[sdiy] Photosensitive PCB's

[oleavitt at ix.netcom.com]

Hello,

The photo process can be a real pain in the toilet muscle sometimes..

It sounds like the spray coating may be too thin and/or overexposure, or the artwork may not be in firm contact with the sensitized surface allowing  the edges of the traces to get exposed.
 
You'll need to experiment with spray coat thickness, applying it evenly, and UV exposure time until you find the magic formula. The pre-sensitized boards are nice in that they are more consistent from board to board.

The positive process is easier, less steps in the process.

Oren

On Fri, 24 May 2002 12:08:34 -0400 Michael Schulze <michael.schulze at oberlin.edu> wrote:

I'ma having a hard time getting the photo sensitive pcb process to work.
I've sprayed my own boards and exposed them with negative art.  When I etch
there seems to be not enough contrast between light and dark, so the traces
are not clearly defined.  By the time I can see the fiberglass in between
the traces the traces are half gone too.

Maybe I am spraying too much coating on???

I've ordered the positive boards to see if that is easier.

Any suggestions on suitable light sources for positive vs. negative boards?
Seems sunlight is too unpredictable - 4 minutes of noon sun in Ohio is not
the same as 4 minutes of noon sun in Florida!

> From: René Schmitz <uzs159 at uni-bonn.de>
> Date: Fri, 24 May 2002 17:15:57 +0200
> To: "Sandro Traversi" <straversi at libero.it>, "Michael Schulze"
> <michael.schulze at oberlin.edu>, <synth-diy at dropmix.xs4all.nl>
> Subject: Re: [sdiy] thermistors
> 
> At 16:06 24.05.02 +0200, René Schmitz wrote:
>> low resistance when some threshold voltage is reached. Ususally they
> 
> Nonsense, instead:
> *high* resistance when some threshold *temperature* is reached.
> 
> Cheers,
> René
> 
> 
> 
> 
> 
> -- 
> uzs159 at uni-bonn.de
> http://www.uni-bonn.de/~uzs159
> 
> 
>