ELECTRONIC PART

PURPOSE:To obtain the film-thickness state of uniform and sufficient amount of solder conformable metal by forming both upper and lower surfaces at the center of a planar lead in a recess shape so that the size of the thickness of the plate of the planar lead in the width direction becomes thick at both end parts in comparison with the central part. CONSTITUTION:A planar lead 1 is formed so that both upper and lower surfaces of the center of the planar lead 1 are depressed in the recess shape. The size of the thickness of the plate of the lead 1 in the width direction is set beforehand so that both end parts 1B gradually become a thick size H in comparison with a size (h) at the central part. The surface of the lead 1 is formed so as to have the recess curve shape gradually so that the planar lead 1 gradually approaches the surface of a solder 2, which is to become the curved shape. Therefore, the surface of the solder is gradually pulled against the surface tension to the side of an end part 1B from a central part 1A by the wettability of the surface of the lead 1. Thus, the solder 2 is plated to corner parts 1C on the entire surface. In this way, the rigid mounting strength of the solder 2 can be obtained.