Homebrew PCBs

well, all i know anyway.

I start out with several sheets of standard 80g copier paper, and the  
silicone (red, high-temp).
Put a sheet on a flat surface (i use a mirror), then i put a bead of  
silicone (10cm long) on one sheet.
Then i take the squeegee (20cm wide stainess with wood handle), and at an  
angle of about 30 degree (paper/squeegee) spread it with 3 or 4 passes.  
This is not so much to get the paper coated but more to get silicone on  
the whole length of the squeegee.
Now i take the sqeegee almost vertical (hold with a fist) and scrape once  
the whole page. The paper comes through. if it is uneven, or the paper  
doesn't come through in places, scrape again. (Angle the squeegee down to  
apply more silicone if there are still bare spots).
When a page is done, take the next one. You do not need a new bead, i  
usually coat 5 pages or so with the initial bead, there is still enough on  
the squeegee. You can start the second page on a very high angle of the  
squeegee already. You will quickly get the hang of it. Scrape off as much  
silicone as possible, at some point it will not be possible to scrape off  
more without ripping the page.

I coat the hole page leaving about 1-2cm at the edge so i don't make the  
glass dirty, i have found with the thin layer it does no longer wrap  
around the drum if the leading edge is coated.

Now leave to cure, i usually test if the rest on the squeegee is cured,  
because it is thicker material so takes longer, it is safe to assume the  
paper is OK then. By the way it pulls off easily of the squeegee when  
hard, no point wiping when soft.

With your sheet ready, print on it.

Prepare the PCB the usual way, sand with 600 or 1000 grit, and wipe with  
acetone.
(hint: use your squeegee to scrape toner off pcbs of previous (faulty)  
transfers, or after etching, you need less acetone).

Now simply put your printed sheet on the PCB and feed through the fuser.  
with my motor speed one pass is enough. I use relatively low pressure on  
the fuser rollers.

Peel as soon as it leaves the printer. you can feel when it is to cold, it  
will be harder to peel, it comes off very easily while hot. I can allow  
about 15cm to leave the fuser before it is cooled too much, so with a 20cm  
board i must start to peel while still fusing.
It will also work if you let it cool and peel later, however i have  
missing spots then sometimes.


When you have done everything right there will be no toner left on the  
paper, and you can print on it again straightaway. if there is toner left  
for some reason use acetone, even if the paper shines through the silicone  
it will not become wet and soft.

Let me know if you need clarification somewhere, or pictures.

ST