Dave, How small are the holes. The reason I ask is I have seen good results with sub micron pillars of resist. Deposited gold then lift off the pillars and the gold on top leaving sub micron holes. Bill Moffat -----Original Message----- From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org] On Behalf Of Dave Lewis Sent: Wednesday, October 14, 2009 6:51 AM To: mems-talk@memsnet.org Subject: [mems-talk] Etching gold through copper micro-holes Hello all, I'm trying to etch gold through micro-hole features in a copper layer (holes produced by a photoresist/lithography process). I've tried aqua regia vapor (maybe if I heat it up... but I don't want to hurt the copper anymore than I have to) and I've tried potassium iodide, iodine, water solution in a liquid state. I've had success as long as the holes in the copper are large enough but I need to access the gold in much smaller holes. It seems like the holes in the copper are too small for anything to gain access to the gold. Please assist me with this problem. Best Regards, Dave Lewis Lake Shore Cryotronics Ohio Dave.Lewis@Lakeshore.com