Verification of ball-on-ring test using finite element analysis

The ball-on-ring (BOR) test is an effective technique used to characterize the biaxial fracture strength of brittle materials. In particular, damages induced by wafer backgrinding process can be evaluated using the BOR test. It is difficult to measure directly the radius of contact area between the loading ball and a specimen, which is needed for stress determination by an analytic solution. In this study, parametric finite element analyses were performed to compare with known closed-form solutions. It was found that the effect of small loading area must not be ignored and that the radius of contact could be precisely determined using Hertz´s contact theory. This can serve as a guideline to accurately obtain the fracture strength of a BOR specimen.