Hi Werner,



What about some consideration for the HAL or solder prep. ? It is known to 
etch" away some of the copper.. thus reducing eventually the thickness of
the barrel at its weakest places ?



Very Best Regards - Roland



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-------Message original-------



De : TechNet E-Mail Forum.; [log in to unmask]

Date : mardi, 01. octobre 2002 23:06:46

A : [log in to unmask]

Sujet : Re: [TN] PCB design with mask over vias.



Hi Rick,

I have seen no evidence, nor do physics-of-failure considerations suggest

there should be any, that there is an "increase in PTV barrel strength by

filling the hole with solder." PTV interconnect structures can suffer 2
major

failure modes: (1) barrel fracture, and (2) inner-layer separation [ILS].

Barrel fracture: I have seen no evidence, nor do physics-of-failure

considerations suggest there should be any, that there is an "increase in
PTV

barrel strength by filling the hole with solder" regarding this failure mode


ILS: Filling the PTV barrel does strengthen the PTV barrel radially--it thus

can resist the compressive loads from the resin thermal expansion trying to

collapse the barrel. There is both experimental evidence and analytical

reasons; however, I have not seen an analysis yet quantifying this effect.



Werner Engelmaier

Engelmaier Associates, L.C.

Electronic Packaging, Interconnection and Reliability Consulting

7 Jasmine Run

Ormond Beach, FL 32174 USA

Phone: 904-437-8747, Fax: 904-437-8737

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



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