Stress and Reliability of Underfills in Heterogeneous Integration Fan-Out Multichip Module Packages

This study aimed to identify the most suitable underfill material for heterogeneous integration fan-out multichip module (HI-FOMCM) packages. ANSYS 3D finite element model (3D-FEM) analysis was used to simulate the bending stress of the underfills at the high bandwidth memory (HBM) chip corner. The results revealed that the storage moduli of underfill had notable effects on bending stress. The reduction of the relevant moduli effectively reduced the bending stress at the HBM chip corner. In addition, a comparison of stress–strain curves revealed that underfills with larger areas under the curves enabled the resulting chip module to withstand greater stress, thereby increasing the reliability and lifespan of products. On the basis of the results, a suitable underfill was selected and applied to chip modules.