US Patent 7234231 Method of manufacturing a lead frame

A manufacturing method of an optical coupling device includes, preparing an elongated lead frame on which a plurality of tie bars are placed between a pair of side rails that are mutually in parallel with each other so as to orthogonally cross the tie bars, with a plurality of lead terminals being placed in a staggered form in a manner so as to orthogonally cross the tie bars, and laterally cutting the elongated lead frame to prepare a plurality of strap-shaped lead frames, in such a manner that the length of protrusion of a cut end of each of the side rails from each of the tie bars is made longer than the length of protrusion of a lead terminal from each of the tie bars.