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Subject: Re: [Homebrew_PCBs] immersed etching

From: Alan King <alan@...>
Date: 2005-04-16

Stefan Trethan wrote:
> The whole thing meaning, in CuCl the foam doesn't circulate because the
> bubbles only go up, but it isn't a problem as with more air the same
> effect can be achieved.

It'll still be making circulation, but maybe not as good a rate..



> What i do not know is if bigger or smaller bubbles are better.
> think/tinker is sure big bubbles are good, 'cause small bubbles are not
> causing enough scrubbing action. OTOH i have tried big bubbles, and it is
> hard to get them evenly distributed over the board and they tend to form
> vertical streaks on the board that are 2 to 3 times faster etched than
> other places. I will rather have smaller bubbles, and slightly longer
> etch, if it is even.
>


Unconstrained, bigger probably is better, causing more direct action in the
liquid as the bubble moves up. But with more smaller bubbles and being kept
toward the board I doubt you'd see much difference, and of course the smaller
should be more even. There are 8-10 inch long 1/4 inch round green tube fish
aerators that put out lots of bubbles, that's what I'm thinking of. Hard to
find a pic, don't know the brand name and you get too much other stuff on a net
search. May just get a couple for trying later if I go out and send a picture.

Alan