Thats interesting your experience were different than what I measured in
my test. The bubbles agitation for my test was very vigorous, so maybe
that had something to do with it. The FeCl3 was full strength as sold
industrially (sp.gr=1.47), the AP was 200g/l almost fresh (very faint
blue color due to previous tests). For AP I was getting about 9 minutes
with 1oz copper at 42°C. 5 minutes sounds fast! Two possible reasons:
you unknowingly have "1/2 oz" PCB material, or the ferric chloride you
were using was for some reason not very potent which made it slow in
comparison. I'm equally curious becuase it could mean my test results
are botched.
If you have access to a micrometer caliper, you can peal copper away
from the board using a heat gun and pair of pliers, burn off the
remaining epoxy stuck to the back of the foil, and measure its thickness
Adam
Phil wrote:
> Very nice site! It would have been very helpfull when I was trying CuCl.
>
> One question, you have a chart that shows AP as generally having about
> 1/4 the etching rate of CuCl and worse than 1/5 the rate of FeCl for a
> given temperature. What was your AP concentration? My experiences
> with AP and FeCl are significantly different from that. Just
> yesterday I etched a 2.5"X3.5" DS 1 oz board in 5 minutes. 1 L of AP
> (250G/L per the directions on the package) heated to about 45C. This
> etchant is getting a bit old - I've done about 10 similar sized boards
> in it so it may even be faster with fresh etchant. This was
> significantly faster than the FeCl etching that I have done at room
> temp (12-14 minutes at 25C approx from memory). I recall room temp AP
> took a little longer than FeCl but not appreciably. I'm mostly
> curious since I'm very happy with AP.
>
> Phil
>