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January 2010

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From:
vladimir Igoshev <[log in to unmask]>
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Date:
Tue, 19 Jan 2010 16:42:55 +0000
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Chris,



Werner is right, it's difficult, yet doable to prove you are dealing with CAF. You'd need to have sectionning, as well as lapping done to find Cu between fibers and resin in the board.



Regards,



Vladimir

SENTEC

SENTEC

11 Canadian Road, Unit 7.

Scarborough, ON M1R 5G1

Tel: (416) 899-1882

Fax: (905) 882-8812

www.sentec.ca



-----Original Message-----

From: Werner Engelmaier <[log in to unmask]>

Date:         Tue, 19 Jan 2010 11:25:37 

To: <[log in to unmask]>

Subject: Re: [TN] TI MSP Early Life Failure?



 Hi Chris,

Your scenario sure points towards CAF given the reflows, the via spacing, the timing of the failures, the high resistance of the shorts.

And yes, 'proving' CAF is difficult at best. What are you trying to do to 'prove' CAF?

IMHO, the best you can do is finding circumstantial evidence--the best is rough drilled hole walls on other vias with Cu-plating along separations of glassfibers and resin.

Werner



 





 



 



-----Original Message-----

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

To: [log in to unmask]

Sent: Tue, Jan 19, 2010 11:13 am

Subject: [TN] TI MSP Early Life Failure?





Hello Technet,

We are working on a failure analysis of a battery operated remote sensing 

device.  Failure is linked to 500ohm short power/ground.  The assembly 

experiences at least (2) 255C reflow thermal excursions.  Failure manifests at 

~6 months.

Slicing/dicing isolation yielded: breakdown between two vias (17 mil spacing) 

and/or MSP input impedance.  Beyond that, original evidence is lost.

We are working the CAF theory, however reproduction of the problem is proving 

difficult, possibly due to the low number of opportunities on the actual board.

For those of you who know that I'm pushing for placement of (the new) CAF 

coupons on panels, yes this is our most recent example of the problem.



I would like to get feedback on the possibility that it was the microcontroller 

instead...



TI MSP430F1612

Level-3-260C-168 HR





Thanks!



Chris Mahanna

Robisan Laboratory Inc.



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