NUMERICAL APPROXIMATION OF THE ENERGY RELEASE RATE IN INTRINSICALLY STRESSED MICRO-SPRING STRUCTURES

摘要

A new highly compliant cantilevered spring interconnect is under development to enable a fine-pitch, high density I/O architecture for the next generation probing and packaging technology. These spring interconnects are developed using stress-engineered thin film layers with a gradient of intrinsic stress - relaxation of these intrinsic stresses causes the spring layers to curl up, forming the spring interconnects. These intrinsic stresses can have a peak magnitude upwards of the material's yield stress. Due to the high intrinsic stress in the spring layers, delamination of the spring layers from the substrate is of concern. This study applies the classical laminate plate theory approach to calculate the energy release rate for delamination propagation in an intrinsically stressed multilayered structure subject to a temperature change. The solution is formulated for a generic multilayered structure and an example using the formulation examines the effects of spring metal thickness, release layer thickness, and anisotropy in the intrinsic stress state for spring interconnect application.