Patent Publication Number: US-2023163055-A1

Title: Semiconductor module

Description:
TECHNICAL FIELD 
     The present disclosure relates to semiconductor modules used for various electronic devices. 
     BACKGROUND ART 
     A conventional semiconductor module will be described below. A conventional semiconductor module which includes: a positive potential switch element connected to a positive potential end of a direct-current power supply; and a negative potential switch element connected to a negative potential end of the direct-current power supply is configured to be able to output alternating-current power from a connection point between the positive potential switch element and the negative potential switch element. At the time when the semiconductor module operates, a voltage detection terminal connected to the positive potential switch element and a voltage detection terminal connected to the negative potential switch element are used to detect a voltage applied to the positive potential switch element and a voltage applied to the negative potential switch element, making it possible to grasp an operating state of the semiconductor module. 
     Note that Patent Literature (PTL) 1, for example, is known as related art document information pertaining to the present application. 
     CITATION LIST 
     Patent Literature 
     PTL 1: Unexamined Japanese Patent Publication No. 2015-115464 
     SUMMARY OF THE INVENTION 
     In the conventional semiconductor module, when the positive potential switch element and the negative potential switch element are arranged close to each other, the voltage detection terminal connected to the positive potential switch element and the voltage detection terminal connected to the negative potential switch element are positioned close to each other. This results in poor insulation between the positive potential switch element and the negative potential switch element. The conventional semiconductor module has reduced reliability, which is problematic. 
     A semiconductor module according to one aspect of the present disclosure includes: a first switch element including a source electrode, a gate electrode, and a drain electrode; a second switch element including a source electrode, a gate electrode, and a drain electrode; a first conductor that has a shape of a plate and is joined to the source electrode of the first switch element, the first switch element is placed on the first conductor; a second conductor that has a shape of a plate and is joined to the source electrode of the second switch element, the second switch element is placed on the second conductor; a positive electrode conductor connected to the drain electrode of the first switch element; an output conductor connected to the first conductor and the drain electrode of the second switch element; a negative electrode conductor connected to the second conductor; a first control conductor connected to the gate electrode of the first switch element; a second control conductor connected to the gate electrode of the second switch element; a first voltage detection terminal provided on the first conductor; a second voltage detection terminal provided on the second conductor; and an exterior resin part having a polyhedral shape and configured to seal the first switch element, the second switch element, the first conductor, the second conductor, a portion of the positive electrode conductor, a portion of the output conductor, a portion of the negative electrode conductor, a portion of the first control conductor, a portion of the second control conductor, a portion of the first voltage detection terminal, and a portion of the second voltage detection terminal. The exterior resin part includes a first exterior surface and a second exterior surface. The first voltage detection terminal protrudes from the first exterior surface. The second voltage detection terminal protrudes from the second exterior surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram illustrating a semiconductor module according to an exemplary embodiment of the present disclosure. 
         FIG.  2    is a top view illustrating a portion of a semiconductor module according to an exemplary embodiment of the present disclosure. 
         FIG.  3    is a top view illustrating a portion of a semiconductor module according to an exemplary embodiment of the present disclosure. 
         FIG.  4    is a perspective view illustrating a semiconductor module according to an exemplary embodiment of the present disclosure. 
         FIG.  5    is a schematic diagram illustrating the configuration of a power supply system including a semiconductor module according to an exemplary embodiment of the present disclosure. 
         FIG.  6    is a cross-sectional view illustrating a portion of the configuration of a semiconductor module according to an exemplary embodiment of the present disclosure. 
         FIG.  7    is a cross-sectional view illustrating a portion of the configuration of a semiconductor module according to a variation of an exemplary embodiment of the present disclosure. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an exemplary embodiment of the present disclosure will be described with reference to the drawings. 
     Exemplary Embodiment 
       FIG.  1    is a schematic diagram illustrating a semiconductor module according to an exemplary embodiment of the present disclosure.  FIG.  2    is a top view illustrating a portion of the semiconductor module according to the exemplary embodiment of the present disclosure.  FIG.  3    is a top view illustrating a portion of the semiconductor module according to the exemplary embodiment of the present disclosure.  FIG.  4    is a perspective view of the semiconductor module according to the exemplary embodiment of the present disclosure. 
     [General Configuration of Semiconductor Module] 
     The general configuration of the semiconductor module will be described with reference to  FIG.  1   . 
     Semiconductor module  1  includes switch elements  2 ,  3 , lead frames  4 ,  5 , positive electrode lead frame  6 , output lead frame  7 , negative electrode lead frame  8 , control lead frames  9 ,  10 , first voltage detection terminal  11 , second voltage detection terminal  12 , and exterior resin part  13 . Switch element  2  and switch element  3  each include a semiconductor. Note that in the exemplary embodiment, the term “lead frame” is used in the description, but there are cases where the “lead frame” is referred to as a “conductor.” 
     Switch element  2  includes source electrode  2 S, gate electrode  2 G, and drain electrode  2 D. Second switch element  3  includes source electrode  3 S, gate electrode  3 G, and drain electrode  3 D. 
     Switch element  2  is placed on lead frame  4  with source electrode  2 S joined thereto. Lead frame  4  is formed in the shape of a plate. Switch element  3  is placed on lead frame  5  with source electrode  3 S joined thereto. Lead frame  5  is formed in the shape of a plate. 
     Positive electrode lead frame  6  is connected to drain electrode  2 D of switch element  2 . Output lead frame  7  is connected to each of lead frame  4  and drain electrode  3 D of switch element  3 . Negative electrode lead frame  8  is connected to lead frame  5 . 
     Control lead frame  9  is connected to gate electrode  2 G of switch element  2 . Control lead frame  10  is connected to gate electrode  3 G of switch element  3 . First voltage detection terminal  11  is connected to lead frame  4 . Second voltage detection terminal  12  is connected to lead frame  5 . 
     [Specific Example of Configuration of Semiconductor Module  1 ] 
     Next, with reference to  FIG.  2    to  FIG.  4   , one example of the configuration of semiconductor module  1  will be described. Note that in the schematic diagram illustrated in  FIG.  1   , one switch element  2  and one switch element  3  are illustrated, but in a specific example of semiconductor module  1  illustrated in  FIG.  2    to  FIG.  4   , switch element  2  is made up of three switch elements  2 , and switch element  3  is made up of three switch elements  3 . Thus, in  FIG.  2    to  FIG.  4   , semiconductor module  1  includes three control lead frames  9  and three control lead frames  10 . 
     Note that in  FIG.  2    and  FIG.  3   , exterior resin part  13  is not illustrated to facilitate understanding of the configuration of semiconductor module  1 . 
     Exterior resin part  13  (refer to  FIG.  4   ) has a polyhedral shape. Exterior resin part  13  seals switch element  2 , switch element  3 , lead frame  4 , and lead frame  5  in the state of avoiding exposure to the outside. Exterior resin part  13  seals a portion of positive electrode lead frame  6 , a portion of output lead frame  7 , a portion of negative electrode lead frame  8 , a portion of control lead frame  9 , a portion of control lead frame  10 , a portion of first voltage detection terminal  11 , and a portion of second voltage detection terminal  12 . 
     As illustrated in  FIG.  2    and  FIG.  3   , in the present exemplary embodiment, first voltage detection terminal  11  and lead frame  4  are formed of a single conductor, and first voltage detection terminal  11  is provided on lead frame  4 . Second voltage detection terminal  12  and lead frame  5  are formed of a single conductor, and second voltage detection terminal  12  is provided on lead frame  5 . However, first voltage detection terminal  11  and lead frame  4  may be formed of different members, and second voltage detection terminal  12  and lead frame  5  may be formed of different members. 
     As illustrated in  FIG.  4   , first exterior surface  13 A and second exterior surface  13 B oppose each other. First voltage detection terminal  11  protrudes from first exterior surface  13 A in direction A, and second voltage detection terminal  12  protrudes from second exterior surface  13 B in direction B. Direction A and direction B are opposite to each other; first voltage detection terminal  11  and second voltage detection terminal  12  are drawn out from exterior resin part  13  in opposite directions. 
     Note that first exterior surface  13 A and second exterior surface  13 B do not need to be completely opposite surfaces; it is sufficient that first exterior surface  13 A and second exterior surface  13 B be located substantially opposite to each other. Furthermore, the directions in which first voltage detection terminal  11  and second voltage detection terminal  12  are drawn out do not need to be completely opposite to each other; it is sufficient that first voltage detection terminal  11  and second voltage detection terminal  12  be drawn out in substantially opposite directions. 
     Note that each of first exterior surface  13 A and second exterior surface  13 B does not necessarily need to be formed of a single flat surface. For example, as illustrated in  FIG.  4   , second exterior surface  13 B includes first surface  131 B and second surface  132 B. 
     First surface  131 B and second surface  132 B are not arranged in parallel; first surface  131 B and second surface  132 B form an obtuse angle. Similar to second exterior surface  13 B, first exterior surface  13 A includes two surfaces that form an obtuse angle. 
     Even when each of first exterior surface  13 A and second exterior surface  13 B is not a single flat surface as illustrated in  FIG.  4   , first exterior surface  13 A and second exterior surface  13 B are regarded as opposing each other in the present disclosure. 
     As illustrated in  FIG.  3   , the linear distance between first voltage detection terminal  11  and second voltage detection terminal  12  is short. However, as illustrated in  FIG.  4   , a portion of first voltage detection terminal  11  and second voltage detection terminal  12  are sealed by exterior resin part  13 , and thus the creepage distance between first voltage detection terminal  11  and second voltage detection terminal  12  is greater than said linear distance. 
     Similarly, even though the linear distance between lead frame  4  and lead frame  5  is short (refer to  FIG.  3   ), the creepage distance between lead frame  4  and lead frame  5  is greater than said linear distance as a result of a portion of lead frame  4  and a portion of lead frame  5  being sealed by exterior resin part  13 . 
     Thus, with the above-described configuration, it is possible to minimize deterioration of the insulation between switch element  2  and switch element  3 , allowing for increased reliability of semiconductor module  1 . 
     [Configuration of Power Supply System  14 ] 
     Next, the configuration of power supply system  14  including semiconductor module  1  described above will be described with reference to  FIG.  5   . Power supply system  14  includes semiconductor module  1 , direct-current power supply device  15 , load device  16 , control circuit  17 , and gate drivers  18 ,  19 . 
     Direct-current power supply device  15  applies a voltage having a positive potential to positive electrode lead frame  6  of semiconductor module  1 . Direct-current power supply device  15  applies a voltage having a negative potential to negative electrode lead frame  8  of semiconductor module  1 . With switch element  2  and switch element  3  repeatedly turning ON and OFF in an alternate manner, load device  16  receives alternating-current power supplied from output lead frame  7 . Control circuit  17  can control the supply of electric power to load device  16  by controlling gate drivers  18 ,  19  on the basis of the voltages detected by first voltage detection terminal  11  and second voltage detection terminal  12 . Load device  16  is, for example, an alternating-current motor. Although not described in detail herein, when load device  16  is a three-phase motor, three semiconductor modules  1  are preferably provided corresponding to the U phase, the V phase, and the W phase. 
     As explained earlier, semiconductor module  1  includes switch element  2 , switch element  3 , lead frame  4 , lead frame  5 , positive electrode lead frame  6 , output lead frame  7 , negative electrode lead frame  8 , control lead frame  9 , control lead frame  10 , first voltage detection terminal  11 , second voltage detection terminal  12 , and exterior resin part  13 . Switch elements  2 ,  3 , lead frames  4 ,  5 , positive electrode lead frame  6 , output lead frame  7 , negative electrode lead frame  8 , control lead frame  9 , control lead frame  10 , first voltage detection terminal  11 , and second voltage detection terminal  12  are directly or indirectly placed on insulator/radiator  20 . Switch elements  2 ,  3 , lead frames  4 ,  5 , positive electrode lead frame  6 , output lead frame  7 , negative electrode lead frame  8 , control lead frame  9 , control lead frame  10 , first voltage detection terminal  11 , and second voltage detection terminal  12 , which are directly or indirectly placed on insulator/radiator  20 , are partially or entirely sealed by exterior resin part  13 . 
     Each of positive electrode lead frame  6 , output lead frame  7 , and negative electrode lead frame  8  has a cross-sectional area larger in a direction in which electric power is supplied than that of each of lead frames  4 ,  5 . Having a large cross-sectional area in a direction in which electric power is supplied leads to improved thermal propagation properties as well as reduced electrical resistance. With this configuration, semiconductor module  1  can be mechanically fixed to direct-current power supply device  15  and load device  16  with high fixing strength maintained. 
     The shape of exterior resin part  13  illustrated in  FIG.  4    is one example of the shape of the exterior resin part. The shape of exterior resin part  13  illustrated in  FIG.  4    is roughly a hexahedron. Note that for convenience in a molding step, etc., exterior resin part  13  may include a chamfered area in a portion of first exterior surface  13 A, second exterior surface  13 B, and the like, or may include a curved portion between surfaces, for example. Even in this case, exterior resin part  13  may be handled as a hexahedron. As mentioned above, each of first exterior surface  13 A and second exterior surface  13 B does not necessarily need to be a single flat surface. 
     The shape of exterior resin part  13  will be described using second exterior surface  13 B. Second exterior surface  13 B includes first surface  131 B and second surface  132 B. First surface  131 B and second surface  132 B are provided at different angles; first surface  131 B and second surface  132 B form an obtuse angle. Similar to second exterior surface  13 B, first exterior surface  13 A includes two surfaces that form an obtuse angle. 
     In other words, exterior resin part  13  does not need to be a complete hexahedron. Exterior resin part  13  does not need to have a polyhedral shape formed of a plurality of flat surfaces only. Exterior resin part  13  may be a polyhedron formed by a plurality of flat surfaces and a plurality of curved surfaces. 
     Exterior resin part  13  seals switch element  2 , switch element  3 , lead frame  4 , and lead frame  5  in the state of avoiding exposure to the outside. Exterior resin part  13  seals a portion of positive electrode lead frame  6 , a portion of output lead frame  7 , a portion of negative electrode lead frame  8 , a portion of control lead frame  9 , a portion of control lead frame  10 , a portion of first voltage detection terminal  11 , and a portion of second voltage detection terminal  12 . A portion of positive electrode lead frame  6 , a portion of output lead frame  7 , a portion of negative electrode lead frame  8 , a portion of control lead frame  9 , a portion of control lead frame  10 , a portion of first voltage detection terminal  11 , and a portion of second voltage detection terminal  12  are exposed from exterior resin part  13 . 
     Insulator/radiator  20  is not exposed to the outside of exterior resin part  13  and is entirely sealed by exterior resin part  13 . Note that insulator/radiator  20  may include a portion exposed to the outside of exterior resin part  13 . 
     Switch element  2  includes source electrode  2 S, gate electrode  2 G, and drain electrode  2 D. Switch element  3  includes source electrode  3 S, gate electrode  3 G, and drain electrode  3 D. Each of switch elements  2 ,  3  is a longitudinal semiconductor switch element of a metal-oxide-film-type field-effect transistor (MOSFET). 
     Next, the configuration of the switch element will be described with reference to  FIG.  6   . 
     As illustrated in  FIG.  6   , in switch element  2 , source electrode  2 S is provided on the upper surface of switch element  2 . Although not illustrated in  FIG.  6   , gate electrode  2 G is also provided on the upper surface of the switch element. This means that source electrode  2 S and gate electrode  2 G are formed on the same surface. Meanwhile, drain electrode  2 D is provided on the lower surface of switch element  2 . This means that drain electrode  2 D is formed on the surface opposite to the surface on which gate electrode  2 G and source electrode  2 S are formed. 
     As in switch element  2 , in switch element  3 , gate electrode  3 G and source electrode  3 S are formed on the same surface, and drain electrode  3 D is formed on the surface opposite to the surface on which gate electrode  3 G and source electrode  3 S are formed. 
     As illustrated in  FIG.  6   , lead frame  4  is directly joined to source electrode  2 S using a jointing material (not illustrated in the drawings), and lead frame  4  is placed on switch element  2 . Similarly, lead frame  5  is directly joined to source electrode  3 S using a jointing material (not illustrated in the drawings), and switch element  3  is placed on lead frame  5 . Lead frames  4 ,  5  are, for example, copper sheets each in the form of a plate or copper alloy sheets each in the form of a plate. For lead frames  4 ,  5 , it is desirable to select shapes and materials that provide low-resistance, good thermal conduction properties with use of aluminum or the like. Lead frames  4 ,  5  do not need to be rectangular as long as lead frames  4 ,  5  are each in the form of a plate instead of being a conductor in the form of a foil or a line and may include a bent portion, a step portion, or the like. 
     Positive electrode lead frame  6  is connected to drain electrode  2 D. Output lead frame  7  is connected to lead frame  4  and drain electrode  3 D. Instead of using wire bonding, jointing materials (not illustrated in the drawings) are used to directly connect drain electrode  2 D and drain electrode  3 D to positive electrode lead frame  6  and output lead frame  7 , respectively. A jointing material (not illustrated in the drawings), a conductor layer (not illustrated in the drawings), or a conductor plate (not illustrated in the drawings) may be interposed between drain electrode  2 D and positive electrode lead frame  6  upon connection. A jointing material (not illustrated in the drawings), a conductor layer (not illustrated in the drawings), or a conductor plate (not illustrated in the drawings) may be interposed between drain electrode  3 D and output lead frame  7  upon connection. 
     It is sufficient that each of the conductor layer (not illustrated in the drawings) and the conductor plate (not illustrated in the drawings) be a high-ampacity, low-resistance conductor having a large cross-sectional area in a direction in which electric power is supplied. It is sufficient that the connection between drain electrode  2 D and positive electrode lead frame  6  be in the state of being joined with substantially no direct-current resistance therebetween. Similarly, it is sufficient that the connection between drain electrode  3 D and output lead frame  7  be in the state of being joined with substantially no direct-current resistance therebetween. 
     It is sufficient that each of the conductor layer (not illustrated in the drawings) and the conductor plate (not illustrated in the drawings) have ampacity substantially equal to that of each of lead frame  4  and lead frame  5 . It is sufficient that the cross-sectional area of each of the conductor layer (not illustrated in the drawings) and the conductor plate (not illustrated in the drawings) in a direction in which electric power is supplied be substantially equal to that of each of lead frame  4  and lead frame  5 . The connection between drain electrode  2 D and positive electrode lead frame  6  may be direct connection or may be indirect connection as long as drain electrode  2 D and positive electrode lead frame  6  have the same potential. The connection between drain electrode  3 D and output lead frame  7  may be direct connection or may be indirect connection as long as drain electrode  3 D and output lead frame  7  have the same potential. 
     With this configuration, loss due to the direct-current resistance between switch element  2  and positive electrode lead frame  6  can be minimized. Similarly, loss due to the direct-current resistance between switch element  3  and output lead frame  7  can be minimized. When switch element  2  and switch element  3  are connected to the conductors each having a large cross-sectional area, heat generated by switch element  2  and switch element  3  can be easily diffused to the outside of semiconductor module  1 . 
     Positive electrode lead frame  6 , a portion of output lead frame  7 , and negative electrode lead frame  8  are, for example, copper or copper alloy sheets each in the form of a plate. For positive electrode lead frame  6 , a portion of output lead frame  7 , and negative electrode lead frame  8 , it is desirable to select shapes and materials that provide low-resistance, good thermal conduction properties with use of aluminum or the like. Positive electrode lead frame  6 , a portion of output lead frame  7 , and negative electrode lead frame  8  do not need to be rectangular as long as positive electrode lead frame  6 , a portion of output lead frame  7 , and negative electrode lead frame  8  are each in the form of a plate instead of being a conductor in the form of a foil or a line and may include a bent portion, a step portion, or the like. 
       FIG.  6    is a partial cross-sectional view illustrating a portion of the configuration of semiconductor module  1 . As illustrated in  FIG.  6   , in the present exemplary embodiment, positive electrode lead frame  6  and drain electrode  2 D are not directly connected, but are connected via conductor layer  21  provided on insulator/radiator  20 . It is desirable that the cross-sectional area of conductor layer  21  in a direction in which electric power is supplied be substantially equal to or larger than the cross-section area of positive electrode lead frame  6  in a direction in which electric power is supplied. The direct-current resistance between lead joining part  6 B of positive electrode lead frame  6  and drain electrode  2 D in conductor layer  21  is preferably lower than the direct-current resistance between distal end  6 A and lead joining part  6 B of positive electrode lead frame  6 . With this configuration, even when positive electrode lead frame  6  and drain electrode  2 D are not directly connected, the electric power loss between positive electrode lead frame  6  and drain electrode  2 D is minimized. As explained earlier, the element connected to source electrode  2 S is lead frame  4 . 
     In  FIG.  6   , lead joining part  6 B is illustrated as a portion of positive electrode lead frame  6 , but lead joining part  6 B may be formed of a welding material such as solder. 
     Lead joining part  6 B may be formed of a portion of positive electrode lead frame  6  melted by a method such as ultrasonic welding of positive electrode lead frame  6  without using a welding material different from positive electrode lead frame  6 . 
     Conductor layer  21  is desirably a copper sheet or a copper alloy sheet or made of a low-resistance material such as aluminum. Insulator/radiator  20  includes stacked insulating layer  20 A and metal layer  20 B provided on the lower surface of insulating layer  20 A. Insulating layer  20 A is preferably made of ceramic or the like which has high thermal conductivity, and metal layer  20 B is preferably made of copper, a copper alloy, aluminum, or the like. 
       FIG.  6    illustrates the relationship between positive electrode lead frame  6 , conductor layer  21 , switch element  2 , and lead frame  4 .  FIG.  6    further illustrates the relationship between positive electrode lead frame  6 , conductor layer  22 , switch element  3 , and lead frame  5 . 
     Control lead frame  9  is connected to gate electrode  2 G. Control lead frame  10  is connected to gate electrode  3 G. It is preferable that control lead frame  9  and gate electrode  2 G be directly connected by a jointing material (not illustrated in the drawings) without using wire bonding. Similarly, it is preferable that control lead frame  10  and gate electrode  3 G be directly connected by a jointing material (not illustrated in the drawings) without using wire bonding. Signals that are transmitted from gate driver  18  to switch element  2  and signals that are transmitted from gate driver  19  to switch element  3  are subject to the pulse-width modulation (PWM) control or the like and include a large number of high-frequency components. Therefore, when control lead frame  9  is directly connected to gate electrode  2 G without using wire bonding, the transmission distance of the signals is shortened, noise interference or the like is suppressed, and the operation reliability of semiconductor module  1  increases. Similarly, when control lead frame  10  is directly connected to gate electrode  3 G without using wire bonding, the transmission distance of the signals is shortened, noise interference or the like is suppressed, and the operation reliability of semiconductor module  1  increases. 
     Since the signals that are transmitted from gate driver  18  to switch element  2  and the signal that are transmitted from gate driver  19  to switch element  3  have small electric-current values, the cross-sectional area of control lead frame  9  in a direction in which electric power is supplied and the cross-sectional area of control lead frame  10  in a direction in which electric power is supplied may have values smaller than the values of the cross-sectional area of positive electrode lead frame  6  in a direction in which electric power is supplied, the cross-sectional area of output lead frame  7  in a direction in which electric power is supplied, and the cross-sectional area of negative electrode lead frame  8  in a direction in which electric power is supplied. 
     First voltage detection terminal  11  is connected to lead frame  4 . Second voltage detection terminal  21  is connected to lead frame  5 . First voltage detection terminal  11  and lead frame  4  are formed of a single conductor, and second voltage detection terminal  12  and lead frame  5  are formed of a single conductor. In other words, first voltage detection terminal  11  and lead frame  4  are electrically connected to each other with no joint or wire bonding therebetween. Second voltage detection terminal  12  and lead frame  5  are electrically connected to each other with no joint or wire bonding therebetween. 
     First voltage detection terminal  11  is provided in order to monitor the operating state of switch element  2 . Second voltage detection terminal  12  is provided in order to monitor the operating state of switch element  3 . The state of connection between first voltage detection terminal  11  and lead frame  4  and the state of connection between second voltage detection terminal  12  and lead frame  5  are extremely stable. Thus, even when external mechanical or thermal stress is applied to semiconductor module  1 , the operating state of semiconductor module  1  can be accurately output to the outside, leading to increased reliability of semiconductor module  1 . First voltage detection terminal  11  integrated with lead frame  4  through which an electric current having a large value tends to flow and which is easily heated is exposed from exterior resin part  13 , making it easy for lead frame  4  to cool down. Thus, the operation reliability of semiconductor module  1  increases. This is also true for lead frame  5  and second voltage detection terminal  12 . 
     First voltage detection terminal  11  and second voltage detection terminal  12  are drawn out from different exterior surfaces (first exterior surface  13 A and second exterior surface  13 B) of exterior resin part  13 . In particular, first voltage detection terminal  11  is drawn out from first exterior surface  13 A of exterior resin part  13  in direction A, and second voltage detection terminal  12  is drawn out from second exterior surface  13 B of exterior resin part  13 , which opposes first exterior surface  13 A, in direction B opposite to direction A. 
     The linear distance between first voltage detection terminal  11  and second voltage detection terminal  12  is short. However, in the above-described configuration, a portion of first voltage detection terminal  11  and a portion of second voltage detection terminal  12  are sealed by exterior resin part  13 , and thus the creepage distance between first voltage detection terminal  11  and second voltage detection terminal  12  is greater than said linear distance. 
     With this configuration, it is possible to minimize deterioration of the insulation between switch element  2  and switch element  3 , allowing for increased reliability of semiconductor module  1 . 
     Note that second voltage detection terminal  12  may be omitted when a high-potential voltage detection terminal connected to positive electrode lead frame  6  is drawn out from first exterior surface  13 A and first voltage detection terminal  11  is drawn out from second exterior surface  13 B. Even in this configuration, the creepage distance between the high-potential voltage detection terminal (not illustrated in the drawings) and first voltage detection terminal  11  is greater than the linear distance between the high-potential voltage detection terminal (not illustrated in the drawings) and first voltage detection terminal  11 . This means that the high-potential voltage detection terminal (not illustrated in the drawings) and first voltage detection terminal  11  are separated by the distance between first exterior surface  13 A and second exterior surface  13 B. As a result, it is possible to minimize deterioration of the insulation between switch element  2  and switch element  3 , allowing for increased reliability of semiconductor module  1 . 
     In semiconductor module  1  described above, single switch element  2  and single switch element  3  are provided, single control lead frame  9  and single control lead frame  10  are provided, and furthermore single first voltage detection terminal  11  and single second voltage detection terminal  12  are provided. 
     However, in semiconductor module  1 , a plurality of switch elements  2  may be connected and arranged in parallel, and furthermore a plurality of switch elements  3  may be provided, as illustrated in  FIG.  2   , etc. 
     In the case where a plurality of switch elements  2  are provided, a plurality of control lead frames  9  are arranged. Similarly, in the case where a plurality of switch elements  3  are provided, a plurality of control lead frames  10  are provided. In the case where a plurality of first voltage detection terminals  11  are provided, at least one first voltage detection terminal  11  is used to detect a voltage. Similarly, in the case where a plurality of second voltage detection terminals  12  are provided, at least one second voltage detection terminal  12  is used to detect a voltage. 
     Lead frame  4  and lead frame  5  are preferably arranged side by side. As a result of switch element  2  and switch element  3  repeatedly turning ON and OFF in an alternate manner, an electric current flows through lead frame  4  in direction C (refer to  FIG.  5   ), and an electric current flows through lead frame  5  in direction D (refer to  FIG.  5   ). Therefore, with lead frame  4  and lead frame  5  arranged side by side in a direction orthogonal to a direction in which lead frame  4  and lead frame  5  extend, inductance components that are generated at lead frame  4  and lead frame  5  can be cancelled out and thus reduced, and electric power loss that occurs in semiconductor module  1  can be reduced. 
     Lead frame  4  and lead frame  5  preferably have similar shapes each in the form of a plate. It is desirable that lead frame  4  and lead frame  5  be arranged so as to extend in parallel. However, these conditions do not need to be completely satisfied regarding a reduction in the above-described inductance components. Even when portions of lead frame  4  and lead frame  5  are arranged roughly in parallel, inductance components that are generated at lead frame  4  and lead frame  5  can be cancelled out and thus reduced, and electric power loss that occurs in semiconductor module  1  can be reduced. 
     Control lead frame  9  is preferably drawn out in the same direction as first voltage detection terminal  11  as illustrated in  FIG.  4   . In this case, first voltage detection terminal  11  and control lead frame  9  are drawn out from the same exterior surface (first exterior surface  13 A). This is also true for control lead frame  10  and second voltage detection terminal  12 ; second voltage detection terminal  12  and control lead frame  10  are drawn from the same exterior surface (second exterior surface  13 B). First exterior surface  13 A and second exterior surface  13 B oppose each other. 
     With this configuration, gate driver  18  connected to control lead frame  9  and gate driver  19  connected to control lead frame  10  can be disposed away from each other, as illustrated in  FIG.  5   . As a result, positioning of gate driver  18  and gate driver  19  has a high degree of flexibility, and the design flexibility of semiconductor module  1  is also high. Furthermore, the distance between switch element  2  and gate driver  18  and the distance between switch element  3  and gate driver  19  can be made short. As a result, the transmission distance of the signals is shortened, and thus noise interference or the like is suppressed, leading to increased operation reliability of semiconductor module  1 . 
     A substrate (not illustrated in the drawings) on which gate driver  18 , gate driver  19 , and control circuit  17  are mounted and a substrate (not illustrated in the drawings) on which semiconductor module  1  is mounted are different; these substrates are preferably provided in layers so as to face each other in parallel. 
     Furthermore, it is preferable that control lead frame  9  and first voltage detection terminal  11  be drawn out from first exterior surface  13 A and bent toward the substrate (not illustrated in the drawings) on which gate driver  18 , gate driver  19 , and control circuit  17  are mounted. In other words, control lead frame  9  and first voltage detection terminal  11  are drawn out from first exterior surface  13 A roughly in parallel with the substrate (not illustrated in the drawings) on which semiconductor module  1  is mounted. 
     Similarly, it is preferable that control lead frame  10  and second voltage detection terminal  12  be drawn out from second exterior surface  13 B and bent toward the substrate (not illustrated in the drawings) on which gate driver  18 , gate driver  19 , and control circuit  17  are mounted. In other words, control lead frame  10  and second voltage detection terminal  12  are drawn out from second exterior surface  13 B roughly in parallel with the substrate (not illustrated in the drawings) on which semiconductor module  1  is mounted. 
     With this configuration, control lead frame  9  and control lead frame  10  are positioned at a distance outside exterior resin part  13 . Similarly, first voltage detection terminal  11  and second voltage detection terminal  12  are positioned at a distance. As a result, it is possible to minimize deterioration of the insulation between switch element  2  and switch element  3 , allowing for increased reliability of semiconductor module  1 . 
     As mentioned earlier, each of positive electrode lead frame  6 , output lead frame  7 , and negative electrode lead frame  8  is preferably shaped such that the cross-sectional area thereof, particularly in a direction in which electric power is supplied, is larger than that of each of lead frame  4  and lead frame  5 . The cross-sectional area of each of control lead frame  9  and control lead frame  10  in a direction in which electric power is supplied preferably has a smaller value than the cross-sectional area of each of positive electrode lead frame  6 , output lead frame  7 , and negative electrode lead frame  8  in a direction in which electric power is supplied. 
     In  FIG.  5   , positive electrode lead frame  6 , output lead frame  7 , and negative electrode lead frame  8  are wider than lead frame  4  and lead frame  5  as viewed from above. 
     The thickness of positive electrode lead frame  6  may be greater than the thickness of lead frame  4 , as illustrated in  FIG.  6   . Similarly, each of the thickness of output lead frame  7  and the thickness of negative electrode lead frame  8  may be greater than the thickness of lead frame  5 . The thickness of control lead frame  9  and the thickness of control lead frame  10  may be less than the thickness of positive electrode lead frame  6 , the thickness of output lead frame  7 , and the thickness of negative electrode lead frame  8 . 
     The thickness of lead frame  4  (denoted as T 1  in  FIG.  6   ), the thickness of lead frame  5 , and the thickness of control lead frame  9  are preferably set equal to the thickness of control lead frame  10 , and the thickness of positive electrode lead frame  6  (denoted as T 2  in  FIG.  6   ), the thickness of output lead frame  7 , and the thickness of negative electrode lead frame  8  are preferably set to have a thickness (thickness T 2 ) greater than thickness T 1 . 
     With this configuration, mechanical fixing strength required for positive electrode lead frame  6 , output lead frame  7 , and negative electrode lead frame  8  to fix to direct-current power supply device  15  and load device  16  is high. Obviously, thickness T 1  which is the thickness of lead frame  4  and the thickness of lead frame  5  preferably has a value such that loss in semiconductor module  1  is minimized and lead frames  4 ,  5  have sufficient ampacity to avoid excessive heat generation or the like. 
     Variation of Exemplary Embodiment 
     In semiconductor module  1  according to a variation illustrated in  FIG.  7   , lead frame  4  includes connecting convex portion  4 A. Source electrode  2 S is connected to connecting convex portion  4 A provided on lead frame  4 . Similar to lead frame  4 , lead frame  5  includes a connecting convex portion, and source electrode  3 S is connected to the connecting convex portion (not illustrated in the drawings) provided on lead frame  5 . 
     Providing connecting convex portion  4 A or the like on lead frame  4  makes it easy to accurately determine the position of a point at which lead frame  4  is joined to switch element  2 . Connecting convex portion  4 A allows switch element  2  to keep space or a creepage distance in a portion that requires insulation. 
     Obviously, a region in which the aforementioned space is provided may be filled with exterior resin part  13 . Furthermore, connecting convex portion  4 A contacts source electrode  2 S in a small region. Therefore, a jointing material, a welding material, or the like is used to stabilize the joint between connecting convex portion  4 A and source electrode  2 S, leading to increased reliability of semiconductor module  1 . 
     Note that although only source electrode  2 S and switch element  2  have been thus far described in detail, the same is true for source electrode  3 S and switch element  3 . 
     In the above description, single switch element  2  and single switch element  3  are used to simplify the description, but in order to increase ampacity, two or more switch elements  2  and two or more switch elements  3  may be arranged in parallel and controlled so as to operate in synchronization, as illustrated in  FIG.  2    and  FIG.  3   . 
     Closing 
     Semiconductor module  1  according to one aspect of the present disclosure includes: switch element  2  including source electrode  2 S, gate electrode  2 G, and drain electrode  2 D; switch element  3  including source electrode  3 S, gate electrode  3 G, and drain electrode  3 D; lead frame  4  (conductor) that has a shape of a plate and is joined to source electrode  2 S of switch element  2 , switch element  3  is placed on lead frame  4 ; lead frame  5  (conductor) that has a shape of a plate and is joined to source electrode  3 S of switch element  3 , switch element  3  is placed on lead frame  5 ; positive electrode lead frame  6  (positive electrode conductor) connected to drain electrode  2 D of switch element  2 ; output lead frame  7  (output conductor) connected to lead frame  4  and drain electrode  3 D of switch element  3 ; negative electrode lead frame  8  (negative electrode conductor) connected to lead frame  5 ; control lead frame  9  (control conductor) connected to gate electrode  2 G of switch element  2 ; control lead frame  10  (control conductor) connected to gate electrode  3 G of switch element  3 ; first voltage detection terminal  11  provided on lead frame  4 ; second voltage detection terminal  12  provided on lead frame  5 ; and exterior resin part  13  having a polyhedral shape and configured to seal switch element  2 , switch element  3 , lead frame  4 , lead frame  5 , a portion of positive electrode lead frame  6 , a portion of output lead frame  7 , a portion of negative electrode lead frame  8 , a portion of control lead frame  9 , a portion of control lead frame  10 , a portion of first voltage detection terminal  11 , and a portion of second voltage detection terminal  12 . Exterior resin part  13  includes first exterior surface  13 A and second exterior surface  13 B. First voltage detection terminal  11  protrudes from first exterior surface  13 A. Second voltage detection terminal  12  protrudes from second exterior surface  13 B. 
     In semiconductor module  1  according to another aspect, first voltage detection terminal  11  and lead frame  4  are a single conductor, and second voltage detection terminal  12  and lead frame  5  are a single conductor. 
     In semiconductor module  1  according to another aspect, first exterior surface  13 A and second exterior surface  13 B oppose each other. 
     In semiconductor module  1  according to another aspect, first exterior surface  13 A includes two planes, and second exterior surface  13 B includes two planes. 
     In semiconductor module  1  according to another aspect, a direction in which first voltage detection terminal  11  protrudes from first exterior surface  13 A is opposite to a direction in which second voltage detection terminal  12  protrudes from second exterior surface  13 B. 
     In semiconductor module  1  according to another aspect, lead frame  4  and lead frame  5  are arranged side by side. 
     In semiconductor module  1  according to another aspect, first voltage detection terminal  11  and control lead frame  9  protrude from first exterior surface  13 A, and second voltage detection terminal  12  and control lead frame  10  protrude from second exterior surface  13 B. 
     In semiconductor module  1  according to another aspect, each of the thickness of control lead frame  9 , the thickness of control lead frame  10 , the thickness of lead frame  4 , and the thickness of lead frame  5  is thickness T 1 , each of the thickness of positive electrode lead frame  6 , the thickness of output lead frame  7 , and the thickness of negative electrode lead frame  8  is thickness T 2 , and the value of T 2  is greater than the value of T 1 . 
     In semiconductor module  1  according to another aspect, lead frame  4  includes connecting convex part  4 A, source electrode  2 S of switch element  2  is connected to connecting convex part  4 A of lead frame  4 , and similar to lead frame  4 , lead frame  5  includes a connecting convex part, and source electrode  3 S of switch element  3  is connected to the connecting convex part of lead frame  5 . 
     INDUSTRIAL APPLICABILITY 
     The semiconductor module according to the present disclosure has the advantageous effect of allowing for increased reliability and is useful in various electronic devices. 
     REFERENCE MARKS IN THE DRAWINGS 
     
         
           1  semiconductor module 
           2 ,  3  switch element 
           2 G gate electrode 
           2 D drain electrode 
           2 S source electrode 
           3 G gate electrode 
           3 D drain electrode 
           3  S source electrode 
           4 ,  5  lead frame 
           4 A connecting convex portion 
           6  positive electrode lead frame 
           6 A distal end 
           6 B lead joining part 
           7  output lead frame 
           8  negative electrode lead frame 
           9 ,  10  control lead frame 
           11  first voltage detection terminal 
           12  second voltage detection terminal 
           13  exterior resin part 
           13 A first exterior surface 
           13 B second exterior surface 
           14  power supply system 
           15  direct-current power supply device 
           16  load device 
           17  control circuit 
           18  gate driver 
           19  gate driver 
           20  insulator/radiator 
           20 A insulating layer 
           20 B metal layer 
           21  conductor layer 
           22  conductor layer