Homebrew PCBs

Congratulations to your first experiments.

You got some answers already, but the answers also depend a bit on the 
KIND of resist. I don't know what product you use, but I will add my 2\ufffd 
anyways if you dont mind :-). So here we go:

1) The side that was on the inner side of the roll goes off easiest. I 
was once told by the supplier that with the resist I use it would not 
matter which side to use first so I never cared too much about this. I 
use two "tesa" stripes that I attach on both sides on a corner of the 
resist and then pull them apart. I then use the side that comes of first...

2) The number of times you have to pass it through the laminator may 
vary and depends on the kind of laminator and also the temperature 
setting. Actually with professional setup one time is enough, and I do 
have one laminator (regular office thingy) where one time is enough 
also. Another laminator I use also takes three passes. You must probably 
"burn" some laminate to get an overall feeling of the process, cause the 
surrounding parameters varry so much among hobbyist users. After all a 
configuration where you have to pass it multiple times, but you end up 
with less scrambled instances is prefereable. Stripping it off and 
relaminate is not the end of the world, but overall a source for loosing 
time.

3) Yep, cut off excess laminate after laminating every side. I use one 
of these sheet cutting machines to cut the resist into a size where 
there is only ~2 mm in excess. Cutting it out somewhat precisely helps 
in arrangeing it nicely and this helps in keeping the instances where 
laminating fails low in count. The laminate must kind of "flow" or 
"hover" above the base material when you feed it into the laminator. 
Some people press the first few millimeters onto the material but hold 
the reminder in the air then feed the laminate by hand as the laminator 
sucks it in. That way they avoid that the laminate gets scrambled.

4) I figure this happened because you exposed it too long. I do both 
things. Usually I try to leave the protection foil on the laminate, but 
sometimes (i.e. if the positioning shafts were not precisely enough 
punched out) I have to hand alling and then peeling the foil off helps 
in that the film is then automatically attached to the laminate due to 
it glueing somewhat.

5) I don't know what you mean with mylar. If you refer to the protective 
foil, then this one comes usually easily off and in one piece.

6) washing soda is the prefect developper. Use caustic soda to later on 
stripp of the resist (after etching)

7) Fluorescent lamp :-) Well, I figure you then also could have leave it 
on your shelf just "as is" to get to a similar result :-). With UV 
tubes, the exposure time is somewhere between 7 - 10 seconds only... You 
will see that some kind of exposure setup will help a great deal here.

Markus

javaguy11111 schrieb:
>
> 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.
>
> 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.
>
> 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! Fortunately, I
> accidentally did not remove all the mylar. The areas where the mylar
> was present during exposure stayed stuck when soaked in the developer.
>
> 5. Make sure you remove all the mylar. Despite the fortunate case in
> 4, you really want to make sure all the mylar is removed before
> developing.
>
> 6. I used Arm and Hammer washing soda for developer and it worked just
> fine.
>
> 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.
>
>