Package Induced Stress Simulation and Experimental Verification

Abstract:
During and after packaging mechanical stresses and deformations can be imposed on the active MEMS structures, which can have a large impact on the device performance, operating range and reliability. This effect can for example be assessed by coupled package and device modelling. To be able to assess this impact for molded sensors, parametric package models have been set-up, which can describe and quantify the mechanical stresses occurring during molding, temperature change and long term operation. Stresses, which build up after molding of a device (i.e. after post-mold cure), are sensitive with regard to the properties of the packaging materials (i.e. CTE, Young’s Modulus, glass transition temperature). For a reliable design, the question arises, which property has the largest impact and how the mechanical stresses can be reduced.