when
I order boards, not when I'm starting to build them.

[Klaus Kragelund]

I am working on a prototype right now with 0402 and fine pitch microcontrollers

I was stubborn enough to assume that all would go like planed, right now I am soldering on stuff I can barely see :-) (but it looks nice)

Cheers

Klaus

[John Larkin]

We don't like 0402's, because they tend to tombstone. That's not a
problem with hand soldering.

Get a Mantis if you plan to do a lot of soldering or rework of small
stuff.

The great thing about BGAs is that you can't see most of the solder
joints, so you don't worry about them.

https://dl.dropboxusercontent.com/u/53724080/PCBs/BGA_Crud.jpg

[krw]

0402s require a tighter process and the pads are sorta semi-circular
but otherwise, they're fine. It's our standard size for Rs and Cs.

>
>Get a Mantis if you plan to do a lot of soldering or rework of small
>stuff.

Absolutely! Your eyes will thank you, though your wallet won't. The
SLWD lens is a big improvement, as well but your wallet will really
hate you (my boss didn't flinch - too much ;-).

[Tim Wescott]

It may be just me, but I do fine with 0402 resistors using a 6X
microscope. At least -- if I do the work at the right time of day.
Right after I've had some tea my hands shake too much -- too much
differential gain, apparently.

[DemonicTubes]

On Tuesday, May 31, 2016 at 11:12:54 AM UTC-6, Lasse Langwadt Christensen wrote:
>
> http://smart-prototyping.com/PCB-Solder-Paste-Stencil.html
>
> $17.70 for a 13x21cm aluminium stencil
>
> -Lasse

Most likely stainless steel stencil in an aluminum frame.

The thrift-store toaster-oven method has to be seen to be believed. At least for me. Now it's all I do for at home projects.

[Lasse Langwadt Christensen]

Den onsdag den 1. juni 2016 kl. 23.41.16 UTC+2 skrev DemonicTubes:
> On Tuesday, May 31, 2016 at 11:12:54 AM UTC-6, Lasse Langwadt Christensen wrote:
> >
> > http://smart-prototyping.com/PCB-Solder-Paste-Stencil.html
> >
> > $17.70 for a 13x21cm aluminium stencil
> >
> > -Lasse
>
> Most likely stainless steel stencil in an aluminum frame.
>

you are right it actually say so on the page; laser cut steel on aluminum
frame

[Spehro Pefhany]

Shipping 2-3 kg for a reasonable size stencil from China will likely
be a few times that though, but it should arrive reasonably fast.

--sp

--
Best regards,
Spehro Pefhany
Amazon link for AoE 3rd Edition: http://tinyurl.com/ntrpwu8

[Phil Hobbs]

>Shipping 2-3 kg for a reasonable size stencil from China will likely
>be a few times that though, but it should arrive reasonably fast.

That's quite the stencil. What's the panel size?

Cheers

Phil Hobbs

[Lasse Langwadt Christensen]

from the page

Effective Area Total Size Price Weight
19.0 x 29.0 cm 37.0 x 47.0 cm $20 1.51kg
24.0 x 34.0 cm 42.0 x 52.0 cm $28 1.98kg
37.0 x 47.0 cm 55.0 x 65.0 cm $44 3.20kg
27.0 x 37.0 cm 45.0 x 55.0 cm $36 2.15kg
40.0 x 40.0 cm 58.4 x 58.4 cm $44 2.97kg

-Lasse

[John Larkin]

This is our standard stencil.

https://dl.dropboxusercontent.com/u/53724080/PCBs/Stencil_1.JPG

Framed like this, it costs around $300.

--

John Larkin Highland Technology, Inc

picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

[krw]

On Wed, 01 Jun 2016 16:25:38 -0700, John Larkin
<jjla...@highlandtechnology.com> wrote:

>On Wed, 1 Jun 2016 16:06:59 -0700 (PDT), Phil Hobbs
><pcdh...@gmail.com> wrote:
>
>>>Shipping 2-3 kg for a reasonable size stencil from China will likely
>>>be a few times that though, but it should arrive reasonably fast.
>>
>>That's quite the stencil. What's the panel size?
>>
>>Cheers
>>
>>Phil Hobbs
>
>This is our standard stencil.
>
>https://dl.dropboxusercontent.com/u/53724080/PCBs/Stencil_1.JPG
>
>Framed like this, it costs around $300.

I was wondering what the "frame" was. The stencils I've seen (at
either the PPoE or our current CMs) don't have a frame.

[John Larkin]

That fits into our stencil printer machines, somehow.

[George Herold]

A prof. I know said you need 1/2 of a beer to do fine
layout work... that would leave me a small time window
as the other 1/2 beer sat there... :^)

George H.

[Lasse Langwadt Christensen]

https://xkcd.com/323/

-Lasse

[krw]

If the programmers writing autonomous vehicle software are in the
Ballmer peak, will they get charged with DWI?

[George Herold]

Grin... that's much above 1/2 a beer.

The prof is an Irishman, and would
certainly suggest 1/2 a Guinness.
and happily consume the other 1/2 in the name of science.

George H.

[John Larkin]

One beer greatly improves my skiing. Same idea.

One rum and coke works about as well.

[Klaus Kragelund]

We have no problems with 0402 in production. Maybe we're just lucky :-)

Cheers

Klaus

[krw]

It seems that it should improve your driving, too. Does the officer
buy that story? ;-)

[John Larkin]

I don't think it does. Driving involves a lot of attention, whereas
skiing works better if you don't think about it too much. Crashing
while skiing is not usually a big deal. In fact, I worry if I don't
crash once in a while on skis. Crashing cars is a nuisance.

[krw]

On Thu, 02 Jun 2016 10:07:09 -0700, John Larkin

Ah, I see. In one, crashing is good. ;-)

[Mike Perkins]

On 27/05/2016 21:20, mkr5000 wrote:
> In all my years as an electronics "hobbyist", I've never bothered to experiment with SMD and reflow soldering.
>

> I have a project now that is a very simple board and may even try some of those DIY techniques I've seen posted but also may send the board out to be populated.
>
> BUT --
>
> inevitably I'll use a combination of SMD and some through hole, (for a pin header, transformer, terminal blocks etc).
>

> My question is --
>
> if I send the board out and ask them to do JUST the SMD components (and I do all the through hole when I get them back) -- will I be able to do the through hole?
>
> will the plated holes clog up ? (even without the flux?) or should I allow for larger diameters etc?
>

> like I say -- complete novice at this. -- thanks

If this is a one-off prototpye, then why not consider handplace and hand
solder each component?

--
Mike Perkins
Video Solutions Ltd
www.videosolutions.ltd.uk

[Phil Hobbs]

On 06/01/2016 07:25 PM, John Larkin wrote:
> On Wed, 1 Jun 2016 16:06:59 -0700 (PDT), Phil Hobbs
> <pcdh...@gmail.com> wrote:
>
>>> Shipping 2-3 kg for a reasonable size stencil from China will likely
>>> be a few times that though, but it should arrive reasonably fast.
>>
>> That's quite the stencil. What's the panel size?
>>
>> Cheers
>>
>> Phil Hobbs
>
> This is our standard stencil.
>
> https://dl.dropboxusercontent.com/u/53724080/PCBs/Stencil_1.JPG
>
> Framed like this, it costs around $300.

Interesting, thanks. So you don't generally panelize stuff going
through that swoopy new P&P?

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

[John Larkin]

On Thu, 2 Jun 2016 20:46:50 -0400, Phil Hobbs
<pcdhSpamM...@electrooptical.net> wrote:

>On 06/01/2016 07:25 PM, John Larkin wrote:
>> On Wed, 1 Jun 2016 16:06:59 -0700 (PDT), Phil Hobbs
>> <pcdh...@gmail.com> wrote:
>>
>>>> Shipping 2-3 kg for a reasonable size stencil from China will likely
>>>> be a few times that though, but it should arrive reasonably fast.
>>>
>>> That's quite the stencil. What's the panel size?
>>>
>>> Cheers
>>>
>>> Phil Hobbs
>>
>> This is our standard stencil.
>>
>> https://dl.dropboxusercontent.com/u/53724080/PCBs/Stencil_1.JPG
>>
>> Framed like this, it costs around $300.
>
>Interesting, thanks. So you don't generally panelize stuff going
>through that swoopy new P&P?
>
>Cheers
>
>Phil Hobbs

Yes, many boards are panelized. Those stencils are downstairs. I'll
take some pix. The frames are the same, I think.

[Spehro Pefhany]

Here's one I bought recently. I want to say it was around $150-200 USD
including shipping. It has both sides of 4 panelized boards.

<http://pages.interlog.com/~speff/usefulinfo/stencil.jpg>

It's about 43 x 52 cm and fairly light (~700g), but they packed it
with cardboard and sheets of sacrificial material from PCB making-
kind of a masonite dense kind of stuff- to keep it intact, so maybe
2kg total.


>Cheers
>
>Phil Hobbs

[John S]

Sonny Bono would disagree with you.

[Tom Gardner]

On 02/06/16 18:07, John Larkin wrote:
> I don't think it does. Driving involves a lot of attention, whereas
> skiing works better if you don't think about it too much. Crashing
> while skiing is not usually a big deal. In fact, I worry if I don't
> crash once in a while on skis. Crashing cars is a nuisance.

I know what you mean, having been skiing since safety
bindings were optional extras.

I also know I've watched one person die, and probably two.
The probable was on the roads. The certain death was
on a ski slope.

I was on a chairlift watching someone go down the piste
fast but smoothly and well in control. When I looked back
a few seconds later, he was sliding down. After ~100yards
he hit a snow cannon with a memorable "crump", and then
didn't move.

At the top I called out the emergency services and wrote
a description of the accident. A couple of days later the
local paper reported that he was an experienced local skier.

My daughter watched the incident, and it was a good talking
point.

OTOH, I've watched people prang aircraft through lack
of attention, without injury :)

[John Larkin]

You can die stepping out of a bathtub or climbing down stairs;
technically, I *did* once die climbing down stairs. Skiing is quite
safe compared to motorcycling or skydiving or smoking cigarettes.

About 40 people die skiing per year. About 700 ppb per visit.
Bicycling is more dangerous. Most skiing deaths come from high-speed
collisions with trees; that is avoidable.

[mkr5000]

Why can't I find anything on "screen printing solder paste" ? Is that out of the question? I can't imagine why -- I've had a small screen print setup for a long time, nice aluminum frames, durable polyester fabric. I would think if it could do ink it could do solder paste ?

Plus the registration on a screen is easy.

All I see are the stencils.

[krw]

I'm sure there is a heart attack or two in there, too.

[John Larkin]

Probably. Exercise at altitude.

--

John Larkin Highland Technology, Inc

[Jasen Betts]

On 2016-06-03, mkr5000 <mike...@gmail.com> wrote:
> Why can't I find anything on "screen printing solder paste" ? Is
> that out of the question? I can't imagine why -- I've had a small
> screen print setup for a long time, nice aluminum frames, durable
> polyester fabric. I would think if it could do ink it could do solder
> paste ?

If the solder particles pass through the weave and the "gum" sticks to the
board better than it sticks to the weave it could work. you also need
to get uniform and repeatable thickness.

> Plus the registration on a screen is easy.
>
> All I see are the stencils.

Stencils are basically the same process but without the weave, since
the aperatures are all convex curves there's no risk of the squeegie
snagging on a promontary, so no need for weave.

--
\_(ツ)_

[John Larkin]

On Thu, 2 Jun 2016 20:46:50 -0400, Phil Hobbs
<pcdhSpamM...@electrooptical.net> wrote:

>On 06/01/2016 07:25 PM, John Larkin wrote:
>> On Wed, 1 Jun 2016 16:06:59 -0700 (PDT), Phil Hobbs
>> <pcdh...@gmail.com> wrote:
>>
>>>> Shipping 2-3 kg for a reasonable size stencil from China will likely
>>>> be a few times that though, but it should arrive reasonably fast.
>>>
>>> That's quite the stencil. What's the panel size?
>>>
>>> Cheers
>>>
>>> Phil Hobbs
>>
>> This is our standard stencil.
>>
>> https://dl.dropboxusercontent.com/u/53724080/PCBs/Stencil_1.JPG
>>
>> Framed like this, it costs around $300.
>
>Interesting, thanks. So you don't generally panelize stuff going
>through that swoopy new P&P?
>
>Cheers
>
>Phil Hobbs

Here are some stencil pics.

https://dl.dropboxusercontent.com/u/53724080/Gear/Stencils/Stencils.zip

--

John Larkin Highland Technology, Inc

lunatic fringe electronics