Hi Werner,
     So since the CTEs of the matls involved are different, as are the
materials used in other elements of the substrate of similar dimensions,
would it be correct to say...(1) the adhesion of the Cu to the fill should
be high enough to elastically tolerate the CTE mismatch without delam; or,
(2) this separation due to 'resin recession' is typical and is not a
reliability risk?  We and the customer are tending to go with (1).


Best regards,
Leo

Director of Applications Engineering
ASAT, Inc.
3755 Capital of Texas Highway, Suite 100
Austin, Texas     78704

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fx      512-383-1590
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-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Werner Engelmaier
Sent: Wednesday, October 19, 2005 6:15 PM
To: [log in to unmask]
Subject: Re: [TN] Delamination at Thermal Via area?


In a message dated 10/19/05 17:23:15, [log in to unmask] writes:
> Hi Leo!
>
> Your pics are up! Go to:
>
> http://www.stevezeva.homestead.com/files/Delam_in_Via.jpg
> http://www.stevezeva.homestead.com/files/Dalam_in_Via_Close.jpg
>
 Hi,
What this pics show is a classical case of 'resin recession.' It happens
with
PTV-barrels all the time; however, the term 'resin recession' is a misnomer.
During excursion to soldering T's, the polymeric fill will expand more than
the Cu-barrel and push the Cu-caps outward plastically deforming them. On
cooling, the resin 'recedes' to its original volume, the plastically
deformed Cu
cannot follow, and you have this classic case of 'resin recession.'


Werner

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