Patent Publication Number: US-9415455-B2

Title: Semiconductor device and semiconductor device manufacturing method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a US application claiming priority from Japanese Application No. 2014-144861 filed Jul. 15, 2014, the disclosure of which is incorporated herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a semiconductor device and semiconductor device manufacturing method. 
     2. Description of the Background Art 
     In a power semiconductor module, a semiconductor chip or the like is fixed with solder to one main surface of an insulating substrate, and a radiating member is fixed with solder to the other main surface of the insulating substrate. 
     However, in such a power semiconductor module, when the solder repeatedly expands and contracts due to temperature change occurring when operating, notches or the like may occur in the solder. Further, thermal strain concentrates in the notches, whereby fatigue damage occurs in the solder, which may cause breakdown or damage of the power semiconductor module. 
     Therefore, in order to restrict the occurrence of notches or the like in the solder, the following kind of technology is known. A plurality of pillars with a thermal expansion coefficient higher than that of the solder is disposed between the insulating substrate and radiating member, and the gap between the insulating substrate and radiating member is widened by the expanded pillars when the solder is heated. Therefore, the melted solder is raised upward, the solder is prevented from collapsing or flowing under its own weight, and the solder strain concentration is reduced by depressing the end portion inwardly (for example, refer to JP-A-2001-168492). 
     SUMMARY OF THE INVENTION 
     It is desirable that thermal conductivity from the insulating substrate to the radiating member is improved by widening the application region of the solder applied between the insulating substrate and radiating member. However, in the heretofore described technology, the application region of the solder is limited by the pillars disposed on the periphery of the solder. Also, in the heretofore described technology, because the thermal expansion of the pillars is utilized in order to widen the gap between the insulating substrate and radiating member, the insulating substrate and radiating member are not parallel when the thermal expansions of the individual pillars vary. Therefore, there is a concern that variation will occur in the thickness of the solder in the gap. When there is a variation in the thickness of the solder, there is also a variation in the thermal conductivity depending on the place of mounting on the insulating substrate. In this way, there is a decrease in the reliability of a semiconductor device obtained by using the heretofore described technology. 
     The invention, having been contrived bearing these points in mind, has an object of providing a semiconductor device and semiconductor device manufacturing method such that the concentration of a thermal strain occurring in solder is restricted, and high reliability is obtained. 
     According to one aspect of the invention, there is provided a semiconductor device including a semiconductor element; an insulating substrate formed from stacking a rectangular shaped circuit plate, insulating plate, and metal plate, wherein the semiconductor element is fixed to the circuit plate, and the metal plate has at least one first groove portion provided in the four corners thereof; a radiating member made of metal and having a predetermined arrangement area to dispose the insulating substrate, the radiating member having at least one second groove portion provided in four corners of the arrangement area; four positioning members disposed between the four corners of the metal plate and the four corners of the radiating member, each of the four positioning members being fitted to each of the first groove portions and second groove portions; and a solder filling a space between the insulating substrate and the radiating member, and covering the positioning members. 
     Also, according to one aspect of the invention, there is provided a semiconductor device manufacturing method including a step of preparing an insulating substrate formed from stacking a rectangular shaped circuit plate, insulating plate, and metal plate, the metal plate having at least one first groove portion provided in the four corners thereof; a step of preparing a radiating member made of metal, the radiating member having at least one second groove portion provided in the four corners of an arrangement area to dispose the insulating substrate; a step of fitting four positioning members in the second groove portion in the four corners of the arrangement area; a step of mounting a solder plate in the arrangement area; a step of fitting the four positioning members in the first groove portion in the four corners of the metal plate, to fix the insulating substrate in the arrangement area; a step of heating and melting the solder plate; a step of filling a space between the insulating substrate and the radiating member with solder melted from the solder plate; and a step of cooling and hardening the melted solder. 
     According to the disclosed technology, it is possible to attain a semiconductor device and semiconductor device manufacturing method such that concentration of thermal strain occurring in solder is prevented, and high reliability is obtained. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view of a semiconductor device of a first embodiment. 
         FIGS. 2A and 2B  are diagrams for describing an insulating substrate of the first embodiment. 
         FIGS. 3A to 3C  are diagrams for describing a radiating member of the first embodiment. 
         FIGS. 4A and 4B  are first diagrams for describing a conventional semiconductor device manufacturing method as an example of reference. 
         FIGS. 5A to 5D  are second diagrams for describing a conventional semiconductor device manufacturing method as an example of reference. 
         FIGS. 6A to 6C  are diagrams for describing a conventional semiconductor device as an example of reference. 
         FIGS. 7A to 7D  are diagrams for describing a semiconductor device manufacturing method of the first embodiment. 
         FIGS. 8A to 8C  are diagrams for describing the semiconductor device of the first embodiment. 
         FIGS. 9A and 9B  are diagrams for describing a semiconductor device of a second embodiment. 
         FIGS. 10A and 10B  are diagrams for describing a semiconductor device of a third embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A description will be given of embodiments, referring to the drawings. 
     First Embodiment 
     A description will be given of a semiconductor device of a first embodiment, using  FIGS. 1 to 3C . 
       FIG. 1  is a sectional view of the semiconductor device of the first embodiment. 
     Also,  FIGS. 2A and 2B  are diagrams for describing an insulating substrate of the first embodiment.  FIG. 2A  shows a plan view of the side of the insulating substrate facing a radiating member, while  FIG. 2B  shows a sectional view taken along a dashed-dotted line X 1 -X 1  of  FIG. 2A . 
       FIGS. 3A to 3C  are diagrams for describing the radiating member of the first embodiment.  FIG. 3A  shows a plan view of the side of the radiating member facing the insulating substrate,  FIG. 3B  shows a sectional view taken along a dashed-dotted line X 2 -X 2  of  FIG. 3A , and  FIG. 3C  shows a perspective view of a positioning member.  FIGS. 3A and 3B  show only one of a plurality of arrangement areas provided on the radiating member. 
     A semiconductor device  10  includes semiconductor elements  60   a  and  60   b , an insulating substrate  20 , a radiating member  30 , a positioning member  50 , and solder  42 , as shown in  FIG. 1 . 
     For example, a switching element can be applied as one of the semiconductor elements  60   a  and  60   b , and a diode as the other. 
     For example, a vertical power semiconductor element, such as an insulated gate bipolar transistor (IGBT) or power metal-oxide-semiconductor field effect transistor (MOSFET), can be applied as the switching element. Also, for example, a power diode element, such as a Schottky barrier diode (SBD) or freewheeling diode (FWD), can be applied as the diode. 
     The embodiment is not limited to the two semiconductor elements  60   a  and  60   b  mounted on the insulating substrate  20 , and it is possible to use semiconductor elements with necessary function and quantity in accordance with the design of the semiconductor device  10 , and the like. 
     The insulating substrate  20  is formed by stacking a circuit plate  22 , an insulating plate  21 , and a metal plate  23 , which are rectangular. A ceramic such as aluminum nitride or aluminum oxide is used for the insulating plate  21 . The circuit plate  22  and metal plate  23  are formed from a metal such as copper, and can be formed using, for example, a direct copper bonding (DCB) method. The circuit plate  22  is formed such that a circuit pattern is selectively formed on the surface of the insulating plate  21 . A main electrode side (for example, a collector electrode or cathode electrode) of the semiconductor elements  60   a  and  60   b  is fixed onto the circuit plate  22  using solders  72   a  and  72   b . Also, a first groove portion  23   a  is provided in each of the four corners as shown in  FIG. 2A , which shows a plan view of the metal plate  23 . The first groove portion  23   a  has a shape corresponding to that of the positioning member  50  to be described hereafter. In this case, for example, the first groove portion  23   a  has an L-shape, and the apex of the L-shape is disposed so as to correspond with a corner portion of the metal plate  23 . Also, the first groove portion  23   a  has a depth such that the bottom portion does not reach the insulating plate  21 . 
     The radiating member  30  is formed from a metal such as copper or aluminum, and the insulating substrate  20  is fixed in a predetermined arrangement area of the radiating member  30 . Further, the radiating member  30  has a function of cooling heat generated by the semiconductor elements  60   a  and  60   b . Also, the radiating member  30  has a second groove portion  30   a  having a shape (herein, an L-shape) in accordance with that of the positioning member  50 , to be described hereafter, in each of the four corners of the arrangement area of the insulating substrate  20  in plan view, as shown in  FIGS. 3A and 3B . Also, each second groove portion  30   a  is disposed so as to face one of the first groove portions  23   a  of the insulating substrate  20 . 
     In the first embodiment, each of the first groove portions  23   a  and each of the second groove portions  30   a  are provided in the four corners of the metal plate  23  and arrangement area respectively, thus, four of each of the first groove portions  23   a  and second groove portions  30   a  are disposed. However, the first groove portions  23   a  and second groove portions  30   a  are formed such that it is sufficient that each of the four positioning members  50  can be fitted into each of the four corners of each of the metal plate  23  and arrangement area, as will be described hereafter. Therefore, for example, it is possible to dispose one continuous first groove portion  23   a  or one continuous second groove portion  30   a  along a peripheral portion of the insulating substrate  20  or radiating member  30 . Alternatively, it is possible to dispose two groove portions whereby two neighboring corners are joined. 
     The positioning member  50  is formed of a material having as a main component one of, for example, copper, nickel, and iron, which are materials that have high leakage with respect to solder. Alternatively, the surface of the positioning member  50  is covered with a material having as a main component one of, for example, copper, nickel, and iron, which are materials that have high leakage with respect to solder. Also, the positioning member  50  has an L-shape, and includes faces  51  and  52 , and a corner portion C having the faces  51  and  52 , as shown in  FIG. 3C . Four positioning members  50  are disposed between the four corners of the metal plate  23  and the four corners of the radiating member  30 , and are fitted into the first groove portions  23   a  in the four corners of the metal plate  23  and the second groove portions  30   a  in the four corners of the arrangement area. Further, the corner portions C of the positioning members  50  are positioned at the four corners of the insulating substrate  20 . Also, the example shown is a case wherein a cross-section of the end portion of the positioning member  50  is a square, but not being limited to square, the cross-section of the end portion may be rectangular. Alternatively, the cross-section of the end portion of the positioning member  50  may be circular or elliptical. In this case, provided only that the positioning member  50  is structured to be an L-shape in plan view, there is no need to maintain that the positioning member  50  has the faces  51  and  52 , and the corner portion C formed from the faces  51  and  52 . Also, when the positioning member  50  is formed from the same material as, for example, the radiating member  30 , the positioning member  50  can also be formed integrally in the place in which the second groove portion  30   a  of the radiating member  30  is formed. 
     The solder  42  is formed from a lead-free solder of a tin-silver series, or the like. The space between the insulating substrate  20  and radiating member  30  is filled with the solder  42 , thereby joining the insulating substrate  20  and radiating member  30 . Also, the solder  42  also has a function of transmitting heat generated from the semiconductor elements  60   a  and  60   b  from the insulating substrate  20  to the radiating member  30 . Furthermore, the solder  42  covers the positioning members  50 . This is because, as the surface of the positioning member  50  has high leakage with respect to solder, the solder  42  can leak outward so as to cover the positioning members  50 . 
     The semiconductor device  10  including this kind of structure is formed such that the solder  42  spreads to the four corners of the insulating substrate  20  so as to cover the positioning members  50 . Therefore, concentration of thermal strain is restricted in at least the four corners of the solder  42 , even when conducting, for example, a temperature cycle test. Also, the semiconductor device  10  is formed such that the gap between the insulating substrate  20  and radiating member  30  is kept even by the positioning members  50  so that the solder  42  filling the gap is also even. Therefore, the conductivity of heat from the insulating substrate  20  to the radiating member  30  can be kept uniform, regardless of the place on the main surface of the insulating substrate  20 . 
     Next, before describing a method of manufacturing this kind of semiconductor device  10 , using  FIGS. 4A to 5D , a description will be given of a conventional semiconductor device manufacturing method as a reference example. 
       FIGS. 4A to 5D  are diagrams for describing a conventional semiconductor device manufacturing method as a reference example. 
     Semiconductor elements mounted on an insulating substrate are omitted from  FIGS. 4A to 5D . Also,  FIG. 4A  shows a plan view of a positioning jig, while  FIG. 4B  shows a sectional view taken along a dashed-dotted line X 3 -X 3  of  FIG. 4A . Also,  FIGS. 5A to 5D  are sectional views wherein a radiating member on the right side of  FIGS. 4A and 4B  and an insulating substrate disposed on the radiating member are enlarged, and show steps of joining the insulating substrate and radiating member using solder. 
     Firstly, a positioning jig  200  having one or more aperture portions  210  is set on a radiating member  130  formed from a metal, such as copper or aluminum, that has a certain thermal conductivity or higher. The positioning jig  200  is formed from a material with low leakage with respect to solder, for example, a carbon material, so that solder does not adhere when soldering. A plating process is performed on the radiating member  130  using, for example, nickel. Due to the plating process, oxidation is prevented when the radiating member  130  is formed from copper, and joinability to solder is improved when the radiating member  130  is formed from aluminum. 
     Also, when setting the positioning jig  200 , a positioning hole  220  of the positioning jig  200  is fitted over a positioning pin  230  fixed to the radiating member  130 . Further, the positioning jig  200  is fixed so that the aperture portions  210  of the positioning jig  200  are each positioned in a predetermined arrangement area on the radiating member  130 . 
     Next, a solder plate  140  is mounted in the aperture portion  210  of the positioning jig  200  set on the radiating member  130 , after which an insulating substrate  120  is mounted on the solder plate  140  ( FIGS. 4A and 4B ). 
     The insulating substrate  120 , in the same way as the insulating substrate  20  of the semiconductor device  10 , is rectangular, and includes an insulating plate  121 , and a circuit plate  122  and metal plate  123  disposed on the front and back surfaces of the insulating plate  121 . 
     Next, a description will be given of steps of joining the insulating substrate  120  and radiating member  130  using solder. 
     As heretofore described, the insulating substrate  120  is set across the solder plate  140  in an arrangement area A (soldering region (planned)) on the radiating member  130  using the positioning jig  200  ( FIG. 5A ). 
     In this state, the whole configuration is heated at a temperature at which the solder plate  140  melts. By so doing, as the thermal expansion coefficient of the radiating member  130  is greater than that of the positioning jig  200 , and the radiating member  130  and positioning jig  200  are fixed to each other by the positioning pin  230 , the radiating member  130  spreads outward (to the right in  FIGS. 5A to 5D ) beyond the positioning jig  200 , centered on the positioning pin  230 . Further, due to the spread of the radiating member  130 , deviation occurs between the original soldering region (planned) of the insulating substrate  120  and the soldering region (actual) ( FIG. 5B ). In particular, the deviation becomes more obvious as the distance from the positioning pin  230  increases. 
     In the state in which the soldering region has deviated in this way, solder  141  melted from the solder plate  140  fills the space between the insulating substrate  120  and radiating member  130  ( FIG. 5C ). 
     Next, the solder  141  filling the space between the insulating substrate  120  and radiating member  130  is cooled, whereby the insulating substrate  120  and radiating member  130  are joined by solder  142  hardened from the solder  141 . By the whole configuration being cooled at this time, the radiating member  130  contracts, and moves inward (to the left in  FIGS. 5A to 5D ). The insulating substrate  120  also moves inward together with the contraction of the radiating member  130 . Meanwhile, inward contraction of the positioning jig  200  is less than that of the insulating substrate  120 . Therefore, it may happen that an end portion of the insulating substrate  120  contacts an inner wall of the aperture portion  210  of the positioning jig  200 , and damages the insulating substrate  120  ( FIG. 5D ). 
     In order to prevent this kind of contact between the insulating substrate  120  and the inner wall of the aperture portion  210 , for example, increasing the aperture area of the aperture portion  210  of the positioning jig  200  is conceivable. When increasing the aperture area, however, there is a decrease in the accuracy of disposing the insulating substrate  120  in the arrangement area on the radiating member  130 . 
     Next, a description will be given, using  FIGS. 6A to 6C , of a reference example of a semiconductor device manufactured in this way. Semiconductor elements mounted on the insulating substrate  120  are omitted from  FIGS. 6A to 6C . 
       FIG. 6A  shows a plan view of the insulating substrate  120  joined to the radiating member  130 , while  FIGS. 6B and 6C  show sectional views taken along the dashed-dotted lines X 4 -X 4  and X 5 -X 5  respectively of  FIG. 6A . 
     In a semiconductor device  100  manufactured via the steps of  FIGS. 4A to 5D , it may happen that the solder  142  joining the insulating substrate  120  and radiating member  130  does not spread to the four corners of the insulating substrate  120 , as shown by the broken line in  FIG. 6A . This is caused by thermal contraction of the solder  142  when cooled, and is obvious in the four corners, of which a considerable portion is exposed to the exterior. The details are explained below. 
     For example, it is assumed that the amount of solder  142  is adjusted, and a good fillet form, wherein the solder  142  spreads downward, can be formed in the vicinity of the center of a side of the insulating substrate  120  ( FIG. 6B ). 
     In this case, however, as contraction of the solder  142  advances from two sides at a corner portion of the insulating substrate  120 , an indentation occurs at a corner portion P of the solder  142 , as shown In  FIG. 6C . When a temperature change occurs when operating in the semiconductor device  100  wherein indentation has occurred at the corner portion P of the solder  142  in this way, thermal strain concentrates in the indentation, and fatigue damage occurs, which may cause breakdown or damage of the semiconductor device  100 . 
     Meanwhile, when attempting to form a good fillet shape, wherein no indentation occurs in the corner portion P, by increasing the amount of the solder  142 , the amount of solder is excessive in the vicinity of the center of a side. Therefore, there may occur a problem such as the solder  142  overflowing in the vicinity of the center of a side, encroaching as far as the circuit plate  122 , and causing a short-circuit. 
     Also, the semiconductor device  100  is formed such that the insulating substrate  120  is simply disposed across the solder  141  on the radiating member  130  by, for example, the steps of joining using solder in  FIGS. 5A to 5D . Therefore, it is also conceivable that the insulating substrate  120  inclines with respect to the radiating member  130  when the solder  141  melts. When the insulating substrate  120  is joined in an inclined state with respect to the radiating member  130 , the thickness of the solder  142  differs depending on the position thereof on the main surface of the insulating substrate  120 . In this kind of semiconductor device  100 , variation occurs in the conductivity of heat from the insulating substrate  120  to the radiating member  130 . 
     There is a possibility of a decrease in the reliability of the semiconductor device  100  manufactured via the steps of  FIGS. 4A to 5D  in this way. 
     Therefore, a description will be given, using  FIGS. 1 to 3C  and  FIGS. 7A to 7D , of a method of manufacturing the semiconductor device  10  of the first embodiment. 
     The mounting, and steps of fixing, the semiconductor elements fixed onto the insulating substrate are omitted from  FIGS. 7A to 7D . Also, in the same way as  FIGS. 5A to 5D ,  FIGS. 7A to 7D  are sectional views wherein the radiating member and the insulating substrate disposed in one place on the radiating member are enlarged, and show steps of joining the insulating substrate and radiating member using solder. Also, descriptions of portions duplicating the description of  FIGS. 1 to 3C  may be omitted. 
     Firstly, the insulating substrate  20  having the configuration illustrated in  FIGS. 2A and 2B  is prepared. Also, the radiating member  30  having the configuration illustrated in  FIGS. 3A and 3B  is prepared. 
     Next, the four positioning members  50  illustrated in  FIG. 3C  are fitted one each into the second groove portions  30   a  in the four corners of the predetermined arrangement area (soldering region) on the radiating member  30 . Also, a solder plate  40  is mounted in the arrangement area on the radiating member  30 . Furthermore, each of the four positioning members  50  is fitted into the first groove portions  23   a  in the four corners of the metal plate  23  of the insulating substrate  20 , thereby fixing the insulating substrate  20  to the predetermined arrangement area on the radiating member  30  ( FIG. 7A ). After this step, a gap of a predetermined distance, which is the thickness of the solder  42  in the semiconductor device  10 , is provided uniformly between the insulating substrate  20  and radiating member  30 . 
     Next, the whole configuration is heated at a temperature at which the solder plate  40  melts, thereby melting the solder plate  40 . The radiating member  30  expands when heated, spreading outward (to the right in  FIGS. 7A to 7D ). At this time, as the insulating substrate  20  is positioned on the radiating member  30  by the positioning members  50 , the insulating substrate  20  moves outward together with the expansion of the radiating member  30  ( FIG. 7B ). Therefore, the insulating substrate  20  does not deviate from the planned soldering region, even though the heated radiating member  30  expands. 
     Solder  41  melted from the heated solder plate  40  spreads outward in the gap between the insulating substrate  20  and radiating member  30 , thereby filling the gap. Also, as the surface of the positioning member  50  has high leakage with respect to the solder  41 , as heretofore described, the solder  41  that reaches the positioning members  50  spreads further outward while covering the positioning members  50 . Further, the corner portion C of the positioning member  50  is disposed in each of the four corners of the insulating substrate  20 , as heretofore described, because of which, when the solder  41  completely covers the positioning members  50  as far as the corner portion C, the solder  41  reaches each of the four corners of the insulating substrate  20  ( FIG. 7  (C)). 
     Also, as the bottom portion of the first groove portion  23   a  is of a depth not reaching the insulating plate  21 , the insulating plate  21 , which has low leakage, is not exposed in the first groove portion  23   a . Therefore, the solder  41 , without being impeded when spreading, spreads to the four corners of the insulating substrate  20  while covering the positioning members  50 . 
     Next, the melted solder  41  is cooled and hardened, whereby the insulating substrate  20  and radiating member  30  are joined by the solder  41  ( FIG. 7D ). Thereupon, the expanded radiating member  30  contracts (to the left in  FIGS. 7A to 7D ). At this time, the insulating substrate  20  positioned by the positioning members  50  on the radiating member  30  moves together with the contraction of the radiating member  30 , in a direction opposite to that when the radiating member  30  expands. Also, at this time of contraction, the insulating substrate  20  is subjected to no damage or the like, nor does the insulating substrate  20  deviate from the planned soldering region, as the positioning jig  200  shown in  FIGS. 5A to 5D  is not used. 
     Next, a description will be given, using  FIGS. 8A to 8C , of the semiconductor device  10  of the first embodiment manufactured in this way. 
       FIG. 8A  shows a plan view of the semiconductor device  10 , while  FIGS. 8B and 8C  show sectional views taken along the dashed-dotted lines X 6 -X 6  and X 7 -X 7  of  FIG. 8A . 
     In the semiconductor device  10  manufactured via the steps illustrated in  FIGS. 7A to 7D , the solder  42  spreads to the four corners of the insulating substrate  20 , thereby joining the insulating substrate  20  and radiating member  30 , as shown by the broken line in  FIG. 8A . 
     For example, the solder  42  includes a good fillet shape spread downward in the vicinity of the center of a side of the insulating substrate  20 , as shown in  FIG. 8B . 
     Also, regarding the four corner portions of the insulating substrate  20 , the solder  42  covers the positioning members  50 , spreading to the four corners of the insulating substrate  20 , as shown in  FIG. 8C . Furthermore, the solder  42  includes a good fillet shape spread downward. 
     Therefore, even when a temperature change occurs when operating in this kind of semiconductor device  10 , there is no concentration of thermal strain in an end portion of the solder  42 , and the temperature cycle resistances improve. 
     When the angle of the corner portion C of the positioning member  50  is acute, the solder  42  can be more effective to reach each of the four corners of the insulating substrate  20 . Further, it is preferable that the angle of the corner portion C is a right angle corresponding to the corner portion of the insulating substrate  20 . 
     Furthermore, in the first embodiment, a predetermined and uniform thickness of the solder  42  can be obtained by controlling the height of the positioning member  50  and the depth of the first groove portion  23   a  and second groove portion  30   a . Therefore, the conductivity of heat from the insulating substrate  20  to the radiating member  30  is of a desired value and uniform, regardless of the place on the main surface of the insulating substrate  20 . Consequently, the semiconductor device  10  of the first embodiment is formed such that an increase in reliability can be achieved. 
     Second Embodiment 
     In a second embodiment, a description will be given of a case wherein a positioning member of another form is applied in the first embodiment. A description of portions duplicating the description of the first embodiment may be omitted. 
       FIGS. 9A and 9B  are diagrams for describing a semiconductor device of the second embodiment. 
       FIG. 9A  shows a perspective view of a positioning member of the second embodiment, while  FIG. 9B , corresponding to  FIG. 8C , shows a sectional view of a corner portion of a semiconductor device using  FIG. 9A . 
     A positioning member  50   a  shown in  FIG. 9A , in the same way as the positioning member  50 , has a surface with high leakage with respect to solder, is of an L-shape in plan view, and includes faces  51   a  and  52   a , and a corner portion Ca configured of the faces  51   a  and  52   a . However, the cross-section of an end portion of the positioning member  50   a  is a trapezoidal shape wherein sides  50   a   2  and  50   a   3  are perpendicular, and a side  50   a   4  is inclined, with respect to a side  50   a   1 . Also, together with the inclination of the side  50   a   4 , the faces  51   a  and  52   a  are also formed such that the insulating substrate  20  side thereof inclines to the inner side of the insulating substrate  20 . 
     Further, the first groove portion  23   a  of the insulating substrate  20  and the second groove portion  30   a  of the radiating member  30  have a groove form formed in accordance with the shape of the positioning member  50   a , so that the positioning member  50   a  can be fitted. 
     A semiconductor device  11  to which the positioning member  50   a  is applied is shown in  FIG. 9B . In the same way as the semiconductor device  10 , the semiconductor device  11  is formed such that the solder  42  fills the gap between the insulating substrate  20  and radiating member  30 , and the solder  42  covers the positioning members  50   a , spreading to the four corners of the insulating substrate  20 . Furthermore, in the case of the positioning member  50   a , the solder  42  covers the inclined faces  51   a  and  52   a  of the positioning member  50   a  so that the solder  42  can form a good fillet shape spreading downward. Therefore, concentration of thermal strain in an end portion of the solder  42  is further restricted, and the temperature cycle resistances improve further. 
     Third Embodiment 
     In a third embodiment, a description will be given of a case wherein a positioning member of another shape is still applied in the first embodiment. 
       FIGS. 10A and 10B  are diagrams for describing a semiconductor device of the third embodiment. 
     As the positioning member  50  is formed such that the corner portion C formed from the faces  51  and  52  is positioned in each of the four corners of the insulating substrate  20 , the melted solder  41  completely buries the faces  51  and  52  and the corner portion C of the positioning members  50  to reach the four corners of the insulating substrate  20 . 
     For example, in a semiconductor device  12 , a positioning member  50   b  has a triangular shape in plan view, including faces  51   b  and  52   b , and a corner portion Cb configured of the faces  51   b  and  52   b , as shown in  FIG. 10A . In this case, by the faces  51   b  and  52   b , and the corner portion Cb formed from the faces  51   b  and  52   b , being positioned in each of the four corners of the insulating substrate  20 , the same advantages as with the positioning member  50  are obtained. Furthermore, provided that the cross-section of an end portion of the positioning member  50   b  has the same trapezoidal shape as the cross-section of the end portion of the positioning member  50   a , the same advantages as with the positioning member  50   a  are obtained. 
     Also, in a semiconductor device  13 , a positioning member  50   c  has a quadrilateral shape in plan view, including faces  51   c  and  52   c , and a corner portion Cc formed from the faces  51   c  and  52   c , as shown in  FIG. 10B . In this case, by the faces  51   c  and  52   c , and the corner portion Cc formed from the faces  51   c  and  52   c , being positioned in each of the four corners of the insulating substrate  20 , the same advantages as with the positioning member  50  are obtained. Furthermore, also, in this case, provided that the cross-section of an end portion of the positioning member  50   c  has the same trapezoidal shape as the cross-section of the end portion of the positioning member  50   a , the same advantages as with the positioning member  50   a  are obtained. 
     In order to not decrease the reliability of the semiconductor devices  10  to  13 , it is desirable that the positioning members  50 ,  50   a ,  50   b , and  50   c  have a size that a localized amount of the solder  42  in the four corners of the insulating substrate  20  does not overly decrease.