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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