Sintered Copper Ink as a Low Cost Replacement for High Temperature Solders

In hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs) that operate at elevated temperatures, an independent cooling loop is used to maintain the reliability of the power electronics, which otherwise would suffer from degradations related to the die-attachment method used in the power electronics. However, the elimination of this extra cooling loop for the power electronics would save on materials and production costs, and would increase overall efficiency. To achieve this goal, this project will develop a new die-attachment method by replacing the current solder materials with a copper nanoparticle ink that can be sintered to attach the dies in the power electronics. A sintered particle based approach can lead to a high-melting, high-conductivity, yet mechanically compliant material, potentially enabling a die-attachment that can endure millions of power cycles without an independent cooling loop. Phase I will be an experimental feasibility study of the ability of sintered copper ink to survive the demanding thermal and power cycling in HEV power electronics. Phase II will involve the development of the materials and processes required to produce, apply, and sinter the ink for die attachment. Commercial Applications and other Benefits as described by the awardee: A successful project would enable a low cost alternative to lead-free high-temperature solders, and would speed the commercialization of HEVs and PHEVs