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Lead Free Acceleration Factors

Idea/Definition Information
Background: 

Numerous papers (Sahasrabudhe, Clech, Lau, others) indicate that ATC test conditions have a different effect on the results of SAC solder fatigue life than they do on SnPb solder fatigue life.

Problem: 

Acceleration factors for SAC and SnPb vary, depending on ATC test conditions, including dwell time and strain.  The lower creep rate of SAC (compared to SnPb) may lead to over-prediction of field life in ATC testing.  ATC is an imperfect predictor of field life.

Approach: 

A test assembly will be designed that includes a variety of different component sizes and types.  The test device will be assembled using two different types of lead free solder, and processed through a standard lead free assembly manufacturing line using typical process conditions.  ATC testing will be conducted according to an experimental design which varies dwell times and conditions.  Additionally, RTC Power Cycling will be conducted and results compared to ATC.