FEM Analysis on Mechanical Stress of 2.5D Package Interposers

概要

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As data transmission rate increases, flip chip plastic ball grid array (FCPBGA) utilizing an interposer for multiple chips is gaining prominence because of high performance. The authors assessed interposer configurations with a set of chip and package assumptions and obtained key parameters for mechanical analysis. The authors studied warpage of interposer, first principal stress in the dielectric layer under the controlled collapse chip connection (C4) bump pad, and von Mises stress at the solder joint between interposer and organic substrate with Si, glass, and organic interposers. The analysis results indicate that the stress under the C4 bump is very low with Si or glass interposer compared to conventional FCPBGA. Also, the results indicate that glass interposer with coefficient of thermal expansion (CTE) of 6 ppm/°C has approximately 30% lower stress than Si interposer at the solder joint between the interposer and the organic substrate.