Homebrew PCBs

>From: Markus Zingg <m.zingg@...>
>Reply-To: Homebrew_PCBs@yahoogroups.com
>To: Homebrew_PCBs@yahoogroups.com
>Subject: Re: [Homebrew_PCBs] Narrowest tracks?
>Date: Mon, 26 May 2003 14:41:16 +0200
>
> >I can do 12/12 mil tracks, with 10 mils if necessary, using an old 
>LaserJet
> >IIIp to produce the transparencies. I was wondering what is the best any 
>of
> >you can do with a laser printer. I've heard of people getting down to 8 
>mils
> >with a better printer than mine, and it should be quite easy using
> >photo-reduction from a 4:1 master.
>
>Leon,
>
>I can do 8 mil - no problem - by directly printing onto transparency
>paper (not using photo-reduction or such) using an older HP LaserJet
>4P. This laser is having a 600 dpi resolution. I'm sure I could go
>even finer since text that I print with a very small font even ends up
>readable but so far never had the need for finer pitch artwork.
>
>I either must be very lucky, or then other factors like the base
>material and it's photosensitive layer, kind of transparency paper I
>use, developper or etching may are also important. What surprizes me a
>bit is to hear how much sucess in this area varies among people. Some
>people only seem to get average results even if they use
>professionally made photo films while others like me can do well with
>just cheap transparency paper.


I'm quite sure I could get 8 mils, with a better printer, as I can get 12 
reliably even with tracing paper.

I think a lot of people have problems because they have the artwork/PCB too 
close to the UV source. The exposure might be nice and short but the 
definition and contrast are often poor. Someone I know just can't get good 
results. He's joked about coming over to the UK (from the US) to see how I 
do it.

Leon
--
Leon Heller, G1HSM Tel: +44 1424 423947
Email:leon_heller@...
My web page: http://www.geocities.com/leon_heller

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