Determination of silicon die initial crack using acoustic emission technique

Three-dimensional chip stacking packaging has become increasingly popular in the electronic packaging industry because of the present market demand on high performance, high capacity and small form factor products. As a result, silicon wafers have to be ground through wafer-thinning processes to achieve greater packaging density. However, induction of cracks on the chips during stacking process or with the use of a device is possible. Therefore, the current research aims to determine the maximum allowable force on a (1 0 0) silicon die using ball-breaker test with an acoustic emission (AE) system. To compare with the experiment data, the finite element analysis was employed using commercial software ANSYS/LS-DYNA3D^® to determine the silicon die strength. The results show that the maximum allowable force for a 30 mm × 30 mm × 0.2 mm (1 0 0) silicon is 14.42 N. The value was introduced to simulation to determine the strength of silicon die. The strength of silicon die is 618 MPa, which is lower than that obtained from a previous research that conducted the ball-breaker test without an AE system, the allowable strength is defined as when silicon is fully cracked. The advantage of the method developed in this research is the AE system could detect the failure instantly and obtain the event of initial cracking. The modified ball-breaker test could avoid an overestimation in determining the die strength.