Jai,
    seems like an ideal place to do lift off.  You could define the areas the
metal has to be using image reversal which gives a overhang of up to 22
degrees wall angle on the pgotoresist.  then deposit the chrome and the
copper.  then lift off the resist and the unwanted metal with no etching
required.  if you need any more help let me know.  Bill Moffat

-----Original Message-----
From: Jai Shinh [mailto:dumbo_work@yahoo.com]
Sent: Friday, March 29, 2002 11:33 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] Cr/Cu wet etching


Hello,

Could anyone help me to solve the problem of wet etching Cr/Cu?  The copper is
on top of the chrome.

I have a hard time protecting the copper when etching the chrome.

For chrome etchants, I've tried 1020 AC from the Transene, and CR-4.

The pattern is 40 microns in width, and Cr/Cu is 100 A/ 1 um.  The undercut is
severe.

Any suggestions will be greatly appreciated.



Regards,

Jai
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