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Subject: Re: [Homebrew_PCBs] Stubborn ferric chloride etching.

From: James <bitsyboffin@...>
Date: 2014-01-10

Is it fresh?  Ferric Chloride does get worn out, the more copper it takes on, the slower it will work, until eventually you'll be there forever.

I'd suggest you try Cupric Chloride, which is simply HCl and H202 after it's etched a board or two and picked up a nice lime green colour.  No heating required, you can see through it, re-usable indefinately, just add just add a cap or two of H202 (depending on how strong your H202 is) when you etch (add and stir before you add the board) and it's good as new. Yes for the real deal you should test the specific gravity etc etc... but you really really don't need to, just eyeball it, lime green good, dark green need peroxide, brown add some HCl too.  Wear eye protection in case of accidents, etch outside.


On 10/01/14 09:44, richanny@... wrote:
 

Using plain hydrated ferric chloride etch, warmed up a little, the last two boards done have been really stubborn to etch away the bridges between narrow tracks and pads. They needed extended time , so much that some narrow tracks just disappeared under the resist, and the boards scrapped.

Any suggestions?

Has anyone had success with an electrolytic technique?

Rich