A film substrate with flexibility includes connection through holes and combining through holes into which connection posts and combining posts of the header are inserted, respectively. Each connection pad is formed around a corresponding connection through hole and adapted to be electrically connected to a corresponding connection post. Each combining pad is formed around a corresponding combining through hole and adapted to be electrically connected to a corresponding combining post. The film substrate includes slots each of which is formed to extend along a plane of the film substrate with a first end side thereof connected to a corresponding through hole. The film substrate includes pad-free parts with neither connection pad nor combining pad each of which is present at a second end side of a corresponding slot on the surface of the film substrate.