We've encountered an odd problem using aqua regia to etch Pt. Instead of
etching the exposed areas, the etchant seems to be etching ONLY under
the areas touched by the resist, and undercutting. Rather like a
catalytic reaction.
Does anyone have a better etchant that might not exhibit this problem?

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Tom Rust
Nanochip Inc
7700 Edgewater Dr., Suite 665
Oakland, CA 94621
(510) 339-6263
(510) 339-9636 FAX
(510) 912-4662 cell
http://www.nanochip.com