That is what I initially thought, but didn't Franklin mean Cu filled via???



Vladimir



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

From: TechNet <[log in to unmask]>

To: [log in to unmask] <[log in to unmask]>

Sent: Tue Mar 18 22:44:41 2008

Subject: Re: [TN] How much stress is needed?



Hi Franklin,

You describe a classic via barrel crack—comes from the thermal expansion 

mismatch between the ED copper and the PCB resin in the z-direction during the 

soldering processes [the hotter the worse—read lead-free] [you should be taking 

my workshop on the subject at IPC EXPO/APEX on the morniong of March 31.



Regards,

Werner Engelmaier

Engelmaier Associates, L.C.

Electronic Packaging, Interconnection and Reliability Consulting

7 Jasmine Run

Ormond Beach, FL 32174 USA

Phone: 386-437-8747, Cell: 386-316-5904

E-mail: [log in to unmask], Website: www.engelmaier.com







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