Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

previous by date index next by date
previous in topic topic list next in topic

Subject: Re: [Homebrew_PCBs] My first try failed miserably..

From: "Stefan Trethan" <stefan_trethan@...>
Date: 2006-04-11

On Tue, 11 Apr 2006 23:53:49 +0200, Ronald Vanschoren
<yahoogroups@...> wrote:

> Would I use a test patter or just expose the whole board? How do I see
>
> what the correct time is then? Will it be as clear as copper on one part
>
> (not exposed long enough) no copper on the other (exposed long enough)?
>


no test pattern is needed, although you might put a transparency on the
exposure unit to add in the attenuation.

You will see after developing clearly the areas that are blank copper,
which is exposed enough, and areas that will not develop well, some resist
will be left, those are not exposed enough. The time is selected so it is
surely long enough to achieve full exposure, but not unnecessarily
overexpose.

ST