On 25/11/12 11:22, Rick Sparber wrote:
> I was looking for a rough estimate. We were starting with fresh ferric
> chloride for each 3" x 4" board and now see that it was not necessary. Maybe
> a better question is - is there a simple test to know when the ferric
> chloride is spent? Maybe put a single, very fine copper wire in the solution
> and time how long it takes to vanish?
Just keep etching PCBs until the etching time takes more than 15mins.
Add HCl acid (and water if it seems too viscous). If that doesn't help, you'll
have to dispose.
If you add the HCl and use air bubbling agitation, you should get CuCl etching
with times of 12mins or less.