Patent ID: 8314349

Claim:
A lead pin, comprising: a shaft portion; and a connection head portion provided to a top end side of the shaft portion, and having a diameter which is larger than a diameter of the shaft portion; wherein the connection head portion includes a bonding surface on an opposite side to the shaft portion side, and the bonding surface includes a flat surface provided in a center part, and extends to a convex surface which is provided in substantially a first ring shape at an outer periphery of the flat surface such that the flat surface is continuous with and smoothly joins the convex surface, wherein a peripheral edge of the flat surface and an inside edge of the convex surface meet at an identical height position and the flat surface does not protrude from the convex surface, the convex surface having a rounded portion with a radius R in substantially a convex shape, the convex surface extending from the peripheral edge of the flat surface to an inclining surface which is provided in substantially a second ring shape at an outside of the convex surface and a height of the inclining surface is lowered toward an outside gradually, the inclining surface widening toward the outside gradually, and wherein a diameter of the flat surface is larger than a diameter of a shaft portion.