Homebrew PCBs

I have used the Sulfamic acid, Thiourea, and stannous chloride since 1973 to tin plate boards.

If you are having problems, make sure your chemicals he correct ones and fresh.  You need Tin(II) chloride SNCl2 CAS 7772-99-8,  Thiourea  SC(NH2)2 CAS 62-56-6 and Sulfamic Acid H3NSO3  CAS 5329-14-6

Formula for various batch sizes:

     100 mL                      50 mL      25 mL  
----------------------------------------------------           
     .5g Stannous Chloride       250mg	    125 mg
      2.0g Thiourea                 1g      500 mg
      3.0g Sulfamic Acid          1.5g      750 mg
      100.0 mL Distilled water    50ml      25ml

Use a fresh batch each time the stuff doesn't last more than a day or so.  Heat to 80 to 120 degrees and make sure you copper board is very clean and bright.
Read the MDS for the chemicals especially Thiourea it has health risks and is fairly nasty.
Craig