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February 2001

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Subject:
From:
Rob Durante <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 2 Feb 2001 15:50:27 -0800
Content-Type:
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text/plain (99 lines)
Hey Rob,

Several areas to look at.

*       Ensure that the nitric acid concentration is >30%v/v, more
preferably ~70%v/v. How old and what is the concentration of the current
acid. If it has a lot of nickel or is low in acid, it will not properly
passivate the SS (i.e. You will not form the passive oxide film)

*       Have there been any incidences in the past where the system has been
left on during nitric passivation? In this case, the tank has been etched
and will not form a passive regardless of what is done to it unless it is
re-electropolished.

*       If the EN bath or its components have been sitting around for some
time and have lost some of their stabilizers, you will see a less stable
passivation system since the EN bath will have a stronger tendency to want
to plate out and will tax the system more. This is attributable to the EN
chemistry.

*       Has the mix of work changed? Some substrates can influence the
stability of bath through leaching out of certain compounds or excessive Pd
adsorption.

*       Has the chemistry been maintained within close limits? Large swings
will tax the system more.

*       Has the tank been damaged by scratching, etc? This prevents
formation of the protective oxide film in these areas.

*       Are the cathodes actively plating in the EN? They should be.

*       Make sure the cathode bar is not being forced against the tank wall by
solution movement.  A  poly spacer bar can be added to the bottom of the
cathode.


Hope this helps,


Best Regards,
Rob Durante
OMG Fidelity
Southern California
(714) 540-7388

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Russell Burdick
Sent: Tuesday, January 30, 2001 7:48 AM
To: [log in to unmask]
Subject: [TN] Anodic Protection of Electroless Nickel

Hello Everyone,

Perhaps any operators of an anodic protected electroless nickel bath can
help a brother out?

System has been up and running for about 10 months; problems with plate out
onto steel liner in the last 2 months. After passivating and stripping
nickel with nitric acid solution bath and anodic protection works fine for
about 3 operating days, then current flows above 1.5 amps and plate out
ensues (at this point the current increases as the bath temp increases).

I have contacted device manufacturer and the chemistry vendor, but would
appreciate any suggestions from my colleagues.

Thanks in advance,

Russell Burdick
Process Engineer
602-276-1600
_________________________________________________________________
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