What did I do wrong

[louis488]

I attempted to remove the solder mask off a few boards.
1 The boards were striped in hot water with lye added. (about 3 cups of water and 2 Table spoons of lye)
2 They were all processed together for about 8 minutes.

Here is the problem some striped perfectly wile other were striped down to the board.

As you can see the board on the right was striped down to the copper and even some of that was removed. The one on the left just had a few bits of mask that did not come off.

Thank you very much
Louis

 

[Lino1406]

What I would do is separate the
"clean" from the "undone" boards
and redo the undone. The reasons
for this is non homogeneity among
boards as well as solution zones

 

[louis488]

What I would do is separate the
"clean" from the "undone" boards
and redo the undone. The reasons
for this is non homogeneity among
boards as well as solution zones

The problem that concerned me was some of the boards were striped down to nothing. The gold and copper or what every was used as a base for the gold plating.

 

[Lino1406]

So the gold is in the sludge formed?
No problem to recover it

 

[eesakiwi]

I have been wondering how to remove the 'solder mask 'or varnish as I call it.

Figured DCM (DiChloroMethane) or Paintstripper would do the job. Wouldn't Caustic soda eat into the metals?

 

[Geo]

I have been wondering how to remove the 'solder mask 'or varnish as I call it.

Figured DCM (DiChloroMethane) or Paintstripper would do the job. Wouldn't Caustic soda eat into the metals?

not any with value. it will attack aluminum vigorously. it reacts more with organics than metals.