Hello Larry
Why don't you try applying the coat by using a screen blank mesh ?.... is the best way for having a even coat in every place of the board.... and there is not going to be any funnny spots if you do the holes first and then apply the photoresist.
The blank mesh sould be a 140 or somthing like that.
Tell me about the results if you decide to use this method.
Regards
Ingeniero Andres F. Hernandez
Pontificia Universidad Javeriana
Celular (300)7825582
Casa (572) 5572655
________________________________
From: Larry Battraw <
lbattraw@...>
To:
Homebrew_PCBs@yahoogroups.comSent: Sat, December 5, 2009 10:07:07 AM
Subject: Re: [Homebrew_PCBs] Re: AQ3000 Waterborne Photoresist questions
Hi, no I am not using a real roller-coating machine, just hand tools. On
the suggestion of another member of this group I tried spinning the board
after coating it and had _much_ better results. I took an old computer fan
that had bad bearings and hot-glued a bottle lid to the center of the rotor
and then hot glued the board with a few dabs of glue to the lid. I ran the
fan at a reduced voltage so it spun up very nicely and slowly and formed a
pretty uniform coating of resist although there were buildups on the very
edges of the board. Two minutes in the oven at 200F and it seemed to do the
trick. There are still lighter patches and darker patches but I don't think
the variation is enough to cause problems and I'm looking forward to
exposing my first board to see how well the resist holds up to etchant.
Thanks-
Larry
On Fri, Dec 4, 2009 at 7:17 PM, jcarlosmor <jcarlosmor@yahoo. com> wrote:
>
>
> Are you using a real roller-coating machine?
>
> Those photoresists (AQ3000) are intended for professional use and generally
> does not accept any kind of fake/hobbyiest process.
>
> You could build a dip-coating machine which is much easier to apply than
> roller-coating.
>
>
> --- In Homebrew_PCBs@ yahoogroups. com <Homebrew_PCBs% 40yahoogroups. com>,
> Larry Battraw <lbattraw@.. .> wrote:
> >
> > Hi, I recently bought the roller-coating version of this photo resist and
> am
> > having a terrible time getting a board to cure properly. What generally
> > happens is that the board will cure somewhat well except for a big,
> jagged
> > "rip" through the center of the board's resist. It looks like a ragged
> tear
> > in the resist and spreads out in sharp edges kind of resembling a
> lighting
> > strike with the streamers of the defect branching out. If anyone is
> > interested I can post a picture of the problem. Has anyone used this
> stuff
> > and had any success with it? I've tried diluting it since it tends to
> > capture bubbles like crazy when spread normally but that just results in
> a
> > pool of concentrated resist in the center of the board and decreasing
> > amounts as it reaches the edges of the board. I would really appreciate
> > some hints since the stuff has great potential to coat large/thick boards
> > that won't fit in a normal laminator with the dry film resist.
> >
> > Thanks!
> > Larry
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>
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