Semiconductor modules, semiconductor devices, and vehicles

Abstract

To prevent degradation of insulation due to ion migration in a semiconductor module.SOLUTION: A semiconductor module (1) has two conductor plates (21, 22) protruding from an encapsulation in which a semiconductor element (40) is encapsulated and facing each other separated by a first distance in a first direction (Z direction), and an insulating material (30) disposed between the two conductor plates and whose dimension (d1) in the first direction is narrower than a width corresponding to the first distance. An insulating layer of insulating material and an air layer (32) are provided along the first direction between the two conductor plates outside the encapsulation.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a semiconductor module, a semiconductor device, and a vehicle. Background Art

[0002] A semiconductor module used in a power converter such as an inverter device includes semiconductor elements such as an IGBT (Insulated Gate Bipolar Transistor), a power MOSFET (Metal Oxide Semiconductor Field Effect Transistor), and an FWD (Free Wheeling Diode).

[0003] In this type of semiconductor module, a sheet-shaped insulating member is inserted between two conductor plates that protrude from a sealing body in which a semiconductor element is sealed and overlap in the width direction, thereby reducing the distance between the conductor plates and reducing inductance.

[0004] For example, Patent Document 1 describes a semiconductor device in which an inter-wire gap portion is disposed in a gap between a first wiring portion of a first lead frame and a second wiring portion of a second lead frame to ensure insulation, so that the first wiring portion and the second wiring portion are arranged close to each other to reduce inductance.

[0005] Further, for example, Patent Document 2 describes a power conversion device including: a capacitor module having a pair of positive and negative first DC terminals obtained by laminating plate conductors via a first insulator; and a power module having a pair of positive and negative second DC terminals obtained by laminating plate conductors via a second insulator.

[0006] Further, for example, Patent Document 3 describes a metal-resin composite structure that can ensure insulation withstand voltage reliability even when metal lead conductors are arranged close to each other to reduce inductance components.

[0007] Furthermore, for example, Patent Document 4 describes a power conversion device in which a first conductor and a second conductor having opposite polarities are arranged such that the direction of current flow is opposite at their overlapping portion, and the inductance is reduced by covering the surfaces of the first conductor and the second conductor with an insulating material. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Re-tabled publication No. 2021 / 29150 [Patent Document 2] Japanese Patent Publication No. 2008-29117 [Patent Document 3] Japanese Patent Publication No. 2012-116126 [Patent Document 4] Japanese Patent Publication No. 2021-10236 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] However, if a sheet-like insulating material interposed between two conductor plates is in contact with both conductor plates, moisture contained in the insulating material can cause ion migration, potentially leading to deterioration of the insulation between the conductor plates or a short circuit.

[0010] In one aspect, the present invention aims to suppress the decrease in insulation performance due to ion migration in semiconductor modules. [Means for solving the problem]

[0011] A semiconductor module according to one embodiment comprises two conductor plates protruding from a encapsulation body in which a semiconductor element is sealed, and facing each other at a distance of a first distance in a first direction, and an insulating material disposed between the two conductor plates, the dimension in the first direction being narrower than the width corresponding to the first distance, wherein an insulating layer of the insulating material and an air layer are provided between the two conductor plates outside the encapsulation body along the first direction. [Effects of the Invention]

[0012] According to the above-described embodiment, it is possible to suppress the decrease in insulation performance due to ion migration in semiconductor modules. [Brief explanation of the drawing]

[0013] [Figure 1] This is a plan view showing an example of the configuration of a semiconductor device according to the first embodiment. [Figure 2] This is a cross-sectional view of the semiconductor device shown along line A-A' in Figure 1. [Figure 3] Figure 1 is a cross-sectional view of the semiconductor device along the line B-B'. [Figure 4] Figure 2 is an enlarged view of the AR region. [Figure 5] This is a cross-sectional view showing a conventional example of a semiconductor module in which an insulating sheet is placed between two conductive plates. [Figure 6] This graph shows an example of the voltage distribution between two conductive plates when an insulating layer and an air layer are placed between them. [Figure 7] This is a partial plan view illustrating an example configuration of a semiconductor module according to the second embodiment. [Figure 8] Figure 7 is a cross-sectional view of the semiconductor module along the line C-C'. [Figure 9] This figure illustrates a specific example of the configuration of a spacer in a semiconductor module according to the second embodiment. [Figure 10] This is a schematic plan view showing an example of a vehicle to which the semiconductor device according to the present invention is applied. [Modes for carrying out the invention]

[0014] Hereinafter, embodiments of a semiconductor module and a semiconductor device to which the present invention is applicable will be described with reference to the drawings. The term "semiconductor device" used in the present specification and claims refers to an integrated device including at least one semiconductor module and a component different from the semiconductor module (for example, a cooler, etc.). The X direction, Y direction, and Z direction shown in the referenced drawings correspond to the longitudinal direction, the lateral direction, and the width direction (height direction) of the semiconductor module, respectively. The illustrated X, Y, and Z axes are orthogonal to each other and form a right-handed coordinate system. In some cases, the X direction may be referred to as the left-right direction, the Y direction as the front-rear direction, and the Z direction as the up-down direction. These directions (front, rear, left, right, up and down) are terms used for convenience of description, and the correspondence between these directions and the X, Y, and Z directions may change depending on the mounting posture of the semiconductor module.

[0015] In the following description of the present specification, for example, the end face on the negative Z-direction side of the illustrated component is referred to as the lower surface, and the end face on the opposite side (that is, the positive Z-direction side) is referred to as the upper surface. In addition, as used herein, "plan view" means a view of the upper surface or lower surface of the semiconductor module viewed from the Z direction.

[0016] The semiconductor module exemplified in the following description can be applied to, for example, a power conversion device such as an inverter device for industrial or vehicle-mounted motors. The configuration of the semiconductor module shown in the drawings referenced in the following description is simplified to the extent that it does not hinder those skilled in the art from understanding the present invention, and does not necessarily match the configuration of an actual semiconductor module. Furthermore, the aspect ratios and the size relationship between members in each drawing are shown schematically or approximately, and do not necessarily match the actual relationship in a semiconductor module. For convenience of description, it is also assumed that the size relationship between members is exaggerated in some cases.

[0017] [First Embodiment] Figure 1 is a plan view showing an example of the configuration of a semiconductor device according to the first embodiment. Figure 2 is a cross-sectional view of the semiconductor device in Figure 1 taken along line A-A'. Figure 3 is a cross-sectional view of the semiconductor device in Figure 1 taken along line B-B'. Figure 4 is an enlarged view of region AR in Figure 2. In Figure 1, the sealing material (sealing insulator) filled in the housing portion 12 of the case 11 is omitted in order to show an example of the configuration inside the housing portion 12 of the case 11 in the semiconductor module 1. In Figure 2, the hatching showing the cross-section of the sealing material 60 filled in the housing portion 12 of the case 11 is omitted.

[0018] The semiconductor device 100 illustrated in Figures 1 to 4 includes a semiconductor module 1 and a cooler 2 positioned on the underside of the semiconductor module 1. The cooler 2 releases heat from the semiconductor module 1 to the outside and has a rectangular parallelepiped shape overall. Although not specifically shown in the figures, the cooler 2 is constructed by providing multiple fins on the underside of a base plate and housing these fins in a water jacket. Note that the configuration of the cooler 2 is not limited to this and can be changed as appropriate.

[0019] The semiconductor module 1 includes a case 11 in which a semiconductor element 40 is housed and sealed, a first conductive plate 21 and a second conductive plate 22 that protrude outward from a first side surface 13 of the case 11 and face each other at a distance d1+d2 (see Figure 3) in the Z direction, and a third conductive plate 23 that protrudes outward from a second side surface 14 of the case 11. The first conductive plate 21, the second conductive plate 22, and the third conductive plate 23 function as electrodes (terminals) of the semiconductor module 1 and are formed from metal plates such as copper plates. The first conductive plate 21, the second conductive plate 22, and the third conductive plate 23 may also be called leads, busbars, etc.

[0020] The case 11 has a housing section 12 for housing semiconductor elements 40 and the like. The case 11 illustrated in Figures 1 to 3 is a rectangular tubular insulating member with open top and bottom surfaces, and the hollow part of the rectangular tube becomes the housing section 12. The first conductor plate 21, the second conductor plate 22, and the third conductor plate 23 each have portions that penetrate the case 11 and protrude into the housing section 12. The case 11 and the first conductor plate 21, the second conductor plate 22, and the third conductor plate 23 are integrally formed, for example, by insert molding. The case 11 is made of an insulating material that has high heat resistance and dimensional stability and low hygroscopicity, such as PPS (Poly Phenylene Sulfide). Note that the insulating material of the case 11 is not limited to a specific insulating material. Also, the shape of the case 11 is not limited to a rectangular tubular shape as illustrated in Figures 1 to 3.

[0021] The semiconductor element 40 is housed in the housing section 12 of the case 11, arranged on a laminated substrate 50. The laminated substrate 50 is composed of, for example, a DCB (Direct Copper Bonding) substrate, an AMB (Active Metal Brazing) substrate, or a metal base substrate. The laminated substrate 50 includes a rectangular insulating plate 51 in plan view, a first metal foil 52 placed on the upper surface of the insulating plate 51, and a second metal foil 53 placed on the lower surface of the insulating plate 51. The laminated substrate 50 is arranged in the housing section 12 such that, for example, the position of the lower surface of the second metal foil 53 in the Z direction substantially coincides with the position of the lower surface of the case 11. The insulating plate 51, the first metal foil 52, and the second metal foil 53 in the laminated substrate 50 are not limited to specific materials. The laminated substrate 50 may also be called a wiring board, etc. The semiconductor element 40 placed on the laminated substrate 50 may also be called a semiconductor chip or die.

[0022] The semiconductor element 40 may be, for example, an RC (Reverse Conducting)-IGBT element that integrates the functions of an IGBT (Insulated Gate Bipolar Transistor) element and an FWD (Free Wheeling Diode) element. In this type of semiconductor element 40, although not shown in the figures, for example, a first electrode is provided on the lower surface, and a second electrode and a third electrode are provided on the upper surface. The first electrode may be, for example, a collector electrode. The second electrode and the third electrode may be an emitter electrode and a gate electrode, respectively. During operation of the semiconductor element 40, the potential of the first electrode may be higher than the potential of the second electrode.

[0023] The semiconductor element 40 is bonded to the first metal foil 52 of the laminated substrate 50 by a bonding material 41, and the first electrode of the semiconductor element 40 is electrically connected to the first metal foil 52 by the bonding material 41. The first metal foil 52 is electrically connected to the second conductor plate 22 by bonding wires 42. The second electrode of the semiconductor element 40 is electrically connected to the first conductor plate 21 by bonding wires 43. The third electrode of the semiconductor element 40 is electrically connected to the third conductor plate 23 by bonding wires 44. The first metal foil 52 and the second conductor plate 22 of the laminated substrate 50 may be electrically connected by plate-shaped conductive members called leads, lead frames, etc., instead of bonding wires 42. Similarly, the second electrode of the semiconductor element 40 and the first conductor plate 21 may be electrically connected by a plate-shaped conductive member instead of a bonding wire 43, and the third electrode of the semiconductor element 40 and the third conductor plate 23 may be electrically connected by a plate-shaped conductive member instead of a bonding wire 44.

[0024] The semiconductor element 40 housed in the housing section 12 of the case 11 is sealed together with the bonding material 41, the first metal foil 52 of the laminated substrate 50, bonding wires 42, 43, 44, etc., by the sealing material 60 filled in the housing section 12. The sealing material 60 filled in the housing section 12 is not limited to a specific insulating material.

[0025] In this embodiment, as described above, the position of the lower surface of the second metal foil 53 of the laminated substrate 50 in the Z direction substantially coincides with the position of the lower surface of the semiconductor module 1. Therefore, the lower surface of the second metal foil 53 of the laminated substrate 50 is exposed on the lower surface of the semiconductor module 1 and is joined to the cooler 2 by a bonding material (not shown). The second metal foil 53 may be placed on the upper surface of the cooler 2 via a thermal conductive material such as thermal grease or thermal compound. The second metal foil 53, which functions as a heat dissipation surface, may also be called a heat sink.

[0026] The configuration within the housing section 12 of case 11 shown in Figures 1 and 2 is merely a schematic representation of an example configuration in a semiconductor module 1 to which the present invention can be applied. The configuration within the housing section 12 of case 11 is not limited to a specific configuration. The shape, number, and location of the semiconductor elements placed within the housing section 12 of case 11 can be changed according to the application of the semiconductor module 1, the required electrical characteristics, etc.

[0027] For example, there may be two or more semiconductor elements arranged in the housing section 12 of case 11. The two or more semiconductor elements may be a combination of one or more switching elements such as IGBTs and power MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) and one or more diode elements such as FWDs. Alternatively, an RB (Reverse Blocking)-IGBT with sufficient voltage resistance against reverse bias may be used as the semiconductor element. Furthermore, the multiple semiconductor elements arranged in the housing section 12 may include elements other than switching elements and diode elements.

[0028] Furthermore, the configuration of the laminated substrate 50 is not limited to a specific configuration. For example, multiple metal foils patterned according to the shape, number, and placement of semiconductor elements may be arranged on the upper surface of the insulating plate 51 in the laminated substrate 50. Also, the case 11 may have a bottom surface with an opening formed therein that corresponds to the planar shape of the second metal foil 53 of the laminated substrate 50.

[0029] As described above, in the semiconductor module 1 of this embodiment, the first conductor plate 21 and the second conductor plate 22 overlap in the Z direction (width direction). In this type of semiconductor module 1, as illustrated in Figures 1 to 4, an insulating sheet 30 is placed between the first conductor plate 21 and the second conductor plate 22. The insulating sheet 30 is a sheet-like or film-like insulating member that ensures insulation between the first conductor plate 21 and the second conductor plate 22, which have different potentials during operation. By placing the insulating sheet 30 between the first conductor plate 21 and the second conductor plate 22, it is possible to reduce the inductance by narrowing the distance between the first conductor plate 21 and the second conductor plate 22. For example, aramid paper, polyimide film, etc., can be used for the insulating sheet 30. The insulating material used to form the insulating sheet 30 and the dimension d1 in the Z direction in the semiconductor module 1 can be appropriately changed according to the required insulation performance. In the following description, the Z-direction dimension d1 of the insulating sheet 30 in the semiconductor module 1 will be referred to as width d1. The width of the insulating sheet 30 may also be called thickness.

[0030] In the semiconductor module 1 of this embodiment, as shown in Figure 4, the distance in the Z direction between the first conductor plate 21 and the second conductor plate 22 is wider than the distance corresponding to the width d1 of the insulating sheet 30. In other words, the Z-direction dimension (width d1) of the insulating sheet 30 in the semiconductor module 1 is narrower than the width corresponding to the distance between the first conductor plate 21 and the second conductor plate 22. Therefore, in the semiconductor module 1 of this embodiment, an insulating layer with a width d1 made of the insulating sheet 30 and an air layer 32 with a width d2 are provided overlapping in the Z direction between the first conductor plate 21 and the second conductor plate 22. The width d2 is the Z-direction dimension of the air layer 32 in the semiconductor module 1. Note that the combination of the width d1 of the insulating layer (insulating sheet 30) and the width d2 of the air layer 32 shown in Figure 4 is not limited to a specific combination. The relationship between the width d1 of the insulating layer and the width d2 of the air layer 32 will be described later with reference to Figure 6.

[0031] In the semiconductor module 1 illustrated in Figures 1 to 4, the insulating sheet 30 is in contact with the first conductor plate 21 and separated from the second conductor plate 22. To maintain the insulating sheet 30 in this state, the semiconductor module 1 of this embodiment uses a spacer 31. In this specification, "spacer" means a member used to separate two objects by a predetermined distance to create an air layer 32 between them. That is, the spacer 31 illustrated in Figures 1 to 4 is a member used to create an air layer 32 with a width d2 between the second conductor plate 22 and the insulating sheet 30. The spacer 31 is embedded in the insulating material that constitutes the side surface of the case 11. Therefore, from the viewpoint of adhesion between the spacer 31 and the insulating material of the case 11, it is preferable to form the spacer 31 with the same insulating material as the insulating material used for the case 11. For example, if the insulating material used for the case 11 is PPS resin, it is preferable that the spacer 31 be made of PPS resin. Note that the combination of the insulating material of the spacer 31 and the insulating material of the case 11 is not limited to a specific combination. For example, the spacer 31 may be made of the same insulating material as the insulating sheet 30. Alternatively, the spacer 31 may be a separate component from the insulating sheet 30, or it may be a convex portion that protrudes from the surface of the insulating sheet 30 as part of the insulating sheet 30. If the spacer 31 is separate from the insulating sheet 30, it may be attached to the insulating sheet 30 using, for example, an adhesive or glue.

[0032] In the semiconductor module 1 illustrated in Figures 1 to 4, the first conductor plate 21 has dimensions larger than the second conductor plate 22 in plan view, and has portions that overlap with and do not overlap with the second conductor plate 22 in plan view. Similarly, the insulating sheet 30 has dimensions larger than the second conductor plate 22 in plan view, and the portion that passes through the insulating material constituting the side surface of the case 11 in plan view has portions that overlap with and do not overlap with the first conductor plate 21. The spacer 31 is positioned in the region within the insulating material constituting the side surface of the case 11 in plan view where the first conductor plate 21 and the insulating sheet 30 overlap, and the second conductor plate 22 does not overlap. Figures 1 and 3 show an example in which two spacers 31 are positioned on either side of the second conductor plate 22 in the Y direction, and each spacer 31 is in contact with the insulating sheet 30 on a single lower surface, but the number and shape of the spacers 31 are not limited to this.

[0033] The case 11 according to this embodiment, in which the first conductor plate 21, the second conductor plate 22, and the third conductor plate 23 are integrated, is formed by known forming methods such as insert molding. When forming the case 11 by insert molding, the insulating sheet 30 is brought into contact with the upper surface of the first conductor plate 21 by a spacer 31, and an air layer 32 is provided between the insulating sheet 30 and the second conductor plate 22 (as shown in Figure 3). Then, the mold used to form the case 11 is closed and the insulating material is injected into the cavity of the mold to form the case 11. At this time, the spacer 31 is set to a height such that when the mold is closed, its lower surface contacts the insulating sheet 30 and its upper surface contacts the mold, so that the insulating sheet 30 remains in contact with the upper surface of the first conductor plate 21. Then, when insulating material is injected into the cavity of the mold and hardened, an insulating layer (a layer of insulating sheet 30) and an air layer 32 are formed between the first conductor plate 21 and the second conductor plate 22 that protrude outward from the case 11, as illustrated in Figures 2 and 4, overlapping in the Z direction (width direction).

[0034] Furthermore, when insulating material is injected into the mold cavity with a gap between the insulating sheet 30 and the second conductor plate 22 corresponding to the width d2 of the air layer 32, a portion of the insulating material that will form the side surface of the case 11 flows between the insulating sheet 30 and the second conductor plate 22 and hardens, as illustrated in Figures 1 and 3. This creates an opening 15 that penetrates the side surface of the case 11 through which the first conductor plate 21 and the second conductor plate 22 pass, as illustrated in Figures 1 and 3. When the housing portion 12 is resin-sealed with the sealing material 60, a portion of the sealing material 60 filled into the housing portion 12 of the case 11 advances into the opening 15 that penetrates the side surface of the case 11, for example, as illustrated in Figure 4. In Figure 4, the position in the X direction of the leading edge surface 60a of the sealing material 60 that has advanced into the opening 15 approximately coincides with the center position in the X direction of the spacer 31, but this is merely an example. The position in the X direction of the leading edge 60a of the sealing material 60 that has advanced into the opening 15 can vary depending on, for example, the width d2 of the air layer 32, the physical properties of the insulating material used as the sealing material 60, the physical properties of the materials forming the side surface of the opening 15 (insulating material used as the insulating sheet 30, conductive material used as the second conductive plate 22, insulating material used as the case 11, etc.), and the sealing process conditions with the sealing material 60. In addition, in Figure 4, the leading edge 60a of the sealing material 60 that has advanced into the opening 15 is shown as a concave surface with its central part in the Z direction set back from its end in the Z direction (located on the negative X direction side (housing part 12 side)), but the leading edge 60a can also be a surface parallel to the YZ plane, or a convex surface with its central part in the Z direction protruding from its end in the Z direction (located on the positive X direction side).

[0035] Figure 5 is a cross-sectional view showing a conventional example of a semiconductor module in which an insulating sheet is placed between two conductive plates. Figure 5 shows an example of a cross-section of a conventional semiconductor module having a configuration similar to the semiconductor module 1 of this embodiment described above with reference to Figures 1 to 4. In Figure 5, the hatching indicating that it is a cross-section of the semiconductor module components has been omitted.

[0036] In a conventional semiconductor module where a first conductor plate 21 and a second conductor plate 22, having different potentials during operation, overlap in the Z direction (width direction), as shown in Figure 5, an insulating sheet 30 placed between the first conductor plate 21 and the second conductor plate 22 is in contact with both of these conductor plates 21 and 22. Here, similar to the semiconductor module 1 described above with reference to Figures 1 to 4, if the first conductor plate 21 is electrically connected to the second electrode of the semiconductor element 40 and the second conductor plate 22 is electrically connected to the first electrode of the semiconductor element 40, then during the operation of the semiconductor module 1, the potential of the second conductor plate 22 becomes higher than the potential of the first conductor plate 21. Therefore, if the semiconductor module is operated with the insulating sheet 30 containing moisture, ion migration occurs. Specifically, during the operation of the semiconductor module, metal ions dissolved from the second conductive plate 22 move to the first conductive plate 21 through the insulating sheet 30, and metal 70 precipitates and grows in a dendritic pattern in the direction from the second conductive plate 22 toward the first conductive plate 21. The dendritic metal 70 is called a dendrite.

[0037] In particular, when power conversion devices such as inverter devices containing the aforementioned semiconductor modules are used in high-temperature, high-humidity environments, ion migration is likely to occur, and the deposited metal (dendrites) 70 grow rapidly. Therefore, if the distance between the first conductor plate 21 and the second conductor plate 22 is narrowed in order to reduce inductance (in other words, if the width d1 of the insulating sheet 30 is narrowed), there is a risk that the metal 70 deposited by ion migration may cause a short circuit between the first conductor plate 21 and the second conductor plate 22 at an early stage.

[0038] In contrast, the semiconductor module 1 of this embodiment, as illustrated in Figures 2 and 4, has an air layer 32 between the second conductor plate 22, which has a higher potential than the first conductor plate 21 during operation, and the insulating sheet 30. Therefore, it is possible to prevent metal ions, which can be a cause of ion migration, from eluting from the second conductor plate 22 into the insulating sheet 30. In other words, the semiconductor module 1 of this embodiment can suppress the occurrence of ion migration caused by moisture present in the insulating sheet 30.

[0039] Figure 6 is a graph showing an example of the voltage distribution of each layer when an insulating layer and an air layer are provided between two conductive plates. In the graph of Figure 6, the horizontal axis represents the width of the air layer 32 (in mm), and the vertical axis represents the voltage distribution (in %).

[0040] When an insulating layer and an air layer 32 are provided between the first conductor plate 21 and the second conductor plate 22, the voltage between the first conductor plate 21 and the second conductor plate 22 is shared according to the width and dielectric constant of the insulating layer and the air layer 32. When the width d1 of the insulating layer (insulating sheet 30) is kept constant and the width d2 of the air layer 32 is changed, as shown in the graph in Figure 6, the voltage shared by the air layer 32 becomes larger than the voltage shared by the insulating layer as the air layer 32 widens. However, if the voltage shared by the air layer 32 increases, partial discharge may occur depending on the rated voltage of electronic equipment such as a power converter including the semiconductor module 1. Also, when the width d2 of the air layer 32 widens, the distance between the first conductor plate 21 and the second conductor plate 22 increases, and for example, the inductance increases. Conversely, if the width d2 of the air layer 32 is thin, for example, changes in temperature and humidity may cause deformation such as bending of the insulating sheet 30, causing a portion of the insulating sheet 30 to come into contact with the second conductor plate 22, which could lead to dielectric breakdown. For this reason, it is preferable to adjust the width d2 of the air layer 32 by obtaining the relationship between the width d2 of the air layer 32 and the voltage distribution of the air layer 32 and the insulating layer in the semiconductor module 1 to which it is applied, so as to prevent contact between the insulating sheet 30 and the second conductor plate 22 and so as not to cause excessive voltage distribution of the air layer 32.

[0041] As described above, in the semiconductor module 1 of this embodiment, the distance between the two conductor plates 21 and 22 that protrude outward from the case 11 and overlap in the Z direction (width direction) is made wider than the distance corresponding to the width d1 of the insulating sheet 30 placed between them, and an insulating layer and an air layer 32 made of the insulating sheet 30 that overlaps in the Z direction are provided between the two conductor plates 21 and 22. For this reason, the semiconductor module 1 of this embodiment and the semiconductor device 100 including the semiconductor module 1 can prevent the occurrence of ion migration caused by moisture absorption of the insulating sheet 30 that protrudes outward from the case 11 and the potential difference between the two conductor plates 21 and 22.

[0042] Furthermore, by providing an air layer 32 to prevent ion migration, it is possible to suppress an increase in the distance between the two conductor plates 21 and 22, compared to, for example, the case where the width d1 of the insulating sheet 30 is widened to ensure insulation between the first conductor plate 21 and the second conductor plate 22. For this reason, the semiconductor module 1 of this embodiment and the semiconductor device 100 including the semiconductor module 1 have a configuration that is also advantageous for suppressing inductance.

[0043] Furthermore, by using the spacer 31 to bring the insulating sheet 30 into contact with the first conductor plate 21 and separating the insulating sheet 30 from the second conductor plate 22, it is possible to prevent a situation where, for example, when forming a case 11 integrated with the first conductor plate 21 and the second conductor plate 22 by insert molding or the like, one part of the insulating sheet 30 comes into contact with the second conductor plate 22 and the other part comes into contact with the first conductor plate 21.

[0044] The semiconductor module 1 according to this embodiment is not limited to one in which the semiconductor element 40 is arranged in a housing portion 12 of a case 11 as illustrated in Figures 1 and 2, but may not have a case 11. For example, the semiconductor module 1 may be formed by sealing a first conductor plate 21, a second conductor plate 22, a third conductor plate 23, and a semiconductor element 40 by transfer molding. That is, the first conductor plate 21 and the second conductor plate 22 that overlap in the Z direction in the semiconductor module 1 of this embodiment only need to protrude outward from the encapsulant in which the semiconductor element is sealed. In this specification and the claims, the term "encapsulant" refers to the volume portion of the semiconductor module 1 that corresponds to the outer shape of the portion made of the encapsulant 60 and insulating material used in the case 11 that seals the semiconductor element 40 and the conductor plates, etc.

[0045] Furthermore, in this specification, as described above, a semiconductor device 100 is defined as a semiconductor module 1 to which a heat dissipation member such as a heat sink, a cooler 2 for cooling the semiconductor module 1 or the heat dissipation member, etc., are attached. However, the semiconductor module 1 itself may be incorporated into electronic equipment such as a power converter as a semiconductor device. Also, the terms "semiconductor module" and "semiconductor device" are merely convenient expressions to distinguish what each refers to and are interchangeable. For example, the semiconductor module 1 in this specification may be replaced with semiconductor device 1, and the semiconductor device 100 in this specification may be replaced with semiconductor module 100 or other terms.

[0046] [Second Embodiment] Figure 7 is a partial plan view illustrating an example of the configuration of a semiconductor module according to the second embodiment. Figure 8 is a cross-sectional view of the semiconductor module of Figure 7 taken along the line C-C'. Figure 7 schematically shows the portion of the case 11 of the semiconductor module 1 of this embodiment through which the first conductor plate 21 and the second conductor plate 22 pass, and the portions of the first conductor plate 21 and the second conductor plate 22 that protrude outward from the case 11. Figure 8 schematically shows only the portion of the cross-section of the semiconductor module 1 from the bottom surface to the top surface that includes the first conductor plate 21 and the second conductor plate 22, as well as the portion near them.

[0047] The schematic configuration of the semiconductor module 1 of this embodiment may be the same as that of the semiconductor module 1 of the first embodiment. In the semiconductor module 1 of this embodiment, as illustrated in Figures 7 and 8, an insulating layer (a layer of insulating sheet 30) and an air layer 32 are provided between the first conductor plate 21 and the second conductor plate 22, which overlap in the Z direction (width direction). In the semiconductor module 1 of this embodiment, a spacer 33 is provided in the insulating material constituting the side surface of the case 11, at a position within the region where the insulating sheet 30 and the second conductor plate 22 overlap. The spacer 33, like the spacer 31 described in the first embodiment, may be a separate component from the insulating sheet 30, formed from the same insulating material as the insulating material used for the case 11 or a different insulating material. The spacer 33, which is separate from the insulating sheet 30, may be attached to the insulating sheet 30 by, for example, an adhesive or glue. The spacer 33 may also be a convex portion provided on the surface of the insulating sheet 30 as a part of the insulating sheet 30.

[0048] In this embodiment, when the spacer 33 is in contact with the second conductor plate 22 and the insulating sheet 30, ion migration may occur due to moisture remaining in the spacer 33 or moisture entering the spacer 33 from the outside. For this reason, the spacer 33 in the semiconductor module 1 of this embodiment may be made of an insulating material with few ionic impurities (for example, a resin material used for encapsulating semiconductor elements). However, the insulating material used for the spacer 33 is not limited to a specific insulating material.

[0049] In the semiconductor module 1 of this embodiment, the portion of the insulating sheet 30 that protrudes outward from the first side surface 13 of the case 11 is in contact with the first conductor plate 21 and separated from the second conductor plate 22. Therefore, as described in the first embodiment, it is possible to prevent the occurrence of ion migration caused by moisture absorption by the portion of the insulating sheet 30 protruding from the case 11 and the potential difference between the two conductor plates 21 and 22.

[0050] By the way, in the semiconductor module 1 of this embodiment, as shown in Figures 7 and 8, if the position in the X direction of the leading edge surface 60a of the sealing material 60 that has advanced from inside the housing portion 12 of the case 11 into the opening 15 between the second conductor plate 22 and the insulating sheet 30 substantially coincides with the center position in the X direction of the spacer 33, then the side surface of the portion of the spacer 33 that protrudes from the sealing material 60 faces the air layer 32, and the end on the positive Z side contacts the second conductor plate 22.

[0051] The insulating material used for the spacer 33 may have a different dielectric constant than the air or encapsulant 60, which are insulators in contact with the spacer 33. Therefore, the annular line (circumference in the example of Figure 7) that contacts the positive Z-direction end of the interface S between the two insulators on the lower surface of the second conductor plate 22 is called a triple junction in the field of electricity. On the side where the spacer 33 and the encapsulant 60 are in contact, the dielectric constants of the spacer 33 and the encapsulant 60 are close, and the insulating properties of the encapsulant 60 are high, so there is no problem. However, if a triple junction P is created on the lower surface of the second conductor plate 22 by a cylindrical spacer 33 as illustrated in Figures 7 and 8, in a semiconductor module 1 where the second conductor plate 22 is a high-voltage electrode, a strong electric field is formed around the triple junction P at the boundary between the side surface of the spacer 33 and the air (air layer 32), which may reduce the insulating properties of the semiconductor module 1.

[0052] Figure 9 illustrates a specific example of the configuration of a spacer in a semiconductor module according to the second embodiment. As shown in Figure 9, the dielectric constant ε1 of the air in contact with the spacer 33 (air layer 32) is lower than the dielectric constant ε2 of the spacer 33 (ε2 > ε1).

[0053] At the triple point P described above, if the angle θ between the interface S of the two insulators (the one with the lower dielectric constant) and the lower surface of the second conductor plate 22 is θ < 90 degrees, the electric field strength at the triple point P theoretically becomes infinite, resulting in a strong electric field. However, if θ > 90 degrees, it becomes 0 (zero). Since the dielectric constant ε1 of air is smaller than the dielectric constant ε2 of the insulating material used for the spacer 33 (ε2 > ε1), as illustrated in Figure 9, by making the angle θ between the interface S of the air (air layer 32) and the spacer 33 and the lower surface of the second conductor plate 22 obtuse (θ > 90 degrees), it is possible to prevent the formation of a strong electric field around the triple point P. The spacer 33 illustrated in Figure 9 has a tapered shape and is positioned between the second conductor plate 22 and the insulating sheet 30 such that it tapers more as it moves toward the negative Z direction (i.e., as it moves further away from the second conductor plate 22). When the top and bottom surfaces of the spacer 33 are circular, the outer shape of the spacer 33 illustrated in Figure 9 is a shape called a frustocone or a trapezoidal solid of revolution. The frustocone spacer 33 is positioned between the second conductor plate 22 and the insulating sheet 30 with the larger bottom surface in contact with the second conductor plate 22. The angle θ in Figure 9 can be any angle θ > 90 degrees and is not limited to a specific angle.

[0054] Furthermore, in the semiconductor module 1 according to this embodiment, for example, as shown in Figure 8, the positive Z-direction end of the tip surface 60a of the sealing material 60 that extends from the housing portion 12 of the case 11 to the opening 15 contacts the second conductor plate 22, and a triple point R is formed by the lower surface of the second conductor plate 22, the tip surface 60a of the sealing material 60, and air (air layer 32). In the semiconductor module 1 according to this embodiment, for example, by selecting the combination of materials and sealing process conditions by the sealing material 60 such that the tip surface 60a of the sealing material 60 becomes a concave surface with the central part in the Z-direction receding to the negative X-direction, it is possible to prevent the formation of a strong step around the triple point R.

[0055] Furthermore, the outer shape of the spacer 33 is not limited to the frustocone described above, as long as it is a shape that can suppress the formation of a strong electric field around the triple point P. For example, the part of the side surface of the spacer 33 that contacts the sealing material 60 that has advanced from the housing portion 12 of the case 11 between the second conductor plate 22 and the insulating sheet 30 does not have to have an obtuse angle with the lower surface of the second conductor plate 22.

[0056] As described above, in the semiconductor module 1 of this embodiment, a spacer 33 is placed between an insulating sheet 30 positioned between two conductor plates 21 and 22 that overlap in the Z direction (width direction) and one of the two conductor plates 21 and 22 (for example, the second conductor plate 22), bringing the insulating sheet 30 into contact with the other conductor plate (for example, the first conductor plate 21). This makes it possible to provide an insulating layer and an air layer 32 that overlap in the Z direction between the portions of the two conductor plates 21 and 22 that protrude from the case 11, similar to the semiconductor module 1 described in the first embodiment. For this reason, the semiconductor module 1 of this embodiment can prevent the occurrence of ion migration caused by moisture absorption by the insulating sheet 30 protruding outward from the case 11 and the potential difference between the two conductor plates 21 and 22.

[0057] Furthermore, by providing an air layer 32 to prevent ion migration, it is possible to suppress the increase in the distance between the portions of the two conductor plates 21 and 22 that protrude from the case 11, thus making this a configuration that is also advantageous for reducing inductance.

[0058] Furthermore, by applying the arrangement of the spacers 33 of this embodiment, an air layer 32 can be easily provided even when it is difficult to secure an area for placing spacers 31 that do not come into contact with the conductor plate to be separated from the insulating sheet 30. For example, in the semiconductor module 1 illustrated in Figure 7, the Y-direction dimension L2 of the portion of the first conductor plate 21 that does not overlap with the second conductor plate 22 is smaller than the Y-direction dimension L1 of the spacer 33. In such a semiconductor module 1, as explained in the first embodiment, it is difficult to bring the insulating sheet 30 into contact with the first conductor plate 21 by the spacers 31 in the portion of the first conductor plate 21 that does not overlap with the second conductor plate 22. For this reason, the method of arranging the spacers 33 of this embodiment can be applied to a wider variety of semiconductor modules 1 compared to the method of arranging the spacers 31 described in the first embodiment. In addition, in the semiconductor module 1 of this embodiment, the number of spacers 33, the number of areas in contact with the insulating sheet 30 on the lower surface of one spacer 33, etc., can be changed as appropriate.

[0059] It should be noted that the semiconductor module 1 according to this embodiment is not limited to having semiconductor elements arranged within the housing portion 12 of the case 11, as described above with reference to Figures 1 and 2, but may also be a semiconductor module without a case 11.

[0060] Furthermore, the semiconductor module 1 of this embodiment may itself be incorporated into electronic equipment such as a power converter as a semiconductor device. The terms "semiconductor module" and "semiconductor device" are merely convenient expressions for identifying what each refers to and are interchangeable. For example, the semiconductor module 1 in this specification may be replaced with semiconductor device 1, and the semiconductor device 100 in this specification may be replaced with semiconductor module 100 or other terms.

[0061] The semiconductor device 100, including the semiconductor module 1 of the above-described embodiment, is not limited to a specific application, but is particularly suitable for use in high-temperature, high-humidity environments. For example, the semiconductor module 1 of the above-described embodiment can be applied to power conversion devices such as inverter devices for automotive motors. A vehicle to which the semiconductor device 100 according to the present invention is applied will be described with reference to Figure 10.

[0062] Figure 10 is a schematic plan view showing an example of a vehicle to which the semiconductor device according to the present invention is applied. The vehicle 101 shown in Figure 10 is composed of, for example, four wheels 102. The vehicle 101 may be, for example, an electric vehicle that drives the wheels with a motor or the like, or a hybrid vehicle that uses the power of an internal combustion engine in addition to a motor.

[0063] The vehicle 101 includes a drive unit 103 that provides power to the wheels 102, and a control device 104 that controls the drive unit 103. The drive unit 103 may consist of, for example, at least one of an engine, a motor, or a hybrid of an engine and a motor.

[0064] The control device 104 performs control (for example, power control) of the drive unit 103. The control device 104 includes a semiconductor device 100 which includes the semiconductor module 1 of the embodiment described above. The semiconductor device 100 may be configured to perform power control to the drive unit 103. The semiconductor device 100 may be configured such that a heat dissipation member such as a heat sink for dissipating heat generated in the semiconductor module 1, a cooler 2 for cooling the semiconductor module 1 or the heat dissipation member, etc., are attached to the semiconductor module 1. The semiconductor device 100 may include a plurality of semiconductor modules 1. Alternatively, the semiconductor device 100 may refer to the semiconductor module 1 itself.

[0065] The semiconductor device 100 (semiconductor module 1) of the control device 104 installed on the vehicle 101 operates while the vehicle 101 is in motion, and may operate in environments with high temperatures (e.g., around 100°C) and high humidity (e.g., 90% humidity). Therefore, by applying the semiconductor device 100 including the semiconductor module 1 according to the above embodiment, it is possible to reduce, for example, the frequency of inspection of the control device 104 and the frequency of replacement of the semiconductor module 1.

[0066] The embodiments of the semiconductor module 1 according to the present invention are not limited to those described above, and may be modified, substituted, or transformed in various ways without departing from the spirit of the technical idea. Furthermore, if the technical idea can be realized in a different way by advances in the technology or by other derived technologies, it may be implemented by that method. Accordingly, the claims cover all embodiments that may fall within the scope of the technical idea.

[0067] The following summarizes the key features of the embodiments described above.

[0068] The semiconductor module according to the above embodiment comprises two conductor plates protruding from a encapsulation body in which a semiconductor element is sealed, and facing each other at a distance of a first distance in a first direction, and an insulating material disposed between the two conductor plates, the dimension in the first direction being narrower than the width corresponding to the first distance, wherein an insulating layer of the insulating material and an air layer are provided between the two conductor plates outside the encapsulation body along the first direction.

[0069] In the semiconductor module according to the above embodiment, the insulating material is in contact with one of the two conductive plates.

[0070] In the semiconductor module according to the above-described embodiment, the insulating material is in contact with the conductor plate of the two conductor plates that has a lower potential during operation.

[0071] The semiconductor module according to the above embodiment includes a spacer that separates the insulating material from at least one of the two conductive plates, the spacer having at least a portion located within the encapsulant.

[0072] In the semiconductor module according to the above-described embodiment, one of the two conductor plates has a portion located within the encapsulation body that overlaps with the insulating material and does not overlap with the other conductor plate, and the spacer separates the insulating material from the other conductor plate and brings it into contact with the one conductor plate in the portion of the one conductor plate that overlaps with the insulating material within the encapsulation body and does not overlap with the other conductor plate.

[0073] In the semiconductor module according to the above-described embodiment, the spacer is placed between one of the two conductor plates and the insulating material, and the insulating material is brought into contact with the other of the two conductor plates.

[0074] In the semiconductor module according to the above-described embodiment, the spacer has a shape that tapers in the direction from one of the conductor plates toward the insulating material.

[0075] In the semiconductor module according to the above embodiment, the angle between the surface of the spacer exposed from the encapsulant and the contact surface of the one conductor plate with the spacer is obtuse.

[0076] In the semiconductor module according to the above-described embodiment, the encapsulant includes a case having a housing portion for housing the semiconductor element and being integrated with a plurality of conductor plates including the first conductor plate and the second conductor plate, and an encapsulating insulator that encapsulates the semiconductor element housed in the housing portion of the case, and wiring members that electrically connect the semiconductor element and the plurality of conductor plates.

[0077] The semiconductor device according to the above-described embodiment comprises the semiconductor module described above, and a cooler disposed on a surface different from the surface on which the first conductor plate and the second conductor plate protrude in the encapsulant of the semiconductor module.

[0078] The vehicle according to the above-described embodiment includes the above-described semiconductor module or semiconductor device. [Industrial applicability]

[0079] As described above, the present invention has the effect of suppressing the decrease in insulation between two conductor plates that overlap with an insulating sheet in between outside the sealant due to ion migration, and is also advantageous in reducing inductance, and is particularly useful for semiconductor modules, semiconductor devices, and vehicles for industrial or electrical applications. [Explanation of Symbols]

[0080] 1. Semiconductor module 11 cases 12 Storage Unit 13, 14 Side view 15 Opening 21, 22, 23 Conductor plates 30 Insulating Sheets 31, 33 Spacers 32 Air layer 40 Semiconductor elements 41 Bonding material 42, 43, 44 Bonding wires 50 Multilayer substrates 51 Insulating board 52, 53 Metal foil 60 Sealing material 60a Tip surface 70 Metals (Dendrites) 100 Semiconductor Equipment 101 vehicles 102 wheels 103 Drive unit 104 Control device

Claims

1. Two conductive plates protrude from a encapsulated body containing a semiconductor element, and are positioned opposite each other at a first distance apart in a first direction, An insulating material is disposed between the two conductor plates, and the dimension in the first direction is narrower than the width corresponding to the first distance, An insulating layer made of the insulating material and an air layer are provided between the two conductive plates outside the sealing body, along the first direction. Semiconductor module.

2. The semiconductor module according to claim 1, wherein the insulating material is in contact with one of the two conductive plates.

3. The semiconductor module according to claim 1, wherein the insulating material is in contact with the conductor plate of the two conductor plates that has a lower potential during operation.

4. The semiconductor module according to claim 1, comprising a spacer that separates the insulating material from at least one of the two conductive plates, wherein at least a portion of the spacer is located within the encapsulant.

5. One of the two conductor plates has a portion located within the sealing body that overlaps with the insulating material and does not overlap with the other conductor plate. The spacer overlaps with the insulating material in the sealing body of one of the conductor plates, but does not overlap with the other conductor plate, thereby separating the insulating material from the other conductor plate and bringing it into contact with the one conductor plate. The semiconductor module according to claim 4.

6. The semiconductor module according to claim 4, wherein the spacer is disposed between one of the two conductor plates and the insulating material, and the insulating material is brought into contact with the other of the two conductor plates.

7. The semiconductor module according to claim 6, wherein the spacer has a shape that tapers in the direction toward the insulating material from the one conductor plate.

8. The semiconductor module according to claim 6, wherein the angle between the surface of the spacer exposed from the sealing body and the contact surface of the one conductor plate with the spacer is an obtuse angle.

9. The aforementioned encapsulant is A case having a housing section for housing the semiconductor element, and integrated with a plurality of conductor plates including the two conductor plates, The case includes a sealing insulator that seals the semiconductor element housed in the housing portion of the case, and the wiring member that electrically connects the semiconductor element and the plurality of conductor plates, The semiconductor module according to claim 1.

10. A semiconductor module according to any one of claims 1 to 9, A cooler is provided which is arranged on a surface different from the surface on which the two conductive plates protrude in the encapsulant of the semiconductor module, A semiconductor device equipped with a semiconductor device.

11. A vehicle comprising the semiconductor device described in claim 10.

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