Homebrew PCBs

----- Original Message ----- 
From: "halfintegerspin" <richard@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Saturday, October 20, 2007 8:17 PM
Subject: [Homebrew_PCBs] how dark must a photomask be?


>I tried photo resist. I sprayed the board myself using 'positiv 20'
> and left it to cure for a few days.
> I printed a few masks on transparency with a laserjet. The masks were
> all quite transparent. I can hold them up to the screen of my laptop
> and read thru them? I didn't think it would be any good but I tried it
> with 3 minutes of UV and the results were pretty good. I didn't bother
> with exposure tests or testing the developer as the mask and board
> didn't look very good...
>
> I had a new toner in the laserjet, the density set to max[5],
> resolution on max, fuser temp normal. the transparency is something
> like hp3770 meant for color laserjet,[mine is an old 4000 monochrome].
> I use the  laserjet config program to set the density as xp overrides
> the settings  otherwise..

I used to use a LaserJet printer with tracing paper for transparencies and 
got quite good results although they weren't very opaque. I get much better 
results with an inkjet printer, though.

Leon
--
Leon Heller
Amateur radio call-sign G1HSM
Yaesu FT-817ND and FT-857D transceivers
Suzuki SV1000S motorcycle
leon355@...
http://www.geocities.com/leon_heller