Reliability modeling of silicon or glass interposers to printed wiring board interconnections

Trend towards ultra-miniaturization of packages and systems has necessitated the use of high I/O interposers or packages made of either silicon or glass. However, both of these materials have low coefficient of thermal expansion (CTE) compared to organic boards, thereby raising interconnection reliability concerns when assembled directly on the organic system boards. This paper presents an approach to address these reliability problems by using novel build-up dielectrics with low Young´s Modulus to reduce the strains induced in the solder ball interconnections to the board. This proposed approach is compatible with surface mount technology and also helps the handling and metallization of thin silicon/glass substrates. Finite element method has been used to analyze the effectiveness of the compliant dielectrics, laminated onto silicon or glass substrates. Parametric study has been performed to analyze the influence of material properties and geometry parameters on the reliability of the SMT interconnections.