Sukrut Prashant Phansalkar and Bongtae Han
Mechanical Engineering Department, University of Maryland, College Park, MD 20742, United States
For more information about this article and related research, please contact Prof. Bongtae Han.
Abstract:
Highly filled thermosets are widely used to encapsulate chips in the semiconductor packaging industry. A complete set of viscoelastic properties are required for package designs with optimum mechanical reliability. A novel test method, based on inert gas pressure, is proposed and implemented to measure the temperature-dependent viscoelastic hydrostatic creep compliance (or compressibility) of filled thermosets. The method utilizes linearly increasing pressure to mitigate a heat generation problem caused by instantaneous gas pressure application. The hereditary integral for the linear pressure application is derived, and the corresponding normal equations are developed to obtain the generalized Kelvin model constants analytically. The proposed method is implemented using an epoxy-based molding compound. Complete implementation schemes are described, and the compressibility master curve is presented. The validity of the proposed method is verified by supplemental long-term hydrostatic creep tests. The accuracy and repeatability of the proposed method are also discussed.
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