Thermal Heat Path Signature of a Standard D2PAK Power Package by Transient Thermal Characterization and Modelling

The miniaturization of electronic devices with enhanced performance comes at the cost of thermal challenges. When a device fails, it is necessary to analyze and isolate the failure in the device. A non-destructive analysis of the device is always preferred over a destructive one. Apart from being cost-effective, the non-destructive analysis also helps us to perform more than one analysis technique on the same device to verify our conclusion regarding the failure of the device.A well-established and suitable method to investigate the thermal performance of active devices like MOSFETs is the transient thermal analysis. Here, the thermal step response of the system is generated and from this the structure function is calculated. Structure functions are direct models of one-dimensional heat flow. They represent the thermal impedance of a Cauer network and thus represent the thermal signature of the heat path for the physical structure.This work aims to demonstrate the application of transient thermal measurements to various commercially available electronic power packages D2PAK, differing in their power ratings and therefore internal architecture and thus heat path, so they are ideally suited as a benchmark for a to perform a detailed interpretation of the obtained structure functions. Various thermal interface materials are used to vary the overall thermal impedance of the assembly systematically and controllably. X-ray tomography, cross-sectioning and EDX were performed from the same packages to determine the geometrical parameters and the materials included for the construction of a finite element models model. The results of the experimental measurements are validated with the results of FEM to evaluate the interpretation of the heat path signature.