Coating structure, heat exchanger, and method for manufacturing heat exchanger

A coating structure is provided with a metal-made substrate (1), an undercoating (2) provided on the substrate, and an insulating film (3) provided on the undercoating. The insulating film has a plurality of films (31, 32) comprising mutually different materials, and the plurality of films are layered in alternating fashion. The undercoating is formed by a method other than a coating method which uses a surface chemical reaction occurring on the substrate, and the portion of the undercoating in contact with the substrate is amorphous. Through this configuration, even when foreign matter adheres to the substrate, the foreign matter can be covered by the undercoating. Providing the insulating film on the undercoating makes it possible to inhibit foreign matter from causing defects in the formation of the insulating film. 涂层构造具备金属制的基材(1)、设于基材上的基底(2)以及设于基底上的绝缘膜(3)。绝缘膜具有由彼此不同的材质构成的多个膜(31、32)，多个膜交替地层叠。基底通过采用在基材上发生的表面化学反应的涂层方法以外的方法形成，在基底中，与基材接触的部位是非结晶的。由此，即使在基材上附着有异物的情况下，也能够通过基底覆盖异物。并且，在该基底上设置绝缘膜，从而能够抑制由异物产生的绝缘膜的形成不