We propose an advanced thermal-moisture analogy scheme to cope with the inherent limitations of the existing analogy schemes. The new scheme is based on the experimentally observed unique hygroscopic behaviour of polymeric materials used in microelectronics; i.e., the saturated concentration is only a function of relative humidity regardless of temperature. A new analogy formulation based on the modified solubility is presented and the scheme is implemented to investigate its accuracy and applicability. The results from a simple case study corroborate that the advanced scheme can be used effectively for package assemblies subjected to general an-isothermal loading conditions.

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