Evaluation of Fatigue Crack Propagation Rate at the Interface between Si Die and Underfill in Real Semiconductor Package Structures

Abstract

In this study, fatigue crack growth rate at Si/UF interface was evaluated by four-point bending fatigue crack growth tests. At the bottom of the Si die, the fatigue crack growth behavior was similar to that of the UF bulk, in which the transition from the threshold to steady-state crack growth was observed. The power exponent of the Paris law in the steady-state region was similar to that of the UF bulk, and the fatigue crack growth rate was different between the side and bottom of the Si die. These results suggest that the fatigue crack growth behavior at the interface strongly depends on the surface roughness of the Si die and the manufacturing process of underfilling.