I am trying to make a PCB stencil by etching thin Aluminum using a toner transfer method.
I am using H2O2 3% and HCL 10% in a 1:1 ratio. I have also tried 3:1 and 1:2 ratios.
The alu has been cleaned with acetone.
I've tried room temp chemicals and putting them in a hot tap water bath.
In all cases the reaction is incredibly slow and weak. After 10 minutes the surface of the alu is covered in bubbles but no pitting.
Any ideas what I a missing? Others have reported this working for them (commonly with copper PCBs) so it seems strange. Perhaps this combination requires HCL at 30%?
Thanks.
Best Answer
Your HCL is a bit weak. You can speed up the reaction exponentially by warming the acid. Here is a complete tutorial on making solder stencils from old soda cans. He uses 31.5% HCL (aka Muriatic Acid) from The Home Depot.
Since Chinese suppliers can make beautiful professional laser cut stainless stencils for next to nothing (with welded frames) I've never been tempted to try it, but I admire his pluck.