Capacitor module and method for manufacturing capacitor module

Abstract

A capacitor module according to the present disclosure comprises a capacitor element having an end surface on which an electrode is provided, and a bus bar which has a plate-shaped main body portion arranged so as to cover the electrode, and a joint portion extending from the main body portion and joined to the electrode, wherein the joint portion is at least partially embedded in the electrode, and the joint portion is provided with a thin-walled portion that is thinner than the main body portion.

Description

Capacitor Module and Method for Manufacturing Capacitor Module

[0001] The present disclosure relates to a capacitor module and a method for manufacturing a capacitor module.

[0002] A capacitor module in which a plurality of capacitor elements are connected by bus bars is known.

[0003] For example, Patent Document 1 discloses a capacitor element assembly in which a connecting fitting in which a support portion and an electrode lead portion are integrated is connected to an element electrode portion of a capacitor element.

[0004] Japanese Patent Laid-Open No. 10-41190

[0005] In the capacitor element assembly described in Patent Document 1, there is still room for improvement in terms of improving the connection strength between the element electrode portion of the capacitor element and the electrode lead portion of the connecting fitting.

[0006] The present disclosure provides a capacitor module and a method for manufacturing a capacitor module capable of improving the bonding strength between an electrode of a capacitor element and a bus bar.

[0007] A capacitor module according to one aspect of the present disclosure includes: a capacitor element having an electrode provided on an end face; a plate-shaped main body portion disposed so as to cover the electrode; and a bus bar having a joint portion extending from the main body portion and joined to the electrode, wherein the joint portion is at least partially embedded in the electrode, and a thin portion thinner than the main body portion is provided in the joint portion.

[0008] A method for manufacturing a capacitor module according to one aspect of the present disclosure includes: preparing a bus bar having a capacitor element having an electrode provided on an end face, a plate-shaped main body portion, and a joint portion extending from the main body portion and at least a tip thereof embedded in the electrode; disposing the joint portion on the electrode of the capacitor element; and welding the electrode and the joint portion by spot welding, wherein the joint portion of the bus bar includes a thin portion thinner than the main body portion.

[0009] According to this disclosure, it is possible to provide a capacitor module and a method for manufacturing a capacitor module that can improve the bonding strength between the electrodes of a capacitor element and the busbar.

[0010] Figure 1 shows a schematic perspective view of a capacitor module according to Embodiment 1 of the present disclosure. Figure 2 shows an exploded perspective view of the capacitor module with the sealing resin omitted. Figure 1 shows a capacitor element built into the capacitor module. Figure 5A shows a first busbar included in the capacitor module of Figure 1. Figure 5A shows a first busbar viewed from a different angle. Figure 5A shows a plan view of the first busbar. Figure 5D shows a cross-sectional view of B-B of Figure 5D shows a second busbar included in the capacitor module of Figure 1. Figure 6A shows a second busbar included in the capacitor module of Figure 1. Figure 6B shows a plan view of the second busbar viewed from a different direction. Figure 6B shows a cross-sectional view of the second busbar. Figure 6B shows a cross-sectional view of A-A of Figure 1. Figure 7 shows a cross-sectional view of R3. Figure 1 shows a capacitor module. A flowchart for explaining the manufacturing method of the capacitor module of Figure 1. Schematic diagram illustrating part of the manufacturing process of a capacitor module. Schematic diagram illustrating part of the manufacturing process of a capacitor module. Schematic diagram illustrating part of the manufacturing process of a capacitor module. Schematic diagram illustrating part of the manufacturing process of a capacitor module. Schematic diagram showing a joint according to modified example 1 of Embodiment 1. Schematic diagram showing the joint in Figure 11A and the electrode in a joined state. Schematic diagram showing a joint according to modified example 2 of Embodiment 1. Schematic diagram showing the joint in Figure 12A and the electrode in a joined state. Schematic diagram showing a joint according to modified example 3 of Embodiment 1. Schematic diagram showing the joint in Figure 13A and the electrode in a joined state. Schematic diagram showing a joint according to modified example 4 of Embodiment 1. Schematic diagram showing the joint in Figure 14A and the electrode in a joined state. Schematic diagram showing a joint according to modified example 5 of Embodiment 1. Schematic diagram showing the joint in Figure 15A and the electrode in a joined state.

[0011] (Background to this disclosure) In a capacitor module equipped with multiple capacitor elements, the connection between the electrodes of the capacitor elements and the busbar is sometimes performed by spot welding. In spot welding, the resistance heat generated by applying pressure with the electrodes and passing an electric current is used to join the metals together. For this reason, it is preferable for the busbar to be thin in order to perform spot welding, but considering the vibration resistance of the capacitor module, the busbar is required to have a certain thickness.

[0012] When joining the electrodes of a capacitor element to a busbar by spot welding, applying pressure can bend the busbar toward the electrode, causing a portion of it to be embedded in the capacitor element's electrode. This improves the joint strength between the capacitor element's electrode and the busbar. Therefore, it is being considered to make the joint portion of the busbar with the capacitor element's electrode thinner.

[0013] For example, Patent Document 1 discloses a capacitor element assembly in which the connecting fitting has an electrode lead portion that is thinner than the support portion. However, in the capacitor element assembly of Patent Document 1, because the electrode lead portion has spring properties, the stress on the electrode lead portion increases due to temperature changes, resulting in a problem in that the bonding strength between the electrode lead portion and the element electrode portion is reduced.

[0014] The present inventors have investigated a capacitor module and a method for manufacturing a capacitor module that can improve the bonding strength between the electrodes of a capacitor element and the busbar, and have arrived at the following invention.

[0015] Embodiments of the present invention will be described below with reference to the attached drawings. Note that in each drawing, elements are exaggerated for the sake of clarity.

[0016] (Embodiment 1) [Overall Configuration] Figure 1 is a schematic perspective view of a capacitor module 1 according to Embodiment 1 of the present disclosure. Figure 2 is a perspective view of the capacitor module 1 of Figure 1 with the sealing resin 50 omitted. Figure 3 is an exploded perspective view of the capacitor module 1 of Figure 2. The X, Y, and Z directions in the figures represent the width, depth, and height directions of the capacitor module 1, respectively.

[0017] As shown in Figures 1 to 3, the capacitor module 1 comprises a capacitor element 10, busbars 20 and 30, a case 40, and a sealing resin 50. In this embodiment, as will be described later, the capacitor module 1 includes two busbars: a first busbar 20 connected to the first electrode 11 of the capacitor element 10 and a second busbar 30 connected to the second electrode 12 of the capacitor element 10.

[0018] In the capacitor module 1, the capacitor element 10 and parts of the first busbar 20 and the second busbar 30 are housed in a case 40 and sealed with sealing resin 50. Parts of the first busbar 20 and the second busbar 30 are exposed from the sealing resin 50 and function as external connection terminals 20a and 30a of the capacitor module 1. In this embodiment, insulating paper 60 is placed between the external connection terminal 20a of the first busbar 20 and the external connection terminal 30a of the second busbar 30 to prevent short circuits.

[0019] In this embodiment, as shown in Figure 3, the capacitor module 1 includes four capacitor elements 10.

[0020] <Case> Case 40 is a case for housing components such as the capacitor element 10. As shown in Figure 1, case 40 has, for example, a roughly rectangular parallelepiped shape. Case 40 is also provided with an opening 41 and a bottom 42 on the opposite side of the opening 41. Therefore, case 40 is formed in a box shape with an opening 41. Case 40 houses the capacitor element 10 and a portion of the first busbar 20 and the second busbar 30.

[0021] Case 40 is formed from, for example, a synthetic resin such as polyphenylene sulfide (PPS resin) or polybutylene terephthalate (PBT resin).

[0022] <Sealing Resin> As shown in Figure 1, the sealing resin 50 is filled into the case 40 to seal the capacitor element 10 housed in the case 40 and a portion of the first busbar 20 and the second busbar 30. The sealing resin 50 is made of a thermosetting resin such as epoxy resin or urethane resin. A material with high fluidity and adhesion may be used as the material for the sealing resin 50.

[0023] <Capacitor Element> Figure 4 is a perspective view showing a capacitor element 10 built into the capacitor module 1 of Figure 1. As shown in Figure 4, the capacitor element 10 has a first electrode 11, a second electrode 12, and a side surface 13 connecting the first electrode 11 and the second electrode 12. The first electrode 11 and the second electrode 12 are provided on both end faces of the capacitor element 10.

[0024] In this embodiment, as shown in Figure 3, the capacitor element 10 is arranged such that the first electrode 11 faces the opening 41 of the case 40 and the second electrode 12 faces the bottom 42 of the case 40.

[0025] In this embodiment, the capacitor element 10 is formed in a columnar shape with an oval end face. That is, the first electrode 11 and the second electrode 12 have an oval shape, and the capacitor element 10 is formed in a columnar shape.

[0026] The capacitor element 10 is a film capacitor composed of a laminate of dielectric films. More specifically, the capacitor element 10 is formed by stacking dielectric films, each having a metal vapor-deposited film on its surface, and then winding them. In this embodiment, the capacitor element 10 is formed into a columnar shape with an oval cross-section by pressing the wound dielectric film into a flattened shape.

[0027] As the dielectric film, for example, a dielectric film formed from a mixed resin solution containing phenoxy resin and MDI (diphenylmethane diisocyanate) can be used. Alternatively, a dielectric film formed from a mixed resin solution containing polyvinyl acetal (PVAA) and tolylene diisocyanate (TDI) may be used. By forming a dielectric film with such a mixed resin solution, the glass transition temperature of the dielectric film can be set to 120°C or higher, thereby improving the heat resistance of the capacitor module. As the metal vapor-deposited film formed on the surface of the dielectric film, for example, metals such as Al and Zn can be used.

[0028] A first electrode 11 is formed on one end face of the wound dielectric film, and a second electrode 12 is formed on the other end face. The first electrode 11 and the second electrode 12 can be formed, for example, by thermal spraying a conductive material containing a metal such as Al or Zn onto the end face of the wound dielectric film.

[0029] The capacitor element 10 is not limited to a film capacitor, but may be other types of capacitors such as ceramic capacitors or electrolytic capacitors.

[0030] As shown in Figure 2, in this embodiment, the first electrode 11 of each of the four capacitor elements 10 is positioned toward the opening 41 of the case 40. Therefore, the second electrode 12 of each of the four capacitor elements 10 is positioned toward the bottom 42 of the case 40.

[0031] <First Busbar> Figure 5A is a perspective view showing the first busbar 20 included in the capacitor module 1 of Figure 1. Figure 5B is a perspective view of the first busbar 20 of Figure 5A from a different angle. Figure 5C is a plan view of the first busbar 20 of Figure 5A. Figure 5D is an enlarged view of region R1 of Figure 5A. Figure 5E is a cross-sectional view taken along line B-B of Figure 5D.

[0032] The first busbar 20 is a component for electrically connecting the first electrodes 11 of the four capacitor elements 10 to the terminals of an external device (not shown).

[0033] The first busbar 20 is formed from a conductive material, such as a plate-shaped metal. As shown in Figures 5A to 5C, the first busbar 20 has a main body portion 21 and a joint portion 22. In this embodiment, an external connection terminal 20a extends from the main body portion 21 toward the outside of the case 40.

[0034] As shown in Figures 2 and 3, the main body portion 21 is positioned to cover the first electrode 11 of the capacitor element 10. The main body portion 21 is also positioned to face the opening 41 of the case 40. In this embodiment, as shown in Figure 5C, the main body portion 21 is positioned to cover the entire first electrode 11 of each of the four capacitor elements 10. The main body portion 21 is formed in a plate shape.

[0035] The main body portion 21 is provided with four through holes 23. As shown in Figure 5C, the four through holes 23 are positioned to overlap with each of the first electrodes 11 of the four capacitor elements 10 in a plan view.

[0036] A connecting portion 22 is provided in each of the through holes 23. The connecting portion 22 is used to electrically connect the first busbar 20 and the first electrode 11. The connecting portion 22 may also be referred to as a terminal portion, lead, etc.

[0037] In this embodiment, as will be described later, the first busbar 20 and the first electrode 11 are electrically connected by joining the joint portion 22 and the first electrode 11 by spot welding. In spot welding, the joint portion 22 and the first electrode 11 are joined by applying pressure to the joint portion 22 in the -Z direction and passing an electric current. As will be described later, the joint portion 22 is at least partially embedded in the first electrode 11. When joining the joint portion 22 and the first electrode 11 by spot welding, the resistance heat generated during spot welding melts a portion of the joint portion 22 and the first electrode 11. Therefore, the pressure applied in the -Z direction during spot welding presses the joint portion 22 against the first electrode 11, and the joint portion 22 is embedded in the molten first electrode 11.

[0038] The joint portion 22 is a part of the first busbar 20 that extends from the main body portion 21. More specifically, the joint portion 22 extends from the edge 21a of the main body portion 21 that defines the through hole 23 and is located inside the through hole 23.

[0039] The joint portion 22 is formed to be thinner than the main body portion 21. Specifically, as shown in Figure 5E, the thickness D1 of the thin-walled portion 24 of the joint portion 22 is thinner than the thickness D2 of the main body portion 21. In other words, the joint portion 22 has a thin-walled portion 24 that is thinner than the main body portion 21.

[0040] In this embodiment, the joint portion 22 further has a thick portion 25 that is thicker than the thin portion 24. The thickness D3 of the thick portion 25 gradually decreases from the main body portion 21 toward the thin portion 24.

[0041] The thin-walled portion 24 is located at the tip of the joint portion 22. The thick-walled portion 25 is located closer to the base of the main body portion 21 than the thin-walled portion 24. Because the thin-walled portion 24 is located at the tip of the joint portion 22, the joint portion 22 is more likely to bend under pressure during spot welding, thereby improving the joint strength between the joint portion 22 and the first electrode 11. Also, because the thick-walled portion 25 is located closer to the base of the joint portion 22, the strength of the joint portion 22 can be improved, and damage to the joint portion 22 can be suppressed.

[0042] As shown in Figure 5E, the joint portion 22 has a first surface 22b that contacts the first electrode 11 and a second surface 22a opposite to the first surface 22b. In this embodiment, the first surface 22b that contacts the first electrode 11 is formed flat. The flat formation of the first surface 22b facilitates joining the first electrode 11 and the joint portion 22.

[0043] As shown in Figures 5A to 5C, in this embodiment, two junctions 22 are joined to the first electrode 11 of one capacitor element 10. By arranging multiple junctions 22 for each first electrode 11, the bonding strength between the first electrode 11 and the junctions 22 can be improved.

[0044] As shown in FIGS. 5C and 5D, in the present embodiment, in a plan view, the tip 22c of the joint portion 22 is formed in a round shape. For example, the tip of the joint portion 22 can be rounded by chamfering the tip of the joint portion 22 by cutting or the like. Since the tip of the joint portion 22 is formed in a round shape, the stress applied to the joint portion 22 due to the expansion and contraction of the capacitor element 10 when the capacitor module 1 is used can be dispersed, so that the occurrence of cracks in the sealing resin 50 can be suppressed.

[0045] <Second bus bar> FIG. 6A is a perspective view showing the second bus bar 30 included in the capacitor module 1 of FIG. 1. FIG. 6B is a perspective view of the second bus bar 30 of FIG. 6A viewed from another direction. FIG. 6C is a plan view of the second bus bar 30 of FIG. 6B. FIG. 6D is an enlarged view of the region R2 of FIG. 6B.

[0046] The second bus bar 30 is a member for electrically connecting the second electrodes 12 of the four capacitor elements 10 and the terminals of an external device (not shown). Similar to the first bus bar 20, the second bus bar 30 has a main body portion 31 and a joint portion 32. Since the configurations of the main body portion 31 and the joint portion 32 of the second bus bar 30 are the same as those of the main body portion 21 and the joint portion 22 of the first bus bar 20, the description will be partially omitted.

[0047] As shown in FIG. 3, the main body portion 31 of the second bus bar 30 is arranged so as to cover the entire second electrodes 12 of the four capacitor elements 10 respectively. Therefore, the main body portion 21 is arranged so as to face the bottom portion 42 of the case 40. Since the main body portion 21 is arranged near the bottom portion 42 of the case 40, the external connection terminal 30a extending from the main body portion 21 is formed longer than the external connection terminal 20a of the first bus bar 20.

[0048] As shown in FIGS. 6A to 6C, four through holes 33 are provided in the main body portion 31. As shown in FIG. 6C, the four through holes 33 are provided at positions overlapping the second electrodes 12 of the four capacitor elements 10 in a plan view.

[0049] Each of the through holes 33 has two joints 32. The joints 32 are used to electrically connect the second busbar 30 and the second electrode 12. The joints 32 and the second electrode 12 are joined by spot welding. In spot welding, the joints 32 and the second electrode 12 are joined by applying pressure to the joints 32 in the +Z direction and passing an electric current through them. The joints 32 are at least partially embedded in the second electrode 12. When the joints 32 and the second electrode 12 are joined by spot welding, the resistance heat generated during spot welding melts parts of the joints 32 and the second electrode 12. Therefore, the pressure applied in the +Z direction during spot welding presses the joints 32 against the second electrode 12, and the joints 32 are embedded in the molten second electrode 12.

[0050] As shown in Figure 6D, the joint portion 32 is formed to be thinner than the main body portion 31. In other words, the joint portion 32 has a thin-walled portion 34 that is thinner than the main body portion 31. In this embodiment, the joint portion 32 further has a thick-walled portion 35 that is thicker than the thin-walled portion 34. The thin-walled portion 34 is located at the tip of the joint portion 32. The thick-walled portion 35 is located closer to the main body portion 31 than the thin-walled portion 34, and its thickness gradually decreases from the main body portion 31 toward the thin-walled portion 34.

[0051] As shown in Figure 6D, the joint 32 has a first surface 32a that contacts the second electrode 12 and a second surface 32b opposite to the first surface 32a. In this embodiment, the first surface 32a that contacts the second electrode 12 is formed flat.

[0052] As shown in Figures 6C and 6D, in this embodiment, the tip of the joint portion 32 is rounded in a plan view. For example, the tip of the joint portion 32 can be rounded by chamfering the tip of the joint portion 32 by cutting or other methods.

[0053] <Joint between the joint and the electrode> Figure 7 is a cross-sectional view taken along line A-A in Figure 1. Figure 8 is an enlarged view of region R3 in Figure 7. The joint between the joint and the electrode will be described in detail with reference to Figures 7 and 8.

[0054] In the capacitor module 1, the electrical connection between the first busbar 20 and the first electrode 11, and the electrical connection between the second busbar 30 and the second electrode 12 are made by spot welding. In spot welding, spot welding electrodes are pressed against the joints 22 and 32, and current is passed through the joints 22 and 32 while applying pressure to them. The resistance heat generated is used to weld the joints 22 to the electrodes 11 and 12 of the capacitor element 10.

[0055] During spot welding, the resistive heat generated causes the electrodes 11 and 12 of the capacitor element 10 and the joint portions 22 and 32 to partially melt. When the joint portions 22 and 32 are pressed against the molten electrodes 11 and 12, the joint portions 22 and 32 bend toward the electrodes 11 and 12 of the capacitor element 10, and at least a portion of the joint portions 22 and 32 are embedded in the electrodes 11 and 12.

[0056] Because the joint portions 22 and 32 have thin-walled portions 24 and 34, they are easily deformed by the pressure applied during spot welding, making them easier to embed in the electrodes 11 and 12 of the capacitor element 10. When the joint portions 22 and 32 are embedded in the electrodes 11 and 12, the bonding strength between the joint portions 22 and 32 and the electrodes 11 and 12 is improved, thereby improving the stability of the capacitor module 1.

[0057] Furthermore, as shown in Figure 8, due to the resistance heat generated during spot welding, a molten and solidified portion 27 is formed near the interface between the joint 22 and the first electrode 11, where the joint 22 and the first electrode 11 have melted together and become one. Although not shown, a molten and solidified portion is also formed near the interface between the joint 32 and the second electrode 12.

[0058] By forming a molten and solidified portion 27 near the interface between the joint portions 22 and 32 and the electrodes 11 and 12, the connection between the joint portions 22 and 32 and the electrodes 11 and 12 can be made stronger.

[0059] [Manufacturing Method for Capacitor Modules] The manufacturing method for capacitor module 1 will be explained with reference to Figure 9. Figure 9 is a flowchart illustrating the manufacturing method for capacitor module 1 shown in Figure 1.

[0060] In step S1, the capacitor elements 10 and busbars 20 and 30 are prepared. In this embodiment, four capacitor elements 10, a first busbar 20 connected to the first electrode 11, and a second busbar 30 connected to the second electrode 12 are prepared.

[0061] The first busbar 20 and the second busbar 30 can be formed, for example, by pressing a plate-shaped metal material. The thin-walled portions of the joints 22 and 32 can be formed, for example, by cutting after pressing.

[0062] Next, in step S2, the junctions 22 and 32 are placed on the electrodes 11 and 12 of the capacitor element 10.

[0063] Next, in step S3, the electrodes 11 and 12 of the capacitor element 10 and the joints 22 and 32 are welded together by spot welding.

[0064] In addition, after connecting the joint 22 of the first busbar 20 and the first electrode 11 in steps S2 and S3, steps S2 and S3 may be performed again to connect the joint 32 of the second busbar 30 and the second electrode 12. Alternatively, welding of the joint 22 and the first electrode 11 and welding of the joint 32 and the second electrode 12 may be performed simultaneously.

[0065] After welding the joints 22 and 32 to the electrodes 11 and 12, in step S4, the capacitor element 10 and the busbars 20 and 30 are housed in the case 40.

[0066] In step S5, the capacitor module 1 is completed when the sealing resin is filled into the case 40 and cured.

[0067] Steps S2 and S3 will be described in detail with reference to Figures 10A to 10D. Figures 10A to 10D are schematic diagrams illustrating part of the manufacturing process of the capacitor module 1. Here, the connection between the junction 22 of the first busbar 20 and the first electrode 11 will be described, but the connection between the junction 32 of the second busbar 30 and the second electrode 12 can be carried out in a similar manner.

[0068] First, in step S2, the first busbar 20 is placed on the first electrode 11 of the capacitor element 10. At this time, the main body 21 is positioned to cover the first electrode 11 of each of the four capacitor elements 10 (see Figure 3). In addition, two junction portions 22 are placed on the first electrode 11 of each of the four capacitor elements 10. Figure 10A shows the state in which the junction portions 22 are placed on the first electrode 11.

[0069] After positioning the joint portion 22 of the first busbar 20 on the first electrode 11 of the capacitor element 10, spot welding in step S3 is performed. In spot welding, first, as shown in Figure 10B, the spot welding electrode 70 is pressed against the tip of the joint portion 22. While applying pressure to the joint portion 22 in the direction of arrow A1 by pressing the electrode 70 against the tip of the joint portion 22, current is passed through the welding area.

[0070] When an electric current is passed through the joint, the resistance heat generated causes the joint 22 and the first electrode 11 to partially melt. As shown in Figure 10C, the pressure from the electrode 70 and the melting of the joint 22 and the first electrode 11 cause the joint 22 to deform toward the first electrode 11. At this time, because the first electrode 11 is melted, at least a portion of the joint 22 is embedded in the first electrode 11.

[0071] Furthermore, as the joint 22 and the first electrode 11 melt due to resistance heat, a molten and solidified portion 27 is formed near the interface between the joint 22 and the first electrode 11, where the joint 22 and the first electrode 11 are fused together and become one.

[0072] Once the spot welding is complete, the joint 22 and the first electrode 11 are joined together, as shown in Figure 10D.

[0073] In this embodiment, the joint portions 22 and 32 of the busbars 20 and 30 are formed thinner than the main body portions 21 and 31. Therefore, resistance heat is easily generated at the joint portions 22 and 32 during spot welding, improving the joint strength between the joint portions 22 and 32 and the electrodes 11 and 12 of the capacitor element 10. Furthermore, since the joint portions 22 and 32 can be easily deformed by the pressure applied during spot welding, the joint portions 22 and 32 can be embedded in the electrodes 11 and 12, thereby further improving the joint strength between the joint portions 22 and 32 and the electrodes 11 and 12. In addition, by ensuring that the main body portions 21 and 31 have the same thickness as conventional busbars 20 and 30, the vibration suppression effect of the capacitor module 1 can be achieved, thereby improving the reliability of the capacitor module 1.

[0074] [Effects] According to the above-described embodiment, the following effects can be achieved.

[0075] The capacitor module 1 comprises a capacitor element 10 and busbars 20 and 30. The capacitor element 10 has electrodes 11 and 12 on its end faces. The busbars 20 and 30 have plate-shaped main body portions 21 and 31 arranged to cover the electrodes 11 and 12, and connecting portions 22 and 32 extending from the main body portions 21 and 31 and joined to the electrodes 11 and 12. The connecting portions 22 and 32 are at least partially embedded in the electrodes 11 and 12. The connecting portions 22 and 32 are provided with thin-walled portions 24 and 34 that are thinner than the main body portions 21 and 31.

[0076] This configuration makes it possible to provide a capacitor module that can improve the bonding strength between the electrodes of the capacitor element and the busbar. Because the bonding portions 22 and 32 have thinner walls than the main body portions 21 and 31, resistance heat is more easily generated during spot welding, and they can be easily deformed by the pressure applied during spot welding. As a result, the bonding strength between the bonding portions 22 and 32 and the electrodes 11 and 12 can be improved, and the reliability of the capacitor module 1 can be improved.

[0077] The joints 22 and 32 may include thicker sections 25 and 35 that are thicker than the thin sections 24 and 34.

[0078] This configuration makes it easier to deform the joints 22 and 32 by applying pressure during spot welding, thereby improving the joint strength between the joints 22 and 32 and the electrodes 11 and 12.

[0079] The thicker sections 25 and 35 may gradually become thinner towards the thinner sections 24 and 34.

[0080] This configuration makes it possible to achieve both the strength of the joints 22 and 32 themselves and the ease with which the joints 22 and 32 can be deformed by the pressure applied during spot welding.

[0081] The thin-walled portions 24 and 34 may be located at the tips of the joint portions 22 and 32.

[0082] This configuration makes it easier to generate resistance heat during spot welding, thereby improving the bonding strength between the joints 22 and 32 and the electrodes 11 and 12.

[0083] When viewed from a direction perpendicular to the direction in which the main body portions 21 and 31 extend, the tips of the joint portions 22 and 32 may be formed in a rounded shape.

[0084] This configuration allows for the distribution of stress on the joints 22 and 32 caused by the expansion and contraction of the capacitor element 10 when using the capacitor module 1. Therefore, damage to the capacitor module 1 can be suppressed, and the reliability of the capacitor module 1 can be improved.

[0085] The main body portions 21 and 31 are provided with through holes 23 and 33, and the connecting portions 22 and 32 extend from the edges 21a and 31a of the main body portions 21 and 31 that define the through holes 23 and 33, and may be located inside the through holes 23 and 33.

[0086] With this configuration, the main body portions 21 and 31 can cover the entire electrodes 11 and 12 of the capacitor element 10, thereby improving the vibration suppression effect of the capacitor module 1.

[0087] The manufacturing method for the capacitor module 1 includes the steps of preparing a capacitor element 10 and busbars 20 and 30, arranging joint portions 22 and 32 on electrodes 11 and 12 of the capacitor element 10, and welding the electrodes 11 and 12 to the joint portions 22 and 32. The capacitor element 10 has electrodes 11 and 12 on its end faces. The busbars 20 and 30 have plate-shaped main body portions 21 and 31 and joint portions 22 and 32 that extend from the main body portions 21 and 31 and whose tips are embedded in the electrodes 11 and 12. The electrodes 11 and 12 and the joint portions 22 and 32 are welded by spot welding. The joint portions 22 and 32 of the busbars 20 and 30 include thin-walled portions 24 and 34 that are thinner than the main body portions 21 and 31.

[0088] This configuration provides a method for manufacturing a capacitor module that can improve the bonding strength between the electrodes of a capacitor element formed by spot welding and the busbar.

[0089] [Modification] In the above-described embodiment, an example was given in which the capacitor module 1 includes four capacitor elements 10, but the invention is not limited to this. The capacitor module 1 may include one or more capacitor elements 10.

[0090] Furthermore, although the above-described embodiment described an example in which the tips of the joint portions 22 and 32 are rounded, the invention is not limited to this. The tips of the joint portions 22 and 32 may be formed to have corners.

[0091] Furthermore, in the above-described embodiment, through holes 23, 33 are provided in the main body portions 21, 31, and the joining portions 22, 32 extend from the edges 21a, 31a of the main body portions 21, 31 that define the through holes 23, 33, and are located inside the through holes 23, 33. However, the invention is not limited to this. Through holes 23, 33 are not provided in the main body portions 21, 31. In this case, the joining portions 22, 32 may extend from the ends of the main body portions 21, 31.

[0092] Figure 11A is a schematic diagram showing a joint 122 according to a modified example 1 of Embodiment 1. Figure 11B is a schematic diagram showing the state in which the joint 122 of Figure 11A and the electrode 11 are joined together.

[0093] As shown in Figures 11A and 11B, the joint portion 122 may consist only of a thin-walled portion 124 that is thinner than the main body portion 121. In other words, the joint portion 122 does not need to have a thick-walled portion. With this configuration, the entire joint portion 122 is formed thinly, which makes it easier to generate resistance heat during spot welding. Due to the resistance heat, the joint portion 122 and the electrode 11 melt together to form a molten and solidified portion 127. In addition, the pressure applied during spot welding allows the joint portion 122 to be easily deformed, which can improve the joint strength between the joint portion 122 and the electrode 11.

[0094] Figure 12A is a schematic diagram showing a joint portion 222 according to a modified example 2 of Embodiment 1. Figure 12B is a schematic diagram showing the state in which the joint portion 222 of Figure 12A and the electrode 11 are joined together.

[0095] As shown in Figures 12A and 12B, the thickness of the joint portion 222 may gradually decrease from the main body portion 221. With this configuration, the tip portion of the joint portion 222 that comes into contact with the spot welding electrode is formed to be thinner, making it easier for resistance heat to be generated during spot welding. Due to the resistance heat, the joint portion 222 and the electrode 11 melt together to form a molten and solidified portion 227.

[0096] Figure 13A is a schematic diagram showing a joint 322 according to a modified example 3 of Embodiment 1. Figure 13B is a schematic diagram showing the state in which the joint 322 of Figure 13A and the electrode 11 are joined together.

[0097] As shown in Figures 13A and 13B, the thin-walled portion 324 of the joint 322 may be formed by a groove 324a provided on the second surface 322b of the joint 322. In this case, the thick-walled portion 325 is located at the tip of the joint 322, and the thin-walled portion 324 is located on the main body portion 321 side of the joint 322. When welding the joint 322 to the electrode 11, the spot welding electrode is pressed against the thick-walled portion 325. Therefore, the molten and solidified portion 327 is formed at the interface between the thick-walled portion 325 and the electrode 11. With this configuration, when the spot welding electrode is pressed against the thick-walled portion 325, which is the tip of the joint 322, the joint 322 can be easily bent. Because spot welding is performed at the thick-walled portion 325, resistance heat is less likely to be generated, but because the thin-walled portion 324 is located at the base of the joint 322, the joint 322 is easily deformed by pressure. Therefore, the joint portion 322 can be easily pressed into the electrode 11, thereby improving the bonding strength between the joint portion 322 and the electrode 11. In addition, the processing cost for forming the thin-walled portion 324 can be kept low, thus reducing the manufacturing cost of the capacitor module 1.

[0098] Figure 14A is a schematic diagram showing a joint 422 according to a modified example 4 of Embodiment 1. Figure 14B is a schematic diagram showing the state in which the joint 422 of Figure 14A and the electrode 11 are joined together.

[0099] As shown in Figures 14A and 14B, the thin-walled portion 424 of the joint 422 is formed by a groove 424a provided on the second surface 422b of the joint 422, and the thin-walled portion 424 may be configured to increase in thickness toward the thick-walled portion 425. In this case, the thick-walled portion 425 is located at the tip of the joint 422, and the thin-walled portion 424 is located on the main body portion 421 side of the joint 422. The molten and solidified portion 427 is formed at the interface between the thick-walled portion 425 and the electrode 11. With this configuration, when the spot welding electrode is pressed against the thick-walled portion 425, which is the tip of the joint 422, the joint 422 can be easily bent. Therefore, the joint strength between the joint 422 and the electrode 11 can be improved. In addition, since the processing cost for forming the thin-walled portion 424 can be kept low, the manufacturing cost of the capacitor module 1 can be reduced.

[0100] Figure 15A is a schematic diagram showing a joint 522 according to a modified example 5 of Embodiment 1. Figure 15B is a schematic diagram showing the state in which the joint 522 of Figure 15A and the electrode 11 are joined together.

[0101] As shown in Figures 15A and 15B, the thin-walled portion 524 of the joint 522 may be composed of a first groove 524a provided on the first surface 522a of the joint 522 and a second groove 524b provided on the second surface 522b of the joint 522b. In this case, the thick-walled portion 525 is located at the tip of the joint 522, and the thin-walled portion 524 is located on the main body 521 side of the joint 522. The molten and solidified portion 527 is formed at the interface between the thick-walled portion 525 and the electrode 11. With this configuration, when the spot welding electrode is pressed against the thick-walled portion 525, which is the tip of the joint 522, the joint 522 can be easily bent. Therefore, the joint strength between the joint 522 and the electrode 11 can be improved.

[0102] (Outline of Embodiments) (1) The capacitor module of the present disclosure comprises a capacitor element having electrodes on its end faces, a busbar having a plate-shaped main body portion arranged to cover the electrodes, and a connecting portion extending from the main body portion and joined to the electrodes, wherein the connecting portion is at least partially embedded in the electrodes, and the connecting portion is provided with a thin-walled portion that is thinner than the main body portion.

[0103] (2) In the capacitor module of (1), the junction may include a thicker portion than the thin portion.

[0104] (3) In the capacitor module of (2), the thick portion may gradually become thinner towards the thin portion.

[0105] (4) In any one of the capacitor modules from (1) to (3), the junction has a first surface that contacts the electrode and a second surface opposite to the first surface, and the thin-walled portion may be formed by a groove provided on the second surface.

[0106] (5) In any one of the capacitor modules from (1) to (4), the junction has a first surface that contacts the electrode and a second surface opposite to the first surface, and the thin-walled portion may be formed by a groove provided on the first surface.

[0107] (6) In any one of the capacitor modules from (1) to (5), the thin-walled portion may be located at the tip of the joint.

[0108] (7) In any one of the capacitor modules from (1) to (6), the tip of the joint may be rounded when viewed from a direction perpendicular to the direction in which the main body extends.

[0109] (8) In any one of the capacitor modules from (1) to (7), the main body is provided with a through hole, and the joint extends from the edge of the main body defining the through hole and may be located inside the through hole.

[0110] (9) A method for manufacturing a capacitor module of the present disclosure includes the steps of preparing a capacitor element, a capacitor element having electrodes on its end faces, a plate-shaped main body portion and a busbar having a joint portion extending from the main body portion with at least its tip embedded in the electrodes, placing the joint portion on the electrodes of the capacitor element, welding the electrodes and the joint portion by spot welding, housing the capacitor element and the busbar in a case, and filling the case with sealing resin, wherein the joint portion of the busbar includes a thin-walled portion that is thinner than the main body portion.

[0111] This disclosure is useful for capacitor modules used in various electronic devices, electrical equipment, industrial equipment, vehicle equipment, etc.

[0112] 1 Capacitor module 10 Capacitor element 11 Electrode (first electrode) 12 Electrode (second electrode) 20 Busbar (first busbar) 21 Main body 21a Edge 22 Joint 22b First surface 22a Second surface 23 Through hole 24 Thin-walled section 25 Thick-walled section 30 Busbar (second busbar) 31 Main body 31a Edge 32 Joint 32a First surface 32b Second surface 33 Through hole 34 Thin-walled section 35 Thick-walled section 40 Case 41 Opening 42 Bottom 50 Sealing resin 60 Insulating paper

Claims

1. A capacitor module comprising: a capacitor element having electrodes on its end faces; a busbar having a plate-shaped main body portion arranged to cover the electrodes; and a connecting portion extending from the main body portion and joined to the electrodes, wherein the connecting portion is at least partially embedded in the electrodes, and the connecting portion is provided with a thin-walled portion that is thinner than the main body portion.

2. The capacitor module according to claim 1, wherein the joint portion includes a thick portion that is thicker than the thin portion.

3. The capacitor module according to claim 2, wherein the thick portion gradually thins out toward the thin portion.

4. The capacitor module according to any one of claims 1 to 3, wherein the joint portion has a first surface that contacts the electrode and a second surface opposite to the first surface, and the thin-walled portion is formed by a groove provided on the second surface.

5. The capacitor module according to any one of claims 1 to 4, wherein the joint portion has a first surface that contacts the electrode and a second surface opposite to the first surface, and the thin-walled portion is formed by a groove provided on the first surface.

6. The capacitor module according to any one of claims 1 to 5, wherein the thin-walled portion is located at the tip of the joint portion.

7. The capacitor module according to any one of claims 1 to 6, wherein the tip of the joint is rounded when viewed from a direction perpendicular to the direction in which the main body extends.

8. The capacitor module according to any one of claims 1 to 7, wherein the main body portion is provided with a through hole, and the joint portion extends from the edge of the main body portion defining the through hole and is located inside the through hole.

9. A method for manufacturing a capacitor module, comprising the steps of: preparing a capacitor element, a capacitor element having electrodes on its end faces, a plate-shaped main body portion, and a busbar having a joint portion extending from the main body portion with at least its tip embedded in the electrodes; placing the joint portion on the electrodes of the capacitor element; welding the electrodes and the joint portion by spot welding; housing the capacitor element and the busbar in a case; and filling the case with a sealing resin, wherein the joint portion of the busbar includes a thin-walled portion that is thinner than the main body portion.

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