Solder fatigue reduction in point focus photovoltaic concentrator modules

Solder fatigue tests have been conducted on point focus photovoltaic concentrator cell assemblies to identify a baseline fatigue life and to quantify the fatigue life improvements that result using a copper-molybdenum-copper low-expansion insert between the solar cell and copper heat spreader. The Coffin-Manson and total strain fatigue models for low-cycle fatigue were evaluated for use in fatigue life predictions. Since both of these models require strain calculations, two strain calculation methods were compared: hand-calculated shear strain and a finite element method shear strain. At present, the available theoretical models for low-cycle solder fatigue are limited in their ability to predict failure