"The Handbook Of Metal Etchants" by Walker and Tarn, is an excellent place to start. It's a very thorough review of metal etchants. The ISBN is 0849336236 http://www.worldcatlibraries.org/wcpa/top3mset/5e4b891fe5f5578ba19afeb4da09e 526.html David Nemeth Senior Engineer Sophia Wireless, Inc. -----Original Message----- From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org]On Behalf Of Lou Chomas Sent: Thursday, May 11, 2006 8:39 PM To: mems-talk@memsnet.org Subject: [mems-talk] Platinum Group Metals Hi All, I'm trying to select a platinum group metal (Pt, Pd, Rh, Ir, Os, Ru, etc.) for use in my device. I was wondering if anyone had any information on the etch resistance of these materials to various etches. In particular, I'd like to know if they can withstand hot phosphoric acid, HF, BOE, and SF6 RIE. Any help or pointers to references would be greatly appreciated. Best, Lou