[sdiy] Photosensitive PCB's

[Jim Patchell]

    When I used to that that sort of thing, I had better luck with the negative
resist rather than the positive resist.

    I made a spinner that I would spin the boards on while I sprayed on the
resist, that would give me a much more even coating.

    You also need to make sure that your artwork is of very high contrast.

    And, I can understand the attraction to making your own PC boards (in fact,
I got flamed just this week on a news group where I expressed these same
sentiments), if there is a board house that can make the boards for you at a
reasonable price, it is sure a lot nicer than having to spend all that time and
messing with the chemicals.  Here in the US, Advanced PCB (http://www.4pcb.com)
will make prototype boards for a total of $80 (for 2, $33 each + shipping).  In
my opinion, making your own PC boards is more an exercise in frustration (its
great when you get good ones, a bummer when you don't).

    -Jim

Michael Schulze 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
> >
> >
> >