CSL-Fabricated Advanced Microchannel Coolers

The Department of Energy and NREL are in an aggressive, ongoing effort to increase efficiency of next-generation hybrid electric vehicles (HEVs), with a key challenge in this effort being the thermal packaging of the electric propulsion system power electronics. Eliminating the secondary cooling loop that is used in current thermal packaging schemes for these systems will result in savings of both weight and cost to the HEV. Additionally, novel packaging architectures such as ceramic microchannel cooling designs are of interest due to their much higher heat flux handling capability than current cooling architecture. Technology Assessment & Transfer, Inc. proposes to use a unique fabrication process, Ceramic Stereolithography (CSL), to fabricate monolithic, integrated, CTE-matched aluminum nitride (AlN) manifold/microchannel cooling modules for HEV power inverters. Various surface metallization techniques will be tested to provide optimum thermal contact, and therefore very high heat transfer, when the power die is directly attached with Au/Sn solder. Commercial Applications and Other Benefits: CSL-fabricated AlN microchannel coolers will provide for a high-efficiency, more cost-effective HEV that will reduce vehicular emissions. The CSL process is based on rapid prototyping, and allows for easy tailoring of the microchannel geometry based on application and size of the power electronics, which translates to quick turnaround on prototypes with little to no tooling. CSL is also inherently scalable (build several parts simultaneously) for future production. In addition to cooling in HEVs, future applications also include uninterruptible power supplies, electric actuators for aircraft, electric propulsion systems for ships, locomotive propulsion systems and distributed power generators