Hi Shweta,
   If your geometry will allow it you might try placing a small voltage
on either the chrome or copper or both to introduce selectivity. We used
a small potential (~2.5V) on chrome electrodes to protect them in a
chromic acid based chrome etchant. We also found that when chrome is
electrically connected to copper, the copper is solvated before the
chrome. This is an electrochemical effect so experiment with applying
voltages or find an electrochemist to talk to.

-Mike Martin

>>> kirt_williams@sbcglobal.net 8/17/2004 2:15:25 PM >>>
CR-14 by Transene had some selectivity on our experiments, etching Cr
5
times faster than Cu.
CR-7 actually etched Cu faster than Cr, so don't use that.
See JMEMS etching papers, as reported earlier on this newsgroup.
    --Kirt Williams

----- Original Message -----
From: "Shweta Humad" 
To: 
Sent: Tuesday, August 10, 2004 2:57 PM
Subject: [mems-talk] Chromium etchant selective to copper
> Does anyone know of a chromium etchant selective to copper?
> Thanks,
> Shweta Humad

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