Hi,
There is a lot of mis-information floating around on filled vs unfilled
plated- through vias (PTVs).
Completely filled PTVs are the most reliable, partially filled PTVs the least
reliable, and unfilled PTVs less reliable than completely filled PTVs, but not
by much. However, since nobody can guarantee that all PTVs in a MLB will be
completely filled with solder, it is much better to prevent solder filling to
avoid the occurence of partially filled PTVs.
Having said all that, it must be pointed out that all of this is only an issue
of practical importance if the product application has an operating
environment with some severity.

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]

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