Finite element analysis of moisture induced thermo-mechanical delamination of semiconductor packages considering in-situ moisture desorption during reflow process

Abstract

Polymers are highly affected by moisture and temperature in terms of reliability of packaging. Especially, interface delamination between dissimilar materials with polymer is one of the major issues to the structural integrity and reliability, which is affected significantly by temperature and moisture concentration. In this paper, moisture absorption characteristics and thermo-mechanical delamination of semiconductor packages were predicted by finite element analysis considering moisture and temperature changes during the reflow process simultaneously based on a home-made user's subroutine. To implement the delamination through finite element analysis, moisture absorption experiments were conducted to evaluate hygroscopic properties (diffusivity, concentration) of the package material with different relative humidities (RH) and temperatures. In addition, adhesion strength of bi-material was evaluated by a micro-scale shear test. The measured adhesion strength of bi-material such as Epoxy molding compound (EMC)/Chip, Chip/substrate, and substrate/EMC were implemented in the user's subroutine with respect to the moisture concentration and temperature. The user's subroutine based finite element analysis code was developed to analyze the combined effect of hygroscopic and thermal deformation. As a result, interface delamination was successfully predicted considering the in-situ moisture desorption and temperature increase during the reflow process and interfacial failure strength considering the temperature and moisture concentration.