Homebrew PCBs

Actually, the acetone is not just to remove any oils. The thought was; if you use acetone to remove the toner after etching, perhaps a residue will help melt the toner on to the substrate, but at the microscopic level. It is very interesting that there is a film. I wasn't certain about this.

This isn't an original idea. I was doing some experiments with glass paint as a solder mask via screen printing and one of the manufacturers

http://www.deltacreative.com/pcid/110/Tips-Technique.aspx

recommended  (paragraph 4 and 5) using their pre-sensitizer before applying the paint. I moved on to UV curable resins because I couldn't develop my technique without some bubbles in the mask. With resins, the issue of bonding to copper without pre-sensitization arose again. Apparently, epoxy-copper bonding is a well known problem; a few of many patents,

3958317
4428987
4844981
6020029
6117536

I don't know if any of this applies to plastic based toner.

I have suspended my quest for a DIY solder mask until it gets warmer in my garage. I was beginning to have some success, but I ran into the problem of adhesion which I think is due UV cure intensity. UV resins cure top down and tinting the resin inhibits the cure at the substrate. I will try a metal-halide lamp when I resume my work.

Quite frankly, I do not have the foggiest idea as to whether the acetone residue is helping or not.

Baxter


--- In Homebrew_PCBs@yahoogroups.com, KeepIt SimpleStupid <keepitsimplestupid@...> wrote:

> (4) Wipe board with acetone (plenty of acetone), let evaporate.
> 
> I'd like to point out that Acetone does leave a film.  You might try Methanol dried with air.  The method we used to use for manual large area glass cleaning  was Trichloroethelene (degreaser) + Acetone + Liquid Freon (effectively banned) and blow off with a filtered air gun. 
> 
> I doubt that changing the cleaning technique would help.  The film might actually be beneficial.  The film has a measurable resistance on glass when measured with an electrometer.  A few picoamps at 100 V.
> 

>