Homebrew PCBs

On Apr 30, 2006, at 2:18 AM, Alan King wrote:

>   No tests, the light output of the LED is simply in the same  
> 390-420 nm
> range needed for the film coating exposure.


Hi.   I'm new to the group, can I ask a newbie question?

Why the emphasis on development of a direct inkjet process?

 From High School in the early 80's, I recall the way PCB's were done  
is to use the UV boards, a photo mask, and the sun.   Not that I've  
done any lately.

I just bought some PCB layout software and I wonder at the enthusiasm  
for this new inkjet process.

The current (pun!) problem is that the ink washes off, even though  
it's been oven-dried?


I wonder if fixing the ink with something like silicone spray would  
protect the ink but still not prevent the acid from etching the traces.

****

I've been playing with Electrolytic Rust Removal this week.   Baking  
Soda, water, a plastic bucket and an old trickle charger.

Add a metal part to the solution, clip it to the negative lead, and  
the positive lead to a piece of scrap metal stuck in the bucket.

The rust on the part turns black and falls off, leaving clean metal.

But come back after a week of cleaning off various metal parts, check  
the scrap metal on the positive lead, and it's been eaten away below  
the water line !


Eaten away by baking soda and electrons.


Makes me wonder if you could dope the solution to work faster under a  
UV light.

Put the printed PCB, sprayed with a fixitive,  in the solution  
clipped to the positive lead, a copper or silver-plated rod on the  
negative lead, shine the UV on the PCB, and in 1/2 hour or so, the  
copper not under the printed area is gone.

A silver salt maybe?    Basically I'm thinking of the old PhotoGray  
solution.


You'd need to mask the copper at the contact point for the positive  
lead too, or it would come off first and the process would stop.


William Carr