Bonding structure and bonding method of heat diffusion member, and cooling unit using the same

A cooling unit comprising:

• a first member having a plate shape and being made of a carbon-base material, the first member serving as a heat diffusion member that transfers heat at least in a thickness direction, which is perpendicular to a plane of the plate shape;
• a heat source disposed at a first side of the first member;
• a second member disposed at least at one of the first side and a second side of the first member;
• a cooler disposed at the second side of the first member for cooling the heat source;
• and
• a bonding member bonding the first member and the second member to each other, wherein:
• the first member has a metal thin film at least on an opposed surface that is opposed to the second member,
• the bonding member is disposed between the opposed surface of the first member and the second member,
• the bonding member is provided by a sintered body of metal particle,
• the heat diffusion member provided by the first member is a first heat diffusion member;
• the second member has a plate shape and is made of a carbon-base material, and
• the second member has a metal thin film at least on an opposed surface opposed to the first heat diffusion member and serves as a second heat diffusion member to transfer heat in the thickness direction.