Patent Publication Number: US-9893643-B1

Title: Semiconductor module, semiconductor device, and electric power device

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to semiconductor modules, semiconductor devices, and electric power devices. 
     Description of the Background Art 
     In a semiconductor module provided with semiconductor elements for switching, surge voltages are generated by switching operations of the semiconductor elements. Particularly when it is used for an electric power use, generation of the surge voltages by switching of large currents and high voltages is problematic. Therefore, a snubber circuit is connected to the semiconductor module in order to absorb the surge voltages. 
     Conventionally, the snubber circuit has been connected to the terminals, which are exposed from a package outer surface of the semiconductor module, by screw clamping or the like. Also, a technique for attaching the snubber circuit by providing the semiconductor module with snubber-circuit-dedicated terminals is known (see Japanese Patent Application Laid-Open No. 2015-223047). 
     In Japanese Patent Application Laid-Open No. 2015-223047, connection terminals of the snubber circuit are pin contacts, have high contact resistance, and large inductance; therefore, there has been a problem that the effect of suppressing the surge voltages is low. Therefore, it has been required to further increase the capacity of the snubber circuit. Also, it has been desired to further improve the effect of suppressing the surge voltages by connecting the snubber circuit more closely to the semiconductor elements provided in the semiconductor module. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a semiconductor module that electrically efficiently connects to a snubber circuit module and effectively suppresses surge voltages. It is another object of the present invention to provide a semiconductor device and an electric power device provided with this semiconductor module. 
     A semiconductor module according to the present invention is provided with: at least one semiconductor element; a circuit pattern disposed on a substrate and joined with a main electrode of the at least one semiconductor element; an outer enclosure member enclosing at least the at least one semiconductor element and a surface of the substrate in a side of the circuit pattern; and a snubber-circuit-connecting opening provided in an outer surface of the outer enclosure member. At least one snubber circuit module is attachable/detachable to/from an interior communicated with the snubber-circuit-connecting opening. A plurality of snubber-circuit electrodes for electrically connecting with the at least one snubber circuit module are joined with the circuit pattern. The plurality of snubber-circuit electrodes are disposed in the interior of the snubber-circuit-connecting opening. In a state that the snubber circuit module is attached in the interior of the snubber-circuit-connecting opening, the snubber circuit module does not stick out from an outer surface of the outer enclosure member. The plurality of snubber-circuit electrodes are in surface-contact with electrodes in the side of the snubber circuit module, respectively. The snubber-circuit opening and the interior are not overlapped with the at least one semiconductor element in a planar view. 
     According to the semiconductor module according to the present invention, the lengths of the snubber-circuit electrodes can be minimized. Since the snubber circuit module can be attached in the vicinity of the semiconductor elements as a result, inductance can be further reduced at the connecting part, and the effect of suppressing surge voltages is further improved. The plurality of snubber-circuit electrodes are brought into surface-contact with the electrodes in the side of the snubber circuit module, respectively. Therefore, in the connecting part, contact resistance and inductance can be further reduced, and the effect of suppressing the surge voltages is further improved. 
     These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a semiconductor module according to a first preferred embodiment; 
         FIG. 2  is a cross-sectional view of the semiconductor module according to the first preferred embodiment along line segment A-A of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of the semiconductor module according to the first preferred embodiment along line segment B-B of  FIG. 1 ; 
         FIG. 4  is a front view of a snubber-circuit-connecting opening of the semiconductor module according to the first preferred embodiment; 
         FIG. 5  is a perspective view of a snubber circuit module according to the first preferred embodiment; 
         FIG. 6  is a cross-sectional view of a state in which the snubber circuit module of the semiconductor module according to the first preferred embodiment is attached; 
         FIG. 7  is a diagram showing a circuit configuration of the semiconductor module and the snubber circuit module according to the first preferred embodiment; 
         FIG. 8  is a diagram showing a circuit configuration of the snubber circuit module according to the first preferred embodiment; 
         FIG. 9  is a cross-sectional view of a semiconductor module according to a modification example of the first preferred embodiment; 
         FIG. 10  is a front view of a snubber-circuit-connecting opening of the semiconductor module according to the modification example of the first preferred embodiment; 
         FIG. 11  is a cross-sectional view in a state in which two snubber circuit modules of the semiconductor module according to the modification example of the first preferred embodiment is attached; 
         FIG. 12  is a front view of a snubber-circuit-connecting opening of a semiconductor module according to another modification example of the first preferred embodiment; 
         FIG. 13  is a perspective view of a semiconductor module according to a second preferred embodiment; 
         FIG. 14  is a cross-sectional view along line segment C-C of  FIG. 13  of the semiconductor module according to the second preferred embodiment; 
         FIG. 15  is a front view of a snubber-circuit-connecting opening of the semiconductor module according to the second preferred embodiment; 
         FIG. 16  is a perspective view of a snubber circuit module according to the second preferred embodiment; 
         FIG. 17  is a diagram showing a first example of a circuit configuration of the semiconductor module and the snubber circuit module according to the second preferred embodiment; 
         FIG. 18  is a diagram showing the first example of the circuit configuration of the snubber circuit module according to the second preferred embodiment; 
         FIG. 19  is a diagram showing a second example of the circuit configuration of the semiconductor module and the snubber circuit module according to the second preferred embodiment; 
         FIG. 20  is a diagram showing the second example of the circuit configuration of the snubber circuit module according to the second preferred embodiment; 
         FIG. 21  is a front view of a snubber-circuit-connecting opening of a semiconductor module according to a modification example of the second preferred embodiment. 
         FIG. 22  is a front view of a snubber-circuit-connecting opening of the semiconductor module according to another modification example of the second preferred embodiment; 
         FIG. 23  is a perspective view of a semiconductor module according to a third preferred embodiment; 
         FIG. 24  is a cross-sectional view along line segment D-D in  FIG. 23  of the semiconductor module according to the third preferred embodiment; 
         FIG. 25  is a top view of the semiconductor module according to the third preferred embodiment; 
         FIG. 26  is a cross-sectional view in a state in which a snubber circuit module of the semiconductor module according to the third preferred embodiment is attached; 
         FIG. 27  is a perspective view of a semiconductor module according to a fourth preferred embodiment; 
         FIG. 28  is a top view of the semiconductor module according to the fourth preferred embodiment; and 
         FIG. 29  is a diagram showing a configuration of an electric power device according to a fifth preferred embodiment. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Preferred Embodiment 
       FIG. 1  is a perspective view of a semiconductor module  100  of a present first preferred embodiment.  FIG. 2  is a cross-sectional view of the semiconductor module  100  along line segment A-A in  FIG. 1 .  FIG. 3  is a top view of the semiconductor module  100 . In  FIG. 3 , illustration of part of an outer enclosure member  6  is omitted in order to facilitate understanding of the view. 
     The semiconductor module  100  in the present first preferred embodiment is provided with a plurality of semiconductor elements  11  and  12 , a circuit pattern, an outer enclosure member  6 , and a snubber-circuit-connecting opening  7 . The semiconductor element  11  and the semiconductor element  12  are switching elements such as Insulated Gate Bipolar Transistor (IGBT), MOSFET, etc. A first main electrode (for example, an emitter electrode) is provided on an upper surface (surface in the +z direction side) of each of the semiconductor elements  11  and  12 , and a second main electrode (for example, a collector electrode) is provided on a lower surface (surface in the −z direction side) thereof. The semiconductor element  11  and the semiconductor element  12  are connected to each other in series via the circuit pattern and wires. 
     The circuit pattern is joined with a principal surface (in other words, the surface in the z-direction side) of an insulating substrate  4  by solder  1   a . The circuit pattern includes first, second, and third circuit patterns  51 ,  52 , and  53 , which are separated from one another. The second main electrode of the semiconductor element  11  is joined with the first circuit pattern  51  by solder  1   b . The first main electrode of the semiconductor element  12  is connected to the third circuit pattern  53  by solder  1   b . The first main electrode of the semiconductor element  11  and the third circuit pattern  53  are electrically connected via wires. The first main electrode of the semiconductor element  12  and the second circuit pattern  52  are electrically connected via wires. 
     The semiconductor module  100  is provided with a P terminal  21 , an N terminal  22 , and an AC terminal  23  as main-electrode terminals. The P terminal  21  is electrically  5  connected to the first circuit pattern  51  via wires. The N terminal  22  is electrically connected to the first main electrode of the semiconductor element  12  via wires. The AC terminal  23  is electrically connected to the third circuit pattern  53  via wires. 
     The outer enclosure member  6  encloses the semiconductor elements  11  and  12  and the surface of the side on which the circuit patterns of the substrate  4  are provided. The outer enclosure member  6  is, for example, insulating resin. Distal-end parts of the P terminal  21 , the N terminal  22 , and the AC terminal  23  are exposed from the outer enclosure member  6 . The distal-end parts of the terminals may be provided with screw holes for connection with external wiring. 
     The snubber-circuit-connecting opening  7  is provided on an outer surface of the outer enclosure member  6 . In the present first preferred embodiment, the snubber-circuit-connecting opening  7  is provided on a lateral surface with respect to the principal surface of the substrate  4  among the outer surfaces of the outer enclosure member  6 . Herein, the lateral surface of the outer enclosure member  6  is a surface perpendicular to a y-direction among the outer surfaces of the outer enclosure member  6 . A snubber circuit module  200  is attachable/detachable to/from an interior  7   a  communicated with the snubber-circuit-connecting opening  7 . The snubber circuit module  200  will be described later. 
     The semiconductor module  100  is provided with a plurality of snubber-circuit electrodes. The plurality of snubber-circuit electrodes include a snubber-circuit P electrode  31  and a snubber-circuit N electrode  32 . The snubber-circuit P electrode  31  is joined with the first circuit pattern  51 , for example, by solder. The snubber-circuit N electrode  32  is joined with the second circuit pattern  52 , for example, by solder. The snubber-circuit P electrode  31  and the snubber-circuit N electrode  32  are disposed in the interior  7   a  of the snubber-circuit-connecting opening  7 . 
       FIG. 4  is a front view of the snubber-circuit-connecting opening  7 . As shown in  FIG. 4 , a terminal part of the snubber-circuit P electrode  31  has two metal plates  31   a  and  31   b , which are stacked with an interval provided therebetween. Similarly, a terminal part of the snubber-circuit N electrode  32  has two metal plates  32   a  and  32   b , which are stacked with an interval provided therebetween. The cross-sectional shape of the snubber-circuit N electrode  32  is similar to the cross-sectional shape of the snubber-circuit P electrode  31 . 
     As shown in  FIG. 2  and  FIG. 3 , the snubber-circuit-connecting opening  7  and the interior  7   a , which is communicated with the snubber-circuit-connecting opening  7 , are disposed at the positions not overlapped with the semiconductor elements  11  and  12  in a planar view. The snubber-circuit-connecting opening  7  and the interior  7   a  are disposed at the positions not overlapped with the wires, which are disposed in the semiconductor module, in the planar view. Thus, the snubber-circuit connecting opening  7  and the interior  7   a  are preferred to be disposed at the positions not overlapped with the circuit patterns and the members other than the snubber-circuit electrodes in the planar view. 
     &lt;Snubber Circuit Module&gt; 
       FIG. 5  is a perspective view of the snubber circuit module  200  in the present first preferred embodiment. The snubber circuit module  200  is provided with an electrode terminal part  60  and a main body part  70 . A snubber circuit is built in the main body part  70 . The electrode terminal part  60  is provided with a P electrode terminal  61  and an N electrode terminal  62 . 
     The thickness of the P electrode terminal  61  of the snubber circuit module  200  is designed to match the interval between the metal plates  31   a  and  31   b  of the snubber-circuit P electrode  31 . Similarly, the thickness of the N electrode terminal  62  of the snubber circuit module  200  is designed to match the interval between the metal plates  32   a  and  32   b  of the snubber-circuit N electrode  32 . 
     The length (in other words, y-direction length) of the snubber circuit module  200  is designed so that the snubber circuit module  200  does not stick out from the outer surface of the outer enclosure member  6  in a state in which the snubber circuit module  200  is attached to the interior  7   a , which is communicated with the snubber-circuit-connecting opening  7 . The width (in other words, x-direction length) of the snubber circuit module  200  is designed to be equal to or less than the width of the snubber-circuit-connecting opening  7 . 
       FIG. 6  is a cross-sectional view of the semiconductor module  100  in a state in which the snubber circuit module  200  is attached. The snubber circuit module  200  is attached by being pushed into the snubber-circuit-connecting opening  7  of the semiconductor module  100 . As shown in  FIG. 6 , the P electrode terminal  61  of the snubber circuit module  200  is inserted between the metal plates  31   a  and  31   b , which are opposite to each other in the snubber-circuit P electrode  31 , and is brought into surface-contact with each of the metal plates  31   a  and  31   b . Similarly, the N electrode terminal  62  of the snubber circuit module  200  is inserted between the metal plates  32   a  and  32   b , which are opposite to each other in the snubber-circuit N electrode  32 , and is brought into surface contact with each of the metal plates  32   a  and  32   b.    
     As shown in  FIG. 6 , in the state in which the snubber circuit module  200  is attached to the interior  7   a , which is communicated with the snubber-circuit-connecting opening  7 , the snubber circuit module  200  does not stick out from the outer surface of the outer enclosure member  6 . The outer surface of the attached snubber circuit module  200  may be disposed in the same plane as the outer surface of the outer enclosure member  6 . 
     When the snubber circuit module  200  is to be detached from the semiconductor module  100 , a user causes a claw of a detaching tool to catch a groove  71   a  of a cutout  71 , which is provided on a main body part  70  of the snubber circuit module  200 , and pulls it out from the snubber-circuit-connecting opening  7 . Alternatively, the cutout  71  per se may be pinched and pulled out with the fingers of the user or a tool. 
     Note that, even in a state in which the snubber circuit module  200  is not attached to the semiconductor module  100 , the semiconductor module  100  can be operated. 
       FIG. 7  is a diagram showing a circuit diagram of the semiconductor module  100  and the snubber circuit module  200 .  FIG. 8  is a diagram showing a circuit configuration of the snubber circuit module  200 . As shown in  FIG. 7 , in the semiconductor module  100 , the semiconductor elements  11  and  12  serving as the switching elements in which freewheeling diodes are built are connected in series. The P terminal  21  and the snubber-circuit P electrode  31  are electrically connected to each other, and the N terminal  22  and the snubber-circuit N electrode  32  are electrically connected to each other. In the snubber circuit module  200 , a capacitor is connected between the P electrode terminal  61  and the N electrode terminal  62 . 
     Note that the configuration of the snubber circuit of the snubber circuit module  200  is not limited to that of  FIG. 8 , and the snubber circuit may include a resistive element, a diode, etc. other than the capacitor. Also, a plurality of snubber circuit modules  200  of snubber circuits having different configurations may be prepared, and the snubber circuit module  200  to be attached to the semiconductor module  100  may be appropriately selected and attached depending on the characteristics of the magnitude, etc. of the surge voltage to be generated. 
     &lt;Effects&gt; 
     The semiconductor module  100  in the present first preferred embodiment is provided with: at least one semiconductor element (more specifically, the semiconductor element  11 ,  12 ); circuit patterns (more specifically, the first, second, third circuit patterns  51 ,  52 ,  53 ) disposed on the substrate  4  and joined with a main electrode of the at least one semiconductor element; the outer enclosure member  6  enclosing at least the at least one semiconductor element and the surface in the side of the circuit patterns of the substrate  4 ; and the snubber-circuit-connecting opening  7  provided in the outer surface of the outer enclosure member  6 . The at least one snubber circuit module  200  is attachable/detachable to/from the interior  7   a  communicated with the snubber-circuit-connecting opening  7 . A plurality of snubber-circuit electrodes (more specifically, the snubber-circuit P electrode  31  and the snubber-circuit N electrode  32 ) for electrically connecting with the at least one snubber circuit module  200  are joined with the circuit patterns. The plurality of snubber-circuit electrodes are disposed in the interior  7   a  of the snubber-circuit-connecting opening  7 . In a state in which the snubber circuit module  200  is attached to the interior  7   a  of the snubber-circuit-connecting opening  7 , the snubber circuit module  200  does not stick out from the outer surface of the outer enclosure member, the plurality of snubber-circuit electrodes are brought into surface contact with the electrodes in the side of the snubber circuit module  200 , respectively, and the snubber-circuit-connecting opening  7  and the interior  7   a  are not overlapped with the at least one semiconductor element in the planar view. 
     If the snubber-circuit-connecting opening  7  and the interior  7   a  are overlapped with the semiconductor elements  11  and  12 , the connecting wires, etc. in the planar view, the snubber-circuit electrodes (more specifically, the snubber-circuit P electrode  31  and the snubber-circuit N electrode  32 ) have to be designed to be long in order to avoid contact with the semiconductor elements and the wires. On the other hand, in the present first preferred embodiment, the snubber-circuit-connecting opening  7  and the interior  7   a  are not overlapped with the semiconductor elements  11  and  12  in the planar view; therefore, the length of the snubber-circuit electrodes can be minimized. As a result, the snubber circuit module  200  can be attached in the vicinity of the semiconductor elements  11  and  12 ; therefore, inductance can be further reduced in the connecting part, and the effect of suppressing surge voltages is further improved. 
     In the semiconductor module  100  in the present first preferred embodiment, the plurality of snubber-circuit electrodes are brought into surface-contact with the electrodes in the side of the snubber circuit module  200 , respectively. Therefore, in the connecting part, contact resistance and inductance can be further reduced, and the effect of suppressing surge voltages is further improved. 
     In the semiconductor module  100  in the present first preferred embodiment, in the state in which the snubber circuit module  200  is attached to the interior  7   a  of the snubber-circuit-connecting opening  7 , the snubber circuit module  200  does not stick out from the outer surface of the outer enclosure member  6 . Therefore, when another devices, etc. are disposed around the semiconductor module  100 , interference of the snubber circuit module  200  with the devices, etc. therearound can be avoided. 
     In the semiconductor module  100  in the present first preferred embodiment, the snubber-circuit-connecting opening  7  is provided in the lateral surface with respect to the principal surface of the substrate  4  among the outer surfaces of the outer enclosure member  6 . Therefore, even when another devices, etc. are disposed in the upper surface side of the semiconductor module  100 , the snubber circuit module  200  can be attached/detached to/from the lateral surface of the semiconductor module  100 . 
     In the semiconductor module  100  of the present first preferred embodiment, each of the terminal parts of the plurality of snubber-circuit electrodes (more specifically, the snubber-circuit P electrode  31  and the snubber-circuit N electrode  32 ) has the plurality of metal plates  31   a  and  31   b  (or the metal plates  32   a  and  32   b ) stacked with the interval provided therebetween, and the electrode terminals (more specifically, the P electrode terminal  61  and the N electrode terminal  62 ) in the side of the snubber circuit module  200  are inserted between the plurality of metal plates and brought into surface-contact. 
     Therefore, each of the terminal parts of the snubber-circuit electrodes is formed by the metal plates stacked with the interval provided therebetween so that the electrode terminal in the side of the snubber circuit module  200  can be inserted between the metal plates and brought into surface-contact. 
     In the semiconductor module  100  in the present first preferred embodiment, the at least one semiconductor element includes two semiconductor elements (more specifically, the semiconductor elements  11 ,  12 ) connected in series, and the plurality of snubber-circuit electrodes include the snubber-circuit P electrode  31  corresponding to the P terminal of the two semiconductor elements connected in series and the snubber-circuit N electrode  32  corresponding to the N terminal of the two semiconductor elements connected in series. Therefore, the snubber circuit can be connected between the P terminal and the N terminal of the semiconductor module  100 . 
     The semiconductor device in the present first preferred embodiment is provided with the semiconductor module  100  and the snubber circuit module  200 , which can be attached/detached to/from the snubber-circuit-connecting opening  7  of the semiconductor module  100 . Therefore, since the snubber circuit module  200  can be attached in the vicinity of the semiconductor element  11  of the semiconductor module  100 , the effect of suppressing surge voltages in the semiconductor device is further improved. 
     In the semiconductor device in the present first preferred embodiment, the cutout  71  is provided on the exterior  70  of the snubber circuit module  200 , and the cutout  71  is utilized when the snubber circuit module  200  is to be pulled out from the snubber-circuit-connecting opening  7 . Therefore, the operation of detaching the snubber circuit module  200  from the semiconductor module  100  becomes easy. 
     Modification Example of First Preferred Embodiment 
       FIG. 9  is a cross-sectional view of a semiconductor module  100 A in a modification example of the first preferred embodiment.  FIG. 10  is a front view of a snubber-circuit-connecting opening  7  of the semiconductor module  100 A. In the semiconductor module  100 , the single snubber circuit module  200  can be attached. On the other hand, in the semiconductor module  100 A, two snubber circuit modules  200  can be attached. 
     In the semiconductor module  100 A, the terminal part of a snubber-circuit P electrode  31  has three metal plates  31   a ,  31   b , and  31   c  stacked with intervals provided therebetween. Similarly, the terminal part of a snubber-circuit N electrode  32  has three metal plates  32   a ,  32   b , and  32   c  stacked with intervals provided therebetween. Since the other configurations of the semiconductor module  100 A are the same as those of the semiconductor module  100 , the description thereof will be omitted. 
       FIG. 11  is a cross-sectional view of the semiconductor module  100 A in a state in which the two snubber circuit modules  200  are attached. Note that, in order to distinguish the two snubber circuit modules  200  for the sake of description, they are described as snubber circuit modules  200 A and  200 B. 
     As shown in  FIG. 11 , a P electrode terminal  61  of the snubber circuit module  200 A is inserted between the metal plates  31   a  and  31   b , which are opposite to each other in the snubber-circuit P electrode  31 , and is brought into surface-contact with each of the metal plates  31   a  and  31   b . A P electrode terminal  61  of the snubber circuit module  200 B is inserted between the metal plates  31   b  and  31   c , which are opposite to each other in the snubber-circuit P electrode  31 , and is brought into surface contact with each of the metal plates  31   b  and  31   c.    
     Similarly, an N electrode terminal  62  of the snubber circuit module  200 A is inserted between the metal plates  32   a  and  32   b , which are opposite to each other in the snubber-circuit N electrode  32 , and is brought into surface-contact with each of the metal plates  32   a  and  32   b . An N electrode terminal  62  of the snubber circuit module  200 B is inserted between the metal plates  32   b  and  32   c , which are opposite to each other in the snubber-circuit N electrode  32 , and is brought into surface-contact with each of the metal plates  32   b  and  32   c.    
     As shown in  FIG. 11 , in the state in which the two snubber circuit modules  200 A,  200 B are attached to the interior  7   a  communicated with the snubber-circuit-connecting opening  7 , the snubber circuit modules  200 A and  200 B do not stick out from the outer surface of the outer enclosure member  6 . 
       FIG. 12  is a front view of a snubber-circuit-connecting opening  7  of a semiconductor module  100 A in another modification example of the first preferred embodiment. As shown in  FIG. 12 , the terminal part of a snubber-circuit P electrode  31  has four metal plates  31   a ,  31   b ,  31   c , and  32   c  stacked with intervals provided therebetween. Similarly, the terminal part of a snubber-circuit N electrode  32  has four metal plates  32   a ,  32   b ,  32   c , and  32   d  stacked with intervals provided therebetween. By virtue of the configuration shown in  FIG. 12 , a plurality of, i.e. three snubber circuit modules  200  can be attached to the snubber-circuit-connecting opening  7  at the same time. 
     In this manner, by increasing the number of the metal plates of the terminal part of the snubber-circuit P electrode  31  and the terminal part of the snubber-circuit P electrode  32 , the number of the snubber circuit modules  200  which can be attached to the snubber-circuit-connecting opening  7  at the same time can be increased. 
     Note that the configurations of the snubber circuits of the plurality of snubber circuit modules  200  which are attached to the snubber-circuit-connecting opening  7  at the same time may be mutually different. 
     &lt;Effects&gt; 
     In the semiconductor module  100 A in the modification examples of the first preferred embodiment, the plurality of snubber circuit modules  200  can be attached to the snubber-circuit-connecting opening  7  at the same time, and the plurality of snubber circuit modules  200  are connected in parallel mutually with respect to the plurality of snubber-circuit electrodes (more specifically, the snubber-circuit P electrode  31  and the snubber-circuit N electrode  32 ). 
     Therefore, in the semiconductor modules  100 A in the modification examples of the first preferred embodiment, since the plurality of snubber circuit modules  200  can be attached in parallel, surge voltages can be further suppressed. 
     Second Preferred Embodiment 
       FIG. 13  is a perspective view of a semiconductor module  101  in a present second preferred embodiment.  FIG. 14  is a cross-sectional view of the semiconductor module  101  along line segment C-C of  FIG. 13 .  FIG. 15  is a front view of a snubber-circuit-connecting opening  7  of the semiconductor module  101 . 
     The semiconductor module  101  is further provided with a snubber-circuit AC electrode  33  compared with the semiconductor module  100 . Since the other configurations are the same as the semiconductor module  100 , the description thereof will be omitted. 
     The snubber-circuit AC electrode  33  is joined with a third circuit pattern  53 , for example, by solder. The snubber-circuit AC electrode  33  is disposed in the interior  7   a  of the snubber-circuit-connecting opening  7 . As shown in  FIG. 15 , a terminal part of the snubber-circuit AC electrode  33  has two metal plates  33   a  and  33   b  stacked with an interval provided therebetween. The cross-sectional shape of the snubber-circuit AC electrode  33  is similar to the cross-sectional shape of the snubber-circuit P electrode  31 . 
       FIG. 16  is a perspective view of a snubber circuit module  201  in the second preferred embodiment. The electrode terminal part  60  of the snubber circuit module  201  is provided with an AC electrode terminal  63  in addition to the P electrode terminal  61  and the N electrode terminal  62 . In the electrode terminal part  60  of the snubber circuit module  201  shown in  FIG. 16 , the electrode terminals are disposed in the order of: the P electrode terminal  61 , the N electrode terminal  62 , and the AC electrode terminal  63 ; however, the disposing order of the electrode terminals is not limited thereto. The disposition of the P electrode terminal  61 , the N electrode terminal  62 , and the AC electrode terminal  63  is appropriately changed depending on the disposition of the snubber-circuit P electrode  31 , the snubber-circuit N electrode  32 , and the snubber-circuit AC electrode  33  provided in the semiconductor module  101 . 
     The thickness of the AC electrode terminal  63  of the snubber circuit module  201  is designed to match the interval between the metal plates  33   a  and  33   b  of the snubber-circuit AC electrode  33 . 
     The cross-sectional view of the semiconductor module  101  in the state in which the snubber circuit module  201  is attached thereto is similar to  FIG. 6 . In the state in which the snubber circuit module  201  is attached to the interior  7   a , which is communicated with the snubber-circuit-connecting opening  7 , the snubber circuit module  201  does not stick out from the outer surface of the outer enclosure member  6 . 
       FIG. 17  is a diagram showing a first example of the circuit configuration of the semiconductor module  101  and the snubber circuit module  201 .  FIG. 18  is a diagram showing the first example of the circuit configuration of the snubber circuit module  201 . As shown in  FIG. 17  and  FIG. 18 , in the snubber circuit module  201 , a resistive element and a capacitor are connected in series between the P electrode terminal  61  and the AC electrode terminal  63 , and a resistive element and a capacitor are connected in series between the AC electrode terminal  63  and the N electrode terminal  62 . 
       FIG. 19  is a diagram showing a second example of the circuit configuration of the semiconductor module  101  and the snubber circuit module  201 .  FIG. 20  is a diagram showing the second example of the circuit configuration of the snubber circuit module  201 . As shown in  FIG. 19  and  FIG. 20 , a snubber circuit may be formed by combining resistive elements, capacitors, and diodes. 
     &lt;Effects&gt; 
     In the semiconductor module  101  in the present second preferred embodiment, the at least one semiconductor element includes the two semiconductor elements (more specifically, the semiconductor elements  11  and  12 ) connected in series; and the plurality of snubber circuit electrodes include the snubber-circuit P electrode  31  corresponding to the P terminal of the two semiconductor elements connected in series, the snubber-circuit N electrode  32  corresponding to the N terminal of the two semiconductor elements connected in series, and the snubber-circuit AC electrode  33  corresponding to the AC terminal of the two semiconductor elements connected in series. 
     Therefore, the snubber circuit can be connected not only between the P terminal and the N terminal of the semiconductor module  101 , but also between the P terminal and the AC terminal and between the AC terminal and the N terminal. By virtue of this, the surge voltages generated by switching of the semiconductor elements  11  and  12  can be further suppressed. 
     Modification Example of Second Preferred Embodiment 
       FIG. 21  is a front view of the snubber-circuit-connecting opening  7  of a semiconductor module  101 A in a modification example of the second preferred embodiment. The single snubber circuit module  201  is attachable to the semiconductor module  101 . On the other hand, two snubber circuit modules  201  are attachable to the semiconductor module  101 A. 
     In the semiconductor module  101 A, the terminal part of the snubber-circuit P electrode  31  has three metal plates  31   a ,  31   b , and  31   c  stacked with intervals provided therebetween. Similarly, the terminal part of the snubber-circuit N electrode  32  has three metal plates  32   a ,  32   b , and  32   c  stacked with intervals provided therebetween. Similarly, the terminal part of the snubber-circuit AC electrode  33  has three metal plates  33   a ,  33   b , and  33   c  stacked with intervals provided therebetween. Since the other configurations of the semiconductor module  101 A are the same as those of the semiconductor module  101 , the description thereof will be omitted. The cross-sectional view of the semiconductor module  101 A in the state in which the two snubber circuit modules  201  are attached thereto is similar to  FIG. 11 . 
       FIG. 22  is a front view of the snubber-circuit-connecting opening  7  of the semiconductor module  101 A in another modification example of the second preferred embodiment. As shown in  FIG. 22 , the terminal part of the snubber-circuit P electrode  31  has four metal plates  31   a ,  31   b ,  31   c , and  31   d  stacked with intervals provided therebetween. Similarly, the terminal part of the snubber-circuit N electrode  32  has four metal plates  32   a ,  32   b ,  32   c , and  32   d  stacked with intervals provided therebetween. Similarly, the terminal part of the snubber-circuit AC electrode  33  has four metal plates  33   a ,  33   b ,  33   c , and  33   d  stacked with intervals provided therebetween. By virtue of the configuration shown in  FIG. 22 , a plurality of i.e., three snubber circuit modules  201  can be attached to the snubber-circuit-connecting opening  7  at the same time. 
     In this manner, the number of the snubber circuit modules  201  which are attachable to the snubber-circuit-connecting opening  7  at the same time can be increased by increasing the number of the metal plates of the terminal part of the snubber-circuit P electrode  31 , the terminal part of the snubber-circuit N electrode  32 , and the terminal part of the snubber-circuit AC electrode  33 . 
     Note that the configurations of the snubber circuits of the plurality of snubber circuit modules  201  which are attached to the snubber-circuit-connecting opening  7  at the same time may be mutually different. 
     Third Preferred Embodiment 
       FIG. 23  is a perspective view of a semiconductor module  102  in a present third embodiment.  FIG. 24  is a cross-sectional view of the semiconductor module  102  along line segment D-D in  FIG. 23 .  FIG. 25  is a top view of the semiconductor module  102 . In  FIG. 25 , illustration of the outer enclosure member  6  is omitted. 
     As shown in  FIG. 23 ,  FIG. 24 , and  FIG. 25 , in the semiconductor module  102 , the snubber-circuit-connecting opening  7  is provided in the upper surface of the outer surface of the outer enclosure member  6 . Herein, the upper surface is the surface (more specifically, the surface in the z direction) opposite to the principal surface of the substrate  4  among the outer surfaces of the outer enclosure member  6 . 
     The semiconductor module  102  is provided with a plurality of snubber-circuit electrodes as well as the semiconductor module  100 . The plurality of snubber-circuit electrodes include the snubber-circuit P electrode  31  and the snubber-circuit N electrode  32 . The snubber-circuit P electrode  31  is joined with the first circuit pattern  51 , for example, by solder. The snubber-circuit N electrode  32  is joined with the second circuit pattern  52 , for example, by solder. The snubber-circuit P electrode  31  and the snubber-circuit N electrode  32  are disposed in the interior  7   a  of the snubber-circuit-connecting opening  7 . 
     The front view of the snubber-circuit-connecting opening  7  of the semiconductor module  102  is similar to  FIG. 4 . As shown in  FIG. 4 , the terminal part of the snubber-circuit P electrode  31  has the two metal plates  31   a  and  31   b  stacked with the interval provided therebetween. Similarly, the terminal part of the snubber-circuit N electrode  32  has the two metal plates  32   a  and  32   b  stacked with the interval provided therebetween. The cross-sectional shape of the snubber-circuit N electrode  32  is similar to the cross-sectional shape of the snubber-circuit P electrode  31 . 
     In the semiconductor module  100 , since the snubber-circuit-connecting opening  7  is provided in the lateral surface of the outer enclosure member  6 , the snubber-circuit P electrode  31  and the snubber-circuit N electrode  32  are disposed so that the terminal parts thereof are directed toward direction horizontal to the substrate  4 . On the other hand, in the semiconductor module  102 , since the snubber-circuit-connecting opening  7  is provided in the upper surface of the outer enclosure member  6 , the snubber-circuit P electrode  31  and the snubber-circuit N electrode  32  are disposed so that the terminal parts thereof are directed toward the perpendicular direction with respect to the substrate  4 . 
     As shown in  FIG. 24  and  FIG. 25 , the snubber-circuit-connecting opening  7  and the interior  7   a  communicated with the snubber-circuit-connecting opening  7  are disposed at the positions which are not overlapped with the semiconductor elements  11  and  12  in a planar view. Moreover, the snubber-circuit-connecting opening  7  and the interior  7   a  are disposed at the positions which are not overlapped with the wires, which are disposed in the semiconductor module, in the planar view. In other words, the snubber-circuit-connecting opening  7  and the interior  7   a  are preferred to be disposed at the positions which are not overlapped with the members excluding the circuit patterns and the snubber-circuit electrodes in the planar view. Since the other configurations of the semiconductor module  102  are the same as those of the semiconductor module  100 , the description thereof will be omitted. 
       FIG. 26  is a cross-sectional view of the semiconductor module  102  in the state  5  in which the snubber circuit module  200  is attached. The snubber circuit module  200  is attached when it is pushed into the snubber-circuit-connecting opening  7  of the semiconductor module  102 . As shown in  FIG. 26 , the P electrode terminal  61  of the snubber circuit module  200  is inserted between the metal plates  31   a  and  31   b , which are opposite to each other in the snubber-circuit P electrode  31 , and is brought into surface-contact with each of the metal plates  31   a  and  31   b . Similarly, the N electrode terminal  62  of the snubber circuit module  200  is inserted between the metal plates  32   a  and  32   b , which are opposite to each other in the snubber-circuit N electrode  32 , and is brought into surface-contact with each of the metal plates  32   a  and  32   b.    
     As shown in  FIG. 26 , in the state in which the snubber circuit module  200  is attached to the interior  7   a  communicated with the snubber-circuit-connecting opening  7 , the snubber circuit module  200  does not stick out from the outer surface of the outer enclosure member  6 . 
     Note that, in the semiconductor module  102 , the configurations of the snubber-circuit P electrode  31  and the snubber-circuit N electrode  32  may be changed like  FIG. 10  or  FIG. 12  so that the plurality of snubber circuit modules  200  may be attached to the semiconductor module  102 . 
     &lt;Effects&gt; 
     The snubber-circuit-connecting opening  7  of the semiconductor module  102  in the present third preferred embodiment is provided in the surface opposite to the principal surface of the substrate  4  among the outer surfaces of the outer enclosure member  6 . Therefore, even if another device, etc. are disposed in the lateral surface side of the semiconductor module  102 , the snubber circuit module  200  can be attached/detached to/from the upper surface of the semiconductor module  102 . 
     Fourth Preferred Embodiment 
       FIG. 27  is a perspective view of a semiconductor module  103  in a present fourth preferred embodiment.  FIG. 28  is a top view of the semiconductor module  103 . Note that, in  FIG. 28 , illustration of the outer enclosure member  6  is omitted. 
     The semiconductor module  103  is further provided with the snubber-circuit AC electrode  33  compared with the semiconductor module  102 . Since the other configurations are the same as those of the semiconductor module  102 , the description thereof will be omitted. 
     The snubber-circuit AC electrode  33  is joined with the third circuit pattern  53 , for example, by solder. The snubber-circuit AC electrode  33  is disposed in the interior  7   a  of the snubber-circuit-connecting opening  7 . 
     The front view of the snubber-circuit-connecting opening  7  in the semiconductor module  103  is similar to  FIG. 15 . As shown in  FIG. 15 , the terminal part of the snubber-circuit AC electrode  33  has the two metal plates  33   a  and  33   b  stacked with the interval provided therebetween. The cross-sectional shape of the snubber-circuit AC electrode  33  is similar to the cross-sectional shape of the snubber-circuit P electrode  31 . 
     The snubber circuit module  201  described in the second preferred embodiment can be attached/detached to/from the semiconductor module  103  in the present fourth preferred embodiment. Note that, in the semiconductor module  103 , the configurations of the snubber-circuit P electrode  31 , the snubber-circuit N electrode  32 , and the snubber-circuit AC electrode  33  may be changed like  FIG. 21  or  FIG. 22  so that the plurality of snubber circuit modules  201  can be attached to the semiconductor module  103 . 
     Fifth Preferred Embodiment 
       FIG. 29  is a diagram showing a configuration of an electric power device in a present fifth preferred embodiment. The electric power device in the present fifth  5  preferred embodiment is provided with a semiconductor device  300 , a load  700 , and an electric power source  400  of the load  700 . The semiconductor device is provided with three semiconductor modules  100 . Snubber circuit modules  200  are attached to the semiconductor modules  100 , respectively. The semiconductor device is an inverter circuit, and the three semiconductor modules  100  correspond to a U phase, a V phase, and a W phase, respectively. 
     As shown in  FIG. 29 , the load  700  is a motor. A rectifier circuit  500  and a smoothing capacitor  600  are connected between the electric power source  400  and the semiconductor device  300 . 
     Note that, instead of the semiconductor modules  100 , the semiconductor modules  101 ,  102 , and/or  103  may be disposed. The snubber circuit modules  201  may be attached to the semiconductor modules  101  and  103 . 
     &lt;Effects&gt; 
     The electric power device in the present fifth preferred embodiment is provided with the semiconductor device  300 , the load  700 , and the electric power source  400  of the load  700 , and the semiconductor device  300  converts the electric power of the electric power source  400  and drives the load  700 . The snubber circuit modules  200  can be connected in the vicinities of the semiconductor modules  100 . Therefore, even in a case in which the semiconductor modules  100  are incorporated in the electric power device to convert the electric power, the surge voltages contained in the converted electric power can be suppressed. 
     Note that, in the first preferred embodiment to the fifth preferred embodiment, the semiconductor elements  11  and  12  may be semiconductor elements containing wide-band-gap semiconductor. The wide-band-gap semiconductor is SiC, GaN, diamond, etc. If the semiconductor elements  11  and  12  contain the wide-band-gap semiconductor, generation of surge voltages become notable since large currents and high voltages can be switched at higher speed. Therefore, generation of the surge voltages can be more effectively suppressed by employing, for the semiconductor modules, the configurations described in the first to fifth preferred embodiments. 
     Note that the present invention can freely combine the embodiments and/or appropriately modify and/or omit the embodiments within the scope of the invention. 
     While the invention has been shown and described in detail, the foregoing description is in all aspects illustrative and not restrictive. It is therefore understood that numerous modifications and variations can be devised without departing from the scope of the invention.