Patent ID: 7637313

Claim:
A heat exchanger, wherein a plurality of substrates are stacked, the plurality of substrate having: a plurality of long plates arranged in parallel, the long plates extending longitudinally; slits disposed between the long plates, the slits extending longitudinally and continuously; and recesses longitudinally and continuously disposed in one-side of main surfaces of some of the long plates, the recesses being disposed in parallel to the long plates and the slits, the long plates of the adjacent substrates are interconnected to form tubes, the recesses form tube internal flow channels, the slits form tube external flow channels, holding plates for holding the long plates at the both ends of the long plates and long holes formed inside the holding plates are disposed on the substrate, extensions of the recesses formed in one-side main surfaces of some of the long plates communicate with the long holes, the long holes in the adjacent substrates are interconnected to form branch flow channels, and the tube internal flow channels formed of the recesses are connected to the branch flow channels.