[sdiy] Moving to Surface Mount - lots of questions

[Harry Bissell]

I'd recommend 0603 resistors. They are half the size of the 1206 package. By the time you use 1206
parts, you eat so much board space that there is little to no benefit over thru-hole parts.  The ICs are
usually quite tiny and the PCB layout will be easier with passive components that sort of match that scale.

You need some optical aids like the Opti-Visor (Donegan Optical). The DA-5 is a good compromise between power
and working distance. You can get an optional flip-down loupe for one eye that brings the magnification WAY UP
when you need it.

Avoid leadless packages, they suck to solder. Yes, more than BBDs they suck...

H^) harry



----- Original Message -----
From: Mike Beauchamp <mikebeauchamp at gmail.com>
To: xyzzy at sysabend.org, sdiy DIY <synth-diy at dropmix.xs4all.nl>
Sent: Tue, 06 Dec 2011 22:03:36 -0500 (EST)
Subject: Re: [sdiy] Moving to Surface Mount - lots of questions

Thanks Tom,
seems like the next big project might be a good time to take the
plunge into SMT.

Mike


On Tue, Dec 6, 2011 at 9:13 PM, Tom Arnold <xyzzy at sysabend.org> wrote:
> On Tue, Dec 06, 2011 at 02:45:09AM -0500, Mike Beauchamp wrote:
>> after assembling a few PCB's with a few hundred resistors, I've been
>> thinking about moving to Surface Mount for my next project. Please
>> convince me, or talk me out of it :)
>
> I can manually stuff a board with 1206 resistors using a soldering iron with
> a small tip much faster then I can stuff through hole.  Enough so that I'm
> slowly switching in that direction.  The large parts are quite easy to deal
> with.  I touch the pad with solder, nail one end of the part down, then hit
> the other end.  no fliping and trimming, no worries about leveling the parts
> when I'm stuffing a bunch of parts between solder passes.  At the very least
> I'd try that.  I think you'd be surprised how easy it is.
>
>> Speed: Having never done it before, how much faster is it to
>> stencil-place-oven as opposed to insert-solder-clip?
>
> Its at least on par if not faster to do the SMD parts.
>
>> Reliability: I know that repairing a through-hole board is easier for
>> most people, but is the reliability of SMT stuff on par with TH?
>
> Seems to be the same.  Rework is a little more difficult but only because I
> havent had enough failures to really get good at it.
>
>> Storage: Those SMD resistors are tiny! What are some good ways to
>> store 30-40 different values so they can easily be grabbed for
>> populating?
>
> I buy reels.  Usually find the values I want for a few dollars a reel
> surplus.  I havent found a great method for storing small quantities.  Right
> now I use little plastic bags in a compartmented plastic box.
>
>> Toxicity: Soldering irritates my asthma, although my fume extractor
>> helps heaps. Does sticking solder paste into an oven cause similar
>> fumes?
>
> I would not use your home oven.  At the very least a cheap toaster oven you
> can run in the garage.  I've been using the skillet method.  If you just
> place the board in an electric skillet you can heat it up quite nicely.
> http://www.sparkfun.com/tutorials/59
>
> With the skillet method you can use your normal smoke filter.
>
> I've done BGAs with the skillet method.  Lots of fun to place several
> hundred little solder balls by hand...
>
> --
>  -----------------------------------------------------------------
>  - Tom Arnold       -  Free Synth DIY webspace http://www.sdiy.org
>  - SynthGeek        -  "...is it a virus, a drug, or a religion?"
>  - K6AET            -  Juanita Shrugs. "What's the difference?
>  --------------------         -- Neal Stephenson,  Snow Crash
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy



-- 
[mike]
_______________________________________________
Synth-diy mailing list
Synth-diy at dropmix.xs4all.nl
http://dropmix.xs4all.nl/mailman/listinfo/synth-diy

-- 
Harry Bissell & Nora Abdullah 4eva