Ralph,

Without addressing CB-100 in particular, here are three important factors to
consider when choosing a fill material for lead-free applications:

1) Z-axis CTE
2) Cu peel strength
3) Tg

Ideally, you want to minimize the CTE mismatch between the laminate and the
fill material. Peel strength becomes key in order to prevent separation
between the Cu and epoxy resin if you will be plating directly to the
surface of the filled via. Generally speaking, a higher Tg is better.

Stephen

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ralph Richart
Sent: Saturday, August 12, 2006 7:03 AM
To: [log in to unmask]
Subject: [TN] CB-100

Does anybody have any background on silver filled vias and its suitability
for Lead Free Assembly?  There are warnings in the literature about heat
excursions, and it seems that lead free assembly would make this worse.  I
found only one email in the archives about delamination associated with
filled vias, but never found any answers as to wether the filled vias were
the cause, and/or what to do about it.

Any insights are appreciated.

thanks

Ralph

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