Date of Graduation

12-2017

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Electrical Engineering

Advisor

Homer Mantooth

Committee Member

Simon Ang

Second Committee Member

Gregory Salamo

Third Committee Member

Juan Balda

Fourth Committee Member

David Huitink

Keywords

3D Packaging, Electronics Packaging, Power Modules, Silicon Carbide, Wide Bandgap, Wire Bondless Packaging

Abstract

This dissertation advances the cause for the 3D packaging and integration of silicon carbide power modules. 3D wire bondless approaches adopted for enhancing the performance of silicon power modules were surveyed, and their merits were assessed to serve as a vision for the future of SiC power packaging. Current efforts pursuing 3D wire bondless SiC power modules were investigated, and the concept for a novel SiC power module was discussed. This highly-integrated SiC power module was assessed for feasibility, with a focus on achieving ultralow parasitic inductances in the critical switching loops. This will enable higher switching frequencies, leading to a reduction in the size of the passive devices in the system and resulting in systems with lower weight and volume. The proposed concept yielded an order-of-magnitude reduction in system parasitics, alongside the possibility of a compact system integration. The technological barriers to realizing these concepts were identified, and solutions for novel interconnection schemes were proposed and evaluated. A novel sintered silver preform was developed to facilitate flip-chip interconnections for a bare-die power device while operating in a high ambient temperature. The preform was demonstrated to have 3.75× more bonding strength than a conventional sintered silver bond and passed rigorous thermal shock tests. A chip-scale and flip-chip capable power device was also developed. The novel package combined the ease of assembly of a discrete device with a performance exceeding a wire bonded module. It occupied a 14× smaller footprint than a discrete device, and offered power loop inductances which were less than a third of a conventional wire bonded module. A detailed manufacturing process flow and qualification is included in this dissertation. These novel devices were implemented in various electrical systems—a discrete Schottky barrier diode package, a half-bridge module with external gate drive, and finally a half-bridge with integrated gate driver in-module. The results of these investigations have been reported and their benefits assessed. The wire bondless modules showed < 5% overshoot under all test conditions. No observable detrimental effects due to dv/dt were observed for any of the modules even under aggressive voltage slew rates of 20-25 V/ns.

Available for download on Saturday, August 01, 2020

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