Development of Equivalent Material Properties of Microbump for Simulating Chip Stacking Packaging

Materials

Chang-Chun Lee¹  Tzai-Liang Tzeng²  Pei-Chen Huang² 

[1] Department of Mechanical Engineering, Research Center for Microsystem Engineering, Chung Yuan Christian University, 200 Chung Pei Road, Chung Li District, Taoyuan City 32023, Taiwan;

关键词: 3D-IC packaging;    microbump interconnect;    finite element analysis;    equivalent material properties;    analysis of variance;   

DOI  :  10.3390/ma8085121

来源: mdpi

【 摘 要 】

A three-dimensional integrated circuit (3D-IC) structure with a significant scale mismatch causes difficulty in analytic model construction. This paper proposes a simulation technique to introduce an equivalent material composed of microbumps and their surrounding wafer level underfill (WLUF). The mechanical properties of this equivalent material, including Young’s modulus (E), Poisson’s ratio, shear modulus, and coefficient of thermal expansion (CTE), are directly obtained by applying either a tensile load or a constant displacement, and by increasing the temperature during simulations, respectively. Analytic results indicate that at least eight microbumps at the outermost region of the chip stacking structure need to be considered as an accurate stress/strain contour in the concerned region. In addition, a factorial experimental design with analysis of variance is proposed to optimize chip stacking structure reliability with four factors: chip thickness, substrate thickness, CTE, and E-value. Analytic results show that the most significant factor is CTE of WLUF. This factor affects microbump reliability and structural warpage under a temperature cycling load and high-temperature bonding process. WLUF with low CTE and high E-value are recommended to enhance the assembly reliability of the 3D-IC architecture.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.