Patent ID: 8264841

Claim:
A heat sink for use with an electronic device, the heat sink comprising: a structure formed of thin plates that are successively stacked one upon another and directly bonded to each other, some of the successively stacked thin plates being etched so that a water channel is formed within the structure, wherein, each of the successively stacked thin plates is made of a single metal material, water in the water channel is substantially exposed only to the single metal material, and the successively stacked thin plates include, in this order, at least (i) a mounting thin plate onto which the electronic device is mounted, (ii) a first radiator-fin thin plate having a first plurality of radiator fins and a first intermediate water channel formation part, (iii) an intermediate thin plate having only (a) a second intermediate water channel formation part and (b) a first exhaust water channel formation hole, a position of the second intermediate water channel formation part in the intermediate thin plate corresponding to a position of the first plurality of radiator fins in the first radiator-fin thin plate, (iv) a second radiator-fin thin plate having (a) a second plurality of radiator fins, (b) a third intermediate water channel formation part, (c) a first supply water channel formation hole, and (d) a second exhaust water channel formation hole, the third intermediate water channel formation part being formed about an island portion in the second radiator-fin thin plate, the second exhaust water channel formation hole being formed in the island portion, and the first supply water channel formation hole being formed partially in the island portion so that water entering through the first supply water channel formation hole is then directed into the third water channel formation part formed about the island portion, (v) a bottom plate having (a) a second supply water channel formation hole and (b) a third exhaust water channel formation hole, wherein: (1) the second supply water channel formation hole in the bottom plate and the first supply water channel formation hole in the second radiator-fin thin plate form a water supply channel, (2) the third intermediate water channel formation part in the second radiator-fin thin plate, the second plurality of radiator fins in the second radiator-fin thin plate, the second intermediate water channel formation part in the intermediate thin plate, the first intermediate water channel formation part in the first radiator-fin thin plate, and the first plurality of radiator fins in the first radiator-fin thin plate form an intermediate water channel through which water flows after passing through the water supply channel, and (3) the first exhaust water channel formation hole in the intermediate thin plate, the second exhaust water channel formation hole in the second radiator-fin thin plate, and the third exhaust water channel formation hole in the bottom thin plate form an exhaust water channel through which water flows after passing through the intermediate water channel.