Homebrew PCBs

> Hello,
>
> I made another PCB, this time more complex, and tried to solve the
>
> problems I had, especially the photo-resist coming out when tried to
>
> clean the board's surface while developing.
>
> I was not able to solve this...
>
>
> I'm thinking that may happend because of some light getting trough the
>
> dark areas in the transparency, so expossing a bit, and so making
>
> photo-resist come out when I try to clean the board while developing...
>
> If I take out the board and clean with lots of fresh water, then it
>
> does not come out anymore.
>
>
> Now the question... I don't know how to solve this. Maybe:
>
>
> - Less expossure time (the problem is I need 0.3mm track separation
>
> sometimes, so it's tricky, as little time doesn't allow to separate  
> them).
>
> - Use acetate paper and laser printer (I was using inkjet paper,
>
> printing in the rough side with a inkjet printer. Should this be a
>
> problem??)
>
> - Take the board out of the developer sooner. When the image appears,
>
> I usually left the board in for about 1 or 1,5 minutes.
>
>
> Do you think this could be right?
>
> Any advice?
>
>
> thank you!

From: "patroclus04" <patroclus04@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Thursday, April 13, 2006 8:42 PM
Subject: [Homebrew_PCBs] Another photo-resist PCB


> Hello,
> I made another PCB, this time more complex, and tried to solve the
> problems I had, especially the photo-resist coming out when tried to
> clean the board's surface while developing.
> I was not able to solve this...
>
> I'm thinking that may happend because of some light getting trough the
> dark areas in the transparency, so expossing a bit, and so making
> photo-resist come out when I try to clean the board while developing...
> If I take out the board and clean with lots of fresh water, then it
> does not come out anymore.
>
> Now the question... I don't know how to solve this. Maybe:
>
> - Less expossure time (the problem is I need 0.3mm track separation
> sometimes, so it's tricky, as little time doesn't allow to separate them).
> - Use acetate paper and laser printer (I was using inkjet paper,
> printing in the rough side with a inkjet printer. Should this be a
> problem??)
> - Take the board out of the developer sooner. When the image appears,
> I usually left the board in for about 1 or 1,5 minutes.
>
> Do you think this could be right?

The problem sounds like insufficient print density, you should be using the 
highest print quality available. On my Epson 870 I use the Photo Quality 
Glossy Film setting, with Mega Electronics JetStar film.

Leon
--
Leon Heller, G1HSM
leon.heller@...
http://www.geocities.com/leon_heller 

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From: "patroclus04" <patroclus04@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, April 14, 2006 10:11 PM
Subject: [Homebrew_PCBs] Re: Another photo-resist PCB


>
> Should the printed transparency come out completely black?? I get some
> dark gray. It seems like good definition though.

Mine comes out black. That might be your problem.

>
> When using a HP deskjet printer, darkest setting, that's what I get.
> I use transparency film with one rough side, and the other one soft.

Are you printing on the correct side? The JetStar film I use should be 
printed on the matt side, the other side is shiny.

>
> I tried a laserjet today, but come out wrost, don't know why... I used
> a LaserJet 6L, darkest setting, and same paper, but printed in the
> soft side. It came out dark gray, but not black, and showing quite
> some "holes"...

I use tracing paper with a laser printer, or Mega Electronics LaserStar 
film. The latter gives better definition but is a lot more expensive.

Leon
--
Leon Heller, G1HSM
leon.heller@...
http://www.geocities.com/leon_heller