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Date: Thu, 3 Apr 2014 14:24:52 +0100
From: Richard Bown <richard AT g8jvm DOT com>
To: geda-user AT delorie DOT com
Subject: Re: [geda-user] printing from PCB
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On Thu, 3 Apr 2014 07:28:21 -0400
Jason White <whitewaterssoftwareinfo AT gmail DOT com> wrote:

> Although I have never seen this before it would seem to be a
> transparent ruler with "calibrated" gray scale blocks printed on it.
> This would seem to be a way to measure opacity of the masking films
> and to make judgments about process variables such as how long should
> the PCB be exposed before developing it. If it is used the way i think
> it is, ie. lay it down on a sensitized PCB and measure how long it
> takes the 8th block to become completely exposed, then it could
> actually be quite handy.
> 
> http://www.stouffer.net/TransPage.htm
>

OK thanks,
I can see the use of it when you are doing a regular run of photo
etching boards, but
when you do one every few months, if that now I'm retired, I find the
biggest problem is the precoated photo resist changes with time, it
goes off.
If it had say some opaque circles on the grey scale it would be
useful to see when the board is fully developed.
but the biggest headache is developer strength and temperature, when
you mix in hot water, too much and it removes the etch resist.
I find the feel of it between finger tips one of the best ways to judge
the develop time, slippery but not slimey, and not enough to remove
your finger prints

Good fun :)


-- 
-- 
Best wishes /73
Richard Bown
Email : richard AT g8jvm DOT com   
HTTP  :  http://www.g8jvm.com
nil carborundum a illegitemis
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