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

----- Original Message -----
From: "Volkan" <v_sahin@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Wednesday, January 06, 2010 8:04 AM
Subject: [Homebrew_PCBs] Dry film tenting problem & pattern plating


> Hi,
> I'm facing dry film tenting problems. It couldn't protect THP holes and
> tents start to break during developing. I did some googling and saw that
> this problem is known and according to Dupont technical articles, it is
> recommended to increase exposure duration to avoid tent break. I tried it
> and I saw great improvement.
> Another recommendation was, to reduce roller pressure to avoid hole sharp
> edge cutting of the film. It is stated that pressure in the holes
> decreases after lamination and it sucks film (film is liquid during
> lamination) to the holes and because of that, sharp hole edges cut the
> film. This cut decreases film strength. Another advise was to decrease the
> lamination temperature. I also tested both, they helped but didn't solve
> the problem completely.
>
> My second try was to use pattern plating method. I tried electroplated tin
> as a resist and ammonium persulfate as an etcher, it didn't act as an
> etch resist and etched away with copper.
>
> Any ideas/suggestions or does anyone faced similar tenting problems?
> Which etcher can be used for tin or nickel etch resist? Is there any
> practical formula for homebrewers?
> I'll appreciate a lot on any guidance.
> Thanks,

There aren't many of us homebrew PCB makers here. Try the Homebrew PCB Yahoo
group. Someone there has probably done something similar.

Leon