Cold-sprayed aluminum capacitors on leadframes for 3D power packaging

Abstract

Size and weight have always been key concerns for power supplies. Today’s approaches of manufacturing integrated power electronics building block modules with the assembly of pre-packaged devices and low-volumetric density capacitors and inductors create major fundamental system integration limitations in reaching high power densities and efficiencies to meet the target SWaP-C (size, weight and performance with low cost). Cold-sprayed aluminum capacitors on leadframe metal foils are demonstrated for the first time for applications in 3D power package integration. This additive manufacturing process allows low-temperature processing of pre-patterned aluminum electrodes on metal lead-frames, insulated metal substrates or even heat-spreaders and cold-plates. Process optimization of cold-spray technologies requires careful study of particle velocity, deposition atmosphere and particle morphology design. Initial process design led to ~22X enhancement in surface area compared to planar capacitors. With further process design and optimization, this approach can extend to above 100X enhancement. Cold-sprayed capacitors are projected to eliminate several process integration and reliability issues that are associated with traditional discrete surface-assembled capacitors.