On 15 Apr 2014 08:29:03 -0700, you wrote:
>Thanks Harvey,
>
>That time estimate was a slight exaggeration, but it probably wasn't a lot more (maybe 5min or so tops).
I've had etch times in the 5 to 6 minutes range, but that was bubbling
fresh H2O2 and heating the solution during the summer. No wonder.
Never was quite so fast.
>I'm also usually doing smaller sized boards. Re: the agitation and heat - That was one of the things I really liked when it was working well at first. It seemed to heat itself up, even in cold weather, and bubble and fizz enough where at the most, I might have stirred the top layer around a bit with a plastic knife, but on the small stuff it barely even needed that.
This is an exothermic reaction, producing heat. That it bubbles and
fizzes so much says that the reaction is likely going way too fast.
Problem with that is there is a bit of slop time (to a point) the
slower the reaction goes, you'll always undercut to some extent.
Obviously a problem with finer traces, not a problem with 0.1 inch
traces for power supplies.
The evenness of the etch is more important that the etch time, so if
you do bubble etch, you want a good (and uniform) bubble curtain.
>
>I built a flat vertical plexiglass tank years back, complete with a bubbler and heater, but that was when I was doing ferric chloride (and later, sodium persulfate). It was messy and hard to clean, and I was thankful that the new etchant didn't need all that, but I may start using the bubbler with it and just dropping the tube in by hand.
It doesn't absolutely need it, but once it changes to CuCl, then it
will. No oxygen left for the reaction.
I'd like to do sodium persulfate, but I have no good (inexpensive
read.....) source for it. Had done Ferric Chloride, and never again,
thanks.
Harvey
>
>Thanks for all the tips on the stuff,
>
>George