Heat transport device and method for manufacturing same

A method of manufacturing a heat transport device, the method comprising:

• a first plastic working process of performing first plastic working with respect to a first flat plate to form a processed plate, the processed plate having first and second main surfaces outwardly opposite to each other, a plurality of first recesses being formed at the first main surface of the processed plate, a plurality of second recesses being formed at the second main surface of the processed plate;
• a first joining process of:
• joining a second flat plate to the first main surface of the processed plate to cover the plurality of first recesses;
• joining a third flat plate to the second main surface of the processed plate via a first spacer to cover the plurality of second recesses;
• and
• forming a first flow passage plate having a first set of flow passages in the plurality of first recesses and the plurality of second recesses, the first flow passage plate being configured with the processed plate, the second flat plate, the third flat plate, and the first spacer;
• a second plastic working process of performing second plastic working with respect to the first flow passage plate to form a second flow passage plate, a plurality of third recesses being formed in a third main surface of the second flow passage plate by the second plastic working, the first set of flow passages being deformed by forming the plurality of third recesses;
• a repeating process of repeating the first plastic working process, the first joining process, and the second plastic working process to form a plurality of the second flow passage plates;
• and
• a second joining process of joining the plurality of the second flow passage plates together via a plurality of second spacers such that one of the plurality of second spacers is placed between two adjacent second flow passage plates of the plurality of the second flow passage plates, a second set of flow passages being formed in a plurality of gaps, each of the plurality of gaps being formed by being enclosed with two adjacent second flow passage plates of the plurality of the second flow passage plates and one of the plurality of second spacers.