DEVELOPMENT OF AN ACCURATE THERMAL MODEL TO BE USED FOR THE EVALUATION OF POWER BIPOLAR TRANSISTOR JUNCTION TEMPERATURE IN AUTOMOTIVE APPLICATION

The objective of this thesis is to perform electrical and thermal measurements of a DPAK Silicon Power Bipolar Transistor for Automotive application, aiming to characterize a thermal model to be used in 3D CATIA-FLoEFD software. The determined thermal model of the BJT will then be useful in order to obtain a correct interpretation of the heat distribution generated by all the components that are integrated in the PCBs, which constitute the brains of the Rear Lamps. The first chapter will provide a brief introduction of the Marelli Automotive Lighting Company, while the following chapters are going to introduce some fundamental principles regarding the heat transmission, the physical behavior of the Power Bipolar Transistor and its thermal characterization when inserted into its discrete package. The final chapters will present the thermal problem related to the power DPAK that was encountered by the Company and its resolution, passing through various steps and electrical/thermal measurements with the help of different instrumentation and softwares. Real measurements, accompained by some logical understandings, will allow to simulate correctly, in the CFD simulation software, the thermal behavior of the considered Transistor when integrated in PCBs used inside Rear Lamps.