Increasing power dissipation by electronic devices requires matching improvements in the technologies used to cool them. Thermal management of electric vehicles poses additional challenges as on-board space is limited and cooling equipment must be compact and lightweight. Topology optimization software can be used to design high-efficiency heat sinks and cold plates with complex geometries, but these are difficult to manufacture using traditional methods. Thermal spray is a process in which a coating material (metal, ceramic, or polymer) is melted in a high velocity gas jet and sprayed onto a surface. It is widely used to apply protective coatings but can also be used an additive manufacturing technique to make devices for electronic cooling including heat sinks, heat pipes and cold plates.

Composite air-cooled heat sinks were made by spraying thin metal layers on polymer scaffoldings, producing lightweight devices that use only a minimal amount of metal where required. A large, flat copper heat pipe (180 mm × 180 mm × 3 mm in size) was made by spraying a porous copper wick on a copper plate that formed one surface of a sealed enclosure. The enclosed volume was evacuated and partially filled with water to form a heat pipe. Optimized, water-cooled heat sinks were made with 1 mm high internal flow channels. A topology optimization model was developed to generate a geometry for flow passages that minimized the temperature non-uniformity. A polymer mask was made by 3D printing with openings where the topology optimization model placed structures in the flow path. The mask was placed in a 74 mm × 51mm × 3 mm recess machined in an aluminum plate and aluminum sprayed over it. The mask was removed, the sprayed structures ground to a uniform height of 1 mm, and the top of the recess sealed by spraying metal. Tests showed that when a heat flux was applied the temperature gradients across the optimized cold plate were much lower than for a conventional cold plate with parallel channels.