Strain Rate-Dependent Interface Characterization for Pad Cratering Failure Study

In the realm of portable electronic devices, the adoption of advanced chip packaging technologies has become ubiquitous, exposing these devices to the risk of drop impact during daily use. Such impacts are common cause of reliability concerns, notably leading to interconnect failures that compromise the structural integrity between the chip package and the printed circuit board (PCB). A critical aspect of this failure mode is pad cratering, a phenomenon that occurs at the interface between the solder pad and the PCB substrate. Traditional research methods have been employed to understand, identify, and mitigate this issue. However, these methods come with challenges in accurately predicting and detecting pad cratering due to limitations in replicating complex real-world conditions and material interactions. This paper proposes an advanced approach by characterizing the strain rate-dependent parameters of the Cohesive Zone Model (CZM) to study the pad cratering problem more effectively. The CZM offers a robust framework for simulating crack initiation and propagation at the microscopic level, particularly at the critical interfaces of PCB materials. This research is devoted to the experimental characterization aimed at pinpointing these crucial CZM parameters by assessing the interface's mechanical behavior under varying strain rates. Our methodologies provide a quantitative and efficient means to evaluate the mechanical stress threshold of the pads under dynamic loading conditions, offering a significant stride towards mitigating pad cratering issues and enhancing the reliability of portable electronic devices.