Lead frame and method of manufacturing the same

A lead frame manufacturing method of manufacturing a lead frame including lead portions, which are extended from a frame portion toward an inside like a teeth of a comb and each of which has a top end portion, a center portion, and a base portion connected to the frame portion, by a stamping to use a die, comprising the steps of:

• forming a plurality of first opening portions, which are formed in almost parallel mutually and each of which includes a narrow center portion and curved both end portions, by punching predetermined portions of a metal plate by a first punch of the die;
• spreading the metal plate to an inside of the first opening portion by push predetermined portions of the metal plate near the center portion and at least a part of both end portions of the first opening portion by a second punch of the die so as to reduce a thickness of the metal plate;
• forming a plurality of second opening portions, which are formed in almost parallel mutually, by punching predetermined portions of the metal plate in outer peripheral portions of the first opening portions by a third punch of the die such that a width of the center portion and a width of the top end portion are defined, and that the center portion and the top end portion, the center portion and the base portion are connected via a first constriction portion and a second constriction portion respectively;
• and
• defining top end portions of the lead portions by punching predetermined portions of the metal plate, which connect the second opening portions mutually, by a fourth punch of the die;
• reducing a thickness of the top end portions by pushing the top end portions by a fifth punch of the die;
• and
• defining a width of the base portion by punching predetermined portions of the metal plate, which connect the second opening portions mutually, by a sixth punch of the die.