Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

New to the group first I want to thank all of you for your help. The
techniques described here have helped me very much. Second I would
like to share my best techniques on making my own pcbs. Many if not
all I discovered from this group collective thoughts. So this is
probably more of an affirmation than a discovery.

I've found that the printer makes all of the difference from success
to failure. I had an old Epson Laser 1000 that I was using and as the
toner got lower and lower I found that it became impossible to make
any toner transfers that I could even use. I purchased a new Dell 1720
and now it's difficult to even make a tt with imperfect results. I'm
currently down to 12 mill traces with no problems and with probably
try 10mils but I believe that is going to be the limit for me. (See my
photos called dwags projects). I use an old iron and PressNPeel.
PressNPeel is a lot cheaper if you order from their website 20 sheets
for 33 dollars. And for my low volume this is great.

As for iron on techniques it is a learned exercise but I have found
that the color of the traces through the blue transparency of
PressNPeel gets darker and less fuzzy. That change in appearance
corresponds with a correct transfer of the toner and signals an end to
the iron heat and pressure. Heat can be checked with thermometer if
you have one find the heat setting that corresponds with about 300 deg F.

For etching I use Hydrogen Peroxide (Wal-Mart 1qt for 99 cents) and
Muratic Acid 4.99 a gallon. In the summer I mix three parts H202 to
one part HCL and in the winter I usually mix two to one. The removal
of copper works quicker if you can expose the copper to air and let
the etching completely drain off then submerge and do again. Takes
about 10 minutes to etch a 4x6 1oz copper pcb. Muratic acid is very
strong and I urge you unless you are familiar with strong reagents
please study safety and storage and waste removal of the etching
before you use this technique. I always have a five gallon bucket full
of water nearby incase of any accidents or spills when I am etching.

After etching I remove the toner with acetone wash in a cold solution
of soapy water to remove any traces of acidity dry and then coat with
a light coat of Shellac. This prevents the copper from oxidizing and
makes soldering a dream. Make sure you use shellac and not a lacquer
or varnish. Shellac has a low melting point 180 deg F and makes an
excellent protective insulating coat for the bottom of the pcb. I
only know of one manufacturer of Spray shellac Zinsser and sometime
you can find it at Lowes. Or you can order it online

After the shellac has dried drill out the holes. I found a great
source of drills on ebay you get 50 carbide ring drills for 32.00
shipping included. They come in 10s of .024, .029, .033, .035, and
.045 diameter onpasinc.com out of Ohio. If you make your entire pad
holes diameter less than the diameter of the drill you intend to use
the etched hole in the center of the pad with act as a center punch
and the drill with find the exact center. Start it slowly and let the
pcb move slightly to accommodate the centering process.

Soldering is straight forward. As you apply heat to the pad you will
see the shellac boiling away this gives you an indication of where and
how much heat is being applied. When it boils away you have perfect
unoxidized copper exposed that can be soldered without any additional
flux.

After the board is assembled I usually brush vigorously with a small
bronze brush. This dulls the solder to a mate finish and makes any
imperfections or bad weld very easy to spot with a magnifying glass
and removes all flux spatters.

Finally after the board is tested and everything works correctly I
give it a final heavy coat of shellac.

Again Thanks for all of your help and I hope these comments help
someone new to this group

Dennis