Abstract: A mounting region is provided at a substantially center of one surface of an insulating layer. A metal layer is provided on the other surface of the insulating layer. A slit is formed to cross a region (an opposite region) of the metal layer that coincides with the mounting region and to divide the metal layer. A plurality of regions (large regions) of the metal layer divided by the slit each include a partial region (small region) of the opposite region. The area of each large region is set corresponding to the area of the small region included therein. Specifically, the small region having the area of A [%] with respect to the whole area of the opposite region is included in the large region having the area of (A±?) [%] with respect to the whole area of the metal layer. Here, ? is an acceptable error range, and the acceptable error range ? is not more than (A×0.3).