Effect of Thermal Cycling Ramp Rates on Solder Joint Fatigue Life

Solder joint fatigue life is commonly determined through accelerated tests by subjecting electronic assemblies to temperature cycling. These tests are time consuming and expensive, but essential in evaluating attachment reliability of packages to printed wiring boards. Faster thermal cycles can reduce the test times and lower the test cost, provided that the failure mechanism remains unaffected. The thermal cycle time is composed of dwell times at the high temperature (T sub (max)) and low temperature (T sub (min)) and the time taken to ramp between the temperature extremes. The dwell time allows for creep and stress relaxation of the solder joint. Therefore, cycle time can be reduced by decreasing ramp times which result in higher ramp rates.