Computer modeling methodhas been used to study the relationship between the material properties and geometry parameters of a flip-chip and its long term reliability under cyclic thermal loading. The material properties and geometry parameters that have been investigated are the Young's modulus and coefficient of thermal expansion of the underfill, the out-of-plane coefficient of thermal expansion of the substrate, the thickness of the substrate and the standoff height. A multi-physics software have been used to analyse a 3D model od the flip-chip and calculate the fatigue failure indicator, the accumulated effective inelastic strain. The life-time of the flip-chip has also been calculated using a Coffin-Manson empirical relationship. The flipchip has a micro-via design and it has been found this has greatly affected the reliability of the chip.
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