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Subject:	Re: [geda-user] Some PCB output --> Printer etching
Date:	Thu, 14 Apr 2016 07:05:30 -0400
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On Thursday 14 April 2016 05:42:30 Nicklas Karlsson 
(nicklas DOT karlsson17 AT gmail DOT com) [via geda-user AT delorie DOT com] wrote:

> > On Thu, 14 Apr 2016 07:55:01 +0200
> >
> > "Nicklas Karlsson (nicklas DOT karlsson17 AT gmail DOT com) [via 
geda-user AT delorie DOT com]" <geda-user AT delorie DOT com> wrote:
> > > Photo resist work as great as the printing on the plastic film. My
> > > printer does not print black areas perfect and I could see the
> > > imperfections on finnished circuit board.
> >
> > I used to use two layers of the film on top of each other to
> > overcome this problem.
>
> There are many tricks. I have read documentation for brother black and
> white laser printer and they claim 1200 dpi resolution while most
> other claim 600 dpi. Most sell color today but if lucky they spent
> some extra on good quality instead.
>
> In the long rung I think DLP with UV light for direct printing is the
> best solution. I think it is good limitation will be with etching
> instead of printing.
>
From some experience I got making PCB's in the 1960's while at a small 
market tv station, we had a DEA brand s pray etcher.  Detail 
reproduction was not a problem.  In those days we worked with tape at 4x 
actual size to make the negative, then had it reduced at a photography 
place that had a 24" Brown camera to the exposing sized film. We had a 
layout grid in toothy plastic, and we often made notes right on the 
negative with each character inside the .1 x .1 grid.  The note 
characters then were only 25 thousandths high & wide, and were perfectly 
reproduced in the finished copper.  That etcher held about 2 gallons of 
ferric chloride that was pretty well used up by the time I made 3 or 4 
boards with it in usually 4sies although the run could go to 30+ copies 
if it was a video distribution amplifier. Give it ten minutes to warm up 
the solution to about 110F, hang the developed boards vertically in it, 
and it sprayed like a windshield wiper against both sides of the board.  
Etch time was then getting slow so it took 8 or 9 minutes.  It etched 
the sharpest detailed boards imaginable, only matched by todays board 
houses in the last 15 to 20 years. Disposing of that much ferric 
chloride when it was spent was a problem though.
>
> Nicklas Karlsson


Cheers, Gene Heskett
-- 
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Genes Web page <http://geneslinuxbox.net:6309/gene>

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