SUBJECT: Ph.D. Proposal Presentation
BY: Chidinma Imediegwu
TIME: Friday, September 30, 2022, 4:00 p.m.
PLACE:, Online
TITLE: Diverse Package Design Approaches for Enhanced Cooling of Power Electronics Substrates
COMMITTEE: Dr. Samuel Graham, Co-Chair (ME)
Dr. Darshan Pahinkar, Co-Chair (ME)
Dr. Yogendra Joshi (ME)
Dr. Antonia Antoniou (ME)
Dr. Muhannad S Bakir (ECE)


Policies across the globe have engendered a push for more renewable and sustainable sources of power, including the electrification of automotive systems. Power electronics play a vital role in regulating the electrical power and waveforms between sources and loads, which is critical to the operation of the electrical drive train in vehicles. However, as devices become smaller and power densities increase, developing techniques to deal with the thermal loads and device reliability will become critical. To this end, a power package design has been developed that brings the thermal management features closer to the device by bonding the dielectric substrate directly to a heat sink of a similar coefficient of thermal expansion (CTE). This is accomplished via transient liquid phase (TLP) bonding, enhancing the thermo-mechanical reliability of the package and eliminating multiple material layers, thereby decreasing the thermal resistance of the assembly. This bond is thoroughly investigated for the composition and assessment of the TLP technique in bonding commercial substrates to low CTE cold plates as a packaging alternative, using experimental methods on various AlN, Al, and Cu substrates. These results are validated through numerical modeling. A complete analysis of the bond material composition, microstructure, and intermetallic phases across the various assemblies is presented. Methods to thermally manage the novel power electronics package using cooling enhancement features attached to or manufactured as an integrated part of the cold plate will be evaluated numerically and experimentally. An examination into possible manufacturing processes for the metal circuit layer atop the dielectric ceramic will be explored to support the development of a functional power package equipped with electronic devices and a cold plate. Finally, alternative approaches to cooling commercial substrates, including bonding DBC to metal foam, mini-channels, and pin-fins, are considered using a low-cost, high thermally conductive TLP substrate.