Homebrew PCBs

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\ufffdC. 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
>