Homebrew PCBs

Years back in the September 1971 issue of "Ham Radio Magazine" Larry Hutchinson had an article "Practical Photofabrication of Printed-circuit boards".  In that article he had an electroless tin-plating bath that worked quite well, did lots of boards with it.

 To 100ml distilled water add  500 milligrams Stannous Chloride, 2 grams Thiourea, and 3 grams of Sulfamic acid.  The chemicals are all powders so they keep but the bath is unstable, so only mix enough for one days job. All you need is enough to cover the board.  Action takes 10 to 20 minutes.  The article suggests a few mg of Alizarin or Alizarin Red S can be added as a brightner.  The Alizarin is very expensive and I could not see much difference in the brightness, I abandon the Alizarin when I ran out. Don't remember any odors, but with all chemicals you should take proper care and dispose properely.

Craig