Fracture strength of photovoltaic silicon wafers cut by diamond wire saw based on half-penny crack system

Abstract

The fracture strength of photovoltaic silicon wafers is affected by factors such as slicing process parameters and saw wire parameters. This paper numerically simulates the process of diamond wire sawing silicon crystals combined with the linear elastic fracture mechanics. A mathematical analysis model has been established to calculate the fracture strength of diamond wire cut silicon wafers in the light of the half-penny crack system. The effect of cutting conditions and saw wire conditions on wafers' fracture strength, and the relationship between wafers’ fracture strength and subsurface micro-crack damage depth (SSD) were studied. The study results show that the numerical calculated values are equivalent to the experimental values of the reference, which proves the correctness of this model. It is found that the wire speed and the abrasive density are positively correlated with the wafers' fracture strength. The feed rate and the maximum size difference of the abrasives are inversely correlated with the wafers' fracture strength. When the ratio of wire speed to feed rate is constant, the wafers' fracture strength has no obvious change. And if the ratio becomes larger, the wafers' fracture strength will become larger. Besides, the wafers' fracture strength is not affected by the change in the abrasive size under the condition that the maximum size difference of abrasives remains unchanged and the wire inner diameter’s change. The SSD is inversely correlated with the wafers' fracture strength. The study results of this paper can provide theoretical guidance for parameter optimization in the sawing process and reduction of wafer breakage probability.