APL Prototype Heatsinks Aim for More Than 50% Less Size and Weight

Inside a retrofitted Pelican case, SPEAR heatsinks sit beside traditional metallic ones. At the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, engineers have built and tested initial units of a 3D-printed design that aims to reduce size and weight by more than 50% while maintaining thermal capacity.

SPEAR is derived from Smart Phase-change Enhanced Re-entry. Its core material is a PCM, or phase-change material: it absorbs and stores heat as it changes from one physical state to another. As the material moves from solid to liquid, it can take in heat without its temperature rising as quickly as a traditional metal heatsink's—much like ice melting in a drink keeps the drink cool.

Traditional phase-change heatsinks are made from complex assemblies of machined parts. Advances in additive manufacturing led the APL team to try a different route: a single-piece heatsink made in-house. The engineers began with a baseline aluminum heatsink, then manufactured two SPEAR designs for side-by-side testing. One had the same volume as the aluminum version; the other was designed to match its thermal capacity while showing the possible reduction in size and weight.

The SPEAR units were filled, sealed and tested with no leaks. An integrated test unit applied heat to several heatsinks at once and recorded the temperature changes in real time. APL says the comparison demonstrated the expected performance and benefits for SWaP constraints—size, weight and power—while its engineers handled the design, 3D printing, hardware, software and packaging themselves.

The approach is designed for systems where electronics generate a lot of heat over short periods but have limited ways to release it. A smaller, lighter heatsink with the same thermal capacity could help fit thermal management into hypersonic, space, radio-frequency, transmitter and interceptor systems. The claim remains at the prototype stage: APL reports initial in-house testing, while no field deployment or production is described.