Hi Larry. Interesting work. Do you find that the Laser printer leaves
tiny holes in the foil pattern?
Which solder gauge do you use for SMT (and copper wick if used for
desoldering)?
My hands are now increasingly unsteady because of an undiagnosed muscle
tic, so my precision tinkering days are over for now. The actual assembly
work and repair work I can send out to a friend, and we share the returns.
He simply follows my instructions. Being blind, I would use a small
stainless steel needle to solder when I worked on PCBS; solder would be
fed through the needle to the work, and I'd follow the needle to the work
with the iron. A very good system (not my idea), and completely
successful. It is irnonic that I, a blind person, must now buy a
magnifying device.
Do you find that cleaning flxu from boards does any damage, or is it no
problem? I've heard of everything being used to clean. Some use ethanal,
others acetone, or distilled water and mild dish soap, or electrosolve. What
do folks use on list to clean any excess flux?
Charles
--
>I've been doing surface mount for many years.
>
>Until the last year or so, I've been able to do without a microscope. But now, my eyes have started the process of
>decreasing near vision. Super small stuff, I just can't get close enough to focus on anymore.
>
>I had been using standard reading glasses you can get at the discount stores. Get the highest magnification
>pair that you can wear without getting dizzy. You would be surprised just how much you can do with just those.
>
>I picked up a great Meiji microscope off Ebay for $600. Now that might sound like a lot, but it's at least a $4000 setup.
>
>I've always had access to microscopes at work, but now I have one in my home shop as well. It really makes a difference.
>
>I can readily do 6 mil traces on 6 mil spaces with Press N Peel Blue or positive photoresist boards and an HP laser printer.
>I've done 5 on 5 but had to hand touch up too many traces. 8 x 8 is a very easy range to hit. Once you start working 6 x 6
>the typical 10 by 10 starts looking BIG! ( these are trace widths and spaces between traces )
>
>I use a .010 drill and Kynar wire wrap wire to bring vias across the two sides. Components that have through hole leads can
>be soldered on both sides with solder paste and small stand off spacer. Flush cutting pliers even let you put vias under
>IC's. Just cut the solder bumps off as close as you can to the board.
>
>TQFP packages are very easy with a microscope or just reading glasses if you use solder paste and a toaster oven to reflow
>the board.
>
>BGA packages are also easy to do. Just use good flux and the toaster oven to reflow them. But solder mask really is needed
>to keep bridging from happening with BGA's. So those boards really need to be sent out to have the blank boards made with
>a good solder mask applied. Most BGA designs will need more than two sides anyway and the escape routing can be a pain even
>on 4 layers. I don't try to make more than 2 layer boards in the home shop.
>
>I usually hand solder all my surface mount boards. If there's a lot of components I'll put all the parts on with paste and
>toaster oven reflow them.
>
>later,
>Larry E.
>
>
>
> ----- Original Message -----
> From: dg140@...
> To: homebrew_pcbs@yahoogroups.com
> Sent: Wednesday, September 11, 2002 11:38 PM
> Subject: [Homebrew_PCBs] making SMT boards
>
>
> Anyone etched surface-mount technology PCBs? How did it go? Simply
> soldering the odd component or touching up an IC or small part seems
> difficult enough. YOu'd think I could find a cheap microscope with all of
> the high tech companies closing and moving herre in Ottawa, but no such
> fortune so far.
>
> Charles
>
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