Patent Publication Number: US-9406603-B2

Title: Semiconductor device and method for manufacturing the semiconductor device

Description:
BACKGROUND OF THE INVENTION 
     A. Field of the Invention 
     The present invention relates to a semiconductor device and a method for manufacturing the same. Particularly, it relates to a semiconductor device mounted with power semiconductor elements etc. and a method for manufacturing the semiconductor device. 
     B. Description of the Related Art 
     An example of a semiconductor device in which semiconductor elements are modularized has a package structure shown in  FIG. 9 . In the semiconductor device shown in  FIG. 9 , cooling plate  51  is arranged in a bottom portion of resin casing  52 . Insulating wiring board  56  is arranged on cooling plate  51 . Insulating wiring board  56  is configured in such a manner that metal layers  54  and  55  are bonded to opposite surfaces of insulating substrate  53 . Metal layer  55  of insulating wiring board  56  and cooling plate  51  are bonded to each other through solder layer  57   a . Semiconductor elements  58  are arranged on insulating wiring board  56 . Metal layer  54  of insulating wiring board  56  and semiconductor elements  58  are bonded to each other through solder layer  57   b . In addition, external terminals  59  are arranged on insulating wiring board  56 . Metal layer  54  of insulating wiring board  56  and external terminals  59  are bonded to each other through solder layer  57   c . Semiconductor elements  58  are electrically connected to external terminals  59  respectively by bonding wires  60 . The inside of resin casing  52  is filled and sealed with sealing resin  61 . 
     High heat dissipation is required particularly in the case of semiconductor elements which generate significant heat, like power semiconductor elements such as IGBTs (Insulated Gate Bipolar Transistor) etc. However, in such a semiconductor device according to the background art, bonding wires  60 , for example, consisting of thin aluminum wires each having a wire diameter of about 300 μm to 400 μm are only connected to the upper surface sides of semiconductor elements  58 . Moreover, since heat is generated in accordance with electricity passing through bonding wires  60 , it is almost impossible to obtain any heat dissipation effect from the upper surface sides of semiconductor elements  58 . 
     A method for improving wiring current density, fusing current resistance, bonding reliability, heat dissipation, etc. has been described in PTL 1 and PTL 2. In PTL 1 and PTL 2, an implant board and semiconductor elements of a semiconductor mounting board are bonded to each other through implant pins in place of the wire bonding wiring structure. 
     A semiconductor device disclosed in PTL 1 will be described with reference to  FIGS. 10 and 11 . Incidentally, portions substantially the same as those in the semiconductor device shown in  FIG. 9  are referred to by corresponding numerals, so that description thereof will be omitted. 
     In the semiconductor device shown in  FIG. 10 , semiconductor elements  58  are arranged on insulating wiring board  56 . Metal layer  54  of insulating wiring board  56  and semiconductor elements  58  are bonded to each other through solder layer  57   b.    
     Implant board  79  is arranged above semiconductor elements  58 . Implant board  79  and semiconductor elements  58  are electrically connected to each other through implant pins  76  of implant board  79 . 
     Implant board  79  includes insulating wiring board  75 , and implant pins  76  press-fitted into via holes  74 . Insulating wiring board  75  is configured in such a manner that metal layers  72  and  73  forming a printed wiring are bonded to opposite surfaces of insulating substrate  71 . Via holes  74  are formed to penetrate insulating substrate  71 , metal layer  72  and metal layer  73  of insulating wiring board  75 . Referring now to  FIG. 11 , collar portion  77  is provided in each implant pin  76 . A constant quantity between one end of the implant pin and collar portion  77  is press-fitted into via hole  74 . Collar portion  77  and insulating wiring board  75  are bonded to each other through bonding material  78   a . Moreover, the other end of implant pin  76  is bonded to insulating wiring board  56  or semiconductor element  58  through bonding material  78   b  
     PTL 1: JP-A-2011-82303   PTL 2: WO 2011/083737   

     SUMMARY OF THE INVENTION 
     However, when the component configuration in the semiconductor device shown in  FIG. 10  is changed for each kind of product so that the heights of components including the semiconductor elements etc. are changed, it is necessary to adjust the length of each implant pin in accordance with the distance between the semiconductor element and the implant board in each bonding place. Therefore, it is necessary to prepare a number of implant boards in accordance with the number of the kinds of products, so that time and labor are required for inventory management of these components. In addition, a plurality of kinds of implant boards must be prepared in accordance with the kinds of products, so that the component cost increases. 
     Therefore, the present invention provides a semiconductor device in which an implant board and semiconductor elements of a semiconductor mounting board are bonded and electrically connected through implant pins and which can be manufactured with high productivity, and provides a method for manufacturing the semiconductor device. 
     The semiconductor device according to the invention is characterized in that the implant pins are bonded to a semiconductor element and/or a circuit pattern of the semiconductor mounting board through cylindrical terminals press-fitted onto the other ends of the implant pins, and the depth with which each of the implant pins is press-fitted into corresponding one of the cylindrical terminals can be adjusted so that total length of the implant pin and the cylindrical terminal which are press-fitted to each other can match up with a distance between the semiconductor element and/or the circuit pattern on the semiconductor mounting board and the implant board. 
     In the semiconductor device according to the invention, the implant pins are bonded to the semiconductor element and/or the circuit pattern of the semiconductor mounting board through the cylindrical terminals press-fitted onto the other ends of the implant pins. Therefore, the depth with which each of the implant pins is press-fitted into corresponding one of the cylindrical terminals can be adjusted so that the total length of the implant pin and the cylindrical terminal which are press-fitted to each other can match up with the distance between the semiconductor element and/or the circuit pattern on the semiconductor mounting board and the implant board. Accordingly, even when the distance between the semiconductor element and/or the circuit pattern on the semiconductor mounting board and the implant board differs from one bonding portion to another, it is not necessary to prepare implant pins whose lengths match up with bonding portions individually. That is, it is not necessary to change the kind of the implant board in accordance with each kind of product, but the implant board can be used in common among a plurality of products. Therefore, inventory management of the components can be easy and the component cost can be suppressed. Thus, the productivity is excellent. 
     In the semiconductor device according to the invention, a plating layer may be provided in a surface of a press-fitting portion of each of the implant pins into corresponding one of the cylindrical terminals and/or an inner circumferential surface of the cylindrical terminal. Preferably, the implant pin press-fitted into the cylindrical terminal is heated to melt the plating layer so that a contact portion between the implant pin and the cylindrical terminal can be bonded to each other by the plating layer. 
     In the semiconductor device according to the invention, a sinter material may be applied to a surface of a press-fitting portion of each of the implant pins into corresponding one of the cylindrical terminals and/or an inner circumferential surface of the cylindrical terminal. Preferably, the implant pin press-fitted into the cylindrical terminal is heated to sinter the sinter material so that a contact portion between the implant pin and the cylindrical terminal can be bonded to each other. 
     According to the aforementioned aspects, the bonding strength between each of the implant pins and corresponding one of the cylindrical terminals is so high that the bonding reliability is excellent. 
     In the semiconductor device according to the invention, preferably, each of the implant pins is in contact with at least 40% of an inner circumference of corresponding one of the cylindrical terminals in a section perpendicular to the implant pin in a contact portion between the implant pin and an inner circumferential surface of the cylindrical terminal. According to this aspect, the conductivity is excellent. Furthermore, the bonding strength between the implant pin and the cylindrical terminal is high, and the bonding reliability is excellent. 
     In the semiconductor device according to the invention, preferably, a protruding portion which protrudes over an outer circumference of each of the implant pins is provided in a press-fitting portion of the implant pin into corresponding one of the cylindrical terminals by drawing, so that the protruding portion can come into contact with an inner circumferential surface of the cylinder terminal. In this aspect, preferably, a value obtained by subtracting an inner diameter of each of the cylindrical terminals from a largest diameter of a press-fitting portion of corresponding one of the implant pins which has not yet been press-fitted is in the range of from 0 to 0.25 mm. 
     In the semiconductor device according to the invention, preferably, a straight columnar portion which is not subjected to drawing is provided in a press-fitting portion of each of the implant pins so that at least a part of the columnar portion can come into contact with an inner circumferential surface of corresponding one of the cylindrical terminals. In this aspect, preferably, a value obtained by subtracting an inner diameter of each of the cylindrical terminals from a largest diameter of a press-fitting portion of corresponding one of the implant pins which has not yet been press-fitted is in the range of from 0 to 0.15 mm. 
     According to the aforementioned aspects, the bonding strength between each of the implant pins and corresponding one of the cylindrical terminals is high and the bonding reliability is excellent. 
     In the semiconductor device according to the invention, preferably, each of the implant pins has a tapered end on the cylindrical terminal side so that the implant pin has a diameter which decreases toward the end. According to this aspect, an operation of press-fitting the implant pin into the cylindrical terminal becomes easy. 
     In the semiconductor device according to the invention, preferably, an inner circumference of each of the cylindrical terminals is formed into a shape which matches up with a press-fitting portion of corresponding one of the implant pins. In this aspect, the contact area of the implant pin with the inner circumference of the cylindrical terminal can be increased. Thus, the conductivity and the bonding strength are excellent. 
     In addition, the semiconductor device manufacturing method according to the invention is a method for manufacturing a semiconductor device, including the steps of: preparing a semiconductor mounting board in which a semiconductor element is mounted on an insulating wiring board; preparing an implant board in which via holes for electric connection are provided in an insulating substrate having a printed wiring and one ends of implant pins are press-fitted into the via holes; and bonding the other ends of the implant pins of the implant board to the semiconductor element and/or a circuit pattern of the semiconductor mounting board so as to make electric connection to the semiconductor element of the semiconductor mounting board; characterized in that: each of cylindrical terminals is press-fitted onto the other end of corresponding one of the implant pins and depth with which the cylindrical terminal is press-fitted is adjusted so that length of the implant pin can match up with a distance between the semiconductor element and/or the circuit pattern on the semiconductor mounting board and the implant board and the implant pin can be bonded to the semiconductor element and/or the circuit pattern of the semiconductor mounting board through the cylindrical terminal. 
     In the semiconductor device manufacturing method according to the invention, a plating layer may be formed in a surface of a press-fitting portion of each of the implant pins into corresponding one of the cylindrical terminals and/or an inner circumferential surface of the cylindrical terminal. The other end of the implant pin of the implant board is made to abut against the semiconductor element and/or the circuit pattern of the semiconductor mounting board through the cylinder terminal and the semiconductor device thus assembled is heated in a reflow furnace in this state. Thus, connection is made between the semiconductor element and the insulating wiring board and connection is made between the cylindrical terminal corresponding to the implant pin and the semiconductor element and/or the circuit pattern of the semiconductor mounting board. In addition thereto, preferably, the plating layer is melted to thereby connect the implant pin and the cylindrical terminal to each other. 
     In the semiconductor device manufacturing method according to the invention, a sinter material may applied in a surface of a press-fitting portion of each of the implant pins into corresponding one of the cylindrical terminals and/or an inner circumferential surface of the cylindrical terminal. The other end of the implant pin of the implant board abuts against the semiconductor element and/or the circuit pattern of the semiconductor mounting board through the cylinder terminal and the semiconductor device thus assembled is heated in a reflow furnace in this state. Thus, connection is made between the semiconductor element and the insulating wiring board and connection is made between the cylindrical terminal corresponding to the implant pin and the semiconductor element and/or the circuit pattern of the semiconductor mounting board. In addition thereto, preferably, the sinter material is sintered to thereby connect the implant pin and the cylindrical terminal to each other. 
     According to the invention, the implant board can be used in common among a plurality of products. Accordingly, inventory management of the components can be performed easily and the component cost can be suppressed so that a semiconductor device in which semiconductor elements are electrically connected by the implant board can be manufactured with high productivity. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing advantages and features of the invention will become apparent upon reference to the following detailed description and the accompanying drawings, of which: 
         FIG. 1  is a schematic sectional view showing an embodiment of a semiconductor device according to the invention; 
         FIG. 2  is an enlarged view of a portion A in  FIG. 1 ; 
         FIGS. 3( a ) and 3( b )  are a schematic view of an external terminal which can be used in the semiconductor device, in which  3 ( a ) is a side view and  3 ( b ) is a sectional view taken along the line C-C in  3 ( a ); 
         FIGS. 4( a ) and 4( b )  are a schematic view of an external terminal which can be used in the semiconductor device, in which  4 ( a ) is a side view and  4 ( b ) is a sectional view taken along the line D-D in  4 ( a ); 
         FIGS. 5( a ) and 5( b )  are a schematic view of an external terminal which can be used in the semiconductor device, in which  5 ( a ) is a side view and  5 ( b ) is a sectional view taken along the line E-E in  5 ( a ); 
         FIGS. 6( a ) and 6( b )  are a schematic view of an external terminal which can be used in the semiconductor device, in which  6 ( a ) is a side view and  6 ( b ) is a sectional view taken along the line F-F in  6 ( a ); 
         FIG. 7  is an important part enlarged sectional view showing another embodiment of the semiconductor device according to the invention; 
         FIG. 8  is an important part enlarged sectional view showing further another embodiment of the semiconductor device according to the invention; 
         FIG. 9  is a schematic sectional view showing an example of a semiconductor device according to the background art; 
         FIG. 10  is a schematic sectional view showing another example of the semiconductor device according to the background art; 
         FIG. 11  is an enlarged view of a portion G in  FIG. 10 ; 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     A semiconductor device according to the invention will be described with reference to the drawings. An embodiment of the semiconductor device according to the invention is shown in  FIG. 1 . 
     In the semiconductor device, cooling plate  1  is arranged in a bottom portion of resin casing  2 . Cooling plate  1  is made of a material having high heat dissipation. For example, copper, aluminum, a copper alloy, an aluminum alloy, etc. may be used as the material of cooling plate  1 . 
     Insulating wiring board  3  is arranged on cooling plate  1 . Insulating wiring board  3  is formed in such a manner that metal layers  5  and  6  are bonded to opposite surfaces of insulating substrate  4 . A predetermined circuit pattern is formed on insulating substrate  4  by metal layer  5 . Metal layer  6  of insulating wiring board  3  and cooling plate  1  are bonded through a solder or sinter material layer  7   a.    
     There is no particular limitation on insulating wiring board  3 . For example, a direct bonding copper board in which a copper plate is bonded directly on a ceramic substrate, an active metal brazed copper board in which ceramics and a copper plate are bonded through a brazing material, or the like, may be used as insulating wiring board  3 . 
     External terminals  9  are bonded to predetermined places of metal layer  5  forming the circuit pattern of insulating wiring board  3 , through a solder or sinter material layer  7   b . In addition, a plurality of semiconductor elements  8   a  and  8   b  are bonded to the same metal layer  5  through a solder or sinter material layer  7   c . Each of semiconductor elements  8   a  and  8   b  varies according to use purposes. For example, a power semiconductor element such as an IGBT, a rectifier element such as an FWD, etc. may be used as semiconductor element  8   a ,  8   b.    
     Implant board  30  is disposed above semiconductor element  8 . Implant board  30  includes insulating wiring board  34 , and implant pins  20  press-fitted into via holes  35 . Insulating wiring board  34  is configured in such a manner that metal layers  32  and  33  forming a printed wiring are bonded to opposite surfaces of insulating substrate  31 . Each of via holes  35  is formed to penetrate metal layer  32 , insulating substrate  31  and metal layer  33  of insulating wiring board  34 . A metal layer (not-shown) connected conductively to metal layer  32  and/or metal layer  33  is formed in an inner surface of each of via holes  35 . The metal layer in the inner surface is connected conductively to implant pin  20 . 
     Lower ends of some of implant pins  20  of implant board  30  are press-fitted into cylindrical terminals  10 . In the embodiment, implant pins  20  which do not have cylindrical terminals  10  are connected to semiconductor element  8   a  through a solder or sinter material layer  7   e . Moreover, cylindrical terminals  10  in implant pins  20  having cylindrical terminals  10  are connected to semiconductor element  8   b  and metal layer  5  through a solder or sinter material layer  7   d.    
     Referring now to  FIG. 2 , collar portion  26  is provided in each of implant pins  20 . A constant quantity L 1  between end  27  of each implant pin and collar portion  26  is press-fitted into pin hole  35 . Each of collar portions  26  and insulating wiring board  34  are bonded through bonding material  36 . 
     Press-fitting depth L 2  of each of implant pins  20  into cylindrical terminals  10  is adjusted for each cylindrical terminal so as to match up with the distance between semiconductor element  8   b  and implant board  30  and the distance between metal layer  5  and implant board  30 . 
     That is, an implant board provided with implant pins having different lengths in accordance with the distance between semiconductor element  8  and implant board  30  and the distance between metal layer  5  and implant board  30  is not used in the invention. According to the invention, the press-fitting depth of each implant pin  20  into a corresponding cylindrical terminal  10  is changed in accordance with each of the distances. Thus, implant board  30  is bonded to semiconductor element  8  or metal layer  5  to make electric connection for each of the semiconductor elements. Therefore, it is not necessary to change the implant board in accordance with each kind of product so that the implant board can be used in common among a plurality of products. 
     Incidentally, when the distance between implant board  30  and semiconductor element  8  or metal layer  5  matches up with the length of each implant pin  20  extending from implant board  30 , implant pin  20  may be bonded to semiconductor element  8  or metal layer  5  not through cylindrical terminal  10 . In the embodiment, the distance between implant board  30  and semiconductor element  8   a  matches up with the length of each implant pin  20  extended from implant board  30 , so that implant pin  20  is bonded directly to semiconductor element  8   a  through a solder or sinter material layer  7   e.    
     In the semiconductor device according to the invention, it is preferable that each implant pin  20  is in contact with 40% or more of the inner circumference of cylindrical terminal  10  in a section taken along the line B-B in  FIG. 2 . The section taken along the line B-B in  FIG. 2  is a section in a direction perpendicular to implant pin  20 , in a contact portion between implant pin  20  and the inner circumference of cylindrical terminal  10 . When the contact area of implant pin  20  with cylindrical terminal  10  is smaller than 40%, bonding strength or conductivity may be insufficient. When the contact area is not smaller than 40%, sufficient bond strength and conductivity can be obtained. 
     In the semiconductor device according to the invention, there is no particular limitation on the shape of implant pin  20 . An implant pin having any shape such as a cylindrical shape or a prismatic shape can be used as implant pin  20 . For example, any of the shapes shown in  FIGS. 3 to 6  may be preferably used as the shape of the press-fitting portion of implant pin  20  into cylindrical terminal  10 . 
     Implant pin  20   a  shown in  FIG. 3  is provided with a press-fitting portion consisting of straight columnar portion  21  which is not subjected to drawing, and reduced diameter portion  23  whose diameter is reduced like a taper from the press-fitting portion toward end  25 . When implant pin  20   a  is press-fitted into cylindrical terminal  10 , columnar portion  21  comes into contact with the inner circumferential surface of cylindrical terminal  10 , so that columnar portion  21  and cylindrical terminal  10  are bonded to each other. Moreover, since end  25  has a reduced diameter like a taper, the center position can be adjusted easily when implant pin  20   a  is press-fitted into cylindrical terminal  10 . Thus, the press-fitting is performed easily. 
     The largest outer diameter R max  of the press-fitting portion of implant pin  20  which has not yet been press-fitted is set so that a difference (R max −R) between the largest outer diameter R max  and an inner diameter R of cylindrical terminal  10  is preferably in the range of from 0 to 0.15 mm. In addition, the difference (R max −R) between the largest outer diameter R max  and the inner diameter R of cylindrical terminal  10  is more preferably in the range of from 0.05 mm to 0.15 mm, especially preferably in the range of from 0.05 mm to 0.10 mm. When the largest outer diameter R max  is set such that the difference is within the aforementioned range, implant pin  20   a  can be press-fitted into cylindrical terminal  10  without causing any damage in implant pin  20   a , any damage in cylindrical terminal  10 , etc. so that implant pin  20   a  and cylindrical terminal  10  can be bonded to each other firmly. 
     Each of implant pins  20   b  to  20   d  shown in  FIGS. 4 to 6  is provided with a press-fitting portion having protruding portion  22  protruding over the outer circumference due to drawing, and reduced diameter portion  23  whose diameter is reduced like a taper from the press-fitting portion toward end  25 . In implant pin  20   b  shown in  FIG. 4 , protruding portion  22  is formed into a cross shape in section. In implant pin  20   c  shown in  FIG. 5 , protruding portion  22  is formed into a Y-shape in section (a shape having three protruding parts protruding radially at equal angles). In implant pin  20   d  shown in  FIG. 6 , protruding portion  22  is formed into a flat plate shape. When the implant pin is press-fitted into cylindrical terminal  10 , protruding portion  22  comes into contact with the inner circumferential surface of cylindrical terminal  10  so that protruding portion  22  and cylindrical terminal  10  are bonded to each other. Moreover, since end  25  is reduced in diameter like a taper, the center position can be adjusted easily when implant pin  20  is press-fitted into cylindrical terminal  10 . Thus, the press-fitting can be performed easily. Incidentally, the shape of the protruding portion formed by drawing is not limited to any of the shapes shown in  FIGS. 4 to 6 . 
     The largest outer diameter R max  of the press-fitting portion in each of implant pins  20   b  to  20   d  which has not yet been press-fitted is set so that a difference (R max −R) between the largest outer diameter R max  and the inner diameter R of cylindrical terminal  10  is preferably in the range of from 0 to 0.25 mm. Moreover, the difference (R max −R) between the largest outer diameter R max  and the inner diameter R of cylindrical terminal  10  is more preferably in the range of from 0.05 mm to 0.25 mm, particularly preferably in the range of from 0.10 mm to 0.20 mm. When the largest outer diameter R max  is set so that the difference is within the aforementioned range, the implant pin can be press-fitted into cylindrical terminal  10  without causing any damage in the implant pin, any damage in cylindrical terminal  10 , etc. so that the implant pin and cylindrical terminal  10  can be bonded to each other firmly. 
     The inner circumference of cylindrical terminal  10  is preferably shaped like a hole which matches up with the press-fitting portion of implant pin  20 . Since the inner circumference of cylindrical terminal  10  is formed into a shape which matches up with the press-fitting portion of implant pin  20 , the contact area of implant pin  20  with the inner circumference of cylindrical terminal  10  can be made large. In addition, the ends of protruding portions  22  engage with the inner circumferences of cylindrical terminals  10  respectively so as to prevent rotation. 
     The inside of resin casing  2  in the semiconductor device according to the invention is filled and sealed with sealing resin  15  such as a gel or an epoxy resin. 
     Next, an embodiment of a semiconductor device manufacturing method according to the invention will be described as a method for manufacturing the aforementioned semiconductor device. 
     First, a method for manufacturing implant board  30  will be described. Implant board  30  is manufactured as follows. Via holes  35  for electric connection are formed in predetermined positions of insulating wiring board  34  so as to penetrate metal layer  32 , insulating substrate  31  and metal layer  33 . After ends  27  of implant pins  20  are press-fitted into via holes  35 , collar portions  26  of implant pins  20  and insulating wiring board  34  are bonded by bonding material  36 . 
     The method for manufacturing the semiconductor device will be described below. 
     Insulating wiring board  3  is disposed on cooling plate  1  so that metal layer  6  side of insulating wiring board  3  can come into contact with cooling plate  1  through a solder or sinter material layer  7   a . Moreover, semiconductor elements  8   a  and  8   b  are disposed on a predetermined circuit pattern of metal layer  5  of insulating wiring board  3  through a solder or sinter material layer  7   c.    
     Next, implant pins  20  extending from implant board  30  are press-fitted into cylindrical terminals  10 . The press-fitting depth of each of implant pins  20  is adjusted so that the length of implant pin  20  can match up with the distance between semiconductor element  8   b  and implant board  30  or the distance between metal layer  5  and implant board  30 . 
     Implant board  30  is disposed above insulating wiring board  3 . Cylindrical terminals  10  are disposed in predetermined positions of semiconductor element  8   b  and metal layer  5  through a solder or sinter material layer  7   d . In addition thereto, implant pins  20  extending from implant board  30  are disposed on semiconductor element  8   a  through a solder or sinter material layer  7   e.    
     The semiconductor device is introduced into a reflow furnace in this state so that the solder or sinter material layers  7   a ,  7   c ,  7   d  and  7   e  are melted or sintered. Thus, cooling plate  1  and metal layer  6  of insulating wiring board  3  are bonded to each other. At the same time, bonding between semiconductor elements  8   a  and  8   b  and metal layer  5  of insulating wiring board  3 , bonding between cylindrical terminals  10  and metal layer  5  of insulating wiring board  3 , bonding between cylindrical terminals  10  and semiconductor element  8   b  and bonding between implant pins  20  and semiconductor element  8   a  are performed. 
     The heating temperature in the reflow time is preferably not higher than 350° C., more preferably in the range of from 250° C. to 330° C. When the heating temperature is higher than 350° C., there is a fear that the semiconductor elements etc. may be thermally damaged. 
     Next, external terminals  9  are disposed in predetermined positions of metal layer  5  through a solder or sinter material layer  7   b . The solder or sinter material layer  7   b  is melted or sintered to bond external terminals  9  and metal layer  5  to each other. Cooling plate  1  is surrounded by resin casing  2 . The inside enclosed by resin casing  2  is filled with sealing resin  15 . The sealing resin is hardened. In this manner, the semiconductor device according to the invention is manufactured. 
     Another embodiment of the semiconductor device according to the invention is shown in  FIG. 7 . In the semiconductor device, plating layer  28  is provided in the surface of the press-fitting portion of each implant pin  20  into cylindrical terminal  10 . When plating layer  28  is melted, the press-fitting portion of implant pin  20  and the inner circumferential surface of cylindrical terminal  10  are bonded to each other. Incidentally, in the embodiment, the plating layer is formed in the surface of the press-fitting portion of implant pin  20 . Alternatively, the plating layer may be formed in the inner circumferential surface of cylindrical terminal  10  or may be formed in both the surface of the press-fitting portion of implant pin  20  and the inner circumferential surface of cylindrical terminal  10 . 
     The thickness of plating layer  28  is preferably not larger than 5 μm prior to press-fitting. Plating layer  28  may be a single layer or may be a laminate of a plurality of plating layers. A layer or a laminate in which at least the outermost layer can be melted at a temperature not higher than 350° C. is preferably used. Sn plating, SnAg-based solder plating, SnBi-based solder plating, SnSb-based solder plating, SnCu-based solder plating, SnIn-based solder plating, etc. may be used as the plating material whose melting temperature is not higher than 350° C. When the melting temperature is not higher than 350° C., the plating material can be melted in the reflow process for soldering the semiconductor elements etc. 
     Next, another embodiment of a semiconductor device manufacturing method according to the invention will be described as a method for manufacturing the aforementioned semiconductor device. In the embodiment, implant pins  20  extending from implant board  30  are press-fitted into cylindrical terminals  10  and the press-fitting depth of each of implant pins  20  is adjusted, in the same manner as in the aforementioned embodiment. In this manner, the length of each of implant pins  20  matches up with the distance between semiconductor element  8   b  and implant board  30  or the distance between metal layer  5  and implant board  30 . Cylindrical terminals  10  are disposed in predetermined positions of semiconductor element  8   b  and metal layer  5  through the solder or sinter material layer  7   d . Moreover, implant pins  20  extending from implant board  30  are disposed on semiconductor element  8   a  through the solder or sinter material layer  7   e.    
     The semiconductor device is introduced into a reflow furnace in this state so that the solder or sinter material layers  7   a ,  7   c ,  7   d  and  7   e  and plating layer  28  are melted or sintered. Thus, through the solder or sinter material layers  7   a ,  7   c ,  7   d  and  7   e , cooling plate  1  and metal layer  6  of insulating wiring board  3  are bonded to each other. At the same time, bonding between semiconductor elements  8   a  and  8   b  and metal layer  5  of insulating wiring board  3 , bonding between cylindrical terminals  10  and metal layer  5  of insulating wiring board  3 , bonding between cylindrical terminals  10  and semiconductor element  8   b , and bonding between implant pins  20  and semiconductor element  8   a  are performed. In addition, implant pins  20  and cylindrical terminals  10  are bonded to each other respectively through plating layer  28 . 
     The heating temperature in the reflow time is preferably not higher than 350° C., more preferably in the range of from 250° C. to 330° C. When the heating temperature is higher than 350° C., there is a fear that the semiconductor elements etc. may be thermally damaged. 
     External terminals  9  are disposed in predetermined positions of metal layer  5  through the solder or sinter material layer  7   b . When the solder or sinter material layer  7   b  is melted or sintered, metal layer  5  and external terminals  9  are bonded to each other. Further, cooling plate  1  is surrounded by resin casing  2 . The internal portion enclosed by resin casing  2  is filled with sealing resin  15 . The sealing resin is hardened. In this manner, the semiconductor device is manufactured. 
     Further another embodiment of the semiconductor device according to the invention is shown in  FIG. 8 . In the semiconductor device, implant pins  20  are press-fitted into cylindrical terminals  10 . Sinter material  29  is applied to the surfaces of the press-fitting portions of implant pins  20  into cylindrical terminals  10  and/or the inner circumferential surfaces of cylindrical terminals  10 . When the sinter material is sintered, the press-fitting portions of implant pins  20  and the inner circumferential surfaces of cylindrical terminals  10  are bonded to each other. 
     A sinter material which can be sintered at a temperature not higher than 350° C. is preferably used as sinter material  29 . For example, an Ag-based sinter material, a Cu-based sinter material, etc. may be used as sinter material  29 . When the sintering temperature is not higher than 350° C., the sinter material can be sintered in the reflow process for soldering the semiconductor elements etc. 
     Next, another embodiment of a semiconductor device manufacturing method according to the invention will be described as a method for manufacturing the aforementioned semiconductor device. 
     In the embodiment, sinter material  29  is applied to the inner circumferential surfaces of cylindrical terminals  10  and/or the press-fitting portions of implant pins  20  into cylindrical terminals  10 . Then, implant pins  20  extending from implant board  30  are press-fitted into cylindrical terminals  10  and the press-fitting depths of implant pins  20  are adjusted. In this manner, the lengths of implant pins  20  match up with the distance between semiconductor element  8   b  and implant board  30  and the distance between metal layer  5  and implant board  30 . Cylindrical terminals  10  are disposed in predetermined positions of semiconductor element  8   b  and metal layer through the solder or sinter material layer  7   d . Moreover, implant pins  20  extending from implant board  30  are disposed on semiconductor element  8   a  through the solder or sinter material layer  7   e.    
     The semiconductor device is introduced into a reflow furnace in this state so that the solder or sinter material layers  7   a ,  7   c ,  7   d  and  7   e  and sinter material  29  are melted or sintered. Thus, through the solder or sinter material layers  7   a ,  7   c ,  7   d  and  7   e , cooling plate  1  and metal layer  6  of insulating wiring board  3  are bonded to each other. At the same time, bonding between the semiconductor elements  8   a  and  8   b  and metal layer  5  of insulating wiring board  3 , bonding between cylindrical terminals  10  and metal layer  5  of insulating wiring board  3 , bonding between cylindrical terminals  10  and semiconductor element  8   b , and bonding between implant pins  20  and semiconductor element  8   a  are performed. In addition thereto, implant pins  20  and cylindrical terminals  10  are bonded to each other by sintering of sinter material  29 . 
     The heating temperature in the reflow time is preferably not higher than 350° C., more preferably in the range of from 250° C. to 330° C. When the heating temperature is higher than 350° C., there is a fear that the semiconductor elements etc. may be thermally damaged. 
     External terminals  9  are disposed in predetermined positions of metal layer  5  through the solder or sinter material layer  7   b . When the solder or sinter material layer  7   b  is melted or sintered, metal layer  5  and external terminals  9  are bonded to each other. Further, cooling plate  1  is surrounded by resin casing  2 . The internal portion enclosed by resin casing  2  is filled with the sealing resin  15 . The sealing resin is hardened. In this manner, the semiconductor device is manufactured. 
     Thus, a semiconductor device and a method for manufacturing the same have been described according to the present invention. Many modifications and variations may be made to the techniques and structures described and illustrated herein without departing from the spirit and scope of the invention. Accordingly, it should be understood that the methods and devices described herein are illustrative only and are not limiting upon the scope of the invention. 
     REFERENCE SIGNS LIST 
     
         
           1 : cooling plate 
           2 : resin casing 
           3 : insulating wiring board 
           4 : insulating substrate 
           5 ,  6 : metal layer 
           7   a ,  7   b ,  7   c ,  7   d ,  7   e : solder or sinter material layer 
           8 ,  8   a ,  8   b : semiconductor element 
           9 : external terminal 
           10 : cylindrical terminal 
           15 : sealing resin 
           20 : implant pin 
           28 : plating layer 
           29 : sinter material 
           30 : implant board 
           31 : insulating substrate 
           32 ,  33 : metal layer 
           34 : insulating wiring board 
           35 : via hole 
           36 : bonding material 
           51 : cooling plate 
           52 : resin casing 
           53 : insulating substrate 
           54 ,  55 : metal layer 
           56 : insulating wiring board 
           58 : semiconductor element 
           59 : external terminal 
           60 : bonding wire 
           61 : sealing resin 
           71 : insulating substrate 
           72 ,  73 : metal layer 
           74 : via hole 
           75 : insulating wiring board 
           76 : implant pin 
           79 : implant board