Homebrew PCBs

Hi Everyone - 

Can immersion silver be used as an etch resistant? I currently use 
Ferric Chloride. 

The reason I ask is that I flood my boards with copper, and the toner 
is a bit starved trying to print large blocks of solid black. If I used 
negative printing and a etch-resistant plating, this problem would go 
away (I hope)!

Thanks
John
Staples Basic Glossy Photo Paper
Ferric Chloride
Mostly audio circuits

--- In Homebrew_PCBs@yahoogroups.com, "thespeakerguy"
<thespeakerguy@...> wrote:
>
> Hi Everyone - 
> 
> Can immersion silver be used as an etch resistant? I currently use 
> Ferric Chloride. 
> 
> The reason I ask is that I flood my boards with copper, and the toner 
> is a bit starved trying to print large blocks of solid black. If I used 
> negative printing and a etch-resistant plating, this problem would go 
> away (I hope)!
> 
> Thanks
> John
> Staples Basic Glossy Photo Paper
> Ferric Chloride
> Mostly audio circuits
>

Gold works good as an etch resist in ferric chloride solutions but
silver probably won't work at all.

Definitely not. You only hope is gold plating or use an alkaline ammonia 
type etchant like the many PCB professionals use.
http://www.chemcut.net/downloads/alkaline-etch-process.pdf
I'd be suspect about the quality of immersion tin coatings, since pin 
holes act like seeds for etchant attack. Electro plated tin is normally 
used, but that bath has problems of its own for a hobbyist's situation.

I'm not being silly, but how about hot dipping the PCB in pot of molten 
solder. The toner should handle the temperature. The etchant can then be 
common ammonium persulfate since that won't destroy the tin/lead alloys, 
unlike pure tin.

The old pattern plate method was to tin/lead electroplate and etch in 
ammonium persulfate or alkaline ammonia etchant. The board would then go 
in hot oil to re-flow the solder and the remove oxides left over from 
etching step.

thespeakerguy wrote:

> Hi Everyone - 
> 
> Can immersion silver be used as an etch resistant? I currently use 
> Ferric Chloride. 
> 
> The reason I ask is that I flood my boards with copper, and the toner 
> is a bit starved trying to print large blocks of solid black. If I used 
> negative printing and a etch-resistant plating, this problem would go 
> away (I hope)!
> 
> Thanks
> John
> Staples Basic Glossy Photo Paper
> Ferric Chloride
> Mostly audio circuits
> 
>

Adam Seychell wrote:
> Definitely not..

sorry, you said immersion silver not immersion tin. I'm don't know if 
silver will survive persulfate etchants. It might.