Abstract:
A package according to the present invention includes: a support for mounting a semiconductor component on the upper surface thereof; a positioning control plate, which is secured to the support and includes an opening or a notch; and a lead provided on the support for establishing electrical continuity between the semiconductor component mounted on the support and an external component. The positioning control plate houses at least a lower part of the semiconductor component inside the opening or the notch, thereby controlling a position of the semiconductor component on the support.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a package for mounting a semiconductor chip therein and also relates to semiconductor device and method for fabricating the device using the package. 
     First, conventional package and semiconductor device will be described with reference to FIGS.  7 ( a ) and  7 ( b ). 
     FIGS.  7 ( a ) and  7 ( b ) illustrate conventional package and semiconductor device formed by mounting a semiconductor chip within the package. Specifically, FIG.  7 ( a ) illustrates a planar layout of the assembly yet to be encapsulated, while FIG.  7 ( b ) illustrates a cross-sectional structure of the assembly taken along the line VIIb—VIIb in FIG.  7 ( a ). As shown in FIGS.  7 ( a ) and  7 ( b ), an outer rail  102  made of an insulator is bonded to a radiating plate  101  made of copper. Input lead  103 A and output lead  103 B pass through the outer rail  102  and are insulated from the radiating plate  101 . 
     As can be seen, the conventional package is made up of the radiating plate  101 , outer rail  102  and input and output leads  103 A and  103 B. 
     As shown in FIG.  7 ( b ), semiconductor chips  104 , in which semiconductor components are formed as power amplifiers, are bonded to the radiating plate  101  of the package with a foil member  105 , which may be an alloy containing tin, inside the outer rail  102 . 
     Circuit boards  106  are also bonded to the radiating plate  101  with the foil member  105  inside the outer rail  102 . As shown in FIG.  7 ( a ), some of the circuit boards  106  are located between the semiconductor chips  104  and the input lead  103 A, while the other between the semiconductor chips  104  and the output lead  103 B. Each of these circuit boards  106  includes a matching circuit, which is formed on an insulating substrate to match the input impedance of the semiconductor components with the output one. The semiconductor chips  104 , circuit boards  106  and input and output leads  103 A and  103 B are connected together via wires  107 . 
     In manufacturing the semiconductor device, the semiconductor device assembled as shown in FIGS.  7 ( a ) and  7 ( b ) is heated within a reflow furnace, thereby melting the foil member  105 . Thereafter, the assembly is cooled down to room temperature, thereby bonding the radiating plate  101  to the semiconductor chips  104  and to the circuit boards  106 . 
     The conventional semiconductor device using such a package has the following drawbacks. Specifically, when the foil member  105  of an AuSn alloy is heated and melted by the reflow treatment, the melted foil member  105  expands on the radiating plate  101 . As a result, the semiconductor chips  104  and the circuit boards  106  are swept by the melted foil member  105  to be displaced from their desired positions. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is preventing semiconductor chips and so on from being displaced from their desired positions on a support of a package when the chips are being bonded to the support. 
     To achieve this object, according to an exemplary embodiment of the present invention, a positioning control plate for mounting semiconductor chips at their desired positions is provided over a support of a package. In an alternate embodiment of the present invention, positioning control recesses are provided within the upper surface of the support. 
     A first exemplary package according to the present invention includes: a support for mounting a semiconductor component on the upper surface thereof; a positioning control plate, which is secured to the support and includes an opening or a notch; and a lead provided on the support for establishing electrical continuity between the semiconductor component mounted on the support and an external component. The positioning control plate houses at least a lower part of the semiconductor component inside the opening or the notch, thereby controlling a position of the semiconductor component on the support. 
     According to the first package, by housing at least the lower part of the semiconductor component inside the opening or the notch during the fabrication process, the semiconductor component can be positioned on the support with respect to the positioning control plate. Thus, even when the bond member, with which the semiconductor component and the support are bonded together, is melted at the time of heat treatment during the fabrication process, it is possible to prevent the semiconductor component from being displaced laterally on the support. As a result, the production yield can be increased noticeably. 
     In one embodiment of the present invention, the first package preferably further includes an outer rail, which is secured to the support to enclose the positioning control plate therein. The semiconductor component is preferably positioned on the support with respect to the positioning control plate and the outer rail. In such an embodiment, the positioning control plate need not be provided around the periphery of the package. In addition, the semiconductor component can be encapsulated easily and with a lot more certainty within the package only by hermetically covering the entire periphery of the outer rail with a plate member. 
     In another embodiment of the present invention, the positioning control plate is preferably formed in such a shape as allowing a melted bond member to pass through corners of the opening or the notch while the semiconductor component is being bonded to the support with the bond member. For example, the sidewalls of the opening or the notch may be partially removed to form recesses at the corners. In such a case, the bond member, which is melted at the time of heat treatment during the fabrication process, does not overflow onto the semiconductor component. 
     In still another embodiment, the first package preferably further includes a platelike control plate bond member, which is provided between the support and the positioning control plate and includes an opening or a notch in substantially the same shape as that of the positioning control plate. In such an embodiment, the positioning control plate can be bonded onto the support if the heat treatment is conducted approximately at the melting point of the control plate bond member. 
     A second package according to the present invention includes: a support for mounting a semiconductor component on the upper surface thereof; and a lead for establishing electrical continuity between the semiconductor component mounted on the support and an external component. The support includes a recess for housing at least a lower part of the semiconductor component therein, thereby controlling a position of the semiconductor component on the support. 
     According to the second package, by housing at least the lower part of the semiconductor component inside the recess during the fabrication process, the semiconductor component can be positioned on the support with respect to the positioning control recess. Thus, even when the bond member, with which the semiconductor component and the support are bonded together, is melted at the time of heat treatment during the fabrication process, it is possible to prevent the semiconductor component from being displaced laterally on the support. 
     A first semiconductor device according to the present invention includes: a support; a positioning control plate, which is secured to the support and includes an opening or a notch; a semiconductor component bonded to the support in such a manner that at least a lower part of the semiconductor component is housed inside the opening or the notch of the positioning control plate; and a lead provided on the support for establishing electrical continuity between the semiconductor component and an external component. 
     The first semiconductor device is formed by using the first package according to the present invention. Accordingly, the semiconductor component is not displaced from, but can be bonded at, its desired position on the support, thus increasing the production yield. 
     In one embodiment of the present invention, the first semiconductor device preferably further includes an outer rail, which is secured to the support to enclose the positioning control plate therein. The semiconductor component is preferably positioned on the support with respect to the positioning control plate and the outer rail. 
     In another embodiment of the present invention, the positioning control plate is preferably formed in such a shape as allowing a melted bond member to pass through corners of the opening or the notch while the semiconductor component is being bonded to the support with the bond member. 
     In still another embodiment, the first semiconductor device preferably further includes a platelike control plate bond member, which is provided between the support and the positioning control plate and includes an opening or a notch in substantially the same shape as that of the positioning control plate. 
     In this particular embodiment, the first semiconductor device preferably further includes a foil member, which is provided between the semiconductor component and the support for bonding the semiconductor component to the support. A melting point of the foil member is preferably lower than that of the control plate bond member. In such an embodiment, if the heat treatment is conducted at a temperature, which is equal to or higher than the melting point of the foil member but lower than that of the control plate bond member, to bond the semiconductor component and the support together, then the control plate bond member is not melted. Accordingly, the positioning control plate is not displaced. 
     A second semiconductor device according to the present invention includes: a support with a recess formed within the upper surface thereof; a semiconductor component bonded to the support in such a manner that at least a lower part of the semiconductor component is housed inside the recess of the support; and a lead provided on the support for establishing electrical continuity between the semiconductor component and an external component. 
     The second semiconductor device is formed by using the second package according to the present invention. Accordingly, the semiconductor component is not displaced from, but can be bonded at, its desired position on the support, thus increasing the production yield. 
     A method for fabricating a semiconductor device according to the present invention includes the steps of: a) securing a positioning control plate, including an opening or a notch, to a support; b) placing a foil member, which is used to bond a semiconductor component onto the support, inside the opening or the notch of the positioning control plate on the support; c) mounting the semiconductor component on the foil member inside the opening or the notch of the positioning control plate on the support such that at least a lower part of the semiconductor component is housed within the opening or the notch; and d) heating the support, on which the semiconductor component has been mounted, to melt the foil member and then cooling down and solidifying the foil member melted, thereby bonding the semiconductor component to the support. 
     According to the method of the present invention, at least the lower part of the semiconductor component is housed inside the opening or the notch of the positioning control plate on the support when the semiconductor component is mounted on the support in the step c). Thus, even when the foil member is melted in the step d), the semiconductor component can be positioned with respect to the positioning control plate. As a result, it is possible to prevent the semiconductor component from being displaced laterally on the support. 
     In one embodiment of the present invention, the step a) preferably includes: placing a platelike control plate bond member between the support and the positioning control plate, the bond member including an opening or a notch in substantially the same shape as that of the positioning control plate, a melting point of the bond member being higher than that of the foil member; and heating the support on which the positioning control plate is placed to melt the control plate bond member and then cooling down and solidifying the control plate bond member melted, thereby bonding the positioning control plate to the support. In such an embodiment, since the control plate bond member is not melted in the step d), the positioning control plate is not displaced on the radiating plate. 
     In another embodiment of the present invention, the foil member is preferably made of an alloy containing gold and tin, and the control plate bond member is preferably made of silver solder with a melting point higher than that of the gold/tin alloy. 
     In still another embodiment, the step d) preferably includes heating the support with a press member placed on the semiconductor component to prevent the semiconductor component from being warped. In such an embodiment, since the semiconductor component is not warped during the heat treatment, the semiconductor component can be bonded onto the support just as originally designed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS.  1 ( a ) and  1 ( b ) illustrate package and semiconductor device formed by mounting a semiconductor chip within the package according to a first embodiment of the present invention: 
     FIG.  1 ( a ) is a plan view of the assembly yet to be encapsulated; and 
     FIG.  1 ( b ) is a cross-sectional view of the assembly taken along the line Ib—Ib in FIG.  1 ( a ). 
     FIG.  2 ( a ) is a plan view illustrating a positioning control plate with openings according to the first embodiment; 
     FIG.  2 ( b ) is a plan view illustrating a positioning control plate with notches according to the first embodiment; and 
     FIG.  2 ( c ) is a plan view illustrating a positioning control plate with notches according to a modified example of the first embodiment. 
     FIGS.  3 ( a ) through  3 ( c ) are cross-sectional views illustrating respective process steps for fabricating a semiconductor device according to the first embodiment. 
     FIGS.  4 ( a ) and  4 ( b ) are cross-sectional views illustrating respective process steps for fabricating the semiconductor device according to the first embodiment. 
     FIG. 5 is a cross-sectional view illustrating package and semiconductor device formed by mounting a semiconductor chip within the package according to a second embodiment of the present invention. 
     FIGS.  6 ( a ) through  6 ( c ) are cross-sectional views illustrating respective process steps for fabricating a semiconductor device according to the second embodiment. 
     FIGS.  7 ( a ) and  7  ( b ) illustrate conventional package and semiconductor device formed by mounting a semiconductor chip within the package: 
     FIG.  7 ( a ) is a plan view of the assembly yet to be encapsulated; and 
     FIG.  7 ( b ) is a cross-sectional view of the assembly taken along the line VIIb—VIIb in FIG.  7 ( a ). 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiment 1 
     Hereinafter, a first exemplary embodiment of the present invention will be described with reference to the accompanying drawings. 
     FIGS.  1 ( a ) and  1 ( b ) illustrate package and semiconductor device formed by mounting a semiconductor chip within the package according to the first embodiment. Specifically, FIG.  1 ( a ) illustrates a planar layout of the assembly yet to be encapsulated, while FIG.  1 ( b ) illustrates a cross-sectional structure thereof taken along the line Ib—Ib in FIG.  1 ( a ). As shown in FIG.  1 ( a ), a rectangular outer rail  12  made of an insulator such as a ceramic is bonded to a radiating plate  11  (i.e., the “support” as defined in the appended claims) made of copper, for example. Input lead  13  and output lead  14  pass through a pair of opposed sides of the outer rail  12  and are insulated from the radiating plate  11 . 
     A positioning control plate  15  made of a metal or carbon is bonded to the radiating plate  11  inside the outer rail  12 . The positioning control plate  15  has a plurality of openings  15   a  for positioning semiconductor chips  21  and circuit boards  22  with respect to the inner walls thereof. In the illustrated embodiment, the semiconductor chips  21 , circuit boards  22  and input and output leads  13  and  14  are electrically connected to each other via wires  23 . 
     As shown in FIG.  1 ( b ), a silver (Ag) solder plate  16  is provided as the control plate bond member between the radiating plate  11  and the positioning control plate  15 . The plate  16  also has a plurality of openings in substantially the same shapes as the openings  15   a  of the positioning control plate  15 . An alloyed foil member  24  made of gold (Au) and tin (Sn) is further provided between the radiating plate  11  and the semiconductor chips  21  and between the radiating plate  11  and the circuit boards  22  to bond the plate  11  and the chips  21  and circuits  22  together. 
     As can be seen, the package according to the first embodiment is made up of: the radiating plate  11 ; outer rail  12 ; input and output leads  13  and  14 ; positioning control plate  15  with the openings  15   a ; and silver solder plate  16  with openings in substantially the same shapes as the openings  15   a.    
     In each of these semiconductor chips  21  according to the first embodiment, a power amplifier, which generates heat at a very high temperature during its operation, is formed. Thus, each semiconductor chip  21  has its thickness reduced as much as possible to decrease the thermal resistance thereof and is plated with gold on the backside. Each of the circuit boards  22  includes a plurality of matching circuits formed on a ceramic substrate. These matching circuits each include surface interconnection lines and backside electrodes for distributing or coupling the power to be amplified by the power amplifiers and matching the input impedance of the power amplifiers with the output one. 
     As shown in FIGS.  1 ( a ) and  1 ( b ), the semiconductor device according to the first embodiment is formed by mounting the semiconductor chips  21  and necessary circuit boards  22  on the alloyed foil member  24  inside the openings  15   a  of the positioning control plate  15  over the radiating plate  11  such that at least the lower parts thereof are housed inside the openings  15   a . In this case, if the positioning control plate  15  is so large that the position thereof is controllable with respect to the outer rail  12 , then the silver solder plate  16  does not have to be provided. 
     FIGS.  2 ( a ) through  2 ( c ) illustrate embodiments and a modified example of the positioning control plate. Specifically, FIG.  2 ( a ) illustrates a planar layout of a positioning control plate with openings for positioning the semiconductor chips and so on. FIG.  2 ( b ) illustrates a planar layout of a positioning control plate with positioning control notches. And FIG.  2 ( c ) illustrates a modified example of the positioning control plate shown in FIG.  2 ( b ). The positioning control plate  15  shown in FIG.  2 ( a ) includes a plurality of openings  15   a . Each of these openings  15   a  has recesses  15   b  formed by partially removing the sidewalls of the positioning control plate  15  at the corners such that the bond member can pass through the recesses  15   b  while the semiconductor chips are being bonded onto the radiating plate. By providing these recesses  15   b , the walls at the corners are closer to the outer periphery of the plate  15  than the other walls are. Accordingly, even when the alloyed foil member  24  as the bond member is melted at the time of heat treatment during the fabrication process of the semiconductor device, the foil member  24  is less likely to overflow onto the upper surfaces of the semiconductor chips  21 . In the illustrated embodiment, the recesses  15   b  are formed at all the corners of each opening  15   a . Alternatively, the recesses  15   b  may be provided only for the corners of openings  15   a  vertically adjacent to each other. 
     The positioning control plate  15 A shown in FIG.  2 ( b ) includes notches  15   c  for positioning the semiconductor chips  21  and so on. Each of these notches  15   c  also has recesses  15   b  at the corners of its walls. 
     The positioning control plate  15 B shown in FIG.  2 ( c ) according to a modified example is different from the positioning control plate  15 A shown in FIG.  2 ( b ) in that the respective ends of the notches  15   c  have been removed. When a positioning control plate with such a shape is used, the sides of semiconductor chips, facing the open sides of the respective notches  15   c , i.e., the leftmost and rightmost sides shown in FIG.  2 ( c ), are positioned with respect to the inner walls of the outer rail  12 . 
     Next, a method for fabricating a semiconductor device with such a structure will be described with reference to the accompanying drawings. 
     FIGS.  3 ( a ) through  3 ( c ) and FIGS.  4 ( a ) and  4 ( b ) illustrate cross-sectional structures corresponding to respective process steps for fabricating the semiconductor device according to the first embodiment. 
     First, as shown in FIG.  3 ( a ), the outer rail  12 , in which the input and output leads  13  and  14  are inserted to face each other, is bonded to the radiating plate  11  such that these leads  13  and  14  are insulated from the radiating plate  11 . Next, the silver solder plate  16  and the positioning control plate  15  are placed in this order on a region of the radiating plate  11  inside the outer rail  12 . Thereafter, the radiating plate  11 , on which the positioning control plate  15  has been placed, is introduced into a reflow furnace and heated up to about 800° C., thereby melting the silver solder plate  16 . Then, the radiating plate  11  is cooled down to room temperature again to solidify the silver solder plate  16 , thereby bonding the radiating plate  11  and the positioning control plate  15  together. These heating and bonding process steps are collectively called a reflow process. The reflow process for the radiating plate  11  and the outer rail  12  may be performed either simultaneously or separately with/from the reflow process for the radiating plate  11  and the positioning control plate  15 . 
     Subsequently, as shown in FIG.  3 ( b ), the alloyed foil member  24  is placed on the radiating plate  11  within the respective openings  15   a  of the positioning control plate  15 , and then the semiconductor chips  21  and circuit boards  22  with a thickness of about 50 μm are mounted on the foil member  24 . As can be seen, the semiconductor chips  21  and circuit boards  22  can be mounted according to this embodiment at their desired positions only by placing these members  21  and  22  into the openings  15   a  of the positioning control plate  15 . In other words, positioning can be performed accurately only by forming the openings  15   a  in predetermined regions of the positioning control plate  15 . Accordingly, there is no need to position the semiconductor chips  21  for respective radiating plates  11 . In addition, even if the radiating plate  11  vibrates to a certain extent during the assembly, it is still possible to prevent the semiconductor chips  21  and circuit boards  22  on the radiating plate  11  from being displaced during this mounting process step. 
     Then, as shown in FIG.  3 ( c ), a press member  31  including protrusions  31   a  and a body  31   b  is prepared. The protrusions  31   a  are formed on the body  31   b  to come into contact with the respective upper surfaces of the semiconductor chips  21  and circuit boards  22  bonded to the radiating plate  11 . Subsequently, the press member  31  is mounted over the radiating plate  11  such that the respective upper surfaces of the protrusions  31   a  of the press member  31  face the corresponding upper surfaces of the semiconductor chips  21  and circuit boards  22 . 
     By using the press member  31 , it is possible to prevent the semiconductor chips  21  from being warped during the reflow process. That is to say, the periphery of the semiconductor chip  21  does not detach itself from the radiating plate  11 . In this embodiment, the press member  31  is made of carbon, which is highly resistant to the reflow process. 
     Next, as shown in FIG.  4 ( a ), the radiating plate  11 , on which the press member  31  has been mounted, is introduced into the reflow furnace again and heated up to about 300° C. By performing the reflow process at such a temperature as not melting the silver solder plate  16 , only the alloyed foil member  24  can be melted. In addition, the semiconductor chips  21  are not warped, either, since the upper surfaces thereof are pressed tight by the press member  31 . Thereafter, the radiating plate  11  is cooled down to room temperature. As a result, the semiconductor chips  21  and circuit boards  22  are bonded to the radiating plate  11  just as designed without causing any displacement. 
     Then, as shown in FIG.  4 ( b ), the press member  31  is removed from the radiating plate  11 . Finally, the input and output leads  13  and  14  are electrically connected to the circuit boards  22  via the wires  23  at respective regions inside the outer rail  12  and the semiconductor chips  21  are also connected to the circuit boards  22  via the wires  23 . As a result, the semiconductor device shown in FIGS.  1 ( a ) and  1 ( b ) is completed. 
     As described above, according to the method of the first embodiment, while the reflow process is performed for the semiconductor chips  21  and circuit boards  22 , the chips  22  and boards  22  over the radiating plate  11  can be positioned with respect to the positioning control plate  15  with the openings  15   a  in substantially the same shapes as the backsides of the chips  21  and boards  22 . Thus, even when the alloyed foil member  24  is melted, the chips  21  and boards  22  are neither swept nor displaced by the melted foil member  24 . As a result, it is possible to prevent the semiconductor chips  21  and circuit boards  22  from being displaced laterally over the radiating plate  11 . 
     In addition, according to this embodiment, the positioning control plate  15  has the recesses  15   b  at the corners of each opening  15   a  as shown in FIG.  2 ( a ), for example. Thus, during the reflow process on the semiconductor chips  21 , the melted foil member  24  can be stored within the recesses  15   b . That is to say, no superfluous foil member  24  melted overflows through the openings  15   a  onto the upper surfaces of the semiconductor chips  21 . 
     As to the positioning control plate  15  shown in FIG.  4 ( b ), the walls of the openings  15   a  are higher than the semiconductor chips  21  and circuit boards  22 . However, the walls of the openings  15   a  only need to be high enough to house at least the lower parts of the chips  21  and boards  22  within the openings  15   a.    
     Also, when the positioning control plate  15 B shown in FIG.  2 ( c ) is used, there is no need to bond the positioning control plate  15 B to the radiating plate  11 . In such a case, the positioning control plate  15 B may be removed from the radiating plate  11  for future use after the semiconductor device is completed. As a result, effective use of resources and reduction in fabrication cost are both realized. 
     Embodiment 2 
     Next, a second exemplary embodiment of the present invention will be described with reference to the accompanying drawings. 
     FIG. 5 illustrates a cross-sectional structure of package and semiconductor device formed by mounting a semiconductor chip within the package according to the second embodiment. In FIG. 5, the same members as those illustrated in FIG.  1 ( b ) are identified by the same reference numerals and the description thereof will be omitted herein. 
     As shown in FIG. 5, the package according to the second embodiment is characterized by including a radiating plate  11 A with a plurality of positioning control recesses  11   a . By housing at least the lower parts of the semiconductor chips  21  and circuit boards  22  within the recesses  11   a  of the radiating plate  11 A, the chips  21  and boards  22  can be positioned on the radiating plate  11 A with respect to the inner walls of the recesses  11   a.    
     In this case, the recesses  11   a  of the radiating plate  11 A may be formed by pressing, for example, to have desired shapes that are substantially the same as the backsides of the semiconductor chips  21  and circuit boards  22 . 
     Hereinafter, a method for fabricating a semiconductor device with such a structure will be described with reference to the accompanying drawings. 
     FIGS.  6 ( a ) through  6 ( c ) illustrate cross-sectional structures corresponding to respective process steps for fabricating a semiconductor device according to the second embodiment. 
     First, as shown in FIG.  6 ( a ), the outer rail  12 , in which the input and output leads  13  and  14  are inserted to face each other, is placed on the radiating plate  11 A such that these leads  13  and  14  are insulated from the radiating plate  11 A. Next, the radiating plate  11 A, on which the outer rail  12  has been placed, is introduced into a reflow furnace and heated up to about 800° C., thereby melting the silver solder member (not shown) therebetween. Then, the radiating plate  11 A is cooled down to room temperature again to solidify the silver solder member, thereby bonding the radiating plate  11 A and the outer rail  12  together. Subsequently, the alloyed foil member  24  is placed within the respective recesses  11   a  of the radiating plate  11 A, and then the semiconductor chips  21  and circuit boards  22  with a thickness of about 50 μm are mounted on the foil member  24 . 
     As can be seen, the semiconductor chips  21  and circuit boards  22  can be mounted according to this embodiment at their desired positions only by placing these members  21  and  22  into the positioning control recesses  11   a . In other words, positioning can be performed accurately only by forming the recesses  11   a  in predetermined regions of the radiating plate  11 A. Accordingly, there is no need to position the semiconductor chips  21  for respective radiating plates  11 A. In addition, even if the radiating plate  11 A vibrates to a certain extent during the assembly, it is still possible to prevent the semiconductor chips  21  and circuit boards  22  on the radiating plate  11 A from being displaced laterally during this mounting process step. 
     Then, as shown in FIG.  6 ( b ), the radiating plate  11 A, on which the semiconductor chips  21  have been mounted, is introduced into the reflow furnace again and heated up to about 300° C., thereby melting only the alloyed foil member  24 . Thereafter, the radiating plate  11 A is cooled down to room temperature again. As a result, the semiconductor chips  21  and circuit boards  22  are bonded to the radiating plate  11 A just as designed without causing any displacement. In this case, if the reflow process is performed with the press member  31  placed on the upper surfaces of the semiconductor chips  21  as in the first embodiment, then the semiconductor chips  21  are not warped, thus bonding the chips  21  to the radiating plate  11 A more strongly. 
     Then, as shown in FIG.  6 ( c ), the input and output leads  13  and  14  are electrically connected to the circuit boards  22  via the wires  23  at respective regions inside the outer rail  12  and the semiconductor chips  21  are also connected to the circuit boards  22  via the wires  23 . As a result, the semiconductor device shown in FIG. 5 is completed. 
     As described above, according to the second embodiment, while the reflow process is performed for the semiconductor chips  21  and circuit boards  22 , the chips  22  and boards  22  can be positioned over the radiating plate  11 A with respect to the recesses  11   a  of the radiating plate  11 A in substantially the same shapes as the backsides of the chips  21  and boards  22 . Thus, even when the alloyed foil member  24  is melted, the chips  21  and boards  22  are neither swept nor displaced laterally by the melted foil member  24  over the radiating plate  11 A.