How a capacitor is manufactured

Abstract

To provide a sealing structure capable of suppressing the retention of an electrolytic solution in a gap even when the gap is formed between a sealing member and a resin layer, for example.SOLUTION: A capacitor (2) includes a capacitor body (4) and a resin layer (8). The capacitor body includes an outer case (10), and a sealing member (14) attached to the opening of the outer case. The resin layer is arranged on the outside of the sealing member. The gas permeability (q2) of the resin layer divided by the gas permeability (q1) of the sealing member is 0.1 or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a capacitor including a resin layer disposed on the outer side of a sealing member. Sa Regarding manufacturing methods, etc. [Background technology]

[0002] The terminal leads of the capacitor are pulled out to the outer surface of the base, bent, and soldered to a wiring board such as a circuit board. Capacitors used in this type of mounting are called surface mount capacitors. Surface mount capacitors are highly versatile and are used, for example, in automobiles.

[0003] When a capacitor is installed outdoors, such as inside an automobile, the environmental temperature around the capacitor increases. For this reason, the capacitor needs to withstand high-temperature environments. For example, a resin layer is formed between the sealing body and the base of the capacitor to improve the hermeticity of the capacitor (for example, Patent Document 1). With this configuration, the heat resistance of the capacitor can be improved. In a capacitor provided with this resin layer and base, an insertion hole is formed in the base, and the terminal lead of the capacitor is disposed on the outside (mounting surface side) of the base through the insertion hole. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-338439 Summary of the Invention [Problem to be solved by the invention]

[0005] In the manufacturing process of a capacitor, a gap may be formed between the sealing material and the resin layer. This gap itself does not reduce the performance of the capacitor. However, if the gas of the electrolyte that has permeated the sealing material is liquefied in the gap and the electrolyte remains in the gap, the conductive electrolyte may accidentally be present in the area that should be occupied by the insulating material. Therefore, the gap between the sealing material and the resin layer poses the problem of causing anxiety to the users of the capacitor.

[0006] Patent Document 1 does not disclose or suggest such a problem, and the configuration disclosed in Patent Document 1 cannot solve such a problem.

[0007] In view of this, an object of the technology disclosed herein is to provide a sealing structure that can prevent the retention of an electrolyte in a gap even if a gap is formed between a sealing material and a resin layer, for example. [Means for solving the problem]

[0011] In order to achieve the above object, one According to an aspect, a method for manufacturing a capacitor includes the steps of: placing a base on the sealing member side of a capacitor body, the capacitor body including an outer case and a sealing member attached to an opening of the outer case; and injecting resin through a resin injection hole in the base to form a resin layer between the base and the sealing member, the resin layer being formed such that the gas permeability of the resin layer divided by the gas permeability of the sealing member is 0.1 or greater, and a gap is formed between the sealing member and the resin layer. Effect of the Invention

[0012] According to the technology of the present disclosure, any of the following effects can be obtained.

[0013] (1) Since the gas permeability of the resin layer is adjusted relative to that of the sealing material, even if a gap occurs between the sealing material and the resin layer of the capacitor, the pressure of the electrolyte gas in the gap can be adjusted in the capacitor when the temperature rises. Therefore, even if the gas in the gap cools to room temperature, the generation of liquid electrolyte in the gap is structurally suppressed.

[0014] (2) Even if gaps occur in the capacitor, electrolyte is prevented from remaining in the gaps.

[0015] (3) By adjusting the gas permeability, the retention of electrolyte in gaps is structurally suppressed, eliminating user concerns. [Brief description of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view showing an example of a capacitor according to an embodiment. [Diagram 2] FIG. 1 is a diagram showing an example of gas permeation. [Diagram 3] FIG. 13 is a diagram for explaining liquid pooling in a gap. [Figure 4] FIG. 1 illustrates an example of a capacitor having a gap. [Diagram 5] FIG. 1 shows a test capacitor. [Figure 6] FIG. 13 is a diagram illustrating an example of a capacitor according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, embodiments will be described with reference to the drawings. Embodiment

[0018] Fig. 1 is a cross-sectional view showing an example of a capacitor according to a first embodiment. The configuration shown in Fig. 1 is just an example, and the technology of the present disclosure is not limited to such a configuration.

[0019] The capacitor 2 is an example of an electronic component, and may be, for example, an electrolytic capacitor or an electric double layer capacitor. The capacitor 2 includes a capacitor body 4, a base 6, and a resin layer 8. The capacitor body 4 includes an exterior case 10, a capacitor element 12, and a sealing member 14. The base 6 is disposed on the sealing member 14 side of the capacitor body 4, and the resin layer 8 is disposed between the base 6 and the sealing member 14 of the capacitor body 4. A gap may be formed between the sealing member 14 and the resin layer 8, or there may be no gap. A gap may be formed between the base 6 and the resin layer 8, or there may be no gap. The gap between the base 6 and the resin layer 8 can guide the gas of the electrolyte that has permeated the resin layer 8 to the outside of the base 6. The capacitor 2 can be mounted on a wiring board such as a circuit board.

[0020] The capacitor body 4 can be used alone as a capacitor. A capacitor element 12 is sealed in an outer case 10, and a sealing member 14 is attached to the opening of the outer case 10. The sealing member 14 is made of, for example, insulating rubber.

[0021] The outer case 10 is, for example, a cylindrical aluminum case with a bottom. The tip of the opening of the outer case 10 is bent at a substantially right angle, so that the end of the outer case 10 opposite the bottom (hereinafter referred to as the "open end") has a flat surface.

[0022] Capacitor element 12 is a wound element in which a separator is interposed between an anode foil and a cathode foil, and terminal leads 16-1 and 16-2 extend from the same element surface. Capacitor element 12 is impregnated with an electrolyte.

[0023] The terminal leads 16-1 and 16-2 are formed of, for example, a metal having good electrical conductivity. The terminal lead 16-1 is an anode side terminal and includes a lead portion drawn from the anode foil of the capacitor element 12 and a terminal portion mounted on a wiring board. The lead portion and the terminal portion are connected and integrated by welding or the like. The terminal lead 16-2 is a cathode side terminal and includes a lead portion drawn from the cathode foil of the capacitor element 12 and a terminal portion mounted on a wiring board. As with the terminal lead 16-1, the lead portion and the terminal portion are connected and integrated by welding or the like. The lead portion is, for example, cylindrical, and the terminal portion has, for example, a surface side mounted on a wiring board that is flattened and has a rectangular cross section. The terminal leads 16-1 and 16-2 pass through the sealing member 14 and are exposed to the outside of the capacitor body 4.

[0024] The base 6 is disposed on the sealing material 14 side of the capacitor body 4. The base 6 is formed of an insulating plate such as an insulating synthetic resin. This insulating synthetic resin only needs to have heat resistance sufficient to withstand the heat generated when mounted on a wiring board, and may be, for example, a polyester-based resin such as polybutylene terephthalate (PBT), polybutylene naphthalate (PBN), or polyethylene terephthalate (PET), a polyamide-based resin such as nylon, polyphenylene sulfide (PPS), polyphenylene oxide (PPO), urea resin, liquid crystal polymer (LCP), phenol resin, or epoxy resin. The base 6 includes insertion holes 18-1 and 18-2, a peripheral wall 22, and guide grooves 24-1 and 24-2.

[0025] The through holes 18-1, 18-2 are holes formed at positions corresponding to the terminal leads 16-1, 16-2. The pair of terminal leads 16-1, 16-2 protruding from the capacitor body 4 pass through a pair of through holes 18-1, 18-2 formed in the base 6 and are led out to the outer surface side of the base 6, i.e., the mounting surface side of the base 6.

[0026] Peripheral wall 22 is disposed on the periphery of base 6, outside the open end of outer case 10, and surrounds the open end of outer case 10. The inner surface of peripheral wall 22 has, for example, a circular shape so as to fit along the outer periphery of bottomed cylindrical outer case 10.

[0027] The guide grooves 24-1 and 24-2 are formed on the mounting surface of the base 6 and extend outward from the insertion holes 18-1 and 18-2. The terminal portions of the terminal leads 16-1 and 16-2 are bent in opposite directions along the guide grooves 24-1 and 24-2 and disposed in the guide grooves 24-1 and 24-2. Therefore, the guide grooves 24-1 and 24-2 guide the terminal portions of the terminal leads 16-1 and 16-2. Note that instead of the guide grooves 24-1 and 24-2, guide protrusions may be provided on the mounting surface of the base 6. The guide grooves 24-1 and 24-2 or the guide protrusions can ensure the stability of the capacitor 2 during mounting.

[0028] The resin layer 8 is provided inside the open end of the exterior case 10, between the seat 6 and the sealing member 14. This resin layer 8 is disposed outside the sealing member 14 and covers, for example, the entire or almost the entire outer surface of the sealing member 14, thereby sealing the outer side surface of the sealing member 14. The resin layer 8 improves the sealing performance of the capacitor body 4 while allowing gas of the electrolyte that has permeated the sealing member 14 to be discharged.

[0029] The resin forming the resin layer 8 is, for example, a sealing resin that seals the outside of the sealing member 14, and is in a liquid state when filled, but solidifies after filling. When filled, the liquid resin fills the gap between the capacitor body 4 and the base 6, and after filling, the resin solidifies to form the resin layer 8. The resin forming the resin layer 8 needs only to have affinity for the base 6, the exterior case 10, and the sealing member 14, and to have gas barrier properties, and should have a linear expansion coefficient of aluminum (approximately 23×10 -6It is preferable that the resin has a linear expansion coefficient close to that of the resin layer 8 ( / °C), has a small amount of shrinkage during curing, and is non-hygroscopic. The resin may be, for example, an epoxy resin, an alkyd resin, a urethane resin, a thermosetting resin, or an ultraviolet curing resin. The epoxy resin may be, for example, a two-liquid mixed type epoxy resin using an acid anhydride, or a one-liquid type epoxy resin. The gas transmission rate q2 of the resin layer 8 is 0.1 times or more the gas transmission rate q1 of the sealing member 14.

[0030] Gas permeability is an index showing the ease of gas permeation through members such as the sealing member 14 and the resin layer 8, and is, for example, the number of moles of gas (e.g., electrolyte gas) that permeates a member per unit area, unit time, and unit partial pressure difference between both sides of the member. Gas permeability is expressed by the following formula (1) using the gas permeability coefficient and the thickness of the member. Gas permeability = gas permeability coefficient / thickness (1) The gas permeability and gas permeability coefficient are defined, for example, in Japanese Industrial Standards JIS K 6275-1:2009 "Vulcanized rubber and thermoplastic rubber -- Determination of gas permeability -- Part 1: Differential pressure method" and JIS K 7126-1:2006 "Plastics -- Films and sheets -- Gas permeability test methods -- Part 1: Differential pressure method," and can be determined by the tests described in these Japanese Industrial Standards.

[0031] For example, if the gas permeability coefficient is 1.0×10 -3 and the thickness is 1.7×10 -3 The gas permeability q1 of the sealing material 14 having a gas permeability coefficient of 0.6×10 -3 and the thickness is 0.8×10 -3 The gas permeability q2 of the resin layer 8, which is m, is calculated to be 0.75 from the formula (1).

[0032] Gas movement in a composite material can be thought of in the same way as current flowing through resistors connected in series. Current I corresponds to the gas flow rate J, voltage V corresponds to the partial pressure difference ΔP between both sides of the material, and electrical resistance R corresponds to the inverse of the material's gas permeability q. The relationship between current I, voltage V, and electrical resistance R is expressed by equation (2) according to Ohm's law, so the relationship between gas flow rate J, partial pressure difference ΔP, and gas permeability q is expressed by equation (3). I = V / R (2) J = ΔP q (3)

[0033] The electrical resistance R of a resistor having a first electrical resistance R1 and a second electrical resistance R2 connected in series is expressed by the following equation (4). R = R1 + R2 (4) The gas permeability q of a multi-layer material having a sealing material 14 with a gas permeability q1 and a resin layer 8 with a gas permeability q2 can be calculated by replacing the electrical resistances R, R1, and R2 with 1 / q, 1 / q1, and 1 / q2, respectively, in formula (4). That is, the gas permeability q of this multi-layer material is expressed by the following formulas (5) and (6). 1 / q=1 / q1+1 / q2 (5) q = (q1 q2) / (q1 + q2) (6)

[0034] For example, the gas permeability q of a multi-layer material including the sealing member 14 having a gas permeability q1 of 0.59 and the resin layer 8 having a gas permeability q2 of 0.75 is about 0.33 from the formula (6). -3 m. For example, if the gas permeability coefficient is 1.0×10 -3 and the thickness is 2.5×10 -3 The gas permeability q1 of the sealing member 14, m, is 0.4 from formula (1). If the gas permeability coefficient of the resin layer 8 is smaller than that of the sealing member 14, the gas permeability q of the multi-layer material is smaller than the gas permeability q1 of the sealing member 14 having the same thickness as the multi-layer material. In other words, the gas shielding function of the multi-layer material is improved compared to the gas shielding function of the sealing member 14 having the same thickness, and the function of suppressing the evaporation of the gasified electrolyte is improved.

[0035] The gas permeabilities q, q1, and q2 can be adjusted by adjusting the gas permeability coefficient or thickness of members such as the resin layer 8 and the plugging member 14. The gas permeability coefficient can be adjusted by adjusting the base material or additives.

[0036] FIG. 2 shows an example of gas permeation through a sealing material and a resin layer. In FIG. 2, a simplified capacitor 2 is shown for the purpose of explanation. In FIG. 2, the arrows indicate the gas flow rate J of the electrolyte, that is, the amount of gas permeation. Also, in FIG. 2, a gap 26 is disposed between the resin layer 8 and the sealing material 14.

[0037] The electrolyte 32 contained in the interior 30 of the exterior case 10 is gasified due to the temperature rise of the capacitor 2. Therefore, gas 34 of the electrolyte 32 is generated in the interior 30 of the exterior case 10, and the internal pressure of the exterior case 10 increases. The increase in internal pressure creates a partial pressure difference between both sides of the sealing member 14, and part of the gas 34 permeates the sealing member 14 and flows into the gap 26. The inflow of the gas 34 increases the pressure in the gap 26. The increase in pressure in the gap 26 creates a partial pressure difference between both sides of the resin layer 8, and part of the gas 34 permeates the resin layer 8 and flows out to the outside, and the gas 34 evaporates.

[0038] 2, in the steady state of evaporation, the flow velocity J2 of the gas 34 permeating through the resin layer 8 is equal to the flow velocity J1 of the gas 34 permeating through the sealing material 14. When the external pressure (i.e., atmospheric pressure) is P, the pressure in the interior 30 is P+ΔP1 (i.e., the pressure difference from the external pressure P is ΔP1), and the pressure in the gap 26 is P+ΔP2 (i.e., the pressure difference from the external pressure P is ΔP2), J1 and J2 can be expressed by equations (3) to (7). J1=J2=(ΔP1-ΔP2)·q1=ΔP2·q2 ···(7) The pressure difference ΔP2 in the gap 26 is expressed by equation (8) from equation (7). ΔP2=ΔP1·q1 / (q1+q2) ···(8) Equation (8) indicates that as the gas permeability q2 of the resin layer 8 increases, the pressure difference ΔP2 in the gap 26 and the pressure (P+ΔP2) in the gap 26 decrease.

[0039] When the gas permeabilities q1, q2 of the sealing material 14 and the resin layer 8 are, for example, 0.59 and 0.75, respectively, the pressure difference ΔP2 in the gap 26 is about 0.44 times ΔP1 from equation (8), and the ratio of the gas permeabilities of the sealing material 14 and the resin layer 8 (hereinafter referred to as the "permeability ratio") is about 1.28. The permeability ratio is defined as the gas permeability q2 of the resin layer 8 divided by the gas permeability q1 of the sealing material 14, that is, q2 / q1.

[0040] When the temperature of the capacitor 2 drops, the gas 34 returns to the electrolyte 32. When the pressure difference ΔP2 described above is small, as shown in A of FIG. 3, no visible electrolyte 32 is generated in the gap 26, and the retention of the electrolyte 32 in the gap 26 can be suppressed. In contrast, when the pressure difference ΔP2 described above exceeds a predetermined pressure difference, the temperature drops and the gas 34 reaches saturation, and the gas 34 adheres to the surface of the sealing member 14 as droplets, and when the temperature drops further, the electrolyte 32 is generated and retained in the gap 26, as shown in B of FIG. 3. In the test results described below, when the pressure difference ratio (i.e., ΔP2 / ΔP1) is 0.91 or less, the occurrence of liquid pools is suppressed. Therefore, according to the test results described below, it is preferable that the predetermined pressure difference described above is 0.91·ΔP1 or less. In addition, the test results described later show that when the aforementioned permeability ratio is 0.1 or more and the gas permeability q2 of the resin layer 8 is 0.1 times or more the gas permeability q1 of the sealing material 14, the occurrence of liquid pools is suppressed. [Capacitor manufacturing process]

[0041] The capacitor manufacturing process is an example of a capacitor manufacturing method of the present disclosure, and this manufacturing process includes a process of forming the capacitor body 4, a process of forming the base 6, a process of attaching the base 6 to the capacitor body 4, a process of molding the terminal leads 16-1, 16-2, and a process of injecting resin.

[0042] In the process of forming the capacitor body 4, first, an anode foil connected to terminal lead 16-1 and a cathode foil connected to terminal lead 16-2 are wound with a separator interposed between them to form capacitor element 12. Capacitor element 12 is impregnated with an electrolyte and this capacitor element 12 is then sealed in exterior case 10, and then a sealing member 14 is attached to the opening of exterior case 10 to form capacitor body 4. Exterior case 10 is made of, for example, aluminum.

[0043] In the process of forming base 6, base 6 is formed into the shape described above from insulating synthetic resin. Note that, although in this embodiment, an electrolytic capacitor is formed by impregnating capacitor element 12 with an electrolytic solution, the present invention is not limited to this, and a hybrid capacitor may be formed by impregnating capacitor element 12, which has been impregnated with a conductive polymer to form a solid electrolyte layer, with the electrolytic solution.

[0044] In the process of attaching the base 6, the terminal leads 16-1, 16-2 of the capacitor body 4 are inserted through the insertion holes 18-1, 18-2 of the base 6. Then, the base 6 is moved and attached to the sealing member 14 side of the capacitor body 4.

[0045] In the molding process of the terminal leads 16-1, 16-2, the terminal leads 16-1, 16-2 are bent along the guide grooves 24-1, 24-2 of the base 6, and the terminal portions of the terminal leads 16-1, 16-2 are placed in the guide grooves 24-1, 24-2. The base 6 is fixed to the capacitor body 4 by this molding process.

[0046] In the resin injection process, for example, liquid resin is injected through a resin injection hole (not shown) of the base 6 to fill the space between the capacitor body 4 and the base 6. The injected resin forms a resin layer 8 between the capacitor body 4 and the base 6. A resin injection device such as a dispenser is used to inject the resin.

[0047] According to the embodiment, the following actions and effects can be obtained.

[0048] (1) As shown in Fig. 4, even if gap 26 that is isolated from the outside occurs between sealing material 14 and resin layer 8, the pressure of the gas in gap 26 can be adjusted in capacitor 2 when the temperature rises. Therefore, even if the gas in gap 26 cools to room temperature, electrolyte is unlikely to be generated.

[0049] (2) Even if gaps 26 occur in capacitor 2, electrolyte 32 is prevented from remaining in gaps 26.

[0050] (3) If gap 26 exists between sealing material 14 and resin layer 8, users of capacitor 2 may be concerned about the retention of electrolyte 32 in gap 26. However, by structurally suppressing the retention of electrolyte 32 through adjustment of gas permeability, it is possible to alleviate users' concerns. EXAMPLES

[0051] The capacitor 2 according to the example has a similar configuration to the capacitor 2 according to the embodiment. The sealing member 14 and resin layer 8 of the capacitor 2 according to the example are formed of materials having the gas permeability coefficient, thickness, and gas permeabilities q1 and q2 shown in the table below. The capacitor according to the comparative example has a similar configuration to the capacitor 2 according to the embodiment, except for the permeability ratio, which is less than 0.1. The sealing member 14 and resin layer 8 of the capacitor according to the comparative example are formed of materials having the gas permeability coefficient, thickness, and gas permeabilities q1 and q2 shown in the table below. [Table 1] [Table 2] The material "EPDM" is ethylene propylene diene rubber.

[0052] A test capacitor 102 shown in FIG. 5 was produced for testing the capacitor 2 according to the embodiment and the capacitor according to the comparative example. The capacitor element 112 of the capacitor 102 has a cut terminal lead 116, and the capacitor 102 includes electrolytic paper 128 attached to the cut terminal lead 116, and also includes a resin layer 108 on the electrolytic paper 128. The resin layer 108 is formed by potting and curing a resin, and closes the opening of the exterior case 110. The capacitor 102 has a gap 126 between the sealing member 114 and the electrolytic paper 128. Note that the base 6 described in the embodiment is omitted in the capacitor 102.

[0053] The following tests are performed on the capacitors 102 according to the examples and comparative examples, taking into consideration the Japanese Industrial Standard JIS C 5101-18:2019 "Fixed capacitors for electronic devices - Part 18: General rules by type - Fixed aluminum solid (MnO2) and non-solid electrolytic capacitors for surface mounting" and the liquefaction of gas at low temperatures. [Test] After performing a 105℃ storage test for 120 hours, leave the sample at -20℃ for 15 minutes.

[0054] The test results are as follows: [Table 3] In the test results, when the transmittance ratio was in the range of 0.1 to 1.28, the occurrence of liquid pools was 0. It was confirmed that the occurrence of liquid pools can be suppressed by setting the transmittance ratio to 0.1 or more.

[0055] Regarding the above-mentioned embodiment or example, features, advantages, modifications, etc. will be listed below.

[0056] (1) Capacitor 2 according to the above-described embodiments and examples includes base 6. However, capacitor 2 does not have to include base 6, for example, as in test capacitor 102 shown in Fig. 5. The arrangement of resin layer 8 allows capacitor 2 to obtain the effects of the above-described embodiments.

[0057] (2) The capacitor 2 according to the above embodiment and example has a resin layer 8 that covers the entire or nearly the entire outer surface of the sealing material 14. However, as shown in Fig. 6, the base 6 may include a protrusion 28. The protrusion 28 is disposed, for example, on the body installation surface of the base 6 and formed around the insertion holes 18-1 and 18-2 to surround the insertion holes 18-1 and 18-2. The protrusion 28 can prevent the resin injected between the base 6 and the sealing material 14 from entering the insertion holes 18-1 and 18-2.

[0058] As explained above, the most preferred embodiment of the present disclosure has been described, however, the technology of the present disclosure is not limited to the above description, and it goes without saying that those skilled in the art can make various modifications and changes based on the gist of the invention described in the claims or disclosed in the specification, and such modifications and changes are naturally included in the scope of the present disclosure. [Industrial Applicability]

[0059] The technology disclosed herein is widely applicable and useful in electronic devices. [Explanation of symbols]

[0060] 2, 102 Capacitor 4. Capacitor body 6 Pedestal 8, 108 Resin layer 10, 110 Outer case 12, 112 Capacitor element 14, 114 Sealing member 16-1, 16-2, 116 terminal leads 18-1, 18-2 Insertion holes 22 Peripheral wall 24-1, 24-2 Guide groove 26, 126 Gap 28 Protrusion 30 inside 32 Electrolyte 34 Gas 128 Electrolytic paper

Claims

[Claim 1] a step of placing a seat on a side of a capacitor body including an outer case and a sealing member attached to an opening of the outer case, the sealing member being disposed on the side of the capacitor body; injecting a resin through a resin injection hole of the base to form a resin layer between the base and the sealing member; Equipped with the resin layer is formed so that a gas permeability of the resin layer divided by a gas permeability of the sealing material is 0.1 or more; A method for manufacturing a capacitor, comprising the steps of: forming a gap between the sealing material and the resin layer;

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