Experimental and Numerical Assessment of Board-Level Temperature Cycling Performance for Eutectic and Pb-free windows-Chip-Scale-Package (wCSP)

This paper examines the board-level solder joint reliability of UTAC's windows-chip-scale-package (wCSP) under temperature cycling (TC) condition, both experimentally and numerically. Five legs of wCSP test vehicles were assembled with different solder ball sizes, mold compound materials and solder materials, i.e., eutectic Pb-Sn and Sn3Ag0.5Cu. Those assemblies were subject to TC condition using UTAC internal TC chamber and data collection system. TC condition was specified using the widely used industry standard, which is -40degC-125degC with 15mins ramp/dwell. For the numerical study, Darveaux's approach, which uses Anand's viscoplasticity constitutive model plus fracture mechanics based fatigue model, was used for legs with eutectic 62Sn36Pb2Ag solders; while for Pb-free legs, various publicly available Pb-free constitutive and fatigue models were applied to evaluate their prediction capability

[1]  R. Darveaux Effect of simulation methodology on solder joint crack growth correlation , 2000, 2000 Proceedings. 50th Electronic Components and Technology Conference (Cat. No.00CH37070).

[2]  B.A. Zahn,et al.  Finite element based solder joint fatigue life predictions for a same die size-stacked-chip scale-ball grid array package , 2002, 27th Annual IEEE/SEMI International Electronics Manufacturing Technology Symposium.

[3]  A. Syed Accumulated creep strain and energy density based thermal fatigue life prediction models for SnAgCu solder joints , 2004, 2004 Proceedings. 54th Electronic Components and Technology Conference (IEEE Cat. No.04CH37546).

[4]  S. Wiese,et al.  Characterization of Lead-Free Solders in Flip Chip Joints , 2003 .

[5]  H. Reichl,et al.  Fatigue life models for SnAgCu and SnPb solder joints evaluated by experiments and simulation , 2003, 53rd Electronic Components and Technology Conference, 2003. Proceedings..

[6]  A. Dasgupta,et al.  Systematic Study on Thermo-Mechanical Durability of Pb-Free Assemblies: Experiments and FE Analysis , 2005 .