There is a growing trend towards using thinner wafers in order to reduce the costs of solar energy. But the current tools employed during the solar cells production are not prepared to work with thinner wafers, decreasing the industrial yield due to the high number of wafers broken. To develop new tools, or modify existing ones, the mechanical properties have to be determined. This paper tackles an experimental study of the mechanical properties of wafers. First, the material characteristics are detailed and the process to obtain wafers is presented. Then, the complete test setup and the mechanical strength results interpreted by a described numerical model are shown.

Monocrystalline silicon wafers are widely used in photovoltaic industry. The trend towards thinner wafers leads to higher breakage rates in the production process. In this context, the characterization of the mechanical strength becomes necessary. Different fracture tests as the ring/ball on ring are carried out. This paper presents different ways to simulate these tests. Analytical methods are applied in a first step. Simplified FE models (with shell elements and an axisymmetric model) that take into account non linearities existing in the test are presented and a 3d solid model is detailed. Results in terms of calculation time, stress distribution, adjustment to the tests and fitting to a Weibull distribution are compared.

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