Method and apparatus for manufacturing lead frames

Claim 1

A method of manufacturing lead frames in the form of a continuous strip comprising the steps of: blanking strip metal stock to form a succession of side-by-side lead frame blanks, each of said blanks comprising a mounting plate portion and three leads extending transversely with respect to the axis of said strip, the center one of said leads being connected to one edge of said mounting plate portion by a connecting strap portion, the outside ones of said leads each having a contact arm on its inner end, said arms extending in opposite directions along the length of said strip, said leads being connected to each other by integral tie bar means, bending said arms laterally of the plane of said strip, bending said connecting strap at a location remote from said one edge to swing said leads in one direction along an arcuate path and to orient said leads in a plane extending transversely of the plane of said strip with said arms disposed on one side of said mounting plate portion and with the free ends of said leads disposed on the side opposite to said one side, further forming said arms substantially to their final configuration, and bending said connecting strap at a location proximate to said one edge of said mounting plate portion to swing said leads along an arcuate path in a direction opposite to said one direction and orient said leads in a plane which is parallel to, and spaced from, the plane of said strip with said arms between said planes.

Claim 2

A method of manufacturing lead frames in the form of a continuous strip comprising the steps of: blanking strip metal stock to form a succession of side-by-side lead frame blanks, each of said blanks comprising a mounting plate portion and three leads extending transversely with respect to the axis of said strip, the center one of said leads being connected to one edge of said mounting plate portion by a connecting strap portion, the outside ones of said leads each having a contact arm on its inner end, said arms extending in opposite directions along the length of said strip, said leads being connected to each other by integral tie bar means, bending said arms laterally of the plane of said strip, bending said connecting strap at a location remote from said one edge to swing said leads in one direction along an arcuate path and to orient said leads in a plane extending transversely of the plane of said strip with said arms disposed on one side of said mounting plate portion and with the free ends of said leads disposed on the side opposite to said one side, further forming said arms substantially to their final configuration, and bending said connecting strap at a location proximate to said one edge of said mounting plate portion to swing said leads along an arcuate path in a direction opposite to said one direction and orient said leads in a plane which is parallel to, and spaced from, the plane of said strip with said arms between said planes.

Claim 6

A method of manufacturing lead frames in the form of a continuous strip comprising the steps of: blanking strip metal stock to form a succession of side-by-side lead frame blanks, each of said blanks comprising a mounting plate portion and three leads beside said mounting plate portion, said leads extending transversely of the axis of said strip, the center one of said leads being connected to one edge of said mounting plate portion by a connecting strap portion, the outside ones of said leads having inner ends spaced from said edge and each having a contact arm extending therefrom, said arms extending parallel to the axis of said strip in opposite directions, said leads being connected to each other by integral tie bar means, bending said arms laterally Of the plane of said strip and partially inwardly towards each other, bending said connecting strap at a first location remote from said one edge to swing said leads about said location in one direction so that said leads are in a plane extending normally of the plane of Said strip with said arms disposed on one side of said mounting plate portion and with the free ends of said leads on the side opposite to said one side, further forming said arms towards each other until the ends of said arms spaced apart by a distance which is less than the width of said strap, bending said connecting strap at a second location proximate to said one edge of said mounting plate portion to swing said leads about said second location in a direction opposite to said one direction thereby to orient said leads in a second plane which is parallel to, and spaced from, the plane of said strip, and further bending said connecting strap portion at said first and second locations to move portions of said leads past said one edge and position said arms at a predetermined location with respect to said mounting plate portion.

Claim 7

A method of manufacturing lead frames in the form of a continuous strip comprising the steps of: blanking strip metal stock to form a succession of side-by-side lead frame blanks, each of said blanks comprising a mounting plate portion and three leads beside said mounting plate portion, said leads extending transversely of the axis of said strip, the center one of said leads being connected to one edge of said mounting plate portion by a connecting strap portion, the outside ones of said leads having inner ends spaced from said edge and each having a contact arm extending therefrom, said arms extending parallel to the axis of said strip in opposite directions, said leads being connected to each other by integral tie bar means, bending said arms laterally Of the plane of said strip and partially inwardly towards each other, bending said connecting strap at a first location remote from said one edge to swing said leads about said location in one direction so that said leads are in a plane extending normally of the plane of Said strip with said arms disposed on one side of said mounting plate portion and with the free ends of said leads on the side opposite to said one side, further forming said arms towards each other until the ends of said arms spaced apart by a distance which is less than the width of said strap, bending said connecting strap at a second location proximate to said one edge of said mounting plate portion to swing said leads about said second location in a direction opposite to said one direction thereby to orient said leads in a second plane which is parallel to, and spaced from, the plane of said strip, and further bending said connecting strap portion at said first and second locations to move portions of said leads past said one edge and position said arms at a predetermined location with respect to said mounting plate portion.

Claim 8

A method of manufacturing lead frames in the form of a continuous strip, each lead frame being of the type comprising a mounting plate disposed in a first plane and three parallel leads disposed in a second plane which is parallel to, and spaced from, said first plane, said leads being joined to each other by an integral tie bar extending transversely of the axes of said leads, the center one of said leads being joined to one edge of said mounting plate by a connecting strap, which extends between said planes, outside ones of said leads extending over said mounting plate and past said one edge and having contact arms on their ends extending laterally in opposite directions, said arms being reversely bent towards said mounting plate and towards each other, the ends of said arms being spaced-apart by a predetermined distance which is less than the width of said connecting strap and being disposed between said planes, said method comprising the steps of: blanking strip stock metal to define said mounting plate, said leads, said tie bar, and said connecting strap in said first plane with said leads extending transversely of the length of said strip and with said contact arms extending laterally in opposite directions from said outside leads, bending said contact arms laterally of said first plane and away from said first and second planes and further bending said arms partially inwardly and towards each other so that the distance between the ends of said arms is greater then the width of said connecting strap, forming a first right angle bend in said strap at a first location adjacent to said center lead whereby said leads are swung along an arcuate path and are directed away from said first and second planes, and said arms are swung along an arcuate path past said strap and are disposed on the opposite side of said first plane from said free ends of said leads, further forming said arms inwardly and towards each other until they are spaced apart by said predetermined distance, forming a second angle bend in said strap at a second location adjacent to said one edge of said mounting plate towards said second plane until said strap extends between said second and first planes whereby said leads and said tie bars are moved along an arcuate path into said second plane and said arms are disposed between said planes and spaced from said mounting plate, and bending said strap at said first and second locations until said strap extend reversely with reference to said planes and said leads extend in said second plane beyond said one edge.

Claim 9

A method of manufacturing lead frames in the form of a continuous strip, each lead frame being of the type comprising a mounting plate disposed in a first plane and three parallel leads disposed in a second plane which is parallel to, and spaced from, said first plane, said leads being joined to each other by an integral tie bar extending transversely of the axes of said leads, the center one of said leads being joined to one edge of said mounting plate by a connecting strap, which extends between said planes, outside ones of said leads extending over said mounting plate and past said one edge and having contact arms on their ends extending laterally in opposite directions, said arms being reversely bent towards said mounting plate and towards each other, the ends of said arms being spaced-apart by a predetermined distance which is less than the width of said connecting strap and being disposed between said planes, said method comprising the steps of: blanking strip stock metal to define said mounting plate, said leads, said tie bar, and said connecting strap in said first plane with said leads extending transversely of the length of said strip and with said contact arms extending laterally in opposite directions from said outside leads, bending said contact arms laterally of said first plane and away from said first and second planes and further bending said arms partially inwardly and towards each other so that the distance between the ends of said arms is greater then the width of said connecting strap, forming a first right angle bend in said strap at a first location adjacent to said center lead whereby said leads are swung along an arcuate path and are directed away from said first and second planes, and said arms are swung along an arcuate path past said strap and are disposed on the opposite side of said first plane from said free ends of said leads, further forming said arms inwardly and towards each other until they are spaced apart by said predetermined distance, forming a second angle bend in said strap at a second location adjacent to said one edge of said mounting plate towards said second plane until said strap extends between said second and first planes whereby said leads and said tie bars are moved along an arcuate path into said second plane and said arms are disposed between said planes and spaced from said mounting plate, and bending said strap at said first and second locations until said strap extend reversely with reference to said planes and said leads extend in said second plane beyond said one edge.