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

Adam,

You are correct about using the iron and wrinkles. I didn't go into
much detail on the process. I lay down the dry film like you
suggested and then put the panel in a nylon turkey bag. Then I use a
small vacuum pump to evacuate the air and iron it down. There are no
wrinkles and its easy to do. Another way is to lay down the dryfilm
on a panel and then run it through the heated roller from an old copy
machine or pouch laminator as you suggested.

Your comments about cleaning the board are absolutely correct as any
oils or finger prints will mess up the adhesion of the dryfilm.

I do have a roll laminator but rarely use it because anything past a
prototype I just silkscreen. You will waste 5 or 6 feet of dryfilm
just getting the laminator "fired up". The dry film I have on my roll
laminator is called KOLON and is made in Korea. It cost approximately
$0.25 per square foot. The best resist I have used is DuPont 4715
which was around $0.38 per square foot last time I ordered. I keep
these rolls refrigerated to extend the shelf life.

Here is something else to consider, there is a liquid resist made by
Peters in Germany. You just mask off an area on a blank silk screen
and print the entire blank board. The blank panel is then dried in an
oven at about 180 degrees F for 20 or so minutes. It dries with no
pin holes and any small dents or imperfections are covered.

All other processing and development is the same as dryfilm. I used
this resist to process inner layers on multilayer boards and it
worked even better than dry film but the cost was higher. We had
almost zero defects when using this method so it was worth the added
cost.

This type of resist would do an excellent job on hobby boards if you
want to get the silk screening equipment for coating the panels. You
can coat a batch of panels and store them for future use. The silk
screening equipment can be used to print equipment panels as well and
is a good thing to have around.

Tom