Homebrew PCBs

Several weeks ago there was a thread about using HCL 
& H2O2 as an etchant. That was a god-send for 
this newbie/lurker. I have used A.P. mostly but am 
unhappy with the cost. F.C. is so nasty that I avoid it 
if possible. The HCL/H2O2 looked perfect.

Last week, I finished my bubble tank (1 gal capacity) so 
I diluted the 30% HCL with an equal amount of D.I. 
water. Due to a brain fart, I don't remember how much 
H2O2 that I added - about 1-2oz, I think..? (Too much?) 

The solution was clear so I put in my first board and the 
etch was perfect after about 15 minutes (room temp). The 
etchant turned bright, clear green by the end of the etch.
I left the bubbler on for about 1/2 hour after the etch. No 
visible color change after the etch.

Since it worked so well for the first board, I assumed that 
I had it "made". Two days ago, I put in my second board 
(4"x6"). After 30 minutes, there was no visible removal of 
the copper, however the toner was sluffing off in the areas 
of large toner (copper flow areas). I pulled the board and 
dunked in a junk board. After 45 minutes, no etch.

Hmmmm.......

I haven't a hint of a suspicion of a clue as to what happened!
It worked so well for one board, then failed miserably
Does anyone on the list have any idea why this would fail?
Unhappily, being a beginner with this, I have no equipment 
 to chemically analyze the etchant.

cheers,
johnd


"Life isn't like a box of chocolates ... it's more like a jar of
jalapenos. What you do today might burn your butt tomorrow. "