Heat sink

A heat sink comprising:

• a container in which a cavity is formed, the container having a first principal surface and a second principal surface opposite the first principal surface;
• a working fluid encapsulated in the cavity, and
• a steam flow path defined in the cavity and through which the working fluid in a gas phase flows, wherein
• the container has a flat portion and a protruding part projecting in an external direction from the flat portion,
• an inner space of the protruding part of the container is in communication with an inner space of the flat portion to form the cavity,
• the protruding part of the container includes a heat receiver that is to be thermally connected with a heating element that is a cooling target, and
• the flat portion of the container has an intermediate portion region continuous from the protruding part and a heat radiator region more distant from the protruding part than the intermediate portion region and thermally connected with a heat radiating fin.