Capacitor element, electrolytic capacitor, insulating material, and method for manufacturing mounting substrate

Abstract

The present invention provides a capacitor element comprising an anode body, a dielectric layer formed on a surface of the anode body, a solid electrolyte layer covering at least a portion of the dielectric layer, a cathode lead layer covering at least a portion of the solid electrolyte layer, and an insulating member arranged in a range from the outermost surface of the cathode lead layer to a depth of 0.001 μm or more.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a capacitor element, an electrolytic capacitor, an insulating material, and a mounting substrate. Background Art

[0002] An electrolytic capacitor comprises a capacitor element having a solid electrolyte layer, a lead frame electrically connected to the capacitor element, and an outer casing that seals the capacitor element. For example, the capacitor element comprises an anode body having a porous surface, a dielectric layer formed on at least a portion of the anode body's surface, a solid electrolyte layer covering at least a portion of the dielectric layer, and a cathode lead layer covering at least a portion of the solid electrolyte layer.

[0003] Patent Document 1 proposes an electrolytic capacitor having multiple capacitor elements, wherein the capacitor elements include an anode portion, a cathode portion, and an anti-corrosion portion. The anode portion is formed of a valve-acting metal having an oxide film layer formed on the surface. The cathode portion is formed in a predetermined area of ​​the surface in a layered shape having a solid electrolyte layer and an outermost layer composed of a conductive material. The anti-corrosion portion electrically insulates the anode portion from the cathode portion.

[0004] Patent Document 2 proposes an electrolytic capacitor having a shielding layer in a region separating an anode region and a cathode region of an electrolytic capacitor substrate having a porous layer on its surface.

[0005] Patent Document 3 proposes a method for manufacturing an electrolytic capacitor including a step of applying a shielding material solution that permeates into a dielectric film and forms a shielding layer on the permeated portion.

[0006] Patent document 4 proposes the following content, namely, an anti-corrosion layer that prevents the penetration of solid electrolyte material is provided in an etching layer formed on the surface of the valve metal, thereby distinguishing the anode part from the cathode part, and forming a first groove on the cathode part side of the anti-corrosion layer, forming a second groove on the anode part side relative to the first groove, and forming an anti-corrosion layer in the second groove.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-165777

[0010] Patent Document 2: International Publication No. 2007 / 061005 Pamphlet

[0011] Patent Document 3: International Publication No. 2000 / 067267 Pamphlet

[0012] Patent Document 4: Japanese Patent Application Laid-Open No. 2007-305661 Summary of the Invention

[0013] Problems to be solved by the invention

[0014] A capacitor element according to a first aspect of the present invention comprises an anode body, a dielectric layer formed on a surface of the anode body, a solid electrolyte layer covering at least a portion of the dielectric layer, a cathode lead layer covering at least a portion of the solid electrolyte layer, and an insulating member arranged in a range from the outermost surface of the cathode lead layer to a depth of at least 0.001 μm.

[0015] A capacitor element according to a second aspect of the present invention includes an anode body, a dielectric layer formed on a surface of the anode body, a solid electrolyte layer covering at least a portion of the dielectric layer, a cathode lead layer covering at least a portion of the solid electrolyte layer, and an insulating member disposed on at least a portion of either the surface or an interior of the capacitor element. At least a portion of the insulating member has fluidity at a temperature of 230° C. or higher.

[0016] An electrolytic capacitor according to a third aspect of the present invention includes the above-described capacitor element and an outer package that seals the capacitor element.

[0017] An insulating material for an electrolytic capacitor according to a fourth aspect of the present invention includes a first curable resin, wherein a cured product of the first curable resin has a glass transition temperature of 150° C. or lower.

[0018] A fifth aspect of the present invention provides a method for manufacturing a mounting substrate, comprising the steps of preparing a substrate on which the electrolytic capacitor is mounted and heating the electrolytic capacitor at 230° C. or higher.

[0019] According to the present invention, the heat-resistant reliability of an electrolytic capacitor can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a cross-sectional view schematically showing a capacitor element according to one embodiment of the present invention.

[0021] Figure 2 It is a cross-sectional view schematically showing a main part of a capacitor element according to one embodiment of the present invention.

[0022] Figure 3 This is a cross-sectional view schematically showing a portion of a capacitor element according to one embodiment of the present invention.

[0023] Figure 4 It is a cross-sectional view schematically showing an electrolytic capacitor according to one embodiment of the present invention.

[0024] Figure 5 This is a flowchart showing a method for manufacturing a capacitor element according to one embodiment of the present invention.

[0025] Figure 6 This is a flowchart showing a method for manufacturing an electrolytic capacitor according to one embodiment of the present invention.

[0026] Figure 7 This is a flowchart showing a method for manufacturing a mounting substrate according to one embodiment of the present invention. DETAILED DESCRIPTION

[0027] Before describing the embodiments, the problems existing in the conventional technology will be briefly described below.

[0028] In electrolytic capacitors, air can sometimes penetrate the porous portion of the anode body connected to the lead frame and enter the capacitor. When oxygen in the intruding air comes into contact with the solid electrolyte layer contained in the capacitor element, the solid electrolyte layer degrades at high temperatures, reducing the electrolytic capacitor's capacitance and increasing its ESR (equivalent series resistance).

[0029] Furthermore, electrolytic capacitors are typically soldered to a substrate through a reflow process. During this reflow process, tiny cracks may develop in the outer packaging. Oxygen intrusion through these cracks can cause degradation of the solid electrolyte layer at high temperatures.

[0030] In view of the above problems, the present invention provides a capacitor element, an electrolytic capacitor, an insulating material, and a method for manufacturing a mounting substrate, which can improve the heat-resistant reliability of an electrolytic capacitor.

[0031] [Capacitor element]

[0032] The capacitor element of this embodiment includes an anode body, a dielectric layer formed on the surface of the anode body, a solid electrolyte layer covering at least a portion of the dielectric layer, a cathode lead layer covering at least a portion of the solid electrolyte layer, and an insulating member arranged in a range from the outermost surface of the cathode lead layer to a depth of at least 0.001 μm.

[0033] The capacitor element of this embodiment includes an anode body, a dielectric layer formed on the surface of the anode body, a solid electrolyte layer covering at least a portion of the dielectric layer, a cathode lead layer covering at least a portion of the solid electrolyte layer, and an insulating member disposed on at least a portion of either the surface or the interior of the capacitor element. At least a portion of the insulating member has fluidity at a temperature of 230°C or above.

[0034] Typically, the peak temperature of the reflow process is 230° C. or higher. The fact that at least a portion of the insulating member has fluidity at 230° C. or higher means that at least a portion of the insulating member flows in the reflow process.

[0035] Specifically, the insulating member of this embodiment disperses within the outer packaging during reflow, effectively blocking any microscopic cracks that may develop within the outer packaging. This improves the oxygen barrier properties of the electrolytic capacitor, and consequently, its heat resistance. It should be noted that, for this purpose, the outer packaging material is less likely to penetrate into the cathode lead layer.

[0036] "Having fluidity" means having a melt flow rate (MFR) of 1 g / 10 minutes or more. The MFR of the insulating member is preferably 10 g / 10 minutes or more. The MFR is measured in accordance with ISO 1133 at a temperature of 230°C and a load of 2.16 kg.

[0037] When the insulating member is dispersed in the outer package, the insulating member preferably has excellent adhesion to the outer package. For example, the insulating member and the outer package preferably contain resins with good compatibility (for example, resins with similar molecular structures).

[0038] The insulating member may include a first curable resin. In this case, the glass transition temperature (Tg) of the cured product of the first curable resin is preferably 150°C or lower. By setting the Tg of the first curable resin sufficiently below 230°C, at least a portion of the insulating member can flow at temperatures above 230°C. The Tg of the cured product of the first curable resin is more preferably 140°C or lower, further preferably 130°C or lower, and particularly preferably 120°C or lower.

[0039] Tg is determined by differential thermal analysis (DTA) evaluated in accordance with JIS K 0129. DTA can be performed using an apparatus equipped with an atomic force microscope (AFM). AFM enables differential thermal analysis in a microscopic area.

[0040] The insulating member may contain the first curable resin in the form of a cured product, a semi-cured product, or an uncured product. For example, the insulating member may be a mixture of at least one of a cured product, a semi-cured product, and an uncured product of the first curable resin, a curing agent, and other additives.

[0041] The first curable resin is not particularly limited as long as the insulating component containing it has fluidity at a temperature of 230° C. or above. The first curable resin may be any of thermosetting and photocurable resins. A photocurable resin may be a resin that is cured by visible light or ultraviolet light. Examples of the first curable resin include epoxy resins, polyimides, silicone resins, phenolic resins, urea resins, melamine resins, unsaturated polyesters, furan resins, polyurethanes, silicone resins (silicone), curable acrylic resins, photoresists, and the like. The first curable resin may be used alone or in combination of two or more.

[0042] The first curable resin preferably comprises a bifunctional epoxy resin because its Tg tends to be lower. The first curable resin may also contain curable resins other than bifunctional epoxy resins, but the proportion thereof is preferably small. The proportion of the bifunctional epoxy resin in the first curable resin is preferably 95% by mass or greater. The bifunctional epoxy resins may be used alone or in combination.

[0043] Examples of epoxy resins other than the bifunctional epoxy resin include polycyclic aromatic epoxy resins such as naphthalene epoxy resins and novolac epoxy resins.

[0044] The first curable resin preferably comprises a bisphenol epoxy resin. This facilitates adhesion of the insulating member to other components of the electrolytic capacitor, such as the outer packaging and lead frame, and further enhances oxygen barrier properties. Bisphenol epoxy resin has a basic skeleton composed of two phenyl groups bonded via a hydrocarbon group or the like.

[0045] Examples of the bisphenol epoxy resin include bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, bisphenol AD ​​epoxy resin, hydrogenated bisphenol A epoxy resin, and hydrogenated bisphenol F epoxy resin.

[0046] The epoxy equivalent of the bisphenol epoxy resin is not particularly limited and may be, for example, 100 or more or 500 or less. If the epoxy equivalent is within the above range, the adhesion of the insulating member is likely to be further improved. The molecular weight (weight average molecular weight) of the bisphenol epoxy resin is not particularly limited and may be, for example, 280 or more or 1000 or less. If the molecular weight of the epoxy resin is within the above range, the epoxy equivalent is likely to be within the above range.

[0047] From the perspective of fluidity and adhesion during reflow, the first curable resin preferably comprises a bisphenol A epoxy resin or a bisphenol F epoxy resin as the bisphenol-type epoxy resin. The proportion of the bisphenol-type epoxy resin in the first curable resin is preferably 95% by mass or greater. The bisphenol-type epoxy resins may be used alone or in combination.

[0048] The insulating member may be a resin composition containing a first curable resin. The resin composition may contain, for example, a first curable resin, a curing agent, a curing accelerator, a flame retardant, a filler, a coupling agent, a colorant, a release agent, and an inorganic ion scavenger.

[0049] Examples of the curing agent include tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, nadic anhydride, methylnadic anhydride, trialkyltetrahydrophthalic anhydride, methylcyclohexene tetracarboxylic dianhydride, hydrogenated methylnadic anhydride, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, ethylene glycol dianhydrotrimellitic anhydride, and the like. anhydride-based curing agents such as glycolbisanhydrotrimellitate), glycerol bis(anhydrotrimellitate) monoacetate, dodecenylsuccinic anhydride, aliphatic dibasic acid condensation anhydride, trialkyltetraphthalic anhydride, and chlorendic anhydride; imidazole-based curing agents such as 2-ethyl-4-methylimidazole, 2-phenylimidazole, 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole, 2,4-diamino-6-[2-methylimidazolyl-(1)]ethyl-s-triazine, 2-phenylimidazoline, and 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole; novolac phenol resin; and aromatic amines.

[0050] Examples of the curing accelerator include phosphorus-based curing accelerators represented by tertiary phosphines such as triphenylphosphine, and quaternary phosphonium salts such as tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-methylphenylborate, tetraphenylphosphonium thiocyanate, and tetrabutylphosphonium decanoate; and nitrogen-based curing accelerators represented by diazabicycloundecene, imidazole compounds, and dicyandiamide.

[0051] Examples of the filler include silica such as fused silica, talc, calcium carbonate, and alumina. The surface of the filler may be treated with a silane coupling agent.

[0052] Examples of the inorganic ion scavenger include ion scavengers that capture metal ions such as Zr, Sb, Bi, Mg, and Al.

[0053] Examples of resins other than the first curable resin that may be contained in the insulating member include thermoplastic resins (for example, polyamide, polyamideimide, polyolefin, polyester, and thermoplastic polyimide).

[0054] The insulating member is disposed on at least a portion of either the surface or the interior of the capacitor element. At least a portion of the insulating member may be disposed on the surface of the cathode lead layer or within the cathode lead layer.

[0055] The cathode lead layer is typically not dense but contains voids. Consequently, oxygen may infiltrate the cathode lead layer, degrading the solid electrolyte layer. By placing an insulating member on the surface or within the cathode lead layer, the oxygen intrusion path can be effectively blocked. Hereinafter, the insulating member placed on at least a portion of either the surface or the interior of the cathode lead layer is referred to as the first insulating member.

[0056] The first insulating member is preferably positioned from the outermost surface of the cathode lead layer to a depth of at least 0.001 μm. This allows for more effective prevention of oxygen intrusion. The first insulating member is preferably positioned from the outermost surface of the cathode lead layer to a depth of at least 0.01 μm, more preferably at a depth of at least 0.1 μm. The penetration depth of the first insulating member need only be 80% of the thickness of the cathode lead layer from the outermost surface. Within this range, oxygen barrier properties can be fully demonstrated.

[0057] The cathode extraction layer may include a metal paste layer containing a metal material on its outermost surface. In this case, the first insulating member is positioned so as to fill the interior of the metal paste layer, for example, gaps between the metal materials. From the perspective of oxygen barrier properties, the ratio of elements derived from the first insulating member to elements derived from the metal material in the metal paste layer is preferably 65 atomic % or greater, more preferably 66 atomic % or greater, and particularly preferably 67 atomic % or greater. From the perspective of electrical resistance, the ratio of elements derived from the first insulating member to elements derived from the metal material is preferably 300 atomic % or less, more preferably 290 atomic % or less.

[0058] The position of the first insulating member can be evaluated using elemental analysis using an electron beam microanalyzer (EPMA), fluorescent X-ray analysis, Raman spectroscopy, Fourier transform infrared spectrophotometry (FT-IR), atomic absorption spectrometry, or other analytical methods. When the first insulating member is formed from a resin composition, the distribution of elements (e.g., C, O, Cl, N, S, etc.) derived from the resin composition in a cross-section of the capacitor element can be confirmed using the above methods.

[0059] The ratio of elements derived from the first insulating member to elements derived from the metal material in the metal paste layer can also be evaluated using the above-described analysis method. If the metal paste layer contains a binder resin, the analysis results may also include elements derived from the binder resin. Since the binder resin is present in trace amounts, the above analysis results obtained by evaluating elements derived from the resin composition can be considered as the results obtained by evaluating elements derived from the first insulating member.

[0060] The metal paste layer sometimes contains a binder resin. Even in this case, the presence or absence of the first insulating member can be confirmed. First, the thickness of the metal paste layer is divided into a first region from the surface of the solid electrolyte layer side to 20% of the thickness of the metal paste layer and a second region outside this region. The binder resin is usually thinly and roughly uniformly arranged throughout the metal paste layer, and its concentration is small and uniform. On the other hand, the first insulating member is concentrated near the surface of the metal paste layer, and its concentration decreases from the surface of the metal paste layer toward the inside. Therefore, when mapping the elements derived from the resin composition in the cross-section of the metal paste layer, the elements confirmed in the first region can be regarded as coming from the binder resin. The concentration of the first insulating member is higher than the concentration of the above-mentioned element in the first region. That is, in the region where the concentration of the above-mentioned element is greater than the concentration in the first region, it can be regarded as that the first insulating member is arranged.

[0061] The penetration depth of the first insulating member is the length from any arbitrary point on the outermost surface of the cathode lead layer to a point on a straight line extending from the arbitrary point along the thickness direction of the cathode lead layer and located furthest from the outermost surface of the cathode lead layer in the region where the first insulating member is located, as determined above. These lengths are measured at five arbitrary points, and the average of these measurements is taken as the penetration depth of the first insulating member.

[0062] When the first insulating member comprises a first curable resin, a cured product of the first curable resin is preferably disposed near the surface of the cathode lead layer. This is because oxygen intrusion can be more effectively suppressed. The cured product of the first curable resin is preferably disposed from the outermost surface of the cathode lead layer to a depth of 0.001 μm or greater, more preferably to a depth of 0.01 μm or greater, and particularly preferably to a depth of 0.5 μm or greater.

[0063] The degree of curing of the first curable resin can be evaluated by, for example, FT-IR. For example, when the first curable resin comprises an uncured epoxy resin, the curing degree of the first curable resin can be evaluated by, for example, FT-IR. -1 Over 1000cm -1 A strong peak derived from the uncured material can be observed below.

[0064] From the perspective of oxygen barrier properties, the first insulating member preferably covers at least a portion of the surface of the cathode lead layer. Alternatively, the first insulating member may cover the entire surface of the cathode lead layer. When observing one main surface of the capacitor element, the first insulating member preferably occupies at least 80% of the area of ​​the cathode lead layer.

[0065] The thickness of the first insulating member covering the surface of the cathode lead layer is not particularly limited. From the perspective of oxygen barrier properties, the thickness of the first insulating member covering the surface of the cathode lead layer is preferably 0.01 μm or greater, more preferably 0.05 μm or greater, and particularly preferably 1 μm or greater. The first insulating member covering the surface of the cathode lead layer is preferably a cured product of a first curable resin.

[0066] The thickness of the first insulating member covering the surface of the cathode lead layer is an average value of the thicknesses of the first insulating member at any five points on the outermost surface of the cathode lead layer.

[0067] The anode body includes an anode portion without a solid electrolyte layer, a cathode portion with a solid electrolyte layer, and a separation portion between the anode and cathode portions. The cathode portion includes a solid electrolyte layer and a cathode lead layer in this order. The anode body has a porous portion on its main surface.

[0068] From the perspective of oxygen barrier properties, at least a portion of the insulating member may be disposed on the surface of the anode portion. Alternatively, at least a portion of the insulating member may be disposed within the anode portion. Hereinafter, the insulating member disposed on at least a portion of either the surface or the interior of the anode portion is referred to as the second insulating member.

[0069] The second insulating member is preferably disposed in a range from the outermost surface of the anode portion to a depth of 0.001 μm or more, more preferably 0.01 μm or more, and particularly preferably 1 μm or more.

[0070] The second insulating member preferably covers at least a portion of the surface of the anode portion. The second insulating member may also cover the entire surface of the anode portion. When observing one main surface of the capacitor element, the second insulating member preferably occupies more than 80% of the area of ​​the anode portion. The thickness of the second insulating member covering the surface of the anode portion is not particularly limited. From the perspective of oxygen barrier properties, the thickness of the second insulating member covering the surface of the anode portion is preferably 0.01 μm or more, more preferably 0.05 μm or more, and even more preferably 1 μm or more.

[0071] From the perspective of oxygen barrier properties, at least a portion of the insulating member may be disposed on the surface of the separation portion. Alternatively, at least a portion of the insulating member may be disposed within the separation portion. Hereinafter, the insulating member disposed on at least a portion of either the surface or the interior of the separation portion is referred to as the third insulating member.

[0072] The third insulating member is preferably disposed in a range from the outermost surface of the separation portion to a depth of 0.001 μm or more, more preferably 0.01 μm or more, and particularly preferably 1 μm or more.

[0073] The third insulating member preferably covers at least a portion of the surface of the separation portion. The third insulating member may also cover the entire surface of the separation portion. When observing one main surface of the capacitor element, the third insulating member preferably occupies more than 80% of the area of ​​the separation portion. The thickness of the third insulating member covering the surface of the separation portion is not particularly limited. From the perspective of oxygen barrier properties, the thickness of the third insulating member covering the surface of the separation portion is preferably 0.01 μm or more, more preferably 0.05 μm or more, and even more preferably 1 μm or more.

[0074] At least a portion of the surface of the separator portion may be covered with an insulating separator member in place of, or in addition to, the third insulating member. This facilitates preventing short circuits between the anode portion and the cathode lead layer. The thickness of the separator member is not particularly limited and may, for example, be from 0.5 μm to 100 μm, or from 10 μm to 50 μm.

[0075] The insulating member is preferably placed on the surface of the cathode lead layer and the surface of the anode portion. This helps prevent oxygen intrusion from the outside. The insulating member is preferably placed inside the cathode lead layer, inside the anode portion, and inside the separator portion. This helps prevent oxygen migration within the capacitor element. The insulating member is preferably placed on the surface of the capacitor element, at the junction with the lead frame (described later). This reduces the likelihood of a gap between the lead frame and the outer packaging, thus helping prevent oxygen intrusion from the outside.

[0076] The positions of the second and third insulating members can also be evaluated using elemental analysis using EPMA, fluorescent X-ray analysis, Raman spectroscopy, FT-IR, atomic absorption spectrometry, or other analytical methods. The distribution of elements (e.g., C, O, Cl, N, S, etc.) originating from each insulating member can be confirmed using these methods.

[0077] The penetration depth of the second insulating member can also be calculated in the same way as the penetration depth of the first insulating member. That is, it is the length from any point on the outermost surface of the anode part to the following location, which is on a straight line drawn along the thickness direction of the anode part with the arbitrary point as the starting point and is farthest from the outermost surface of the anode part in the area where the second insulating member is arranged. The above-mentioned lengths are measured at any five points, and their average value is taken as the penetration depth of the second insulating member. The penetration depth of the third insulating member can also be calculated in the same way by replacing the anode part with the separation part. The thickness of the second insulating member covering the surface of the anode part is the average value of the thickness of the second insulating member at any five points on the outermost surface of the anode part. The thickness of the third insulating member covering the surface of the separation part can also be calculated in the same way by replacing the anode part with the separation part.

[0078] The compositions of the second insulating member and the third insulating member may be the same as or different from the composition of the first insulating member.

[0079] Hereinafter, the capacitor element of this embodiment will be described in detail with reference to the drawings. However, this embodiment is not limited thereto.

[0080] Figure 1 1 is a cross-sectional view schematically showing the capacitor element according to the present embodiment. Figure 1 For the sake of convenience, the insulating member is omitted.

[0081] Capacitor element 110 is, for example, in a sheet shape. Capacitor element 110 includes an anode body 11, a dielectric layer 12 covering at least a portion of anode body 11, a solid electrolyte layer 13 covering at least a portion of the dielectric layer, and a cathode lead layer 14 covering at least a portion of solid electrolyte layer 13. Cathode lead layer 14 includes a carbon layer 141 and a metal paste layer 142.

[0082] Anode body 11 includes an anode portion 11a, a separator portion 11b, and a cathode-forming portion 11c. A porous portion (not shown) is disposed on both main surfaces of anode body 11. A core portion (not shown) is sandwiched between the two porous portions. A thin-walled portion is formed in a portion of separator portion 11b. Separation member 15 is disposed on the surface of the thin-walled portion.

[0083] Figure 2 It is a cross-sectional view schematically showing a main part of the capacitor element according to the present embodiment. Figure 2 , for convenience, a portion of the solid electrolyte layer and the cathode lead layer and the first insulating member are shown.

[0084] First insulating members 21 (21a and 21b) are disposed within and on the surface of metal paste layer 142. First insulating member 21a extends from the outermost surface of metal paste layer 142, which constitutes cathode lead layer 14, to a depth of T1a. First insulating member 21a is disposed to fill voids formed within metal paste layer 142. The surface of metal paste layer 142 is further covered with first insulating member 21b having a thickness of T1b. This prevents oxygen from entering the cathode lead layer, thereby suppressing degradation of the solid electrolyte layer.

[0085] Figure 3 It is a cross-sectional view schematically showing a portion of the capacitor element according to the present embodiment. Figure 3 , for convenience, a portion of the end portion of the capacitor element including the anode portion is shown.

[0086] A first insulating member 21a and a first insulating member 21b are disposed within and on the surface of the metal paste layer 142, respectively. A second insulating member 22a and a second insulating member 22b are disposed within and on the surface of the anode portion 11a, respectively. The second insulating member 22a penetrates into the interior of the anode portion 11a beyond the dielectric layer 12. The surface of the anode portion 11a is further covered by the second insulating member 22b. A separating member 15 is disposed in the thin-walled portion of the separating portion 11b. The third insulating member 23 extends below the separating member 15 and penetrates into the interior of the separating portion 11b. This suppresses the intrusion of oxygen into the anode portion, the separating portion, and the cathode lead layer, thereby making it easier to suppress degradation of the solid electrolyte layer.

[0087] (Anode)

[0088] The anode body comprises a formed body or a sintered body of foil (metal foil) or particles, wherein the foil comprises a valve metal as a conductive material, and the particles comprise a valve metal. The formed body or the sintered body has a porous structure. Examples of valve metals include titanium, tantalum, aluminum, and niobium. The anode body comprises one or more of the above-mentioned valve metals. The anode body may comprise the above-mentioned valve metals in the form of an alloy or an intermetallic compound. The thickness of the anode body is not particularly limited. The thickness of the anode body excluding the thin-walled portion is, for example, greater than 15 μm and less than 300 μm, or may be greater than 80 μm and less than 250 μm. The thickness of the anode body as a formed body or a sintered body is, for example, greater than 15 μm and less than 5 mm.

[0089] The main surface of the anode body is roughened by electrolytic etching or the like. Therefore, the anode body includes a porous portion formed on one side of the main surface. The entire anode body may be porous. However, from the perspective of strength, the anode body preferably includes porous portions disposed on both main surfaces and a core portion having a lower porosity and sandwiched between these porous portions. The porous portion is a region having many fine pores. The core portion is, for example, a region that has not been electrolytically etched.

[0090] (Dielectric layer)

[0091] The dielectric layer is formed on at least a portion of the surface of the anode body. The dielectric layer is formed, for example, by anodizing the surface of the anode body using a chemical conversion treatment or the like. Therefore, the dielectric layer may contain an oxide of a valve metal. For example, when aluminum is used as the valve metal, the dielectric layer may contain Al2O3. It should be noted that the dielectric layer is not limited to this; any layer that functions as a dielectric may be used.

[0092] (Solid electrolyte layer)

[0093] The solid electrolyte layer may be formed so as to cover at least a portion of the dielectric layer, or may be formed so as to cover the entire surface of the dielectric layer.

[0094] The solid electrolyte layer comprises, for example, a manganese compound and a conductive polymer. Examples of the conductive polymer include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, polyphenylene, polyphenylene vinylene, polyacene, and polythiophene vinylene. These may be used alone or in combination of two or more, or may be copolymers of two or more monomers.

[0095] It should be noted that, in this specification, polypyrrole, polythiophene, polyfuran, and polyaniline refer to polymers with polypyrrole, polythiophene, polyfuran, and polyaniline as their basic skeletons, respectively. Therefore, polypyrrole, polythiophene, polyfuran, and polyaniline may also include their respective derivatives. For example, polythiophene includes poly(3,4-ethylenedioxythiophene).

[0096] The conductive polymer can be included in the solid electrolyte layer together with the dopant. The dopant can be a monomolecular anion or a polymer anion. Specific examples of monomolecular anions include p-toluenesulfonic acid and naphthalenesulfonic acid. Specific examples of polymer anions include polyvinylsulfonic acid, polystyrenesulfonic acid, polyallylsulfonic acid, polyacryloylsulfonic acid, polymethacryloylsulfonic acid, poly(2-acrylamide-2-methylpropanesulfonic acid), polyisoprenesulfonic acid, and polyacrylic acid. They can be used alone or in combination of two or more. In addition, they can be polymers of a single monomer or copolymers of two or more monomers. Among them, polymer anions derived from polystyrenesulfonic acid are preferred.

[0097] (Cathode extraction layer)

[0098] The cathode lead layer may be formed so as to cover at least a portion of the solid electrolyte layer, and may be formed so as to cover the entire surface of the solid electrolyte layer.

[0099] The cathode lead layer includes, for example, a carbon layer and a metal (eg, silver) paste layer formed on the surface of the carbon layer. The structure of the cathode lead layer is not limited thereto, and any structure may be used as long as it has a current collecting function.

[0100] <Carbon layer>

[0101] The carbon layer comprises a carbon material and has electrical conductivity. The carbon material is not particularly limited. Examples of the carbon material include graphite, carbon black, graphene sheets, and carbon nanotubes.

[0102] The carbon layer may contain a binder resin and / or additives as needed. The binder resin is not particularly limited, and examples thereof include known binder resins used in the production of capacitor elements. Examples of the binder resin include the aforementioned thermoplastic resins or curable resins. Examples of additives include dispersants, surfactants, antioxidants, preservatives, alkalis, and / or acids.

[0103] <Metal paste layer>

[0104] The metal paste layer contains a metal material. The metal material is not particularly limited. From the perspective of electrical conductivity, the metal material may contain silver.

[0105] The shape of the metal material is not particularly limited. The metal material may include spherical and / or flaky metal particles. The average aspect ratio of the spherical metal particles (hereinafter referred to as spherical particles) is, for example, less than 1.5. The average aspect ratio of the flaky metal material is, for example, greater than 1.5, or greater than 2. For example, the first insulating member is configured to fill the gaps between the metal particles.

[0106] The volume ratio of the metal material contained in the metal paste layer is not particularly limited as long as it is greater than 0%. From the perspective of easily reducing electrical resistance, the volume ratio may be 60% or more, 70% or more, or 80% or more.

[0107] The metal paste layer may further contain a binder resin. The volume ratio of the binder resin in the metal paste layer is not particularly limited. From the perspective of electrical resistance, the volume ratio of the binder resin in the metal paste layer may be 60% or less, 20% or less, or 10% or less. The above volume ratio may be 0.1% or more. The above volume ratio may also be 0%. The volume ratio of each component in the metal paste layer can be confirmed, for example, using energy dispersive X-ray spectroscopy (SEM-EDX).

[0108] The thickness of the metal paste layer is not particularly limited. For example, the thickness of the metal paste layer can be 0.1 μm to 50 μm, or 1 μm to 20 μm. The thickness of the metal paste layer is the average value of five points in a cross section of the metal paste layer in the thickness direction.

[0109] (Separate components)

[0110] The separation member is insulating and covers at least a portion of the surface of the separation portion. This makes it easier to prevent a short circuit between the anode portion and the cathode lead layer.

[0111] The separating member may be a conventionally known insulating tape (resist tape), or may be formed by adhering a composition containing the same insulating resin as the first insulating member.

[0112] [Electrolytic capacitors]

[0113] The electrolytic capacitor of this embodiment includes the above-mentioned capacitor element.

[0114] An electrolytic capacitor may include multiple capacitor elements. The multiple capacitor elements are stacked. The number of stacked capacitor elements is not particularly limited, but is, for example, 2 or more and 20 or less. The anode portions of the stacked capacitor elements are electrically connected by welding. Furthermore, the cathode lead layers of the stacked capacitor elements are also electrically connected.

[0115] It suffices that at least one of the plurality of capacitor elements is the capacitor element of this embodiment. The other capacitor elements may be conventionally known capacitor elements. It is preferred that all of the plurality of capacitor elements arranged in the electrolytic capacitor be the capacitor elements of this embodiment.

[0116] (Outer packaging)

[0117] Electrolytic capacitors may include an outer casing that seals the capacitor element. The outer casing protects the capacitor element from impact, moisture, and other effects.

[0118] The outer packaging includes a first sealing member. The first sealing member preferably does not exhibit fluidity above 230°C. This prevents the first sealing member from flowing during reflow, thereby protecting the capacitor element. Furthermore, the insulating member included in the capacitor element flows above 230°C, thereby blocking cracks that may develop in the outer packaging during reflow.

[0119] The first sealing member includes a first sealing resin. The first sealing resin is not particularly limited. Examples of the first sealing resin include curable resins and engineering plastics. Examples of the curable resin include various curable resins exemplified as the first curable resin. Engineering plastics include general-purpose engineering plastics and super engineering plastics. Examples of engineering plastics include polyimide and polyamide-imide.

[0120] Wherein, the first sealing member preferably comprises a curable resin (hereinafter referred to as the second curable resin). The first sealing member may comprise the second curable resin in the form of a cured product, may comprise it in the form of a semi-cured product, or may comprise it in the form of an uncured product. The first sealing member may be a resin composition comprising the second curable resin. The resin composition may, for example, comprise the second curable resin, a curing agent, a curing accelerator, a flame retardant, a filler, a coupling agent, a colorant, a release agent, or an inorganic ion scavenger.

[0121] The Tg of the cured product of the second curable resin is preferably higher than the Tg of the cured product of the first curable resin. This makes it easier to suppress the flow of the first sealing member even when heating the insulating member under conditions that cause it to flow. The Tg of the cured product of the second curable resin is more preferably 140°C or higher, and even more preferably 150°C or higher. Preferred examples of such a second curable resin include biphenyl epoxy resins and o-cresol novolac epoxy resins.

[0122] The outer package preferably includes both a first sealing member having no fluidity at 230° C. or higher and a second sealing member at least part of which has fluidity at 230° C. or higher. In this case, the second sealing member is preferably dispersed in the first sealing member to block cracks generated in the first sealing member.

[0123] Such a second sealing member may be derived from an insulating member included in the capacitor element. In other words, the second sealing member may be at least a portion of the insulating member that has flowed during the reflow process and then dispersed in the first sealing member.

[0124] Alternatively, the second sealing member may also be added to the first sealing member during the sealing process. In this case, the second sealing member preferably comprises the same curable resin as exemplified as the first curable resin, i.e., a bifunctional epoxy resin, preferably comprising a bisphenol epoxy resin. The curable resin contained in the second sealing member (hereinafter referred to as the third curable resin) may be a cured product, a semi-cured product, or an uncured product. The second sealing member may be a resin composition comprising the third curable resin. The resin composition may, for example, comprise a third curable resin, a curing agent, a curing accelerator, a flame retardant, a filler, a coupling agent, a colorant, a release agent, or an inorganic ion scavenger. The composition of the second sealing member may be the same as or different from that of the insulating member.

[0125] (Lead Frame)

[0126] Electrolytic capacitors typically have lead frames connected to the capacitor elements. The anode lead frame is, for example, welded to the anode portion. The cathode lead frame is bonded to the cathode lead layer using a conductive adhesive, solder, or resistance welding or laser welding. The conductive adhesive is, for example, a mixture of a curable resin and carbon particles or metal particles.

[0127] The material of the lead frame is not particularly limited, as long as it is electrochemically and chemically stable and conductive, and can be either metal or non-metal. Its shape is also not particularly limited. From the perspective of height reduction, the lead frame thickness (the distance between the main surfaces of the lead frame) is preferably 25 μm to 200 μm, more preferably 25 μm to 100 μm.

[0128] A portion of the lead frame is sealed within the outer packaging along with the capacitor element. The portion of the lead frame that emerges from the outer packaging is bonded to the substrate via solder. To aid in the solder connection, the lead frame can be covered with a metal material. During the reflow process, the metal material melts along with the solder, strengthening the solder connection.

[0129] During the reflow process, the metal material covering the lead frame, which is sealed by the outer packaging, also melts. The molten metal flows over the lead frame and out of the outer packaging. This creates a gap between the lead frame and the outer packaging. This gap communicates with the outside world, allowing oxygen to enter the electrolytic capacitor from the outside through this gap.

[0130] The capacitor element of this embodiment includes an insulating member that flows during reflow. Therefore, the insulating member can block the gap between the lead frame and the outer package, thereby suppressing the intrusion of oxygen through the gap.

[0131] The metal material is not particularly limited as long as it melts during the reflow process. The metal material can be appropriately selected by considering the peak temperature of the reflow process and the Tg of the cured product of the first curable resin. The melting point of the metal material is preferably, for example, less than 230°C and higher than the Tg of the cured product of the first curable resin. This allows the insulating member to quickly move and fill the gap when the metal material flows out.

[0132] As such metal materials, for example, Sn and solder materials specified in JIS Z 3282-1999 can be mentioned. As solder materials, lead-containing solders such as Sn-Pb, Pb-Sn, Sn-Pb-Sb, Sn-Pb-Bi, Sn-Pb-Cd, Sn-Pb-Cu, Sn-Pb-Ag, Pb-Ag, and Pb-Ag-Sn can be mentioned; and lead-free solders such as Sn-Sb, Sn-Bi, Sn-Cu, Sn-Cu-Ag, Sn-In, Sn-In-Ag-Bi, Sn-Ag, Sn-Ag-Cu, Sn-Ag-Bi-Cu, Sn-Zn, and Sn-Bi-Zn can be mentioned.

[0133] From the perspective of oxygen barrier properties, it is desirable to firmly adhere the metal material to the insulating member. For example, the bonding strength between the insulating member and the metal material is preferably 8.5 MPa or more, more preferably 9.0 MPa or more.

[0134] The above-mentioned joint strength measurement was carried out in accordance with the test piece shape and test conditions of ISO19095-1 to 4, which are international standards for the test method for evaluating the properties of resin-metal joints. Specifically, the overlapping test piece (type B) was used with a joint area of ​​50 mm. 2The strength (ie, shear strength) of the two-layer structure of the mold resin and the insulating member when the insulating member side is peeled off from the lead frame is defined as the bonding strength between the insulating member and the metal material.

[0135] To further improve oxygen barrier properties, it is preferable to place an insulating member at least on the surface of the capacitor element where it joins the lead frame. Because the insulating member and the metal material have different fluidities, gaps created by the movement of the metal material are quickly closed by the movement of the insulating member.

[0136] Figure 4 Electrolytic capacitor 100 includes one or more capacitor elements 110 , an anode lead frame 120A bonded to anode portion 11 a , a cathode lead frame 120B bonded to a cathode lead layer, and an outer package 130 sealing capacitor element 110 .

[0137] [Insulation materials for electrolytic capacitors]

[0138] This embodiment includes an insulating material for forming the above-mentioned insulating member. The insulating material of this embodiment includes the above-mentioned first curable resin. The glass transition temperature of the cured product of the first curable resin is 150°C or less. The first curable resin preferably includes a bifunctional epoxy resin. Specifically, the first curable resin preferably includes a bisphenol epoxy resin.

[0139] [Mounting substrate]

[0140] The mounting substrate of this embodiment includes a substrate and the above-mentioned electrolytic capacitor mounted on the substrate. The electrolytic capacitor is connected to the substrate by, for example, soldering. The solder is not particularly limited, and for example, the solder materials exemplified as metal materials can be used.

[0141] The substrate is not particularly limited. Examples of the substrate include conventionally known glass substrates, resin substrates, ceramic substrates, and silicon substrates, as well as flexible and / or bendable substrates such as flexible substrates and stretchable substrates.

[0142] [Method for manufacturing capacitor element]

[0143] The capacitor element of the present embodiment can be manufactured, for example, using a method comprising the following steps: a step of preparing an anode body having a porous portion; a step of forming a dielectric layer on at least a portion of the surface of the anode body; a step of dividing the anode body having the dielectric layer into an anode portion, a cathode forming portion, and a separation portion between the anode portion and the cathode forming portion; a step of forming a cathode lead-out layer covering at least a portion of the solid electrolyte layer to obtain a precursor of the capacitor element; and a step of imparting a material of an insulating component to a predetermined position of the precursor.

[0144] After the above-mentioned separation step and before the step of forming the cathode lead layer, a step of compressing or removing a part of the porous part of the separation part to form a thin-walled part in the separation part; and a step of arranging a separation member on at least a part of the surface of the thin-walled part can be performed.

[0145] In the above-described imparting step, the entire capacitor element precursor can be immersed in a raw material liquid containing an insulating resin. This allows the insulating resin to adhere to the interior and surface of the cathode lead layer, the interior and surface of the anode portion, and the interior of the separator. In other words, the first, second, and third insulating members can be positioned in predetermined positions in a single step. In this case, the first, second, and third insulating members have the same composition.

[0146] Furthermore, the entire stack of multiple capacitor element precursors can be immersed in a raw material solution containing an insulating resin. This allows the insulating resin to adhere not only to the interior and surface of the cathode lead layer, the interior and surface of the anode portion, and the interior of the separator, but also to the separators (or separator members) between adjacent capacitor elements.

[0147] When applying the materials of the insulating members using methods other than those described above, the applying step may include applying the material of the first insulating member to the cathode lead layer, applying the material of the second insulating member to the anode portion, and applying the material of the third insulating member to the separator portion. The order of the above steps is not limited.

[0148] The method for manufacturing a capacitor element according to this embodiment will be described below by taking as an example a case where a plurality of capacitor element precursors are stacked in the providing step and the entire obtained stack is immersed in a raw material liquid containing an insulating resin. Figure 5 1 is a flowchart showing a method for manufacturing a capacitor element according to this embodiment.

[0149] (1) Anode body preparation step (S11)

[0150] As a raw material of the anode body, for example, a metal foil containing a valve metal is used.

[0151] At least one main surface of the metal foil is roughened. By the roughening, a porous portion having many fine pores is formed on at least the main surface of the metal foil.

[0152] For example, roughening can be achieved by electrolytic etching of the metal foil. Electrolytic etching can be performed using, for example, direct current electrolysis or alternating current electrolysis. Etching conditions are not particularly limited and can be appropriately set depending on the depth of the porous portion, the type of valve metal, and the like.

[0153] (2) Step of forming a dielectric layer (S12)

[0154] A dielectric layer is formed on the surface of the anode body. The method for forming the dielectric layer is not particularly limited. The dielectric layer can be formed, for example, by subjecting the anode body to a chemical conversion treatment. In the chemical conversion treatment, for example, the anode body is immersed in a conversion solution such as an ammonium adipate solution and then heat-treated. Alternatively, the anode body can be immersed in the conversion solution and a voltage applied.

[0155] (3) Step of dividing the anode body and forming a thin-walled portion in the separated portion (S13)

[0156] The anode body, on which the dielectric layer is formed, is divided into an anode portion, a cathode-forming portion, and a separation portion between the anode and cathode-forming portions. A thin-walled portion is then formed in at least a portion of the separation portion. For example, the thin-walled portion can be formed by compressing or removing a portion of the porous portion in at least a portion of the separation portion. Compression and removal can also be combined as needed. Compression can be performed by pressing, for example. Removal of the porous portion can be performed by cutting, laser processing, or the like.

[0157] (4) Step of arranging a separation member on the surface of the separation portion (S14)

[0158] The separation member is disposed on the surface of the separation portion. By disposing the separation member before the step of forming the solid electrolyte layer, it is possible to suppress the conductive polymer from creeping up to the anode portion during the formation of the solid electrolyte layer.

[0159] The separation member is configured, for example, by attaching insulating tape (such as an anti-corrosion tape) to the surface of the separation portion. Alternatively, the separation member material may be applied to the separation portion. The separation member material is applied to the separation portion by printing, using a dispenser, or by transfer.

[0160] (5) Step of forming a solid electrolyte layer (S15)

[0161] A solid electrolyte layer is formed on the surface of the dielectric layer.

[0162] The solid electrolyte layer can be formed by chemically polymerizing and / or electrolytically polymerizing raw material monomers or oligomers in the presence of an anode. The solid electrolyte layer can also be formed by applying a solution containing a conductive polymer dissolved therein or a dispersion containing a conductive polymer dispersed therein to the dielectric layer.

[0163] The raw material monomers or oligomers are monomers or oligomers that serve as the raw materials for the conductive polymer. Examples include pyrrole, aniline, thiophene, and their derivatives. The polymerization solution used in chemical polymerization and / or electrolytic polymerization may contain the above-mentioned dopant in addition to the raw material monomers or oligomers.

[0164] (6) Step of forming a cathode lead layer (S16)

[0165] A cathode lead layer is formed by applying, for example, a carbon paste and a silver paste in this order on the surface of the solid electrolyte layer. This provides a precursor for a capacitor element.

[0166] (7) Step of producing a laminate (S17)

[0167] Multiple capacitor element precursors are stacked and the anodes are joined to form a laminate. The anodes are then joined by welding and / or riveting to achieve electrical connection. The welding method is not particularly limited and may include laser welding or resistance welding.

[0168] (8) Step of immersing the laminate in a raw material liquid of an insulating member (S18)

[0169] The entire obtained laminate is immersed in a raw material solution for the insulating member, so that the raw material solution adheres to the interior and surface of the cathode lead layer, the interior and surface of the anode portion, the interior and surface of the separator, and between the separators (or separators) of adjacent capacitor element precursors.

[0170] Afterwards, drying and heat treatment are performed as needed, thereby placing the first insulating member inside and on the surface of the cathode lead layer, the second insulating member inside and on the surface of the anode portion, the third insulating member inside and on the surface of the separator, and the insulating member between the separators (or separator members) of adjacent capacitor elements. By operating in this manner, a stacked capacitor element is obtained.

[0171] The amount of the raw material liquid to be applied is not particularly limited and can be adjusted by, for example, the concentration, viscosity, and immersion time of the raw material liquid.

[0172] It is desirable that the viscosity of the raw material liquid is not too high. The viscosity of the raw material liquid measured at 25°C using a dynamic viscoelasticity measuring device is preferably 6000 mPa·s or less, more preferably 5500 mPa·s or less. If the viscosity of the raw material liquid is within this range, it is easy to penetrate into the cathode lead layer. The above viscosity of the raw material liquid is preferably 5 mPa·s or more, more preferably 50 mPa·s or more. The above viscosity is measured, for example, using a viscoelasticity measuring device under the conditions of a measurement temperature of 25°C and a measurement time of 180 seconds (the same applies hereinafter).

[0173] From the perspective of improving the oxygen blocking effect, it is desirable that the proportion of insulating resin contained in the raw material liquid is large. The proportion of insulating resin contained in the raw material liquid is preferably 80% by mass or more, more preferably 90% by mass or more. It is particularly desirable that the raw material liquid does not contain liquid components that dissolve or disperse the insulating resin. The proportion of liquid components contained in the raw material liquid is preferably less than 10% by mass, more preferably less than 5% by mass. The liquid component is not particularly limited and can be appropriately selected according to the type of curable resin. The liquid component can be water, a non-aqueous solvent, or a mixture thereof. The so-called non-aqueous solvent is a general term for liquids other than water, including organic solvents and ionic liquids.

[0174] In addition, after the capacitor element is obtained by applying the above-mentioned raw material liquid to a precursor of the capacitor element, a plurality of capacitor elements may be stacked.

[0175] Alternatively, the raw material liquid can be applied to a predetermined position of the capacitor element precursor by coating or dispensing methods using various coaters or dispensers, transfer (roller transfer, etc.), etc. In this case, the composition and viscosity of the raw material liquid can be varied depending on the application position.

[0176] [Method for Manufacturing Electrolytic Capacitor]

[0177] Electrolytic capacitors are manufactured, for example, using a method comprising the steps of preparing one or more capacitor elements obtained by the above-described method, electrically connecting a lead frame to the capacitor element, and sealing the capacitor element and a portion of the lead frame with an outer packaging body. Here, a method for manufacturing an electrolytic capacitor comprising a plurality of stacked capacitor elements is described. Figure 6 1 is a flowchart showing a method for manufacturing an electrolytic capacitor according to this embodiment.

[0178] (a) Capacitor element preparation step (S21)

[0179] A laminated capacitor element is produced by the above-mentioned methods (1) to (8).

[0180] (b) Lead frame connection step (S22)

[0181] An anode lead frame is electrically connected to the anode portion of at least one capacitor element, and a cathode lead frame is electrically connected to the cathode lead layer. The anode portion and the anode lead frame are electrically connected, for example, by welding. The cathode lead layer and the cathode lead frame are electrically connected, for example, by bonding the cathode lead layer and the cathode lead frame with a conductive adhesive.

[0182] (c) Sealing step (S23)

[0183] The stacked capacitor elements and a portion of the lead frame are sealed with a first sealing member. Sealing is performed using a molding technique such as injection molding, insert molding, or compression molding. For example, a predetermined mold is used to fill the first sealing member material (sealing material) containing a curable resin or thermoplastic resin so as to cover one end of the stacked capacitor elements and lead frame, and then heating is performed.

[0184] It is desirable that the viscosity of the sealing material is not too low. The viscosity of the sealing material measured at 25°C using a dynamic viscoelasticity measuring device is generally 4000 mPa·s or more, and may be 10000 mPa·s or more. The sealing material may not have fluidity at 25°C. In other words, the viscosity of the sealing material may be evaluated as being difficult to be viscous or solid at 25°C. If the viscosity of the sealing material is within this range, the moisture resistance and impact resistance of the electrolytic capacitor are easily improved. The above-mentioned viscosity of the sealing material that flows at 25°C may be, for example, 100000 mPa·s or less, or 60000 mPa·s or less.

[0185] [Method for manufacturing mounting substrate]

[0186] The mounting substrate can be manufactured, for example, by a method including a step of preparing a substrate on which an electrolytic capacitor is mounted and a step of heating the electrolytic capacitor at 230° C. or higher. Figure 7 This is a flowchart showing the method for manufacturing the mounting substrate according to the present embodiment.

[0187] (i) Electrolytic Capacitor Preparation Step (S31)

[0188] An electrolytic capacitor was fabricated using the methods (a) to (c) above.

[0189] (ii) Heating (reflux) step (S32)

[0190] The electrolytic capacitor is placed on a substrate with solder material interposed between them and heated to 230°C or higher. This allows the electrolytic capacitor to be mounted on the substrate. During this process, the insulating material flows and disperses within the outer packaging, plugging any microscopic cracks that may have occurred within the outer packaging.

[0191] Example

[0192] Hereinafter, the present invention will be specifically described based on Examples and Comparative Examples; however, the present invention is not limited to the following Examples.

[0193] Example 1

[0194] An electrolytic capacitor A1 including a laminated body in which seven capacitor elements were stacked was produced according to the following procedure.

[0195] (1) Fabrication of capacitor elements

[0196] An aluminum foil (100 μm thick) was prepared as a substrate, and the surface of the aluminum foil was etched to produce an anode body having a porous portion (35 μm thick on one main surface of the aluminum foil and 35 μm thick on the other main surface). The anode body was immersed in a 0.3 mass% phosphoric acid solution (70°C) and a DC voltage of 70 V was applied for 20 minutes to form a dielectric layer composed of aluminum oxide (Al2O3) on the surface of the anode body.

[0197] The anode body was divided into an anode portion, a cathode forming portion, and a separation portion therebetween. A portion of the separation portion was compressed by pressing to form a thin portion (35 μm thick). An insulating anti-corrosion tape (separating member) was attached to the thin portion.

[0198] The anode body having the dielectric layer formed thereon is immersed in a liquid composition containing a conductive material to form a pre-coat layer.

[0199] A polymerization solution containing pyrrole (monomer of the conductive polymer), naphthalenesulfonic acid (dopant), and water was prepared. The anode body, which had been formed with a dielectric layer and a precoat layer, was immersed in the resulting polymerization solution and electrolytic polymerization was performed at an applied voltage of 3 V to form a solid electrolyte layer.

[0200] After applying a dispersion of graphite particles in water to the solid electrolyte layer and drying it, a carbon layer was formed on the surface of the solid electrolyte layer. Next, a silver paste containing silver particles and a binder resin (epoxy resin) was applied to the surface of the carbon layer. The binder resin was then heated to cure, forming a metal paste layer (silver paste layer, 15 μm thick). This process formed a cathode lead layer composed of the carbon layer and the metal paste layer, resulting in a capacitor element precursor.

[0201] The seven obtained precursors were stacked, and the anode portions were welded together by laser welding to obtain a stacked body.

[0202] The resulting laminate was immersed in a raw material liquid (solvent-free type, viscosity (25°C) 100 mPa·s) containing a two-component curing bisphenol F epoxy resin (Tg 100°C). The laminate was then heat-treated to cure the impregnated raw material liquid. This procedure yielded a capacitor element with an insulating member. The raw material liquids were a mixture of Liquid A, consisting of 4-tert-butylphenyl glycidyl ether and bisphenol F epoxy resin (mass ratio) = 75:25, and Liquid B, containing an acid anhydride curing agent and an imidazole curing accelerator.

[0203] The configuration of the insulating member was confirmed using Raman spectroscopy, Fourier transform infrared spectroscopy, TEM / EDS (transmission electron microscopy / energy dispersive X-ray spectroscopy) or TEM / EELS (transmission electron microscopy / electron beam energy loss spectroscopy). In the laminate, the insulating member was configured inside the anode body, inside the separator, inside the cathode lead layer, and between the separators of adjacent capacitor elements. The insulating member was configured in the range from the outermost surface of the cathode lead layer to a depth of 0.005 μm. In addition, it was confirmed that the insulating member configured in the range from the outermost surface of the cathode lead layer to a depth of 0.005 μm was a cured product. In the metal paste layer, the ratio of the element derived from the insulating material to the silver atoms was 65 atomic %.

[0204] The insulating member was disposed in a range from the outermost surface of the anode portion to a depth of 0.005 μm. The insulating member was disposed below the resist tape in a range from the outermost surface of the separation portion to a depth of 0.005 μm.

[0205] (2) Assembly of electrolytic capacitors

[0206] Two lead frames (Sn-plated copper) were bonded to the stacked capacitor elements. The stacked capacitor elements and a portion of each lead frame were then sealed with a sealing material (the material of the first sealing member) containing a biphenyl-type epoxy resin (Tg 180°C), thereby forming an outer package and completing electrolytic capacitor A1.

[0207] Example 2

[0208] A capacitor element was produced in the same manner as in Example 1, except that the insulating member was impregnated so as to be arranged in a range from the outermost surface of the cathode lead layer to a depth of 0.005 μm, thereby completing an electrolytic capacitor A2.

[0209] The insulating member disposed within the cathode lead layer was confirmed to be a cured product. In the metal paste layer, the ratio of elements derived from the insulating material to silver atoms was 65 atomic %. The insulating member was also disposed on the surface of the cathode lead layer. The thickness of the insulating member covering the surface of the cathode lead layer was 4.8 μm.

[0210] An insulating member was also disposed on the surface of the anode portion and within a range from the outermost surface of the anode portion to a depth of 0.005 μm. The thickness of the insulating member covering the surface of the anode portion was 4.8 μm. Furthermore, an insulating member was disposed below the resist tape on the surface of the separator portion and within a range from the outermost surface of the separator portion to a depth of 0.005 μm. The thickness of the insulating member covering the surface of the separator portion was 4.8 μm.

[0211] Example 3

[0212] A capacitor element was produced in the same manner as in Example 1, except that the insulating member was impregnated so as to be arranged in a range from the outermost surface of the cathode lead layer to a depth of 0.01 μm, thereby completing an electrolytic capacitor A3.

[0213] The insulating member disposed inside the cathode lead layer was confirmed to be a cured product. In the metal paste layer, the ratio of the element derived from the insulating material to the silver atoms was 66 atomic %.

[0214] The insulating member was also disposed in a range from the outermost surface of the anode portion to a depth of 0.01 μm. Furthermore, the insulating member was disposed below the resist tape in a range from the outermost surface of the separation portion to a depth of 0.01 μm.

[0215] Example 4

[0216] A capacitor element was produced in the same manner as in Example 1, except that the insulating member was impregnated so as to be arranged in a range from the outermost surface of the cathode lead layer to a depth of 0.01 μm, thereby completing an electrolytic capacitor A4.

[0217] The insulating member disposed within the cathode lead layer was confirmed to be a cured product. In the metal paste layer, the ratio of elements derived from the insulating member relative to silver atoms was 66 atomic %. The insulating member was also disposed on the surface of the cathode lead layer. The thickness of the insulating member covering the surface of the cathode lead layer was 5.2 μm.

[0218] An insulating member was placed on the surface of the anode portion and from the outermost surface of the anode portion to a depth of 0.01 μm. The thickness of the insulating member covering the surface of the anode portion was 5.2 μm. Furthermore, an insulating member was placed on the surface of the separator portion below the resist tape and from the outermost surface of the separator portion to a depth of 0.01 μm. The thickness of the insulating member covering the surface of the separator portion was 5.2 μm.

[0219] Example 5

[0220] A capacitor element was produced in the same manner as in Example 1, except that the insulating member was impregnated so as to be arranged in a range from the outermost surface of the cathode lead layer to a depth of 0.05 μm, thereby completing an electrolytic capacitor A5.

[0221] It was confirmed that all the insulating members disposed inside the cathode lead-out layer were solidified. In the metal paste layer, the ratio of elements derived from the insulating members to silver atoms was 67 atomic %.

[0222] Furthermore, an insulating member was disposed from the outermost surface of the anode portion to a depth of 0.05 μm. Furthermore, an insulating member was disposed below the resist tape from the outermost surface of the separation portion to a depth of 0.05 μm.

[0223] Example 6

[0224] A capacitor element was produced in the same manner as in Example 1, except that the insulating member was impregnated so as to be arranged in a range from the outermost surface of the cathode lead layer to a depth of 0.05 μm, thereby completing an electrolytic capacitor A6.

[0225] The insulating member disposed within the cathode lead layer was confirmed to be entirely solidified. In the metal paste layer, the ratio of elements derived from the insulating member relative to silver atoms was 67 atomic %. The insulating member was also disposed on the surface of the cathode lead layer. The thickness of the insulating member covering the surface of the cathode lead layer was 5.0 μm.

[0226] An insulating member was placed on the surface of the anode portion and from the outermost surface of the anode portion to a depth of 0.05 μm. The thickness of the insulating member covering the surface of the anode portion was 5.0 μm. Furthermore, an insulating member was placed below the resist tape on the surface of the separator portion and from the outermost surface of the separator portion to a depth of 0.05 μm. The thickness of the insulating member covering the surface of the separator portion was 5.0 μm.

[0227] Example 7

[0228] A capacitor element was fabricated in the same manner as in Example 1, except that the insulating member was impregnated so as to be arranged in a range from the outermost surface of the cathode lead layer to a depth of 0.1 μm, thereby completing an electrolytic capacitor A7.

[0229] The insulating member disposed within the cathode lead layer was confirmed to be entirely solidified. In the metal paste layer, the ratio of elements derived from the insulating member relative to silver atoms was 67 atomic %. The insulating member was also disposed on the surface of the cathode lead layer. The thickness of the insulating member covering the surface of the cathode lead layer was 5.1 μm.

[0230] An insulating member was placed on the surface of the anode portion and from the outermost surface of the anode portion to a depth of 0.1 μm. The thickness of the insulating member covering the surface of the anode portion was 5.1 μm. Furthermore, an insulating member was placed below the resist tape from the outermost surface of the separator portion to a depth of 0.1 μm.

[0231] Example 8

[0232] A capacitor element was produced in the same manner as in Example 1, except that the insulating member was impregnated so as to be arranged in a range from the outermost surface of the cathode lead layer to a depth of 1.0 μm, thereby completing an electrolytic capacitor A8.

[0233] The insulating member, located from the outermost surface of the cathode lead layer to a depth of 0.9 μm, was confirmed to be a cured product. In the metal paste layer, the ratio of elements derived from the insulating member to silver atoms was 85 atomic %. The insulating member was also located on the surface of the cathode lead layer. The thickness of the insulating member covering the surface of the cathode lead layer was 5.1 μm.

[0234] An insulating member was placed on the surface of the anode portion and from the outermost surface of the anode portion to a depth of 1.0 μm. The thickness of the insulating member covering the surface of the anode portion was 5.1 μm. Furthermore, an insulating member was placed below the resist tape on the surface of the separator portion and from the outermost surface of the separator portion to a depth of 1.0 μm. The thickness of the insulating member covering the surface of the separator portion was 5.1 μm.

[0235] Example 9

[0236] A capacitor element was produced in the same manner as in Example 1, except that the insulating member was impregnated so as to be arranged in a range from the outermost surface of the cathode lead layer to a depth of 5.0 μm, thereby completing an electrolytic capacitor A9.

[0237] The insulating member disposed within the cathode lead layer was confirmed to be entirely solidified. In the metal paste layer, the ratio of elements derived from the insulating member relative to silver atoms was 170 atomic %. The insulating member was also disposed on the surface of the cathode lead layer. The thickness of the insulating member covering the surface of the cathode lead layer was 5.0 μm.

[0238] An insulating member was placed on the surface of the anode portion and from the outermost surface of the anode portion to a depth of 5.0 μm. The thickness of the insulating member covering the surface of the anode portion was 5.0 μm. Furthermore, an insulating member was placed below the resist tape on the surface of the separator portion and from the outermost surface of the separator portion to a depth of 5.0 μm. The thickness of the insulating member covering the surface of the separator portion was 5.0 μm.

[0239] Example 10

[0240] A capacitor element was produced in the same manner as in Example 1, except that the insulating member was impregnated so as to be arranged in a range from the outermost surface of the cathode lead layer to a depth of 10.0 μm, thereby completing an electrolytic capacitor A10.

[0241] The insulating member disposed within the cathode lead layer was confirmed to be entirely solidified. In the metal paste layer, the ratio of elements derived from the insulating member to silver atoms was 276 atomic %. The insulating member was also disposed on the surface of the cathode lead layer. The thickness of the insulating member covering the surface of the cathode lead layer was 4.9 μm.

[0242] An insulating member was placed on the surface of the anode portion and from the outermost surface of the anode portion to a depth of 10.0 μm. The thickness of the insulating member covering the surface of the anode portion was 4.9 μm. Furthermore, an insulating member was placed below the resist tape on the surface of the separator portion and from the outermost surface of the separator portion to a depth of 10.0 μm. The thickness of the insulating member covering the surface of the separator portion was 4.9 μm.

[0243] Example 11

[0244] A capacitor element was produced in the same manner as in Example 1, except that the insulating member was impregnated so as to be arranged in a range from the outermost surface of the cathode lead layer to a depth of 15.0 μm, thereby completing an electrolytic capacitor A11.

[0245] The insulating member, located from the outermost surface of the cathode lead layer to a depth of 12.0 μm, was confirmed to be a cured product. In the metal paste layer, the ratio of elements derived from the insulating member relative to silver atoms was 283 atomic %. The insulating member was also located on the surface of the cathode lead layer. The thickness of the insulating member covering the surface of the cathode lead layer was 5.2 μm.

[0246] An insulating member was placed on the surface of the anode portion and from the outermost surface of the anode portion to a depth of 15.0 μm. The thickness of the insulating member covering the surface of the anode portion was 5.2 μm. Furthermore, an insulating member was placed below the resist tape on the surface of the separator portion and from the outermost surface of the separator portion to a depth of 15.0 μm. The thickness of the insulating member covering the surface of the separator portion was 5.2 μm.

[0247] Comparative Example 1

[0248] An electrolytic capacitor R1 was produced in the same manner as in Example 1 except that the precursor was not impregnated with the insulating member.

[0249] [evaluate]

[0250] (1) Dispersion state of insulating components

[0251] To mount the electrolytic capacitors A1 to A11 produced using the above process on a substrate, they were subjected to a reflow process at a maximum temperature of 235°C in accordance with IPC / JEDEC J-STD-020. The position of the insulating member was then evaluated using Raman spectroscopy. In all electrolytic capacitors A1 to A11, it was confirmed that a portion of the insulating member was dispersed within the first sealing member.

[0252] (2) Bonding strength test

[0253] After forming a coating film of the insulating member on the surface of the lead frame substrate using the above-mentioned insulating member raw material liquid, a molding resin was used to produce a bonding area of ​​50mm. 2 A test piece was tested. A varying load was applied to the test piece, and the shear peel strength was measured when the test piece was peeled from the lead frame. The bond strength between the two-layer structure of the molded resin and the insulating member and the lead frame was 8.5 MPa.

[0254] (3) Electrostatic capacitance and ESR

[0255] The electrolytic capacitors A1 to A11 and R1 manufactured by the above-described operation were evaluated for capacitance and ESR change rate according to the following procedure.

[0256] In an environment of 20°C, a 4-terminal LCR meter is used to measure the initial electrostatic capacitance value C0 (μF) and the initial ESR value X0 (mΩ) of the electrolytic capacitor at a frequency of 100kHz. Then, the rated voltage is applied to the electrolytic capacitor at a temperature of 145°C for 500 hours (heat resistance test). Thereafter, the electrostatic capacitance value C1 (μF) and the ESR value X1 (mΩ) are measured respectively using the same method as above. Thereafter, the value obtained by subtracting the initial electrostatic capacitance value C0 from the electrostatic capacitance value C1 is divided by the initial electrostatic capacitance value C0 and multiplied by 100 times to calculate the rate of change (%) of electrostatic capacitance, and the value obtained by subtracting the initial ESR value X0 from the ESR value X1 is divided by the initial ESR value X0 and multiplied by 100 times to calculate the rate of change (%) of ESR. The results are shown in Table 1.

[0257] [Table 1]

[0258] electrolytic capacitors Change rate of electrostatic capacitance ESR value change rate A1 -55％ 276％ A2 -52％ 267％ A3 -23％ 68％ A4 -22％ 65％ A5 -21％ 53％ A6 -20％ 50％ A7 -19％ 47％ A8 -8％ 38％ A9 -6％ 32％ A10 -4％ 29％ A11 -3％ 27％ R1 -63％ 450％

[0259] In electrolytic capacitors A1-A11, the rate of change in capacitance and ESR before and after the heat resistance test was smaller than in Comparative Example 1. It is believed that in electrolytic capacitors A1-A11, the impregnation of the insulating member (epoxy resin) into the cathode lead layer inhibits contact between air and the solid electrolyte layer, suppressing degradation of the conductive polymer and thereby improving the heat resistance of the electrolytic capacitors.

[0260] Industrial applicability

[0261] The electrolytic capacitor of the present invention can suppress the degradation of the conductive polymer contained in the solid electrolyte layer even when exposed to a high-temperature atmosphere, thereby suppressing the reduction of electrostatic capacitance. In addition, it can also suppress the increase of ESR. Therefore, it can be used for various applications such as applications requiring low ESR and high electrostatic capacitance of electrolytic capacitors and applications exposed to heat. These applications are merely illustrative and are not limited to them.

[0262] Description of Reference Numerals

[0263] 100 Electrolytic capacitor, 110 Capacitor element, 11 Anode body, 12 Dielectric layer, 13 Solid electrolyte layer, 14 Cathode lead layer, 141 Carbon layer, 142 Metal paste layer, 15 Separating member, 21 First insulating member (insulating member), 21a First insulating member arranged inside, 21b First insulating member arranged on the surface, 22 Second insulating member (insulating member), 22a Second insulating member arranged inside, 22b Second insulating member arranged on the surface, 23 Third insulating member (insulating member), 120A Anode lead frame, 120B Cathode lead frame, 130 Outer packaging body.

Claims

1. A capacitor element comprising: Anode, a dielectric layer formed on the surface of the anode body, a solid electrolyte layer covering at least a portion of the dielectric layer, a cathode lead layer covering at least a portion of the solid electrolyte layer, and an insulating member at least partially penetrating into the cathode lead layer, the penetration depth of which is from the outermost surface of the cathode lead layer to a depth of 0.001 μm or more; The insulating member includes a first curable resin, and the first curable resin includes a bisphenol epoxy resin. At least a portion of the insulating member has fluidity at 230° C. or above, The term "having fluidity" means that the melt flow rate measured under conditions of a temperature of 230°C and a load of 2.16 kg in accordance with ISO 1133 is 1 g / 10 minutes or more.

2. The capacitor element according to claim 1, wherein The penetration depth of the insulating member is in the range from the outermost surface of the cathode lead layer to a depth of 0.01 μm or more.

3. The capacitor element according to claim 1 or 2, wherein The insulating member also covers at least a portion of a surface of the cathode lead layer.

4. The capacitor element according to claim 1, wherein The penetration depth of the cured product of the first curable resin is in the range of 0.001 μm or more from the outermost surface of the cathode extraction layer.

5. The capacitor element according to claim 1, wherein The glass transition temperature of the cured product of the first curable resin is 150° C. or lower.

6. A capacitor element comprising: Anode, a dielectric layer formed on the surface of the anode body, a solid electrolyte layer covering at least a portion of the dielectric layer, a cathode lead layer covering at least a portion of the solid electrolyte layer, and an insulating member disposed on at least a portion of either the surface or the interior of the capacitor element; At least a portion of the insulating member penetrates into the cathode lead layer, At least a portion of the insulating member has fluidity at 230° C. or above, The fluidity mentioned above means that the melt flow rate measured at a temperature of 230°C and a load of 2.16 kg according to ISO 1133 is 1 g / 10 minutes or more. The insulating member includes a first curable resin, The glass transition temperature of the cured product of the first curable resin is 150° C. or lower.

7. The capacitor element according to claim 6, wherein At least a portion of the insulating member is disposed on a surface of the cathode lead layer.

8. The capacitor element according to claim 6, wherein The penetration depth of the insulating member is in the range of from the outermost surface of the cathode lead layer to a depth of 0.001 μm or more.

9. The capacitor element according to claim 6, wherein The penetration depth of the insulating member is in the range from the outermost surface of the cathode lead layer to a depth of 0.01 μm or more.

10. The capacitor element according to claim 6, wherein The insulating member includes a first curable resin, The penetration depth of the cured product of the first curable resin is in the range of 0.001 μm or more from the outermost surface of the cathode extraction layer. The capacitor element according to claim 10 , wherein The first curable resin includes a bifunctional epoxy resin.

12. The capacitor element according to claim 10, wherein The first curable resin includes a bisphenol-type epoxy resin.

13. The capacitor element according to claim 1 or 6, wherein The cathode lead layer has a metal paste layer containing a metal material on the outermost surface. At least a portion of the insulating member penetrates into the metal paste layer. In the metal paste layer, a ratio of the element derived from the insulating member to the element derived from the metal material is 65 atomic % or more.

14. The capacitor element according to claim 1 or 6, wherein The anode body includes an anode portion where the solid electrolyte layer is not formed, a cathode portion where the solid electrolyte layer is formed, and a separation portion between the anode portion and the cathode portion. The insulating member is disposed on a surface of the anode portion.

15. The capacitor element according to claim 1 or 6, wherein The anode body includes an anode portion where the solid electrolyte layer is not formed, a cathode portion where the solid electrolyte layer is formed, and a separation portion between the anode portion and the cathode portion. The insulating member is disposed inside the anode portion.

16. The capacitor element according to claim 1 or 6, wherein The anode body includes an anode portion where the solid electrolyte layer is not formed, a cathode portion where the solid electrolyte layer is formed, and a separation portion between the anode portion and the cathode portion. The insulating member is disposed on a surface of the separation portion.

17. The capacitor element according to claim 1 or 6, wherein The anode body includes an anode portion where the solid electrolyte layer is not formed, a cathode portion where the solid electrolyte layer is formed, and a separation portion between the anode portion and the cathode portion. The insulating member is disposed inside the separation portion.

18. The capacitor element according to claim 1 or 6, wherein The anode body includes an anode portion where the solid electrolyte layer is not formed, a cathode portion where the solid electrolyte layer is formed, and a separation portion between the anode portion and the cathode portion. The insulating member is disposed on a surface of the cathode lead layer and a surface of the anode portion.

19. The capacitor element according to claim 1 or 6, wherein The anode body includes an anode portion where the solid electrolyte layer is not formed, a cathode portion where the solid electrolyte layer is formed, and a separation portion between the anode portion and the cathode portion. The insulating member is disposed inside the cathode lead layer, inside the anode portion, and inside the separator.

20. An electrolytic capacitor comprising: The capacitor element according to any one of claims 1 to 19 and The outer package of the capacitor element is sealed.

21. The electrolytic capacitor according to claim 20, wherein The outer packaging body includes a first sealing member, The first sealing member has no fluidity at 230° C. or higher.

22. The electrolytic capacitor according to claim 21, wherein The outer package further includes a second sealing member dispersed in the first sealing member. At least a portion of the second sealing member has fluidity at 230° C. or higher.

23. The electrolytic capacitor according to claim 22, wherein The second sealing member is formed from the insulating member.

24. The electrolytic capacitor according to any one of claims 21 to 23, wherein The insulating member includes a first curable resin, The first sealing member includes a second curable resin, The glass transition temperature of the cured product of the second curable resin is higher than the glass transition temperature of the cured product of the first curable resin.

25. The electrolytic capacitor according to any one of claims 20 to 23, further comprising a lead frame connected to the capacitor element. The lead frame is covered with metal material.

26. The electrolytic capacitor according to claim 25, wherein The insulating member includes a first curable resin, The melting point of the metal material is higher than the glass transition temperature of the cured product of the first curable resin.

27. The electrolytic capacitor according to claim 25, wherein The bonding strength between the insulating member and the metal material is 8.5 MPa or greater.

28. The electrolytic capacitor according to claim 25, wherein The insulating member is disposed at least at a joint portion between the surface of the capacitor element and the lead frame.

29. A method for manufacturing a mounting substrate, comprising: A process for preparing a substrate on which the electrolytic capacitor according to claim 21 or 22 is mounted and The electrolytic capacitor is heated at 230° C. or higher.

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