At 11:35 AM 1/28/98 -0500, you wrote:

>I have a question regarding this whole thread: I have tried using the
>special paper that you print onto using a laser printer and then "iron" on
>to the board, and I have had very little luck

I have tried (over the years) the following:


Plotting directly on the PCB with various resist pens.

This worked fine for wide traces on small boards.  I had problems with
larger boards, which I suspect could be cured by going to a flat bed
plotter.  (I have purchased one, but have no documentation on it so far. Sigh)


Press-N-Peel  (A forerunner of TEC-200)

This was just a mylar sheet with teflon on it.  Toner would not stick to it
very well.  Never really had any luck with this at all.


TEC-200  (The blue stuff)

I had problems at first with the toner sticking to the PCB. I bought a
laminator that is sold with the Eagle Design stuff, and used the laminator
to apply the blue stuff to the PCB.  Not too bad.  You can get some fairly
narrow traces.  The big problem is that the toner tends to smear towards the
end, which limits the size board you can do.  I suspect you can run up to 8"
by 5" with this set up.


PrintGoCo

This is a small silk screen set up for doing screen printing at home.  I
used up two batches of supplies (10 screens total) figuring out how to get a
good clean master screen.  They supply a filter sheet that you are supposed
to use when exposing a laser printer/copier.  This is a thermal unit, they
use two very large flash bulbs to heat the carbon in a special ink, or the
toner.  A thin plastic film on the screen melts.  The problem I kept running
into was some of the toner kept sticking to the master, and that portion
would not print.  I found that by running the laser printer copy through the
laminator, with a plain sheet of paper over it, would fuse the toner enough
to allow production of a good master.  The screen appears to be way under
100 threads per inch, so I suspect you would not be able to run more than
one trace between .1" pads.  The ink supplied with the unit is good for
printing on paper, but does not work for PCBs.  I suspect this system may
turn out to work fairly well for small runs (10-100) 3" x 5" PCBs once I
find a suitable ink.

(The unit costs about $125 US and comes with enough supplies for 5 masters.)


Gel Paper (Sugar Paper)

A lot like the blue stuff, except that the paper coating dissolves in water.
I don't I would try this without the laminator.  I found getting good toner
adhesion fairly tricky.


Still to try:

Photo exposed silk screening.  Speedball makes a small screen printing set.
I have actually finished getting the screen preped.  (You have tape the
edges and shellac them, and then bolt the screen to a hunk of plywood.  The
speedball screen appears to have about 200 threads per inch.  You coat the
screen with a compound, and then expose the screen.  I have not yet come up
with an exposure box, but I may be able to do this in the net couple of months.

The nice thing about this approach is the board size you can work with.  I
purchased a 300 thread per inch 30" by 24" screen in Orlando for less than $50.

If you allow the developed screen to sit around for a few days, the pattern
becomes fairly permanent.  Not really bad if don't mind spending $20-$25 for
a pattern you want to keep around and print once in a while.

As always, I'll try and keep everyone posted.


If anyone could get me the information on where to buy the copper sheet, I'd
like to try laser printing on it, and plotting on it directly.

Anyone have additional information on Home PCB fabrication they don't mind
sharing?  Might save me a little time and money. :-)

Wynn Rostek