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