--- In
Homebrew_PCBs@yahoogroups.com, "javaguy11111"
<javaguy11111@...> wrote:
>
> I finally got a chance to experiment some with the dry film resist. I
> just did a quick test where I applied the resist and put pennys on the
> surface. Here is what I have learned so far.
>
> 1. There is a coating on each side of the resist. A plastic and a
> mylar side. Make sure you remove the plastic side before laminating.
> How do you tell which side is which? I am not sure yet. I just got
lucky.
>
The mylar cover is crinkly, the plastic film is very soft.
> 2. Lamination with my stock GBC H200 laminator works great. I ran it
> through three times and it stuck just fine. It was easier than when I
> do toner transfer.
>
> 3. Be careful of the resist overlapping the board. After laminating I
> found my pcb stuck to my carrier. No real problem. I just cut it out
> with the knife.
>
A component of the resist is cyano-acrylate! IE. super-glue.
When fresh, it is extremely sticky.
> 4. Leave the mylar film on until you finish exposing. I did not do
> that. When I went to develop all my resist washed away!
You are supposed to leave the mylar on for 15 minutes AFTER
exposure, it traps gases that are part of the polymerization process.
If you peel it too soon, it doesn't fully polymerize.
>
> 7. Exposure time under a fluorescent lamp was about 30 minutes. Good
> enough for a quick test and maybe for one board I am working on that
> is does not have fine pitched components. I will need a better light
> source for my more complex board.
>
Although it is expensive, get a Stauffer transmission test scale,
(ST-7 or ST-21) at a professional photography store (hard to find
these days). You put it on a blank part off the edge of the film and
it shows you how strong your exposure is.
Jon