MULTILAYER SUBSTRATE, ELECTRONIC DEVICE, AND A METHOD FOR MANUFACTURING A MULTILAYER SUBSTRATE

A multilayer substrate includes a base including insulating layers stacked on one another, a first principal surface, and a second principal surface, a heat transfer member extending through a first insulating layer nearest to the first principal surface, a second coefficient of thermal conductivity of a material of the heat transfer member is higher than a first coefficient of thermal conductivity of a material of the insulating layers, a first metal film adhered to the first principal surface, the first metal film overlapping the heat transfer member when viewed from the layer stacking direction, and a first joining member disposed between the heat transfer member and the first metal film and being made of a material with a coefficient of thermal conductivity which is higher than the first coefficient of thermal conductivity of the material of the insulating layers.