Semiconductor module with cooling mechanism and production method thereof

Abstract

A semiconductor module is provided which includes a semiconductor unit which is made by a resin mold. The resin mold has formed therein a coolant path through which a coolant flows to cool a semiconductor chip embedded in the resin mold. The resin mold also includes heat spreaders, and electric terminals embedded therein. Each of the heat spreaders has a fin heat sink exposed to the flow of the coolant. The fin heat sink is welded to a surface of each of the heat spreaders through an insulator, thus minimizing an electrical leakage from the heat spreader to the coolant.

1 . A semiconductor module comprising:
 a resin molded package which includes a resin mold, the resin mold having embedded therein a power semiconductor chip which has a first and a second surface opposed to each other and on which a semiconductor power device is fabricated, a first heat spreader, a second heat spreader, and electric terminals coupled electrically with the semiconductor power device, the first heat spreader having a first surface and a second flat surface opposed to the first surface and being disposed at the first surface thereof in connection with the first surface of the power semiconductor chip, the second heat spreader having a first surface and a second flat surface opposed to the first surface and being disposed at the first surface thereof in connection with the second surface of the power semiconductor chip, a portion of each of the electric terminals being exposed outside the resin mold, the resin mold also having forted therein a coolant path that is a portion of a coolant path through which a coolant flows to cool the semiconductor chip;   first and second insulating films disposed over the second flat surfaces of the first and second heat spreaders, respectively;   first and second fin heat sinks joined to the first and second insulating films, respectively;   a first cover disposed on a first surface of the resin molded package;   a second cover disposed on a second surface of the resin molded package; and   a fastener which fastens the first and second covers to hold the resin molded package.   
     
     
         2 . A semiconductor module as set forth in  claim 1 , wherein the resin mold has formed therein positioning recesses which are shaped to conform with contour of the first and second fin heat sinks and serve to position the first and second fin heat sinks. 
     
     
         3 . A semiconductor module as set forth in  claim 1 , wherein the first heat spreader has a first metal plate disposed on the semiconductor chip, the first insulating film disposed on a surface of the first metal plate that is the second surface of the first heat spreader, and a first metal film disposed on the first insulating film away from the first metal plate, wherein the second heat spreader has a second metal plate disposed on the semiconductor chip, the second insulating film disposed on a surface of the second metal plate that is the second surface of the second heat spreader, and a second metal film disposed on the second insulating film and electrically kept away from the second metal plate, and wherein the first and second fin heat sinks are welded to the first and second metal films, respectively. 
     
     
         4 . A semiconductor module as set forth in  claim 1 , wherein the first and second fin heat sinks are attached to the second flat surfaces of the first and second heat spreaders through first and second adhesive layers, respectively, wherein the first and second adhesive layers are made of an insulating material and form the first and second insulating films, respectively, and wherein the first and second heat spreaders are made of the same material as that of the first and second fin heat sinks. 
     
     
         5 . A semiconductor module comprising:
 a resin molded package which includes a resin mold, the resin mold having embedded therein a power semiconductor chip which has a first and a second surfaces opposed to each other and on which a semiconductor power device is fabricated, a first heat spreader, a second heat spreader, and electric terminals coupled electrically with the semiconductor power device, the first heat spreader having a first surface and a second flat surface opposed to the first surface and being disposed at the first surface thereof in connection with the first surface of the semiconductor chip, the second heat spreader having a first surface and a second flat surface opposed to the first surface and being disposed at the first surface thereof in connection with the second surface of the power semiconductor chip, a portion of each of the electric terminals being exposed outside the resin mold, the resin mold also having fox fined therein a coolant path that is a portion of a coolant path through which a coolant flows to cool the semiconductor chip;   first and second fin heat sinks joined to the second flat surfaces of the first and second heat spreaders through first and second adhesive layers, respectively, the first and second adhesive layers being made of material exhibiting electric conductivity;   a first cover disposed on a first surface of the resin molded package;   a second cover disposed on a second surface of the resin molded package; and   a fastener which fastens the first and second covers to hold the resin molded package.   
     
     
         6 . A semiconductor module comprising:
 a plurality of resin molded packages each of which includes a resin mold, the resin molded packages being laid to overlap each other as a package stack, the resin mold having embedded therein a power semiconductor chip which has a first and a second surface opposed to each other and on which a semiconductor power device is fabricated, a first heat spreader, a second heat spreader, and electric terminals coupled electrically with the semiconductor power device, the first heat spreader having a first surface and a second flat surface opposed to the first surface and being disposed at the first surface thereof in connection with the first surface of the semiconductor chip, the second heat spreader having a first surface and a second flat surface opposed to the first surface and being disposed at the first surface thereof in connection with the second surface of the power semiconductor chip, a portion of each of the electric terminals being exposed outside the resin mold, the resin mold also having formed therein a coolant path that is a portion of a coolant path through which a coolant flows to cool the power semiconductor chip;   first and second insulating films disposed over the second fiat surfaces of the first and second heat spreaders of each of the resin molded packages, respectively;   first and second fin heat sinks joined to the first and second insulating films of each of the resin molded packages, respectively, so that adjacent two of the resin molded packages are arranged to have the first and second fin heat sink facing one another;   a first cover disposed on a first surface of the package stack;   a second cover disposed on a second surfaced of the package stack; and   a fastener which fastens the first and second covers to hold the package stack.   
     
     
         7 . A semiconductor module as set forth in  claim 6 , wherein each of the first and second fin heat sinks is equipped with corrugated fins, and wherein the fins of the first fin heat sink of one of adjacent two of the resin molded packages are arrayed 180° out of phase with the fins of the second fin heat sink of the other of adjacent two of the resin molded packages. 
     
     
         8 . A semiconductor module as set forth in  claim 6 , wherein each of the first and second fin heat sinks is equipped with an array of straight strips which define fins, and wherein the fins of the first fin heat sink of one of adjacent two of the resin molded packages are aligned with the fins of the second fin heat sink of the other of adjacent two of the resin molded packages through a gap in a direction in which the resin molded packages are laid to overlap each other as the package stack. 
     
     
         9 . A semiconductor module as set forth in  claim 6 , wherein each of the first and second fin heat sinks is equipped with an array of straight strips which define fins, and wherein tops of the fins of the first fin heat sink of one of adjacent two of the resin molded packages overlap tops of the fins of the second fin heat sink of the other of adjacent two of the resin molded packages in a direction perpendicular to a direction in which the resin molded packages are laid to overlap each other as the package stack. 
     
     
         10 . A semiconductor module as set forth in  claim 6 , wherein each of the first and second fin heat sinks is equipped with a plurality of pins which define fins, wherein tops of the fins of the first fin heat sink of one of adjacent two of the resin molded packages overlap tops of the fins of the second fin heat sink of the other of adjacent two of the resin molded packages in a first direction perpendicular to a second direction in which the resin molded packages are laid to overlap each other as the package stack, and wherein the fins of the first fin heat sink of one of adjacent two of the resin molded packages are staggered to the fins of the second fin heat sink of the other of adjacent two of the resin molded packages in the first direction. 
     
     
         11 . A semiconductor module as set forth in  claim 6 , wherein each of the first and second fin heat sinks is equipped with a plurality of pairs of arrays of pins which define fins, wherein tops of the fins of the first fin heat sink of one of adjacent two of the resin molded packages overlap tops of the fins of the second fin heat sink of the other of adjacent two of the resin molded packages in a first direction perpendicular to a second direction in which the resin molded packages are laid to overlap each other as the package stack, and wherein the pairs of the arrays of the fins of the first fin heat sink of one of adjacent two of the resin molded packages are staggered to the pairs of the arrays of the fins of the second fin heat sink of the other of adjacent two of the resin molded packages in the first direction. 
     
     
         12 . A method of producing a semiconductor module which includes a resin molded package and a coolant path comprising:
 a first step of preparing a semiconductor sub-assembly of a power semiconductor chip, a first heat spreader, a second heat spreader, and electric terminals, the semiconductor chip having a first and a second surface opposed to each other and being equipped with a semiconductor power device connecting with the electric terminals;   a second step of placing the semiconductor sub-assembly in a given molding tool and making a resin mold in which the semiconductor sub-assembly is disposed as the resin molded package, the first heat spreader having a first surface and a second flat surface opposed to the first surface and being disposed at the first surface thereof in connection with the first surface of the power semiconductor chip, the second heat spreader having a first surface and a second flat surface opposed to the first surface and being disposed at the first surface thereof in connection with the second surface of the power semiconductor chip, a portion of each of the electric terminals being exposed outside the resin mold, the resin mold also having formed therein a coolant path that is a portion of a coolant path through which a coolant flows to cool the power semiconductor chip; and   a third step of holding the resin molded package through covers to complete the semiconductor module,   wherein the first heat spreader has a first metal plate disposed on the power semiconductor chip, the first insulating film disposed on a surface of the first metal plate that is the second surface of the first heat spreader, and a first metal film disposed on the first insulating film and electrically kept away from the first metal plate, wherein the second heat spreader has a second metal plate disposed on the power semiconductor chip, the second insulating film disposed on a surface of the second metal plate that is the second surface of the second heat spreader, and a second metal film disposed on the second insulating film and electrically kept away from the second metal plate, and wherein the first and second fin heat sinks are joined to the first and second metal films, respectively, through ultrasonic welding.   
     
     
         13 . A method as set forth in  claim 12 , wherein the second step forms the resin mold so as to cover the semiconductor sub-assembly fully and then removes a portion of the resin mold so as to expose one of the first and second metal films.