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October 2005

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Subject:
From:
"Barmuta, Mike" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Barmuta, Mike
Date:
Mon, 31 Oct 2005 07:35:14 -0800
Content-Type:
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text/plain (171 lines)
Hi Rudy and All: Careful on compartmentalizing the cause of peeling plating
to only improper cleaning or oxidation. In general terms it's true that
things like stripping, cleaning, surface preparation, rinsing and activation
can result in peeling plating. Which I would include in your
cleaning/oxidation category. However the list of overall causes is quite
long.

I know this doesn't really apply to Steve's original question, he's more
concerned with the cure than the cause.

FYI  Here is a partial list of some other causes of plating adhesion on
bussed Ni-Au that may be of value to those fighting this problem.

Additional food for thought:

*       Improper sealing or conformance of the plating resist around the
circuits.

*       Plating resist not compatible with the temperatures and chemistry of
the preclean and plating process.

*       Plating resist not compatible with the gas evolution of the Au plate
at the cathode.

*       Entering the plating at an incorrect amperage.

*       Malfunctioning rectifier.

*       Bad anode connections

*       Bad cathode connections

*       Incorrect anode/cathode ratio

*       Incorrect anode/cathode spacing.

*       Improper metal concentration in the plating bath

*       Organic contamination in the plating bath.

*       Trace metal contamination.

*       pH of plating bath out of specification.

*       Excessive brightner/leveler in the plating bath.

I've spent many late Friday nights chasing these problems around the board
shop after the dreaded scream "PEELERS" emanated from the QA dept. Why was
it always Friday afternoon when they found them??


Regards

Michael Barmuta

Staff Engineer

Fluke Corp.

Everett WA

425-446-6076




-----Original Message-----
From: TechNet [  <mailto:[log in to unmask]> mailto:[log in to unmask]]On Behalf
Of R Sedlak
Sent: Friday, October 28, 2005 12:56 PM
To: [log in to unmask]
Subject: Re: [TN] Gold Plating Peeling...


Steve:   The usual cause of peeling plating is plating on to a dirty/oxized
surface.

Can it be reworked.... possibly, making sure that you get rid of the
original problem which caused the problem initially.

Can it be reworked in a way which is essentially guaranteed to work 99+% of
the cases?  Probably not.

Perhaps some sort of incoming inspection/test might be worth considering?

Rudy Sedlak
RD Chemical Company

Steve Gregory <[log in to unmask]> wrote:
Well, I just got back from "Sin City", and as they say; "no rest for the
wicked".

I really wasn't that wicked, but I was confronted with a new problem this
morning.

We just built some assemblies and conformal coated them, but when they were
being
de-masked, the gold plating on the fingers started peeling up! Check out:

 <http://www.stevezeva.homestead.com/files/Peeling_Plating.jpg>
http://www.stevezeva.homestead.com/files/Peeling_Plating.jpg
 <http://www.stevezeva.homestead.com/files/Peeling_Plating_2.jpg>
http://www.stevezeva.homestead.com/files/Peeling_Plating_2.jpg

I have a couple of questions:

Can I repair this?

If I repair this, should all fingers be stripped and repaired?

Kind regards,

-Steve Gregory-
Senior Process Engineer
LaBarge Incorporated
Tulsa, Oklahoma
(918) 459-2285
(918) 459-2350 FAX
__________________________________________________________________
This message may contain information that is privileged and confidential to
LaBarge, Inc. It is for use only by the individual or entity named above.
If you are not the intended recipient, you may not copy, use or deliver
this message to anyone. In such event, you should destroy the message and
kindly notify the sender by reply e-mail.

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