Semiconductor devices

Abstract

A semiconductor device prevents damage to a nut holding member that holds a nut. The semiconductor device (1) of the present invention comprises: a main terminal (3) that is connected to an external conductor by means of a bolt; a nut (6) into which the front end of the bolt is screwed; and a nut holding member (5) that holds the nut. The nut holding member has a recess (52) for accommodating the nut. A notch (54) is formed in a portion of a peripheral wall (53) that forms the recess.

Description

Technical Field

[0001] The present invention relates to a semiconductor device. Background Art

[0002] The semiconductor device has a substrate provided with semiconductor elements such as an IGBT (Insulated Gate Bipolar Transistor), a power MOSFET (Metal Oxide Semiconductor Field Effect Transistor), and a FWD (Free Wheeling Diode), and is used in inverter devices and the like.

[0003] In such a power semiconductor device, a housing member for accommodating a substrate is formed of resin, and a hexagonal nut is inserted into the housing member to fix a terminal member of an external wiring with a bolt (for example, see Patent Document 1). Specifically, in Patent Document 1, a nut insertion hole for inserting a hexagonal nut is formed in the housing member. In addition, a terminal member insertion hole for inserting a terminal member is formed around the nut insertion hole.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2015-56614 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] However, according to Patent Document 1, it is conceivable that the wall around the nut insertion hole will become thinner based on the positional relationship between the nut insertion hole and the terminal member insertion hole. Therefore, there is a concern that the housing member (the wall around the nut insertion hole) may be damaged due to the inability to withstand the rotational force of the nut when tightening the bolt.

[0009] The present invention has been made in view of the above-mentioned problems, and one object of the present invention is to provide a semiconductor device capable of preventing damage to a nut holding member for holding a nut.

[0010] Solutions for solving problems

[0011] A semiconductor device according to one embodiment of the present invention is characterized in that it comprises: a main terminal connected to an external conductor by means of a bolt; a nut into which the front end of the bolt is screwed; and a nut retaining member that retains the nut, wherein the nut retaining member has a recess for accommodating the nut, and a notch is formed in a portion of a peripheral wall portion forming the recess.

[0012] Effects of the Invention

[0013] According to the present invention, it is possible to prevent the nut holding member that holds the nut from being damaged. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a perspective view showing an example of a semiconductor device.

[0015] Figure 2 It is a top view of a nut holding member according to a comparative example.

[0016] Figure 3 It is a partial enlarged view of the nut holding member according to the present embodiment.

[0017] Figure 4 It is a partial enlarged view of a nut holding member according to a modified example.

[0018] Figure 5 It is a top view of a nut holding member according to another modified example.

[0019] Figure 6 It is a plan view showing a variation of a nut holding member according to another modified example.

[0020] Description of Reference Numerals

[0021] 1: semiconductor device; 2: housing member; 3: main terminal; 4: control terminal; 5: nut retaining member; 6: nut; 6a: outer peripheral surface (opposite surface); 21: through hole; 23: main terminal support portion; 24: control terminal support portion; 25: insertion groove; 30: main surface portion; 31: foot portion; 32: through hole; 50: nut receiving portion; 51: bulging portion; 52: recessed portion; 52a: inner peripheral surface; 53: peripheral wall portion; 53a: thin-walled portion; 54: notch portion; 55: gap. DETAILED DESCRIPTION

[0022] Next, a semiconductor device to which the present invention can be applied will be described. Figure 1 2 is a perspective view showing an example of a semiconductor device. The semiconductor device shown below is only an example and is not limited thereto, and can be appropriately changed. Figure 1In the present invention, the long side direction of the semiconductor device is defined as the X direction, the short side direction is defined as the Y direction, and the height direction is defined as the Z direction. In addition, depending on the situation, the X direction is sometimes referred to as the front-back direction, the Y direction is sometimes referred to as the left-right direction, and the Z direction is sometimes referred to as the up-down direction. These directions (front-back, left-right, up-down, and left-right directions) are for the convenience of explanation. Figure 1 The terms used may change the correspondence between the XYZ direction and each direction depending on the mounting posture of the semiconductor device. In addition, in this specification, the top view refers to the state of observing the upper surface of the semiconductor device from the positive direction of the Z axis.

[0023] like Figure 1 As shown, the semiconductor device 1 is obtained by packaging a plurality of semiconductor elements (not shown), and is configured by accommodating a substrate (not shown) on which the semiconductor elements are mounted in a case member 2 .

[0024] Semiconductor elements are formed on semiconductor substrates such as silicon (Si) and silicon carbide (SiC). As semiconductor elements, switching elements such as IGBT (Insulated Gate Bipolar Transistor), power MOSFET (Metal Oxide Semiconductor Field Effect Transistor), and diodes such as FWD (Free Wheeling Diode) can be used. In addition, as semiconductor elements, RC (Reverse Conducting)-IGBT obtained by integrating IGBT and FWD, RB (Reverse Blocking)-IGBT with sufficient withstand voltage for reverse bias, etc. can also be used.

[0025] The substrate is a laminated substrate formed by laminating a metal layer and an insulating layer, and has a rectangular shape in a top view that is long in the X direction. In addition, an electronic circuit is formed on the surface of the substrate using a pattern of the metal layer, and three main terminals 3 and two control terminals 4 are connected to the electronic circuit. In addition, a semiconductor element is mounted in the electronic circuit. The laminated substrate may also include a plurality of laminated substrates.

[0026] The main terminal 3 is formed by bending a metal plate, and has a gate shape or an arch shape when viewed from the X direction. Specifically, the main terminal 3 has a main surface 30, which faces the surface of the substrate and is parallel to the XY plane; and a pair of legs 31, which extend from both ends of the main surface 30 in the Y direction toward the substrate in the Z direction. The lower end of the leg 31 is connected to the electronic circuit on the surface of the substrate.

[0027] A through hole 32 penetrating in the thickness direction (Z direction) is formed at the center of the main face 30. Bolts (not shown) for connecting external conductors such as bus bars are inserted into the through hole 32. Three main terminals 3 are arranged side by side at substantially the center in the Y direction of the substrate along the long side direction (X direction (the insertion direction of the nut holding member 5 described later)) of the substrate at a prescribed interval, for example. In addition, the number of main terminals 3 arranged is not limited to this, and it may be one, two, or four or more.

[0028] The control terminal 4 is composed of a pair of elongated bodies extending along the Z direction and arranged side by side in the Y direction, and is formed of a metal plate, for example. The lower end of the control terminal 4 is connected to the electronic circuit on the substrate surface. Two control terminals 4 are arranged side by side in the X direction end portion of the substrate in the Y direction, for example. In Figure 1 two control terminals 4 are arranged at positions deeper (rearward) in the X direction than the main terminal 3. The semiconductor element, the electronic circuit, the main terminal 3, and the control terminal 4 can be electrically connected to each other to form an inverter circuit.

[0029] The housing member 2 has a rectangular parallelepiped box shape with an opening on the bottom surface side (below), and is formed of a resin material, for example, to cover the upper part of the substrate. Countersunk holes 20 are formed at the four corners in the XY direction of the housing member 2, and through holes 21 penetrating in the Z direction are formed at the bottoms of the countersunk holes 20. The through holes 21 are through holes for bolts (not shown) for mounting the semiconductor device 1. A metal base plate can be arranged at the opening on the bottom surface side of the housing member 2. A laminated substrate can be mounted above the base plate.

[0030] In addition, as Figure 1 shown, in a state where the housing member 2 covers the substrate, the upper ends of the main face 30 and the control terminal 4 are exposed to the outside. Each terminal is supported by a support portion formed in the housing member 2. Specifically, the housing member 2 has a main terminal support portion 23 for supporting the main terminal 3 and a control terminal support portion 24 for supporting the control terminal 4.

[0031] The main terminal support portion 23 has a shape protruding from the upper surface of the housing member 2 to support the upper end portions of a pair of leg portions 31, that is, both end portions in the Y direction of the main face 30. In Figure 1 three pairs of main terminal support portions 23 facing each other in the Y direction are formed at prescribed intervals in the X direction corresponding to the positions of the main terminals 3. The control terminal support portion 24 has a rectangular parallelepiped shape extending along the Z direction so as to surround the periphery of the control terminal 4.

[0032] In addition, a groove extending in the X direction is formed on the upper surface of the housing member 2 below the main surface 30 and between the pair of legs 31. The groove constitutes an insertion groove 25 into which the nut holding member 5 described later can be inserted. The insertion groove 25 has a left-right width (width in the Y direction) corresponding to the facing interval of the pair of legs 31, and extends in the X direction at a predetermined depth. Specifically, the left-right width of the insertion groove 25 is set to be smaller than the facing interval of the pair of legs 31.

[0033] The nut holding member 5 is configured to hold a plurality of nuts 6. For example, a standard hexagonal nut can be used for the nut 6. The nut holding member 5 is configured by a strip extending in the X direction, and is formed of, for example, a resin material. The nut holding member 5 has a left-right width and a length in the X direction corresponding to the left-right width (width in the Y direction) and the length in the X direction of the insertion groove 25, and a nut receiving portion 50 for receiving the nut 6 is formed corresponding to each main surface portion 30.

[0034] Specifically, the nut receiving portion 50 is configured such that a concave portion 52 having a hexagonal shape in plan view corresponding to the shape of the nut 6 is formed on the upper surface of three bulging portions 51 bulging in the Z direction corresponding to the main terminal supporting portions 23 of the housing member 2. That is, three nut receiving portions 50 are formed side by side at a predetermined interval in the X direction corresponding to the position of the through hole 32 of the main surface portion 30.

[0035] The hexagonal recess 52 is formed so that the extending direction of the pair of outer peripheral surfaces 6a (opposing surfaces 6a) of the predetermined hexagonal shape of the nut 6 is toward the extending direction of the nut holding member 5, that is, the X direction, which will be described in detail later. In other words, the direction in which the pair of outer peripheral surfaces 6a of the predetermined hexagonal shape of the nut 6 face each other is consistent with (parallel to) the direction in which the pair of legs 31 face each other. In addition, it is preferred that the depth of the recess 52 is the same as the thickness of the nut 6, or is greater than the thickness of the nut 6.

[0036] By inserting the nut holding member 5 into the specified position of the insertion groove 25 in a state where the nut 6 is accommodated in each nut receiving portion 50, the through hole 32 of each main surface portion 30 and the threaded hole of the nut 6 are aligned in the X direction and the Y direction. That is, the nut holding member 5 is inserted until each main surface portion 30 and the nut 6 accommodated in the recess 52 face each other in the Z direction. More specifically, the nut holding member 5 is inserted until the center of the nut 6 accommodated in the recess 52 is aligned with the center of the through hole of the main surface portion 30. Moreover, the front end of the bolt (not shown) can be passed through the through hole 32 via an external conductor (not shown) and then screwed into the nut 6. As a result, the external conductor can be connected to the main surface portion 30 of the main terminal 3 by threaded fixing.

[0037] In addition, when the nut holding member 5 is inserted below the main terminal 3 of the gate shape as described above, the width dimension of the nut holding member 5 in the Y direction is restricted by the opposing interval of the pair of legs 31. Therefore, when the recess 52 corresponding to the shape of the nut 6 is formed within the width dimension of the nut holding member 5, there may be a portion where the thickness of the wall around the recess 52 becomes thinner. Therefore, it can be assumed that, depending on the size of the nut 6, the thin-walled portion cannot withstand the tightening torque of the bolt, thereby damaging the nut holding member 5.

[0038] Here, refer to Figure 2 Let's explain the above phenomenon in detail. Figure 2 It is a top view of a nut holding member according to a comparative example. Figure 2 (A) is the overall top view. Figure 2 (B) is Figure 2 A partial enlarged view of (A). Figure 2 For the sake of convenience, Figure 1 The nut retaining members shown have several different shapes, but Figure 2 It is just a schematic diagram, the basic functions are Figure 1 In addition, the structure annotations that have appeared are the same as Figure 1 Same mark.

[0039] like Figure 2 As shown in (A), the nut holding member 5 involved in the comparative example is composed of a long strip having a long side direction in the X direction. Three recesses 52 as nut receiving portions are formed side by side along the long side direction. The recess 52 has a hexagonal shape in plan view as described above, and its center is located at the width center of the nut holding member 5 in the Y direction.

[0040] In addition, if Figure 2 As shown in (B), in the recess 52, the direction in which the pair of outer peripheral surfaces 6a of the predetermined hexagonal shape of the nut 6 face each other is consistent with (parallel to) the direction in which the pair of legs 31 face each other. In this way, when the width dimension of the nut holding member 5 is set within the facing interval of the pair of legs 31 and the recess 52 for accommodating the nut 6 is formed within the width dimension, a thin-walled portion 53a exists in a part of the peripheral wall portion 53 forming the recess 52. Specifically, the thin-walled portion 53a is composed of the peripheral wall portion 53 existing between one leg 31 and the recess 52.

[0041] Thus, when the nut 6 is held by the nut holding member 5 of the resin molded product, in the comparative example, the nut 6 is held in the recess 52 in a state where the outer peripheral surfaces 6a of the nut 6 and the inner peripheral surfaces 52a of the recess 52 are in contact as a whole. In this case, due to the tightening torque when the bolt is screwed into the nut 6, stress is concentrated on the thin-walled portion 53a having a relatively small strength. As a result, there is a concern that the nut holding member 5 may be damaged starting from the thin-walled portion 53a.

[0042] Therefore, although it is also possible to increase the thickness of the nut holding member 5 or use a high-strength material, as mentioned above, the width dimension of the nut holding member 5 is limited, and it may also become a cause of increased material cost. In addition, when the resin molded product has a thin-walled portion 53a, the resin will not fully flow into the thin-walled portion 53a during molding, which may also become a cause of poor molding.

[0043] Therefore, the inventor of the present invention focused on the thin-walled portion 53a and came up with the present invention. Specifically, in the present embodiment, a notch is formed in the thin-walled portion 53a to eliminate the stress concentration point when the bolt is tightened. Figure 3 The nut holding member according to the present embodiment will be described. Figure 3 It is a partial enlarged view of the nut holding member involved in this embodiment. Figure 3 (A) is a partial stereoscopic view of the nut retaining member. Figure 3 (B) is a top view thereof. Figure 3 The nut retaining member 5 shown is Figure 2 The only difference is that a notch 54 is formed in a part of the peripheral wall 53 that forms the recess 52. Therefore, the same reference numerals are used to indicate the structures that have already appeared, and the description is appropriately omitted. In addition, the shape of the peripheral wall 53 is not particularly specified, and the entire wall portion that surrounds the outer periphery of the recess 52 in a manner that forms the recess 52 is indicated, and its boundary is not particularly shown in the drawings. That is, in this specification, the peripheral wall 53 includes all parts equivalent to the wall that surrounds the outer periphery of the recess 52. In addition, in Figure 3 In the figure, for convenience of explanation, only the notch portion 54 formed corresponding to one recessed portion 52 is shown, but it is assumed that the notch portions 54 are formed corresponding to the other recessed portions 52 .

[0044] like Figure 3 As shown in (A), a notch 54 is formed in a part of the peripheral wall 53 forming the recess 52. More specifically, as Figure 3 As shown in (B), the notch 54 is formed in the peripheral wall portion 53 facing the pair of legs 31. The extended surface of the inner peripheral surface 52a of the recessed portion 52 abutted by the two corners of the outer peripheral surface 6a of the nut 6 facing the legs 31 is formed on the peripheral wall portion 53 (at Figure 3In (B), the peripheral wall portion 53 on the right side of the paper is opened to form a notch portion 54. As a result, the following state is achieved: an outer peripheral surface 6a of the nut 6 facing the leg portion 31 is exposed to the outside from the nut holding member 5. That is, the outer peripheral surface 6a is not in contact with the inner peripheral surface 52a of the recess 52. In addition, Figure 3 In the plan view, the notch portion 54 has an isosceles trapezoidal shape with a waist formed by an extension of the inner peripheral surface.

[0045] Thus, in this embodiment, the thin-walled portion 53a (see Figure 2 ) is formed into a part of the peripheral wall portion 53 of the nut 6, so that the outer peripheral surface 6a of the nut 6 intentionally does not contact the thin-walled portion 53a. As a result, it is possible to make the other relatively thick peripheral wall portions 53 bear stress without applying a load to the thin-walled portion 53a. Therefore, it is possible to prevent stress concentration from occurring in the portion with relatively weak strength when the bolt is tightened. Since there is no thin-walled portion 53a that may be damaged, the damage of the nut retaining member 5 itself can be prevented. That is, according to the present invention, by forming a notch in the thin-walled portion 53a that may be damaged due to stress concentration in advance, the damage of the nut retaining member 5 caused by stress concentration when the bolt is tightened can be prevented in advance. In addition, by eliminating the thin-walled portion 53a, the fluidity of the resin is not hindered, and poor molding can also be prevented.

[0046] Next, refer to Figure 4 A modification example will be described. Figure 4 1 is a partial enlarged view of a nut holding member according to a modified example. In the modified example, only the parts different from the above-mentioned embodiment are described, and the same reference numerals are given to the existing structures and the description thereof is omitted as appropriate.

[0047] exist Figure 4 The nut holding member 5 shown in the figure has a predetermined gap 55 formed between the inner peripheral surface 52a and the outer peripheral surface 6a in such a manner that the inner peripheral surface 52a of the recess 52 located at a position 120 degrees around the axis of the recess 52 (or the nut 6) with respect to the portion where the notch 54 is formed does not abut against the outer peripheral surface 6a of the nut 6. That is, the gap 55 is provided between the outer peripheral surface 6a of the nut 6 located at a predetermined angular interval with respect to the notch 54 and the inner peripheral surface 52a of the recess 52 facing the outer peripheral surface 6a. The shape of the gap 55 in a plan view has an isosceles trapezoid with the inner peripheral surface 52a as the upper base and the outer peripheral surface 6a as the lower base.

[0048] According to this structure, the outer peripheral surface 6a of the nut 6 does not contact the inner peripheral surface 52a of the recess 52 not only in the notch portion 54 but also in the portion where the gap 55 is provided. That is, three portions where the outer peripheral surface 6a of the nut 6 contacts the inner peripheral surface 52a of the recess 52 can be provided at predetermined angular intervals (120 degree intervals), and the stress received by the peripheral wall portion 53 can be evenly dispersed when the bolt is tightened. As a result, the possibility of damage to the nut holding member 5 can be further reduced.

[0049] In addition, in the present embodiment, the main terminal 3 is configured to have a gate-shaped structure so that the nut holding member 5 is inserted into the housing member 2 from the long side direction (X direction), but the present invention is not limited to this structure. For example, the main terminal 3 may be configured to have an L-shaped structure as viewed from the X direction so that the nut holding member 5 is inserted into the housing member 2 from the Y direction. In addition, the present invention can be applied as long as it is a structure in which a thin-walled portion 53a may exist due to the width dimension of the nut holding member 5, without being limited to the shape of the main terminal 3.

[0050] In addition, in the present embodiment, the notch 54 is formed only in the peripheral wall 53 on one side of the pair of legs 31 facing each other, but the present invention is not limited to this structure. The notch 54 may also be formed on the other side. In addition, the notch 54 is formed in a structure in which one outer peripheral surface 6a is exposed to the outside as a whole, but the present invention is not limited to this structure. The shape of the notch 54 can be appropriately changed. For example, the notch 54 can be formed by forming a notch in a part of the peripheral wall 53 so that a part of one outer peripheral surface 6a is exposed to the outside according to (considering) the stress concentration position.

[0051] In addition, in the present embodiment, the direction in which the pair of outer peripheral surfaces 6a of the predetermined hexagonal shape of the nut 6 faces each other is consistent with the direction in which the pair of legs 31 faces each other, but the present invention is not limited to this structure. Figure 5 As in the modified example shown, the nut 6 is rotated 90 degrees about the axis to form the recess 52 so that the diagonal line of the nut 6 coincides with the direction in which the pair of legs 31 face each other. In this case, it is preferable to form the notch 54 on both left and right sides.

[0052] In addition, in the present embodiment, the notch 54 is configured to have an isosceles trapezoidal structure in which the waist is formed by the extension of the inner peripheral surface when viewed from above, but the present invention is not limited to this structure. The shape of the notch 54 can be appropriately changed. Figure 6 A modified example such as (A) and (B). Figure 6 (A) is to make Figure 3 The example in which the recessed portion 52 shown in (B) is rotated clockwise by a predetermined angle, Figure 6 (B) is to make Figure 3In this case, the extended surface of the inner peripheral surface 52a defining the outer surface shape of the notch 54 may be parallel to the inner peripheral surface 52a connected to the extended surface, and as shown in FIG. Figure 6 (A) and Figure 6 As shown in (B), the notch 54 is not an isosceles trapezoid when viewed from above. In addition, the length of the notch 54 opening at the end of the peripheral wall 53 in the Y direction may be shorter than one side of the nut 6. Figure 3 In (B), for example, a pair of extended surfaces facing each other in the X direction may be parallel to each other, and the notch portion 54 may be formed in a rectangular shape in plan view.

[0053] In the present embodiment, the shape of the gap 55 in plan view is an isosceles trapezoid with the inner peripheral surface 52a as the upper base and the outer peripheral surface 6a as the lower base, but the present invention is not limited to this structure. For example, the shape of the gap 55 may be a rectangular shape in plan view.

[0054] In addition, in the present embodiment, three main terminals 3 are arranged side by side in the X direction, but the present invention is not limited to this structure. The number of main terminals 3 is not limited to multiple, and may be single, for example, 1, 2, or 4 or more. In addition, the parallel direction is not limited to the X direction, and can be changed appropriately.

[0055] Furthermore, although the present embodiment and the modified examples have been described, the above-described embodiment and the modified examples may be combined in whole or in part to form another embodiment.

[0056] In addition, the present embodiment is not limited to the above-mentioned embodiment and modification examples, and various changes, substitutions, and modifications can be made within the scope of the main purpose of the technical idea. Moreover, if the technical idea can be realized by other methods due to technological progress or other derived technologies, the method can also be used for implementation. Therefore, the claims cover all embodiments that can be included in the scope of the technical idea.

[0057] The characteristic points of the above-mentioned embodiments are summarized below.

[0058] The semiconductor device described in the above embodiment is characterized in that it comprises: a main terminal, which is connected to an external conductor by means of a bolt; a nut, into which the front end of the bolt is screwed; and a nut retaining member, which retains the nut, the nut retaining member having a recess for accommodating the nut, and a notch portion is formed in a portion of a peripheral wall portion forming the recess.

[0059] In the semiconductor device described in the above embodiment, it is characterized in that the main terminal is connected to an electronic circuit formed on a substrate, and the semiconductor device also has a shell member, which accommodates the substrate and exposes a portion of the main terminal to the outside, and the shell member has an insertion groove into which the nut retaining member can be inserted, and the nut retaining member is inserted until a portion of the main terminal is facing the nut accommodated in the recess.

[0060] In the semiconductor device described in the above embodiment, the main terminal is characterized in that: the main surface portion is opposite to the substrate and exposed to the outside from the shell member; and a pair of legs are extended from both ends of the main surface portion toward the substrate, a through hole for the bolt to pass through is formed on the main surface portion, the insertion groove is formed between the pair of legs, the nut retaining member is inserted until the center of the nut accommodated in the recess is aligned with the center of the through hole, and the notch portion is formed in the portion of the peripheral wall portion facing the pair of legs.

[0061] In the semiconductor device described in the above embodiment, a plurality of the main terminals are arranged side by side along the insertion direction of the nut holding member, a plurality of the recesses are provided corresponding to the plurality of the main terminals, and the notch portions are formed corresponding to each of the recesses.

[0062] In the semiconductor device described in the above embodiment, the nut is composed of a hexagonal nut, the recess has a top view hexagonal shape corresponding to the shape of the nut, and the direction in which a pair of facing surfaces of the specified hexagonal shape of the nut face each other is consistent with the direction in which the pair of legs face each other.

[0063] In the semiconductor device described in the above embodiment, the recess has a gap between an outer peripheral surface of the nut located at a predetermined angular interval with respect to the notch and an inner peripheral surface of the recess facing the outer peripheral surface.

[0064] Industrial Applicability

[0065] As described above, the present invention has an effect of preventing the nut holding member that holds the nut from being damaged, and is particularly useful in semiconductor devices.

Claims

1. A semiconductor device, characterized in that: have: Main terminals, which are connected to external conductors by means of bolts; a nut into which the front end of the bolt is screwed; and a nut holding member which holds the nut, The nut holding member has a recess for receiving the nut. A notch is formed in a portion of the peripheral wall portion forming the recess, the notch opening the peripheral wall portion to expose a portion of the outer peripheral surface of the nut to the outside of the nut holding member. The recess has a gap between the outer peripheral surface of the nut located at a predetermined angular interval with respect to the notch and the inner peripheral surface of the recess facing the outer peripheral surface. The gap is an isosceles trapezoid in a plan view with the outer peripheral surface as a lower base and the inner peripheral surface as an upper base.

2. The semiconductor device according to claim 1, wherein: The main terminal is connected to an electronic circuit formed on the substrate. The semiconductor device further includes a housing member for housing the substrate and exposing a portion of the main terminal to the outside. The housing member has an insertion groove into which the nut holding member can be inserted, The nut holding member is inserted to a position where a portion of the main terminal faces the nut accommodated in the recess.

3. The semiconductor device according to claim 2, wherein: The main terminal has: a main surface portion facing the substrate and exposed to the outside from the housing member; and a pair of legs extending from both ends of the main surface toward the substrate, A through hole is formed in the main surface portion for the bolt to pass through. The insertion groove is formed between the pair of legs, The nut holding member is inserted until the center of the nut accommodated in the recess is aligned with the center of the through hole. The notch portion is formed at a portion of the peripheral wall portion that faces the pair of leg portions.

4. The semiconductor device according to claim 3, wherein: A plurality of the main terminals are arranged side by side along the insertion direction of the nut holding member, A plurality of the recesses are provided corresponding to the plurality of the main terminals, The notch portions are formed corresponding to the respective recessed portions.

5. The semiconductor device according to claim 4, wherein: The nut is composed of a hexagonal nut, The recess has a hexagonal shape corresponding to the shape of the nut in a plan view, and a direction in which a pair of facing surfaces of the nut defining the hexagonal shape face each other coincides with a direction in which the pair of legs face each other.

6. The semiconductor device according to claim 1, wherein: The notch portion has an isosceles trapezoidal shape in a plan view, the waist of which is formed by an extension of the inner peripheral surface of the recessed portion that faces the outer peripheral surface of the nut.

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