NaCl is sodium chloride, not nitric acid. And it doesn't etch gold.
(Otherwise there wouldn't be any pirates' booty left on the sea floor.)

Roger Shile

-----Original Message-----
From: Nik Dee
Subject: [mems-talk] Gold etching (Nik Dee)

Hi guys, I have been using HCl (hydrochloric) and NaCl (nitric) acid to
etch the
gold away. I recently realised that if there is copper in the sample the
acid
attacks the copper and has no affect on the gold surface anymore. Does
anybody
know any etching recipe that i can remove the gold without affecting the
copper?