Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, "Chuck Kelsey" <wb2edv@...> wrote:
>
> Thanks guys for all the tips.
> 
> Is anyone doing toner transfers and consistently getting perfect
results? 
> Maybe my expectations are too high and I'll have to live with some
"hand  drawn" missing traces.
> 

> 
> Chuck
> WB2EDV


Hi Chuck,
I originally had problems like yours with TT way back and had switched
to Positive Photo. After reading here, I decided to try it again and I
get consistently very good results. I never have a trace lift, my
biggest problem is if I press to hard then the traces widen and if I'm
doing 8/8, there isn't much room for error. Even 8/8 I can do well 9
times out of 10 or better.

I think your problem is not enough heat. Most laminators I looked at
only go to about 200F and that's not near hot enough. I think most
guys here modify them to get hotter. I did see one that went to 200C
and that might work.

I use an Iron myself. I bought a cheap Sunbeam and I set it on max
(cotton), let it warm up for a few minutes while I align the image on
the board (I usually drill 3 alignment holes, 2 to use and one to
double check). Then I carefully place the iron directly on the paper
to tack it to the board in the right spot.

Then I place another sheet of thin typing paper over the TT sheet and
slowly move the iron around for about 2 minutes. If it's double sided,
then I repeat on the second side.

I simply prep the board with Dawn dish soap and a Scotchbrite pad.
Scrubbing in swirls and both directions. I only scrub for maybe a half
minute each side tops and then rinse and set on a clean paper towel
and blot dry.  That's it. If I touch or get some dirt on the board,
then I wipe the spot with 99% alcohol.

My Printer is an HP1200 and it works great (I use a reman cartridge
with no problems). The HP8500 at work also works good, but not as good
as the 1200. 

My transfer paper is Hammermill "Office One Gloss" # 0 10199 16302 8
It's available from Sam's Club online (# 16302-0) and I've also found
it at Office Max. It's a fairly light paper with slight gloss to it
and it's cheap! :-)

After ironing the board, I let it cool a little and then throw it in a
sink of water. No time limit on how long it can sit in there. I
usually leave it a couple of minutes, come back and rub off the outer
glossy layer and then let it soak for a while more. The rest comes off
easily. Sometimes a light pass with a magic scrub sponge to remove
what's between the small traces (it's like foam rubber).  The traces
are quite resilient, I've never had one come off, but toner is plastic
so you can scrub through it if you're to aggressive.

After that I etch, no sealer or anything, it works perfect each time.
I use Ferric Chloride to etch (Radio Shack still or powder bags from
Jameco). I tried the Hydrochloric once but it will attack the toner if
you don't get it out right away. The FeCl is much harder to over-etch
with. Good if you forget boards once in a while. ;-)

My etch tank is a tupper-ware like container with a ribbed bottom that
I set in hot water before I drop the board in.

Phil (KA0HBG)