Homebrew PCBs

Hi Bob, it was a long time ago, but from what I remember the emulsion 
was nothing special, just common silk screen emulsion. Color was red and 
smelled a bit like PVA glue. After coating, drying, exposing and 
developing, the emulsion became quite solid and difficult to remove. 
However it would "swell" slightly in etchant, and I think somehow a 
microscopic amount of etchant would reach to the copper surface, causing 
the bond to break and it lifts off. Unlike photoresists, these emulsions 
don't seem to be completely impermeable to aqueous solutions.

Adam

Bob_xyz wrote:
> Adam - What emulsion did you try and what was your etchant? I seem 
> to recall a discussion on this topic recently but I'm not sure any 
> conclusions came of it.
> 
> Ron - Thanks for all the info on screening.
> 
> 
> Regards, Bob
> 
> 
> --- In Homebrew_PCBs@yahoogroups.com, Adam Seychell 
> <a_seychell@y...> wrote:
> 
>>Thanks Ron the informative reply.
>>
>>Silkscreening a one off PCB is like I figured, lots of messing 
> 
> around. I 
> 
>>suspect it would add another hour to two of labor.
>>
>>I bought some silkscreen emulsion once, in a futile attempt to use 
> 
> it as 
> 
>>a liquid photoresist for etching PCBs. First, I could not get thin 
> 
> even 
> 
>>coatings, and 2nd the cured emulsion is not resistant to etchants 
>>(swells and lifts of copper). Just letting others no it ain't work.
>>
>>Adam
>>
> 
> 
> 
> 
> 
> 
> 
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBs
> 
> If Files or Photos are running short of space, post them here:
> http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
> Yahoo! Groups Links
> 
> 
> 
>  
> 
> 
>