Hi Richard,
Well, this notion may come from the Engelmaier-wild solder joint reliability
model for leaded components, where the stencil thickness appears in the
equation. This model appears imn a number of IPC documents. However, I can
tell you that this parameter is in the equation much more as a parameter to
balance the unit rather than a variable to actively influence reliability.
Also at the time of the development of the model, only 10 and 8 mil stencils
were in use.

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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