The first base insulating layer 26 is, for example, formed of an insulating material such as a synthetic resin. Examples of the synthetic resin include polyimide resin, polyamide imide resin, acrylic resin, polyether nitrile resin, polyether sulfone resin, polyethylene terephthalate resin, polyethylene naphthalate resin, and polyvinyl chloride resin. Preferably, the first base insulating layer 26 is formed of polyimide resin.

To be specific, the first base insulating layer 26 has a thickness of, for example, 1 μm or more, or preferably 3 μm or more and, for example, 30 μm or less, or preferably 15 μm or less.

The second base insulating layer 27 is disposed on the metal supporting board 8 so as to cover the first base insulating layer 26. The second base insulating layer 27 includes a main body portion-insulating layer 31 corresponding to the main body portion 13 and a gimbal portion-insulating layer 32 corresponding to the gimbal portion 14.

The main body portion-insulating layer 31 is formed so as to correspond to the conductor layer 10 (to be specific, the external terminals 57 and wires 60 to be described later) of the main body portion 13 shown in FIG. 1.

As shown in FIG. 2, the gimbal portion-insulating layer 32 includes a board opening portion-insulating layer 34 corresponding to the board opening portion 16, a mounting portion-insulating layer 35 corresponding to the mounting portion 18, and the bridged portion 36.