Comparison of Test Methods for Strength Characterization of Thin Solar Wafer

The Photovoltaic industry still tends towards thinner wafers with larger area leading to higher breakage rate in production processes. Strength characterization is needed in order to understand the fracture process and to optimize process steps. In this work different methods to measure the strength of photovoltaic wafer are presented and performed. Due to large deflection in experiment non-linear numerical methods must be used for strength evaluation. Besides the large influence of thickness variation it was found that the 4-point bending test and the ballon-ring test are appropriate test methods. In twist test calculating reliable fracture stress values in comparison to the fracture behavior was more difficult. This test method seems to be less suitable for strength characterization.