Homebrew PCBs

I did a little research on the silkscreen emulsions by looking at the chemical consultants web site and the MSDS for some of their products.  http://www.ccidom.com/  

Turns out SS emulsions are Diazo activated and come both pre-activated and user activated with the Diazo. ( P-Diaozeoiphenylanin Bisulfate and Paraformaldehyde).  This is sort similar to the stuff used in photo resists if you look at some of the patents.  The difference is in the base material that gets polymerized.  The SS emulsion uses a Vinyl Acetate monomer but the PCB photo resist use a Novolack resin, which is a phenol formaldehyde (Bakelite).

According to Wikipedia the Diazo  inhibits the dissolution of the novolac resin  but after exposure to UV the dissolution rate increases even beyond that of the pure novolack.  It's even more soluble in a mild basic solution (1-2% sodium carbonate solution) after exposure.

The SS emulsions are removed by olain water wash on the exposed areas.  An oxidizer ( Sodium Periodate) solution cam be used to remove the hardened emulsion to reclaim the screen.

The real question is the how does the vinyl acetate hold up to hot etchants and what sort of  resolution can one get.

Would be nice to  DIY  formulate AZ111 , though I suspect that a replacement product is available that would work as well.  The issue is where to get it in small volumes.   Would be nice if one could mix as needed  to eliminate the shelf life issues.

Not done any searching on Novolack. 

Craig.