Soft-Metal Packaging for Cryogenic-Resistant Power Modules
The Problem
Wire bond printed circuit boards (PCBs) and flex-PCBs need soft encapsulation material to remain flexible for stress relieving. However, there is no soft encapsulation material available for low temperatures, especially for cryogenic temperatures. Currently used materials, like silicone gel and epoxy resin, are ineffective during thermal cycling due to becoming brittle at low temperatures, resulting in increased inductance and parasitic loss. High parasitic loss at cryogenic temperatures means power modules are inefficient and lack durability in thermal cycling.
The Solution
Researchers at the University of Tennessee have proposed a new packaging method for power modules that remains flexible even at cryogenic temperatures. An indium layer of insulating material is directly soldered between the semiconductor die and direct bonded copper layer, resulting in lower loop inductance and better protection against power loss. This packaging method is also more compact than traditional methods. This technology will improve electric component performance and reduce parasitic loss in low temperature applications, such as eVTOL, space, quantum computing, data centers, and other cryogenic applications.
Proposed packaging for a single die (front view):
Benefits
| Benefit |
|---|
| >50% reduction in parasitic loss at cryogenic temperatures |
| Can withstand mechanical stresses of cryogenic thermal cycling |
| Compact, lightweight, and easy to manufacture design |
| Direct solder provides a low inductance connection to the semiconductor die |
| Encapsulant material properties do not change at cryogenic temperatures |
More Information
- Gregory Sechrist
- Technology Manager
- 865-974-1882 | gsechris@tennessee.edu
- UTRF Reference ID: 24156
- Patent Status:
Innovators
Dr. Hua "Kevin" Bai
Associate Professor, Min H. Kao Department of Electrical Engineering and Computer Science, UT Knoxville
Dr. Bai received his PhD in Electrical Engineering from Tsinghua University in Beijing, China in 2007. His research interests include EV related battery chargers, motor drive systems, and applications of wide-bandgap devices.
Read more about Dr. Hua "Kevin" BaiDr. Fei "Fred" Wang
Professor and Condra Chair of Excellence in Power Electronics, Min H. Kao Department of Electrical Engineering and Computer Science, UT Knoxville
Dr. Wang holds the Condra Chair of Excellence in Power Electronics and is a Professor in Electrical Engineering at The University of Tennessee. He is a founding member and the Technical Director of the NSF-DOE Engineering Research Center CURENT. He is conducting research on: design, modeling, control, and integration of advanced power electronics converters; motor drives; wide bandgap device characterization, modeling, packaging, control, and application; power electronics application to...
Read more about Dr. Fei "Fred" Wang