Method for manufacturing a base of a pressure mount type semiconductor device

Claim 1

A method for manufacturing a base of a pressure mount type semiconductor device which has a base body of electrically and thermally conductive material and a vertically extending cylindrical wall integral with the top of said base body at the middle portion thereof and adapted to engage a pellet pressurizing member therewithin so that said pellet pressurizing member is restrained against upward movement, said base body further having an integral annular projection of weldable material around said cylinderal wall which is used to projection weld a shell to the upper surface of said base to cover a semiconductor pellet within the cylindrical wall, and a stud on the bottom of said base body to be threaded later, said method comprising the steps of preparing a metal blank having a lower metal layer of electrically and thermally conductive and extrudable metal material having a relatively large thickness as compared to the overall thickness of the blank and an upper and annular metal layer of extrudable copper-nickel alloy having a relatively small thickness as compared to the overall thickness of the blank and secured to said lower metal layer on the upper surface thereof, said lower metal layer being exposed through said upper layer at the middle portion of said blank; placing said blank in a blank holding first cavity in an extruder die assembly which has an annular recess in the bottom surface therein with said upper annular metal layer of extrudable copper-nickel alloy against said bottom surface, said first cavity having a second cavity in the central portion of the bottom thereof with an enlarged portion around the end thereof opening into said first cavity and a knockout pin extending into said second cavity from the end of the die assembly opposite from said first cavity, and while holding the knockout pin in said second cavity, driving a punch having a stud forming bore therein into said first cavity from the open end thereof for extruding the material of said lower metal layer into said stud forming bore for forming a stud and extruding the material of said annular metal layer of copper-nickel alloys into the annular recess to form said integral annular projection and extruding the material of the lower metal layer into the enlarged portion of said second cavity around said knockout pin to form said cylindrical wall, whereby said annular projection, said cylindrical wall and said stud are simultaneously formed from said metal blank.

Claim 2

A method for manufacturing a base of a pressure mount type semiconductor device which has a base body of electrically and thermally conductive material and a vertically extending cylindrical wall integral with the top of said base body at the middle portion thereof and adapted to engage a pellet pressurizing member therewithin so that said pellet pressurizing member is restrained against upward movement, said base body further having an integral annular projection of weldable material around said cylinderal wall which is used to projection weld a shell to the upper surface of said base to cover a semiconductor pellet within the cylindrical wall, and a stud on the bottom of said base body to be threaded later, said method comprising the steps of preparing a metal blank having a lower metal layer of electrically and thermally conductive and extrudable metal material having a relatively large thickness as compared to the overall thickness of the blank and an upper and annular metal layer of extrudable copper-nickel alloy having a relatively small thickness as compared to the overall thickness of the blank and secured to said lower metal layer on the upper surface thereof, said lower metal layer being exposed through said upper layer at the middle portion of said blank; placing said blank in a blank holding first cavity in an extruder die assembly which has an annular recess in the bottom surface therein with said upper annular metal layer of extrudable copper-nickel alloy against said bottom surface, said first cavity having a second cavity in the central portion of the bottom thereof with an enlarged portion around the end thereof opening into said first cavity and a knockout pin extending into said second cavity from the end of the die assembly opposite from said first cavity, and while holding the knockout pin in said second cavity, driving a punch having a stud forming bore therein into said first cavity from the open end thereof for extruding the material of said lower metal layer into said stud forming bore for forming a stud and extruding the material of said annular metal layer of copper-nickel alloys into the annular recess to form said integral annular projection and extruding the material of the lower metal layer into the enlarged portion of said second cavity around said knockout pin to form said cylindrical wall, whereby said annular projection, said cylindrical wall and said stud are simultaneously formed from said metal blank.