The first insulating layer 32 and the third insulating layer 37 are each formed of a PET film. It is only required that a material for the first insulating layer 32 have insulating properties, and, for example, polyvinyl chloride and polypropylene may be used. The first insulating layer 32 includes a cutout portion 322, and a part of the surface of the first conductive layer 31 is exposed from the cutout portion 322. One surface of the first insulating layer 32 is caused to adhere to the first conductive layer 31 through use of an adhesive or a double-sided pressure-sensitive adhesive tape.

The first conductive layer 31 and the second conductive layer 36 are each formed of an aluminum sheet.

The second insulating layer 33 and the fourth insulating layer 38 are each formed of a double-sided pressure-sensitive adhesive tape including an insulating base sheet and pressure-sensitive adhesive layers formed respectively on both sheet surfaces of the base sheet. The second insulating layer 33 is bonded to the third insulating layer 37, and further, the fourth insulating layer 38 is mainly bonded to the insulating rear case 62 (FIG. 12). The second insulating layer 33 and the fourth insulating layer 38 are not required to have such high insulating properties as those of the first and third insulating layers 32 and 37. Therefore, the thicknesses of the base sheets of the second insulating layer 33 and the fourth insulating layer 38 may be smaller than those of the first and third insulating layers 32 and 37.