Metallographic Preparation of Solar Cell Samples for Quality Assurance and Material Evaluation

Wafer-based PV modules, which accounted for 87% of the market in 2010 [1], include soldered cell strings. Yet, soldering is a critical process for the production yield because it introduces severe thermo-mechanical stress into the cell. The quality of solder joints will determine a module's reliability over its 20-25 years lifetime. The purpose of this work is to present a metallographic preparation method and the corresponding characterization of solder joints. These methods may be used for qualification of initial and aged joints thus providing an off-line quality control tool in the manufacturing of cell strings for PV modules. It is also an effective method in the development of new cell and module designs and in the evaluation of new materials.