Design and reliability analysis of a novel wafer level package with stress buffer mechanism

Abstract To enhance the reliability of the wafer level package (WLP) for larger chip sizes, WLPs with a compliant layer under the pads have to relieve the thermal stress on the solder joint. Usually, the thicker the stress compliant layer, the better the reliability. However, the fabrication process restricts the thickness. With that in mind, this paper proposes a novel WLP with a bubble‐like buffer mechanism, which is composed of a bubble‐like plate and a buffer layer. The main goal is to study the effects of both the geometric dimensions and material properties of the bubble‐like layer on the packaging reliability. For parametric analysis, a 2‐D non‐linear finite element analysis (FEA) is conducted. Furthermore, the experimental results are compared in order to verify that the adopted FEA procedures are reliable.

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