US Patent 10119770 Planar heat pipe

A planar heat pipe includes a container having a hollow portion provided at a central portion thereof with two opposing plate-shaped bodies, and a working fluid enclosed in the hollow portion. The hollow portion is provided with a wick structure. At least one of the plate-shaped bodies is a composite member of two or more types of metal members that are laminated and integrated. A metal member of the composite member forming a layer that contacts the hollow portion has a thermal conductivity of greater than or equal to 200 W/m·K and a metal member of the composite member forming a layer that contacts an exterior has a thermal conductivity of less than or equal to 100 W/m·K, a peripheral portion of the hollow portion being sealed.