Simple:
Don't use ferric chloride. Try HCL and Hydrogen peroxide (which becomes Cupric chloride) or the other old school etchant - Ammonium chloride.
Message
Re: Ferric chloride staining PCB substrate
2017-07-04 by Dave Sage
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Archive for Homebrew_PCBs.
Message
2017-07-04 by Dave Sage
Simple:
Don't use ferric chloride. Try HCL and Hydrogen peroxide (which becomes Cupric chloride) or the other old school etchant - Ammonium chloride.