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