Regis:
        Most of the Reliability data generated from LLTC is individual
company Proprietary information , I can share what I have with you . I
have been LLTC testing microvia materials and soldermasks for over two
years , and can tell you that the system in total contributes to
failure, some soldermask/dielectric combinations begin to show cracks
in the soldermask in as little as 50 cycles ( + 125C to -25C ) with
electrical failures in 100 cycles, others form visible cracks at 1500
cycles with  no electrical failures even at 3500 cycles.
        In general if failures occur they occur very early in the
thermal cycle process due to bad via manufacture, ( Residues and
insufficient copper contact) or geometrical phenomena, or failures do
not occur even after several thousand cycles .
        A point to remember is that if properly manufactured the via is
metallurgically the same as the rest of the copper on the board and with
no entrainment of material or gases due to manufacture, or no residues
on the interface the Via is actually more sound than a thru hole.

        I have the ability to run some in LLTC should you need a few
samples processed

        I have more information but it is product and manufacture
specific in nature and might tend to be construed as commercial in
orientation . I would be happy to discuss product specifics directly
with you while we continue generic , Microvia specific items here on the
net for all to enjoy.

Russell Smith
Ciba Specialty Chemicals
407-291-2333
or page at 1-800-759-8888
pin # 2126080
.


 ----------
From: Regis Froats
To: [log in to unmask]
Subject: [TN] LLTC Testing for Micro-vias
Date: Monday, January 11, 1999 11:46AM

        Does anyone have, or know where I can find data on liquid to
liquid
thermal reliability testing of micro-vias?

 --
Regis Froats <[log in to unmask]>
Process Engineer - Herco Technology Corp.
13330 Evening Creek Drive North
San Diego, Ca. 92128
Pho:619.679.2800 - Fax:619.679.7565

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