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Subject: Re: [Homebrew_PCBs] Re: buying LED's for a exposure box

From: Markus Zingg <homebrew-pcb@...>
Date: 2008-02-21

Dave,

I think undercutt becomes a real issue if you apraoch 4mil traces. I
don't think it's an issue above 10mils provided you take the usual care
(make sure your film is printed in a way where the ink is on the side of
the photosensitive surface of the PCB).

A not good enough film quality will also cause trouble, but I would not
call that "undercut". So, in this context, LEDs have the advanteage to
let you aproach really fine traces and one obviousely can build a box
that is physically smaller than a tube based setup.

With the prices given from these e-bay sellers it's IMHO a no brainer
though.

Markus

Dave McD schrieb:
>
> Chris and others,
>
> Won't increasing the emission angle of the LEDs increase the
> undercutting effect and ultimately the resolution achievable when
> exposing a board using these LEDs? Since we are talking homebrew
> boards, how much do we really need to worry about light collumation vs
> the granularity (resolution) of the artwork? Is there some sort of
> rough formula?
>
> dave mc
>
>
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