Message-ID:   <[email protected]>

Here are replies to my query on Ni-compatible Cu etchants.

Adam




We use a couple of etchants to release Nickel structures from a copper
surface.

 The first, 16 g Sodium Chlorite and 32 g of ammonium bicarbonate in 1 liter
of water is a very slow etch  that will not etch into tight spaces very
well.  We use it to remove surface copper.  It has no effect on Ni
whatsoever.

The second is much more vigorous, and will only attack Ni if you have some
copper contamination in the nickel plate.  It is ammonium chloride and
cupric chloride in 20% ammonia solution.  Let me know if you want to try it,
and I will get you the precise proportions we use.


Jason Tauscher
Silicon Designs., Inc.
[email protected]
www.silicondesigns.com







Adam- try the following mixture, it works well for us.

1.  15g CuSO4.5H2O dissolved completely in DI water

2.  400ml concentrated NH4OH

3.  Enough DI water to make one liter, mix well

The stuff acts as a redox etchant and won't touch nickel.  Etch rate is
about 3000A/min for evaporated Cu and can be used for a long time as long as
you store it in a tightly sealed container.

rob

*******************************************************
Robert L. Wood
MEMS Technology Applications Center

MCNC
3021 Cornwallis Road
Research Triangle Park, NC 27709-2889

Voice: 919-248-9284
Fax: 919-248-1455

[email protected] 
http://mems.mcnc.org/ 






We have developed the following formula for Cu etching and we have not had
any problem with Ni pitting.  The etching process is well behaved with a
very smooth Cu-surface morphology maintained throughout the etching process.


HNO3:H3PO4:CH3COOH = 0.5:50.0:49.5 (volume)
Application condition: room temperature
Etching rate: ~ 10 to 20 Å/sec


Good luck.


Xiaochuan Zhou
Xeotron Corporation
[email protected]






Hi,

Best way to solve these problem is to use a caustic etchant. An
excellent one is to use CuSO4 mixed with Ammonia. It will build a
tetra-ammin complex Cu(NH3)4++ which is the active etchant of the
Copper. It will never attac Nickel.

Best regards

Armin







Hi Adam,

Try 50% NH4OH mixed with 50% H2O2 in a 1:1 ratio.  The reaction is
exotermic and will bubble vigorously.  I use it often on LiGA Nickel and
have not seen any effects on electroplated nickel.

Regards,
Yohannes M. Desta