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December 2001

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Subject:
From:
Werner Engelmaier <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 6 Dec 2001 11:19:17 EST
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Hi Gary,
Actually 'hole wall pullaway' describes what is physically happeningg about
as accurately as 'resin recession.'  What is happening is that during a
solder float the large thermal expansion of the resin will plastically deform
the PTH hole walls inward. During cooling, the resin returns to its former
geometry, while the Cu wall is plastically deformed and does not. That is the
reason why 'resin recession' is more common with thinner PTV plating and PTHs
without non-functional lands.
As you correctly point out, etchback is something entirely different.

Werner Engelmaier

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