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July 2008

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Subject:
From:
Paul Reid <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Paul Reid <[log in to unmask]>
Date:
Mon, 21 Jul 2008 18:12:21 -0400
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I have sent some nickel problem photos for your review. 

These are unusual, reliability test influencing, problems with nickel, found in microsectioning. One section, section Ni_A_ is as received, the rest are after thermal cycle testing (IST). I have not included thin plating, bubbles and nicks, inclusions, nickel voids, etched copper due to nickel voids, nickel microsectioning artifacts and other nickel fabrication defects. These are of the more insidious types of nickel defects. Of course you can't see the gold. We do not stain (micro etch) to be able to view the nickel grain structure. We only desmear and enhance the copper crystals, as a rule, with a peroxide ammonia microetch.

I cannot attest that these are all electroless nickel problems so we may have some NiG and ENiG photos in this group.

I could probably write a book on nickel and it's role in reliability testing of PWBs, but, I will spare you (and my fingers) in this instance.

I will ask Steve to post these pictures (5) for all to see.

A = Nickel infiltration "as received"
B = Nickel infiltration with knee crack after thermal cycle testing
C = Nickel protection after thermal testing (bottom crack) and nickel crack initiation (top crack)- very rare picture
D = Nickel pull away after thermal cycle testing
E = Nickel rupture after lead-free (260°C) assembly simulation and thermal cycle testing - a lead free temp induced nickel failure that has not yet been defined! Werner and I have been reviewing this class if defects and I would appreciate comments.

Sorry I can't be more comprehensive.

Sincerely,

Paul Reid

Program Coordinator

PWB Interconnect Solutions Inc.
235 Stafford Rd., West, Unit 103
Nepean, Ontario
Canada, K2H 9C1

613 596 4244 ext. 229
Skype paul_reid_pwb
[log in to unmask] <mailto:[log in to unmask]>




-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Pete Houwen
Sent: Monday, July 21, 2008 9:58 AM
To: [log in to unmask]
Subject: [TN] looking for ENiG photos

Our purchasing group is trying to qualify a new low cost PCB vendor, and I have some reservations. I have been examining their sample boards, and while one oif them shows a normal ENiG grain under 800x magnification, the other is flat and dull. I believe it might be just gold plating. It's hard to tell from the cross sectons they sent (those display their own set of concerns). I'm trying to find some images to compare these, but I'm having no luck. Does anyone know of a good site where I might find some ENiG and Gold images?

Thanks,

Pete

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