Semiconductor unit

Abstract

The invention provides a technology which can ensure insulation between a screw used for installing a cooler and a horizontal terminal of a semiconductor module and reduce the size of a semiconductor unit. A semiconductor unit includes: a semiconductor module (1) having a semiconductor device and a horizontal terminal (7) electrically connected to the semiconductor device and protruding from a side surface in a horizontal direction; a substrate (3), the upper surface of which is bonded to the semiconductor module (1), and which has a plurality of screw holes (3a) penetrating from the upper surface to the lower surface; a cooler (2) which is mounted on the lower surface of the substrate (3) and cools the semiconductor module (1); and a plurality of screws (4) that mount the cooler (2) to the lower surface of the substrate (3) by being respectively screwed into the plurality of screw holes (3a) of the substrate (3). At least one screw hole (3a) among the plurality of screw holes (3a) is provided with a countersink part (3b) having a depth smaller than the thickness of the substrate (3) in a portion on the upper surface side of the substrate (3).

Description

Technical Field

[0001] This disclosure relates to semiconductor units. Background Technology

[0002] Typically, semiconductor modules such as IGBT (Insulated Gate Bipolar Transistor) modules, intelligent power modules (IPMs) or transfer-molded power modules (T-PMs) are connected to a cooler via a substrate to dissipate heat caused by power loss, and thus form a semiconductor unit (see, for example, Patent Document 1).

[0003] When using screws to mount the substrate and cooler, it is necessary to consider heat dissipation, the torque when the screw is tightened, the insulation distance between the screw that serves as the reference potential and the terminal with a high voltage potential, and the miniaturization of the semiconductor unit. Existing technical documents Patent documents

[0004] Patent Document 1: International Publication No. 2019 / 181198 Summary of the Invention The technical problem that the invention aims to solve

[0005] However, in the prior art, ensuring the insulation between the screws used to mount the cooler and the horizontal terminals of the semiconductor module is contradictory to miniaturizing the semiconductor unit, and therefore, it is difficult to achieve both.

[0006] Therefore, the purpose of this disclosure is to provide a technique that can simultaneously ensure insulation between the screws used to mount the cooler and the horizontal terminals of the semiconductor module, and the miniaturization of the semiconductor unit. Technical means for solving technical problems

[0007] The semiconductor unit disclosed herein includes: a semiconductor module having a semiconductor device and a horizontal terminal electrically connected to the semiconductor device and projecting horizontally from the side; a substrate having the semiconductor module bonded to its upper surface and having a plurality of screw holes extending from the upper surface to the lower surface; a cooler mounted on the lower surface of the substrate for cooling the semiconductor module; and a plurality of screws for mounting the cooler to the lower surface of the substrate by screwing the screws into the plurality of screw holes of the substrate, wherein at least one of the screw holes is provided on the upper surface side of the substrate with a countersunk portion having a depth smaller than the thickness of the substrate. Invention Effects

[0008] According to this disclosure, it is possible to simultaneously ensure insulation between the screws used to mount the cooler and the horizontal terminals of the semiconductor module, and to achieve miniaturization of the semiconductor unit. Attached Figure Description

[0009] Figure 1 This is a perspective view showing the structure of the semiconductor cell involved in Embodiment 1. Figure 2 This is a top view of the semiconductor cell involved in Embodiment 1. Figure 3 This is a cross-sectional view of the screw fastening area between the substrate and the cooler in Embodiment 1 and its surrounding area. Figure 4 This is a cross-sectional view of the screw fastening area between the substrate and the cooler and its surrounding area when the screw holes are not countersunk. Figure 5 This is a top view of the semiconductor cell involved in Embodiment 2. Figure 6 This is a top view of the semiconductor cell involved in Embodiment 3. Figure 7 This is a top view of the semiconductor cell involved in Embodiment 4. Figure 8 This is a cross-sectional view of the screw fastening area between the substrate and the cooler in Embodiment 5 and its surrounding area. Figure 9 This is a top view of the semiconductor cell involved in Embodiment 6. Figure 10 This is a top view of the semiconductor cell involved in Embodiment 7. Figure 11 This is a cross-sectional view of the screw fastening area between the substrate and the cooler and its surrounding area in Embodiment 8. Figure 12 This is a top view of the semiconductor cell involved in Embodiment 10. Figure 13 This is a top view of the semiconductor cell involved in Embodiment 11. Figure 14 This is a top view of a semiconductor cell when the number of screw holes on the P, N electrode sides and the AC electrode side are the same. Figure 15 This is a top view of the semiconductor cell involved in Embodiment 12. Figure 16 This is a top view of the semiconductor cell involved in Embodiment 13. Detailed Implementation

[0010] <Implementation Method 1> The following description uses the accompanying drawings to illustrate Embodiment 1. Figure 1 This is a perspective view showing the structure of the semiconductor cell involved in Embodiment 1. Figure 2 This is a top view of the semiconductor cell involved in Embodiment 1. Furthermore, Figure 2 This shows the state after screw 4 has been removed.

[0011] like Figure 1 and Figure 2 As shown, the semiconductor unit includes six semiconductor modules 1, a substrate 3, a cooler 2, and nine screws 4. The semiconductor modules 1 are IGBT (Insulated Gate Bipolar Transistor) modules, Intelligent Power Modules (IPMs), or Transfer-molded Power Modules (T-PMs). Each semiconductor module 1 includes a semiconductor device (not shown) built into it, multiple horizontal terminals 7 protruding horizontally from the side of the semiconductor module 1, and multiple control terminals 8 protruding from the side of the semiconductor module 1 and bent upwards from the front end. The horizontal terminals 7 are connected to busbars 10, etc.

[0012] like Figure 2 As shown, when viewed from above, the front ends of the multiple horizontal terminals 7 are located on the inner periphery side relative to the outer periphery of the substrate 3. Furthermore, the number of semiconductor modules 1 is not limited to six; one or more is sufficient.

[0013] Semiconductor devices include IGBTs and MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors). The material constituting a semiconductor device is, for example, silicon (Si). However, the material constituting a semiconductor device is not limited to silicon; it can also be a wide-bandgap semiconductor material such as silicon carbide (SiC), gallium nitride (GaN), or diamond (C). Furthermore, one or more semiconductor devices are acceptable.

[0014] Horizontal terminal 7 is electrically connected to the semiconductor device inside semiconductor module 1. Control terminal 8 is electrically connected to the semiconductor device inside semiconductor module 1 and transmits control signals input from the outside to the semiconductor device.

[0015] The substrate 3 is rectangular. On the upper surface of the substrate 3, six semiconductor modules 1 are arranged side by side along the long side. At least one pair of semiconductor modules 1 are arranged in a position that is linearly symmetrical with respect to the long side of the substrate 3, with horizontal terminals 7 provided in the center. Figure 2In this configuration, three pairs of two semiconductor modules 1 are arranged, but the configuration is not limited to this. Each semiconductor module 1 is bonded to the upper surface of the substrate 3 by solder (not shown). On the outer periphery of the substrate 3, a plurality of (e.g., nine) screw holes 3a extending from the upper surface to the lower surface are provided. However, the number of screw holes 3a is not limited to nine.

[0016] Cooler 2 is mounted on the lower surface of substrate 3 to cool semiconductor module 1. In cooler 2, at positions opposite to the nine screw holes 3a on substrate 3, there are nine screw holes 2a, each communicating with one of the nine screw holes 3a (see reference). Figure 3 The cooler 2 is mounted to the lower surface of the substrate 3 by screwing nine screws 4 into the nine screw holes 3a of the substrate 3 and the nine screw holes 2a of the cooler 2, respectively. The screws 4 are made of conductive metal. Hereinafter, the screws 4 will also be referred to as conductive screws 4. The cooler 2 is water-cooled, and its interior is filled with a cooling medium (not shown) for cooling the semiconductor module 1.

[0017] Next, the construction of the screw hole 3a, a feature of Embodiment 1, will be described. Figure 3 This is a cross-sectional view of the screw fastening area between the substrate 3 and the cooler 2 in Embodiment 1 and its surrounding area.

[0018] like Figure 2 and Figure 3 As shown, nine screw holes 3a are provided along the outer periphery of the substrate 3. Specifically, the nine screw holes 3a are only provided at the four corners of the substrate 3 and on the long side of the outer periphery of the substrate 3. In addition, the nine screw holes 3a are not provided in the region where the spacing between adjacent horizontal terminals 7 in adjacent semiconductor modules 1 is small, but are provided on the outer periphery of the region where the spacing between adjacent horizontal terminals 7 is large.

[0019] At least one of the nine screw holes 3a has a countersunk hole 3b on its upper surface side, the depth of which is less than the thickness of the substrate 3. In Embodiment 1, all screw holes 3a have countersunk holes 3b. To accommodate the head 4a of the screw 4, the countersunk hole 3b is formed with a diameter larger than the diameter of the head 4a and a depth greater than the height of the head 4a. Furthermore, the countersunk hole 3b is formed with a diameter larger than the screw hole 3a of the substrate 3. The depth d1 of the countersunk hole 3b is 1 mm or less, and the depth d2 of the screw hole 3a of the substrate 3 is 2 mm or more.

[0020] Next, regarding the effects of implementation method 1, and in... Figure 4 The following comparison is made with the case where the screw hole 3a shown does not have a countersunk portion 3b. Figure 4 This is a cross-sectional view of the screw fastening area and its surroundings between the substrate 3 and the cooler 2 when the screw hole 3a is not provided with the countersunk portion 3b.

[0021] Figure 4 In this design, the head 4a of the screw 4 is positioned higher than the upper surface of the substrate 3. When miniaturizing the semiconductor unit, the distance r2 between the screw 4 and the horizontal terminal 7 becomes shorter, making it difficult to ensure insulation between the screw 4 and the horizontal terminal 7. Therefore, it is difficult to simultaneously ensure insulation between the screw 4 used to mount the cooler 2 and the horizontal terminal 7 of the semiconductor module 1, and to achieve miniaturization of the semiconductor unit.

[0022] In contrast, in Embodiment 1, the semiconductor unit includes: a semiconductor module 1 having a semiconductor device and a horizontal terminal 7 electrically connected to the semiconductor device and protruding horizontally from the side; a substrate 3 having the semiconductor module 1 bonded to its upper surface and having a plurality of screw holes 3a extending from the upper surface to the lower surface; a cooler 2 mounted on the lower surface of the substrate 3 for cooling the semiconductor module 1; and a plurality of screws 4, which are screwed into the plurality of screw holes 3a of the substrate 3 to mount the cooler 2 to the lower surface of the substrate 3. At least one of the screw holes 3a, on the upper surface side of the substrate 3, is provided a countersunk portion 3b with a depth smaller than the thickness of the substrate 3.

[0023] Therefore, as Figure 3 As shown, the head 4a of the screw 4 is housed in the countersunk hole 3b, therefore, the distance r1 between the screw 4 and the horizontal terminal 7 is... Figure 4 The distance r2 becomes longer compared to the previous case. Therefore, insulation between screw 4 and horizontal terminal 7 can be ensured. As a result, it is possible to ensure insulation between screw 4 used to mount cooler 2 and horizontal terminal 7 of semiconductor module 1, as well as miniaturization of semiconductor unit.

[0024] Furthermore, when viewed from above, the front end of the horizontal terminal 7 is located on the inner periphery side compared to the outer periphery of the substrate 3. Therefore, when multiple semiconductor units are arranged side by side, the semiconductor units can be arranged close to each other.

[0025] Furthermore, when the semiconductor module 1 is a power transfer molded module, the improvement in insulation between the screw 4 used to mount the cooler 2 and the horizontal terminal 7 of the semiconductor module 1 will be further enhanced.

[0026] <Implementation Method 2> Next, implementation method 2 will be described. Figure 5 This is a top view of the semiconductor cell involved in Embodiment 2. Furthermore, Figure 5 The diagram shows the state after screw 4 has been removed. Furthermore, in Embodiment 2, structural elements identical to those described in Embodiment 1 are labeled with the same reference numerals and their descriptions are omitted.

[0027] like Figure 5 As shown, in Embodiment 2, when viewed from above, the countersunk hole portion 3b is located closer to the outer periphery of the substrate 3 than the front end of the horizontal terminal 7, and is configured not to overlap with the horizontal terminal 7. In other words, the countersunk hole portion 3b is disposed between the outer end line of the substrate 3 and the front end line of the horizontal terminal 7. Furthermore, the outer end line of the substrate 3 is a line along the outer end of the substrate 3, and the front end line of the horizontal terminal 7 is a line connecting the front ends of the plurality of horizontal terminals 7.

[0028] In embodiment 2, when viewed from above, the countersunk portion 3b does not overlap with the horizontal terminal 7, thus making it easy to tighten the screw 4 when mounting the cooler 2 onto the substrate 3.

[0029] <Implementation Method 3> Next, implementation method 3 will be described. Figure 6 This is a top view of the semiconductor cell involved in Embodiment 3. Furthermore, Figure 6 The diagram shows the state after screw 4 has been removed. Furthermore, in Embodiment 3, structural elements identical to those described in Embodiments 1 and 2 are labeled with the same reference numerals and their descriptions are omitted.

[0030] like Figure 6 As shown, in embodiment 3, at least one of the nine screw holes 3a does not have a countersunk portion 3b. Figure 6 In the case of the screw holes 3a provided along the long side of the substrate 3, the two screw holes 3a located in the center are not provided with countersunk holes 3b.

[0031] In embodiment 3, by providing a screw hole 3a without a countersunk portion 3b, the tightening torque of the screw 4 can be enhanced compared to a screw hole 3a with a countersunk portion 3b, thus improving the installation strength of the cooler 2.

[0032] <Implementation Method 4> Next, implementation method 4 will be described. Figure 7 This is a top view of the semiconductor cell involved in Embodiment 4. Furthermore, Figure 7 The diagram shows the state after screw 4 has been removed. Furthermore, in Embodiment 4, structural elements identical to those described in Embodiments 1-3 are labeled with the same reference numerals and their descriptions are omitted.

[0033] like Figure 7 As shown, in embodiment 4, at least one of the screw holes 3a provided in the four corner screw holes 3a of the substrate 3 does not have a countersunk hole 3b. Figure 7 In this embodiment, two of the screw holes 3a provided at the four corners of the substrate 3 are not provided with countersunk portions 3b. However, this is not a limitation. One or more of the screw holes 3a provided at the four corners of the substrate 3 may also be provided without countersunk portions 3b.

[0034] In Embodiment 4, similarly to Embodiment 3, the installation strength of the cooler 2 can be improved.

[0035] <Implementation Method 5> Next, implementation method 5 will be described. Figure 8 This is a cross-sectional view of the screw fastening area between the substrate 3 and the cooler 2 in Embodiment 5, and its surrounding area. Furthermore, in Embodiment 5, structural elements identical to those described in Embodiments 1-4 are labeled with the same reference numerals and their descriptions are omitted.

[0036] like Figure 8 As shown, in Embodiment 5, the countersunk hole 3b has a tapered shape that tapers at its front end in the direction from the upper surface of the substrate 3 toward the lower surface. The screw holes 3a of the substrate 3 and 2a of the cooler 2 also have tapered shapes that taper at their front ends in the direction from top to bottom. The depth d1 of the countersunk hole 3b is 1 mm or less, and the depth d2 of the screw holes 3a of the substrate 3 is 2 mm or more. Furthermore, Figure 8 In the diagram, the dashed line represents the area that is removed during the typical countersinking process.

[0037] In addition, each of the head 4a and shaft 4b of the screw 4 has a tapered shape that tapers at the front end in a direction from top to bottom.

[0038] In embodiment 5, compared with conventional countersinking, the amount of cutting the substrate 3 can be reduced, thus improving the strength of the substrate 3. Furthermore, when screwing the screw 4 into the screw hole 3a, the engagement of the countersink portion 3b and the head 4a of the screw 4 is made easier while suppressing deviation between the two.

[0039] <Implementation Method 6> Next, implementation method 6 will be described. Figure 9 This is a top view of the semiconductor cell according to Embodiment 6. Furthermore, in Embodiment 6, structural elements identical to those described in Embodiments 1-5 are labeled with the same reference numerals and their descriptions are omitted.

[0040] In embodiments 1 to 5, by providing a countersunk hole 3b to the screw hole 3a, the insulation between the screw 4 used to mount the cooler 2 and the horizontal terminal 7 of the semiconductor module 1 is ensured, while miniaturization of the semiconductor unit is achieved.

[0041] In contrast, such as Figure 9 As shown, in embodiment 6, instead of providing a countersunk portion 3b for the screw hole 3a, a non-conductive screw 14 is used as the screw screw screwed into the screw hole 3a. Specifically, at least one of the plurality of screws is a non-conductive screw 14. The non-conductive screw 14 is formed, for example, from an insulating resin.

[0042] Figure 9 In the case, the screws screwed into the screw holes 3a at the four corners of the substrate 3 are conductive screws 4, and the other screws are non-conductive screws 14.

[0043] In embodiment 6, insulation can be ensured regardless of the distance between the non-conductive screw 14 used to mount the cooler 2 and the horizontal terminal 7 of the semiconductor module 1. Therefore, without providing the countersunk portion 3b, it is possible to ensure both insulation between the non-conductive screw 14 used to mount the cooler 2 and the horizontal terminal 7 of the semiconductor module 1, and miniaturization of the semiconductor unit.

[0044] <Implementation Method 7> Next, implementation method 7 will be described. Figure 10 This is a top view of the semiconductor cell according to Embodiment 7. Furthermore, in Embodiment 7, structural elements identical to those described in Embodiments 1-6 are labeled with the same reference numerals and their descriptions are omitted.

[0045] like Figure 10 As shown, in Embodiment 7, compared to the structure of Embodiment 6, a conductive screw 4 is screwed into at least one of the screw holes 3a provided at the four corners of the substrate 3. Figure 10 In the middle, the conductive screw 4 is screwed into two screw holes 3a in the screw holes 3a located at the four corners of the substrate 3.

[0046] In embodiment 7, by making a portion of the screws at the four corners of the base plate 3, which has a large clamping torque load, conductive screws 4 can be used to improve the installation strength of the cooler 2.

[0047] <Implementation Method 8> Next, implementation method 8 will be described. Figure 11 This is a cross-sectional view of the screw fastening portion between the substrate 3 and the cooler 2 in Embodiment 8, and its surrounding area. Furthermore, in Embodiment 8, structural elements identical to those described in Embodiments 1-7 are labeled with the same reference numerals and their descriptions are omitted.

[0048] In embodiments 6 and 7, instead of providing a countersunk portion 3b for the screw hole 3a, a non-conductive screw 14 is used as the screw that is screwed into the screw hole 3a.

[0049] In contrast, such as Figure 11 As shown, in embodiment 8, the head 4a of at least one of the plurality of screws 4 is covered with insulating resin 15 in place of the non-conductive screw 14.

[0050] In embodiment 8, similar to embodiment 6, insulation can be ensured regardless of the distance between the screw 4 used to mount the cooler 2 and the horizontal terminal 7 of the semiconductor module 1. Therefore, without providing the countersunk portion 3b, both ensuring insulation between the screw 4 used to mount the cooler 2 and the horizontal terminal 7 of the semiconductor module 1 and miniaturization of the semiconductor unit can be achieved.

[0051] <Implementation Method 9> Next, Embodiment 9 will be described. Furthermore, in Embodiment 9, structural elements identical to those described in Embodiments 1 through 8 are labeled with the same reference numerals and their descriptions are omitted.

[0052] Although not illustrated, in embodiment 9, at least one screw hole 3a provided at the four corners of the substrate 3 is screwed into which a screw 4 with its head 4a covered by insulating resin 15 is screwed.

[0053] In embodiment 9, by setting a portion of the screws at the four corners of the substrate 3 as screws 4 covered by insulating resin 15, the processes and costs involved in covering with insulating resin 15 can be reduced.

[0054] <Implementation Method 10> Next, implementation method 10 will be described. Figure 12 This is a top view of the semiconductor cell according to Embodiment 10. Furthermore, Figure 12 The diagram shows the state after screw 4 has been removed. Furthermore, in Embodiment 10, structural elements identical to those described in Embodiments 1-9 are labeled with the same reference numerals and their descriptions are omitted.

[0055] In embodiments 1 to 9, the nine screw holes 3a are provided only at the four corners of the substrate 3 and on the long side of the outer periphery of the substrate 3.

[0056] In contrast, such as Figure 12 As shown, in embodiment 10, the seven screw holes 3a are only provided on the long side of the outer periphery of the substrate 3. Furthermore, Figure 12 The diagram shows the case where the screw hole 3a of embodiments 1 to 5 is provided with a countersunk portion 3b, but the structure of embodiments 6 to 9 can also be adopted using embodiment 10.

[0057] In embodiment 10, the screw hole 3a is not provided on the short side of the outer periphery of the substrate 3. Therefore, compared with the case where the screw hole 3a is provided on the short side of the outer periphery of the substrate 3, the size of the substrate 3 in the short side direction can be miniaturized, thereby enabling further miniaturization of the semiconductor unit.

[0058] <Implementation Method 11> Next, implementation method 11 will be described. Figure 13This is a top view of the semiconductor cell involved in Embodiment 11. Figure 14 This is a top view of a semiconductor cell when the number of screw holes 3a on the P, N electrode sides and the AC electrode side is the same. Furthermore, Figure 13 and Figure 14 The diagram shows the state after screw 4 has been removed. Furthermore, in Embodiment 11, structural elements identical to those described in Embodiments 1-10 are labeled with the same reference numerals and their descriptions are omitted.

[0059] like Figure 13 As shown, in embodiment 11, the horizontal terminal 7 includes: a first horizontal terminal 17 connected to a P electrode or an N electrode on one long side of the substrate 3; and a second horizontal terminal 27 connected to an AC electrode on the other long side of the substrate 3. Viewed from above, the first horizontal terminal 17 and the second horizontal terminal 27 protrude from the sides of the diagonally opposite semiconductor module 1. Furthermore, Figure 13 In the diagram, the P and N electrode sides are those connected to the P or N electrode, and the AC electrode side is those connected to the AC electrode. Furthermore, the number of screw holes 3a differs on one long side and the other long side of the outer periphery of the substrate 3. That is, the number of screw holes 3a differs on the P and N electrode sides and the AC electrode side of the substrate 3. On the P and N electrode sides... Figure 13 The middle is the upper side, and the AC electrode side is... Figure 13 The middle is the bottom side. Also, Figure 13 The diagram shows the case where the screw hole 3a of embodiments 1 to 5 is provided with a countersunk portion 3b, but the structure of embodiments 6 to 9 can also be adopted using embodiment 11.

[0060] In implementation method 11, with Figure 14 Compared to the case where the number of screw holes 3a is the same on the P, N, and AC electrode sides, the arrangement of screw holes 3a can be made more flexible.

[0061] <Implementation Method 12> Next, implementation method 12 will be described. Figure 15 This is a top view of the semiconductor cell according to Embodiment 12. Furthermore, Figure 15 The diagram shows the state after screw 4 has been removed. Furthermore, in Embodiment 12, structural elements identical to those described in Embodiments 1-11 are labeled with the same reference numerals and their descriptions are omitted.

[0062] like Figure 15 As shown, in embodiment 12, when viewed from above, a portion of the nine screw holes 3a are located on the inner periphery of the substrate 3 relative to the front end of the horizontal terminal 7. Figure 13In this configuration, a portion of the two screw holes 3a are located closer to the inner periphery of the substrate 3 relative to the front end of the horizontal terminal 7, but the number of screw holes 3a located closer to the inner periphery of the substrate 3 relative to the front end of the horizontal terminal 7 is not limited to two. Furthermore, Figure 15 The diagram shows the case where the screw hole 3a of embodiments 1 to 5 is provided with a countersunk portion 3b, but the structure of embodiments 6 to 9 can also be adopted using embodiment 12.

[0063] In embodiment 12, a plurality of screw holes 3a are provided such that a portion of them are located on the inner periphery of the substrate 3 relative to the front end of the horizontal terminal 7, thereby enabling miniaturization of the semiconductor unit.

[0064] <Implementation Method 13> Next, implementation method 13 will be described. Figure 16 This is a top view of the semiconductor cell according to Embodiment 13. Furthermore, Figure 16 The diagram shows the state after screw 4 has been removed. Furthermore, in Embodiment 13, structural elements identical to those described in Embodiments 1-12 are labeled with the same reference numerals and their descriptions are omitted.

[0065] In embodiments 1 to 12, nine screw holes 3a are provided on the outer periphery of the region where the spacing between adjacent horizontal terminals 7 in adjacent semiconductor modules 1 is relatively large.

[0066] In contrast, such as Figure 16 As shown, in embodiment 13, when viewed from above, the horizontal terminal 7 and the plurality of screw holes 3a have overlapping areas. Figure 16 In the top view, six of the eight screw holes 3a overlap with the horizontal terminal 7, and the remaining two screw holes 3a overlap with the control terminal 8. However, the number of screw holes 3a overlapping with the horizontal terminal 7 in the top view is not limited to this. Furthermore, Figure 16 The diagram shows the case where the screw hole 3a of embodiments 1 to 5 is provided with a countersunk portion 3b, but the structure of embodiments 6 to 9 can also be adopted using embodiment 13.

[0067] In embodiment 13, by providing multiple screw holes 3a so that they overlap with the horizontal terminal 7 when viewed from above, the semiconductor unit can be miniaturized.

[0068] It is possible to freely combine various implementation methods, or appropriately modify or omit various implementation methods.

[0069] The various methods disclosed herein are summarized and recorded below as appendices.

[0070] (Note 1) A semiconductor unit includes: A semiconductor module having a semiconductor device and a horizontal terminal electrically connected to the semiconductor device and protruding horizontally from the side. A substrate, the semiconductor module being bonded to its upper surface, having a plurality of screw holes extending from the upper surface to the lower surface; A cooler, mounted on the lower surface of the substrate, for cooling the semiconductor module; and A plurality of screws are used to mount the cooler to the lower surface of the substrate by screwing them into the respective screw holes of the substrate. A countersunk hole portion with a depth smaller than the thickness of the substrate is provided on the upper surface side of at least one of the screw holes.

[0071] (Note 2) The semiconductor unit as described in Note 1 When viewed from above, the front end of the horizontal terminal is located on the inner periphery side relative to the outer periphery of the substrate.

[0072] (Note 3) Semiconductor units as described in Note 1 or 2 When viewed from above, the countersunk portion is located on the outer periphery of the substrate relative to the front end of the horizontal terminal, and does not overlap with the horizontal terminal.

[0073] (Note 4) The semiconductor unit as described in any one of Notes 1 to 3 At least one of the screw holes in the plurality of screw holes is not provided with the countersunk portion.

[0074] (Note 5) The semiconductor unit as described in any one of Notes 1 to 4 The plurality of screw holes include screw holes located at the four corners of the substrate. At least one of the screw holes at the four corners is not provided with a countersunk portion.

[0075] (Note 6) The semiconductor unit as described in any one of Notes 1 to 5 The countersunk portion has a tapered shape that tapers at its front end in the direction from the upper surface of the substrate toward the lower surface.

[0076] (Appendix 7) A semiconductor unit, A semiconductor module having a semiconductor device and a horizontal terminal electrically connected to the semiconductor device and protruding horizontally from the side. A substrate, the semiconductor module being bonded to its upper surface, having a plurality of screw holes extending from the upper surface to the lower surface; A cooler, mounted on the lower surface of the substrate, for cooling the semiconductor module; and A plurality of screws are used to mount the cooler to the lower surface of the substrate by screwing them into the respective screw holes of the substrate. At least one of the plurality of screws is a non-conductive screw.

[0077] (Note 8) The semiconductor unit as described in Note 7 The plurality of screw holes include screw holes located at the four corners of the substrate. A conductive screw is screwed into at least one of the screw holes located at the four corners.

[0078] (Appendix 9) A semiconductor unit, A semiconductor module having a semiconductor device and a horizontal terminal electrically connected to the semiconductor device and protruding horizontally from the side. A substrate, the semiconductor module being bonded to its upper surface, having a plurality of screw holes extending from the upper surface to the lower surface; A cooler, mounted on the lower surface of the substrate, for cooling the semiconductor module; and A plurality of screws are used to mount the cooler to the lower surface of the substrate by screwing them into the respective screw holes of the substrate. The head of at least one of the plurality of screws is covered with insulating resin.

[0079] (Note 10) The semiconductor unit as described in Note 9 The plurality of screw holes include screw holes located at the four corners of the substrate. The screw, whose head is covered by the insulating resin, is screwed into at least one of the screw holes located at the four corners.

[0080] (Note 11) The semiconductor unit as described in any one of Notes 1 to 10, The substrate is formed in a rectangular shape. The plurality of screw holes are provided only on the long side of the outer periphery of the substrate.

[0081] (Note 12) The semiconductor unit as described in Note 11 The number of screw holes is different on one long side and the other long side of the outer periphery of the substrate.

[0082] (Note 13) The semiconductor unit as described in Note 12 Equipped with multiple of the aforementioned semiconductor modules, Multiple semiconductor modules are arranged side-by-side along the long side of the substrate. The horizontal terminals include a first horizontal terminal connected to a P electrode or an N electrode on one of the long sides of the substrate, and a second horizontal terminal connected to an AC electrode on the other long side of the substrate.

[0083] (Note 14) The semiconductor unit as described in Note 13 In a pair of semiconductor modules in which the horizontal terminals are provided at positions that are linearly symmetrical with respect to the long side direction of the substrate, at least one pair is arranged side by side along the long side direction of the substrate. The plurality of screw holes are disposed on the outer periphery of a region where the horizontal terminals of adjacent semiconductor modules are spaced far apart.

[0084] (Note 15) The semiconductor unit as described in Note 13 When viewed from above, the first horizontal terminal and the second horizontal terminal protrude from the sides of the semiconductor module, which are diagonally opposite each other.

[0085] (Note 16) The semiconductor unit as described in Note 13 When viewed from above, the semiconductor module also has a control terminal that protrudes from the diagonally opposite side of the semiconductor module, with the front end bent upwards, and transmits control signals.

[0086] (Note 17) The semiconductor unit as described in any one of Notes 1 to 16, When viewed from above, a portion of the plurality of screw holes is located on the inner periphery of the substrate relative to the front end of the horizontal terminal.

[0087] (Note 18) The semiconductor unit as described in any one of Notes 1 to 16 When viewed from above, the horizontal terminal has an overlapping area with the plurality of screw holes.

[0088] (Note 19) The semiconductor unit as described in any one of Notes 1 to 18 The semiconductor module is a transfer-molded semiconductor module. Label Explanation

[0089] 1 Semiconductor Module 2 Cooler 3 substrate 3a Screw hole 3b Counterbored section 4 screws 4a Head 7 Horizontal Terminals 8 control terminals 15 Insulating Resin 17 First horizontal terminal 27. Second horizontal terminal.

Claims

1. A semiconductor unit, characterized by comprising: including: a semiconductor module having a semiconductor device, and a horizontal terminal electrically connected to the semiconductor device and protruding in a horizontal direction from a side surface; a substrate having the semiconductor module joined to an upper surface thereof, and having a plurality of screw holes passing through from the upper surface to a lower surface; a cooler installed to the lower surface of the substrate, and cooling the semiconductor module; and a plurality of screws installing the cooler to the lower surface of the substrate by being screwed into the plurality of screw holes of the substrate respectively, a portion of the upper surface of the substrate at at least one of the plurality of screw holes is provided with a counterbore portion having a depth smaller than a thickness of the substrate.

2. The semiconductor unit according to claim 1, wherein a front end of the horizontal terminal is located more inwardly with respect to an outer peripheral end of the substrate in plan view.

3. The semiconductor unit according to claim 1 or 2, wherein the counterbore portion is located more outwardly with respect to a front end of the horizontal terminal and does not overlap the horizontal terminal in plan view.

4. The semiconductor unit according to any one of claims 1 to 3, wherein the counterbore portion is not provided at at least one of the plurality of screw holes.

5. The semiconductor unit according to any one of claims 1 to 4, wherein the plurality of screw holes include screw holes provided at four corners of the substrate, the counterbore portion is not provided at at least one of the screw holes provided at the four corners.

6. The semiconductor unit according to any one of claims 1 to 5, wherein the counterbore portion has a tapered shape in which a front end is tapered in a direction from the upper surface of the substrate toward the lower surface. including:

7. A semiconductor unit, characterized by comprising: a semiconductor module having a semiconductor device, and a horizontal terminal electrically connected to the semiconductor device and protruding in a horizontal direction from a side surface; a substrate having the semiconductor module joined to an upper surface thereof, and having a plurality of screw holes passing through from the upper surface to a lower surface; a cooler installed to the lower surface of the substrate, and cooling the semiconductor module; and a plurality of screws installing the cooler to the lower surface of the substrate by being screwed into the plurality of screw holes of the substrate respectively, at least one of the plurality of screws is a non-conductive screw.

8. The semiconductor unit according to claim 7, wherein the plurality of screw holes include screw holes provided at four corners of the substrate, a conductive screw is screwed into at least one of the screw holes provided at the four corners. including: a semiconductor module having a semiconductor device, and a horizontal terminal electrically connected to the semiconductor device and protruding in a horizontal direction from a side surface; 9. A semiconductor unit, characterized by a substrate having the semiconductor module joined to an upper surface thereof, and having a plurality of screw holes passing through from the upper surface to a lower surface; ​ ​ a cooler installed to the lower surface of the substrate to cool the semiconductor module; and a plurality of screws to install the cooler to the lower surface of the substrate by being screwed into a plurality of screw holes of the substrate, a head of at least one of the plurality of screws is covered with an insulating resin.

10. The semiconductor unit according to claim 9, wherein the plurality of screw holes include screw holes provided at four corners of the substrate, the screw whose head is covered with the insulating resin is screwed into at least one of the screw holes provided at the four corners.

11. The semiconductor unit according to any one of claims 1 to 10, wherein the substrate is formed in a rectangular shape, the plurality of screw holes are provided only on the long side of the outer periphery of the substrate.

12. The semiconductor unit according to claim 11, wherein the number of the screw holes differs between one long side and the other long side of the outer periphery of the substrate.

13. The semiconductor unit according to claim 12, wherein a plurality of the semiconductor modules are provided, the plurality of semiconductor modules are arranged side by side in the long direction of the substrate, the horizontal terminal includes a first horizontal terminal connected to a P electrode or an N electrode on one long side of the substrate and a second horizontal terminal connected to an AC electrode on the other long side of the substrate.

14. The semiconductor unit according to claim 13, wherein two of the semiconductor modules provided with the horizontal terminal at positions symmetrical with respect to the long direction of the substrate are arranged side by side in the long direction of the substrate, the plurality of screw holes are provided on the outer periphery of a region where the horizontal terminals of the adjacent semiconductor modules are spaced apart.

15. The semiconductor unit according to claim 13, wherein the first horizontal terminal and the second horizontal terminal protrude from the side surface of the semiconductor module that becomes a diagonal when viewed from above.

16. The semiconductor unit according to claim 13, wherein the semiconductor module further has a control terminal protruding from the side surface of the semiconductor module that becomes a diagonal when viewed from above, and the control terminal is curved toward the upper side at the front end and transmits a control signal.

17. The semiconductor unit according to any one of claims 1 to 16, wherein a part of the plurality of screw holes is located closer to the inner periphery of the substrate with respect to the front end of the horizontal terminal when viewed from above.

18. The semiconductor unit according to any one of claims 1 to 16, wherein the horizontal terminal and the plurality of screw holes have an overlapping region when viewed from above.

19. The semiconductor unit according to any one of claims 1 to 18, wherein the semiconductor module is a transfer molded semiconductor module.

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