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Subject:
From:
Chris Mahanna <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Chris Mahanna <[log in to unmask]>
Date:
Mon, 11 Oct 2010 16:36:24 -0400
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Werner, I’ve tried to describe it better

Fan-out clocking correlation: The fractures/poor wetting appear to start at the trace to land junction, rather than what one might expect from t-cycling fatigue, or ict strain.  In the pictures I posted, I tried to show the damage clocking around with the traces.
I thought that I had heard or read somewhere that this is common, but you guys are a lot faster than a literature search.
Chris

From: Werner Engelmaier [mailto:[log in to unmask]]
Sent: Monday, October 11, 2010 4:10 PM
To: [log in to unmask]; Chris Mahanna
Subject: Re: [TN] Mech. damage or poor wetting?

Hi Chris,
What do you mean by 'fanout clocking?'
I think you have a combination of 'Black Pad' and component warpage.
'What points to 'Black Pad' is the periphery location—during soldering the periphery gets a lot more heat than the interior, thus more Ni goes into solution with Sn, thus leaving a higher P-concentration at periphery pads, thus they are weaker, thus component warping causes interfacial separation on the periphery & pad cratering where the P-concentration is lower.
Werner

-----Original Message-----
From: Chris Mahanna <[log in to unmask]>
To: [log in to unmask]
Sent: Mon, Oct 11, 2010 2:40 pm
Subject: Re: [TN] Mech. damage or poor wetting?

Here are a few pictures

http://ipc-technet.groupsite.com/gallery/16011



this job is a mixed bag.  Currently we suspect soldering, cratering, ICT and

t-cycling damage



Chris



From: [log in to unmask]<mailto:[log in to unmask]> [mailto:[log in to unmask]<mailto:[log in to unmask]>]

Sent: Monday, October 11, 2010 2:22 PM

To: TechNet E-Mail Forum; Chris Mahanna

Cc: [log in to unmask]<mailto:[log in to unmask]>

Subject: Re: [TN] Mech. damage or poor wetting?





Hi Chris - do you have any pictures you can share?



Dave Hillman

Rockwell Collins

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Chris Mahanna <[log in to unmask]<mailto:[log in to unmask]>>

Sent by: TechNet <[log in to unmask]<mailto:[log in to unmask]>>



10/11/2010 11:29 AM

Please respond to

TechNet E-Mail Forum <[log in to unmask]<mailto:[log in to unmask]>>; Please respond to

Chris Mahanna <[log in to unmask]<mailto:[log in to unmask]>>





To



[log in to unmask]<mailto:[log in to unmask]>



cc



Subject



[TN] Mech. damage or poor wetting?















We have a BGA dye-n-pry job that shows board side sj damage with a strong

correlation to fan-out clocking.

We also have some microsection evidence of poor wetting.

All damage/dye is on perimeters.



Is this an indication of heat sinking and subpar wetting, or can it be

completely mechanical?  Both?



Thanks



Chris



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