Power core (PC) Embedding a Plurality of IC Devices and Sandwiched Between Two Dissimilar Insulated Metal Substrates (IMS’): Predicted Thermal Stresses

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Journal of Materials Science: Materials in Electronics

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Power core (PC) sandwiched between two insulated metal substrates (IMS) and embedding active and passive integrated circuit (IC) devices is currently viewed as an attractive advanced packaging option having a strong potential in the automotive industry and beyond. A natural reliability concern, however, is the level of the thermally induced stresses in a tri-material assembly of the type in question. Accordingly, an analytical (mathematical) stress model is developed for the evaluation of these stresses. The stresses include normal stresses acting in the cross-sections of the assembly components, and the interfacial shearing and peeling stresses acting at the interfaces of these components and at the interfaces of the embedded IC devices. The model can be helpful in the stress-analysis and physical design of the assemblies, in which the PC is sandwiched between two IMS’. It can be used also in other areas of engineering, where tri-material assemblies comprised of dissimilar materials and subjected to the change in temperature are employed. The general concepts are illustrated by a detailed numerical example. The analysis is an extension of the study carried out earlier for a bow-free assembly. It is noteworthy that although the calculations are carried out for the case when the assembly is cooled down from an elevated temperature to a low temperature, since a linear approach is used and the stresses are proportional to the change in temperature, whatever its sign or the magnitude is, the developed model is equally applicable to any change in temperature.



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