Adam Seychell wrote:
> Russell Shaw wrote:
>
>>>Phil wrote:
>>>
>>>>Very nice site! It would have been very helpfull when I was trying CuCl.
>>
>>...
>>Adam Seychell wrote:
>> > 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
>>
>>Ferric chloride works faster if it is diluted with water (to 1 part or 2
>>parts water). A properly cleaned 35um copper pcb should etch in 5 minutes
>>at room temperature with gentle/moderate bubble agitation.
>>
>
> yep, 5~6 minutes sounds ok for FeCl. But I didn't think AP at 45°C
> wouldn't be that fast as Phil is finding, maybe at 70°C however.
>
>>http://www.jtbaker.com/msds/englishhtml/f1060.htm
>
> Thats a good link on FeCl. They say diluting 1 part FeCl (sp.gr 1.47) to
> 2 parts water doesn't effect etch rate. I didn't try diluting it. I
> can't be bothered repeating all the experiments again :(.
>
> Adam
The msds says FeCl3 6H2O is crystals, so the liquid stuff you buy must
be mixed with water anyway. Maybe it etches faster with the extra
dilution just because it is less viscous and the copper can diffuse
away from the metal surface faster.