JP2011198907A - Multilayer solid electrolytic capacitor and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer solid electrolytic capacitor, capable of preventing the leakage of a molten metal generated when welding an anode, and to provide a method of manufacturing the multilayer solid electrolytic capacitor.SOLUTION: In the multilayer solid electrolytic capacitor, a laminate 8 is configured by laminating capacitor elements (C1, C2 and C3) forming the anodes 6 on one side of a plate-shaped anode element and a cathode consisting of a dielectric film 2, a solid-state electrolytic layer 3 and cathode leading-out layers 4 and 5 on the other side, and the anodes 6 are superposed mutually and welded on a lead terminal 9. In the multilayer solid electrolytic capacitor, when the direction perpendicular in the direction from the anodes 6 to the cathode is used as the cross direction, the two anodes 6 vertically adjoined and superposed in the superposed anodes 6 are welded mutually at centers in the cross direction. In the multilayer solid electrolytic capacitor, the anodes 6 on the upper side are lifted from the anodes 6 on the lower side at both ends in the cross direction and form a storage space in this case, and the molten metals 13 generated from the two anodes 6 in a welding case are stored in the storage space.

Description

  The present invention relates to a multilayer solid electrolytic capacitor and a method for manufacturing the same.

  Conventionally, a capacitor element in a solid electrolytic capacitor has an anode portion made of a valve metal such as aluminum or tantalum as an anode portion, an oxide film layer formed on the other surface as a dielectric film, and a dielectric film. It is known that a cathode part is formed by sequentially forming a solid electrolyte layer, a carbon layer, and a silver layer on the surface of a body membrane (see, for example, Patent Document 1). In general, manganese dioxide, a TCNQ complex, a conductive polymer, or the like is used as the solid electrolyte layer.

  In recent years, in order to realize a large capacity of the solid electrolytic capacitor, a multilayer solid electrolytic capacitor in which a plurality of flat capacitor elements are laminated so as to have a predetermined capacity has been put into practical use (for example, patents). Reference 2). In this multilayer solid electrolytic capacitor, the anode part and the lead terminal of the capacitor element are sandwiched between the upper rotating electrode and the lower rotating electrode for resistance welding, and a current is passed through the anode part and the lead terminal so that the anode parts of the capacitor element and the capacitor The anode part of the element and the lead terminal are welded.

Japanese Patent No. 2996992 JP 2000-68158 A

  However, in general, in the multilayer solid electrolytic capacitor as described above, the anode portions and the anode portions and the lead terminals are welded over the entire width direction of the anode portions, and the anode portions are in close contact with each other without any gap. For this reason, in the conventional multilayer solid electrolytic capacitor, the molten metal generated from the anode part during welding leaks around the anode part and adheres to places other than the welded part of the capacitor element and the lead terminal, When forming the exterior resin, the mold may be damaged. In addition, this may cause a defective appearance of the finished product. And in order to prevent this, it was necessary to provide the special process for removing the leaked molten metal after resistance welding, and had become a factor of manufacturing cost increase.

  In view of the above problems, an object of the present invention is to provide a multilayer solid electrolytic capacitor capable of preventing leakage of molten metal that occurs during welding of an anode part, and a method for manufacturing the same.

  In order to solve the above-described problems, a multilayer solid electrolytic capacitor according to the present invention includes an anode portion on one side of a flat anode element made of a valve metal, a dielectric film, a solid electrolyte layer, and a cathode lead layer on the other side. A laminate type in which m capacitor elements (where m is an integer of 2 or more) are laminated to form a laminate, and the anode portions of the laminate are overlapped and welded onto a lead terminal. A solid electrolytic capacitor in which the direction extending from the anode portion to the cathode portion is a longitudinal direction, and the direction orthogonal to the longitudinal direction is a width direction, n superimposed (where n is 2 or more and m or less) (The integer number) of the anode parts that are stacked adjacent to each other in the vertical direction are welded to each other in the center part in the width direction, and the upper anode part floats up from the lower anode part at both ends in the width direction. Forming Characterized in that the molten metal resulting from the two anode portions in welding the two anode portion is received in the receiving space.

  According to this configuration, since the upper anode part floats from the lower anode part at both ends in the width direction, an accommodation space is formed between the upper anode part and the lower anode part. Can be kept in the accommodating space without leaking out around the anode part. Further, according to this configuration, since the accommodation space between the upper anode part and the lower anode part is filled with the molten metal, high welding strength can be obtained.

  In the multilayer solid electrolytic capacitor, it is preferable that the accommodation space is formed between all anode parts included in the n anode parts.

  According to this configuration, since the molten metal generated during welding can be retained in the accommodation space formed between all the anode portions, leakage of the molten metal can be reliably prevented.

  In the multilayer solid electrolytic capacitor, n is 5 or less, a plane passing through the width direction center where the two anode parts are welded and a width direction end of the lower anode part, and the width direction center Is preferably 5 ° or more and 40 − {(n−2) × 10} ° (where n ≦ 5) or less, and The cross-sectional shape in the width direction of the upper anode portion can be, for example, a U-shape or a V-shape that is bent away from the lower anode portion as it goes from the center portion in the width direction to both ends in the width direction. .

  According to this configuration, an accommodation space having a certain range of sizes can be formed between all the anode portions. As a result, even if there is a variation in the size of the accommodation space, the width direction center where the two anode portions are welded, the plane passing through the width direction end of the lower anode portion, and the width direction center and the upper anode If the angle formed by the plane passing through the width direction end of the part is included in the above range, the molten metal can be reliably retained in the accommodation space. Furthermore, by making the cross-sectional shape of the upper anode part U-shaped or V-shaped, the amount of molten metal that can be retained in the accommodation space can be increased.

  The method for producing a multilayer solid electrolytic capacitor according to the present invention includes an anode part on one side of a flat anode element made of a valve metal, and a cathode part comprising a dielectric film, a solid electrolyte layer and a cathode lead layer on the other side. A multilayer solid electrolytic capacitor in which m capacitor elements (where m is an integer of 2 or more) are laminated to form a laminate, and the anode portions of the laminate are overlapped and welded onto a lead terminal Wherein the direction extending from the anode portion to the cathode portion is the longitudinal direction, and the direction orthogonal to the longitudinal direction is the width direction, n superimposed (where n is 2 or more and m or less) The upper anode part is lifted from the lower anode part at both ends in the width direction, and is accommodated by welding two anode parts, which are superposed adjacent to each other in the vertical direction, among the anode parts of (integer) Forming a space , Characterized in that so as to be accommodated in the accommodating space molten metal resulting from the two anode section.

  According to this configuration, the molten metal generated during welding can be retained in the accommodation space formed between the upper anode part and the lower anode part by raising the upper anode part. It is possible to prevent leakage to the vicinity of the anode portion and adhesion to places other than the welded portion of the capacitor element and the lead terminal. Thereby, it is possible to prevent damage to the mold during formation of the exterior resin and poor appearance of the finished product due to adhesion of the molten metal without providing a special process for removing the molten metal.

  Further, the welding in the above manufacturing method is performed by sandwiching n anode parts and lead terminals between the lower electrode and a disk-like upper electrode disposed opposite to the lower electrode, and n anode parts on the lead terminal. N anode parts are arranged on the lead terminal, and the outer peripheral curved surface of the upper electrode is brought into contact with the center part in the width direction of the anode part located on the uppermost side among the n anode parts. In addition, with the lower electrode in contact with the lead terminal, it is preferable to weld the n anode parts on the lead terminal by applying a predetermined pressure to the n anode parts and the lead terminal and passing a current. .

  According to this configuration, the housing space can be formed simultaneously with the resistance welding process without providing a special process for forming the housing space between the anode portions. Further, according to this configuration, the anode portion can be welded only at the center portion in the width direction by shortening the contact width between the outer peripheral curved surface of the disc-shaped upper electrode and the uppermost anode portion.

  The term “width direction center” in this specification means a portion excluding both ends in the width direction, and includes a position shifted from the “width direction center” in a strict sense.

  ADVANTAGE OF THE INVENTION According to this invention, the lamination type solid electrolytic capacitor which can prevent the leakage of the molten metal which arises in the case of welding of an anode part, and its manufacturing method can be provided.

1A is a top view, and FIG. 2B is a longitudinal sectional view of a capacitor element according to an embodiment of the present invention. 1 is a perspective view of a multilayer solid electrolytic capacitor according to an embodiment of the present invention. It is sectional drawing of the width direction of the anode part in one Embodiment of this invention. It is a side view which shows the state which has arrange | positioned the laminated body in one Embodiment of this invention on a lead terminal. It is a figure which shows the state just before welding of the anode part and lead terminal in one Embodiment of this invention, Comprising: (a) is a side view, (b) is a width direction sectional drawing of an anode part. It is width direction sectional drawing of an anode part which shows the state immediately after welding of the anode part and lead terminal in one Embodiment of this invention.

  An example of a preferred embodiment of the present invention will be specifically described with reference to the drawings. In the following description, the direction from the anode part to the cathode part of the capacitor element is defined as the longitudinal direction, and the direction orthogonal to the longitudinal direction is defined as the width direction.

  FIG. 1A is a top view of a capacitor element used in the multilayer solid electrolytic capacitor according to this embodiment, and FIG. 1B is a longitudinal sectional view. As shown in the figure, the capacitor element C in this embodiment is composed of an anode element 1, a dielectric film 2, a solid electrolyte layer 3, a carbon layer 4, a silver layer 5, and a creeping prevention material 7.

  The anode element 1 is a flat thin plate having a width (w) of 3 mm whose main component is aluminum which is a valve action metal, and one side thereof constitutes an anode portion 6. Dielectric film 2 is an oxide film layer formed on the other surface of anode element 1. The solid electrolyte layer 3 is a layer formed on the surface of the dielectric film 2, for example, by chemical polymerization, electrolytic polymerization, or impregnation of an electrolyte containing a conductive polymer such as polyethylenedioxythiophene (PEDT). It is a formed layer. The carbon layer 4 and the silver layer 5 are cathode lead layers sequentially formed on the surface of the solid electrolyte layer 3, and together with the solid electrolyte layer 3 constitute a cathode portion. The creeping prevention material 7 is a ring-shaped film that is provided between the anode portion 6 and the solid electrolyte layer 3 and insulates and isolates the anode portion 6 and the cathode portion.

  FIG. 2 is a perspective view of the multilayer solid electrolytic capacitor according to the present embodiment. As shown in the figure, the multilayer solid electrolytic capacitor according to this embodiment includes a laminate 8 in which m (m = 3 in this embodiment) capacitor elements are laminated, an anode terminal 9 and a cathode terminal 10. A lead terminal and an exterior resin 11.

  The stacked body 8 is formed by stacking three capacitor elements C1, C2, and C3 in the same direction so that the anode portions 6 overlap each other. The cathode portions of the capacitor elements C1, C2, and C3 and the cathode portion of the capacitor element C1 and the cathode terminal 10 are connected by a conductive paste 12 such as a silver paste.

  Further, the anode parts 6 of the capacitor elements C1, C2, and C3 and the anode part 6 and the anode terminal 9 of the capacitor element C1 on the lowermost side are welded only at the center in the width direction, and the capacitor element C2 (C3) The anode portion 6 is lifted from the anode portion 6 of the capacitor element C1 (C2) at both ends in the width direction.

  Specifically, as shown in FIG. 3, the anode portion 6 of the capacitor element C2 (C3) is separated from the anode portion 6 of the capacitor element C1 (C2) from the center portion in the width direction toward both ends in the width direction. It has a U-shaped cross-sectional shape that bends. Therefore, between the anode part 6 of the capacitor element C2 and the anode part 6 of the capacitor element C1, there is an accommodation space formed by the anode part 6 of the capacitor element C2 being lifted. And this accommodation space is filled with the molten metal 13 which melted out from the anode part 6 of the capacitor elements C2 and C1 during welding. Similarly, an accommodation space is also formed between the anode portion 6 of the capacitor element C3 and the anode portion 6 of the capacitor element C2, and this accommodation space is melted from the anode portion 6 of the capacitor elements C3 and C2 during welding. The molten metal 13 is filled.

  Here, as shown in FIG. 3, the width direction center of the anode part 6 of the capacitor element C3 (C2) and the plane passing through the tip of the one end part in the width direction and the center of the anode part 6 of the capacitor element C2 (C1) in the width direction. If the angle formed with the plane passing through the width direction end is θ and the number of welded anode portions 6 is n (n = 3 in the present embodiment), θ is 5 ° or more and 40 − {(n -2) It is preferable that it is below x10} degree. If θ is included in the above range, the molten metal 13 is surely accommodated in the accommodation space even if the size of the accommodation space formed between the anode portions 6 of the capacitor elements C1, C2, and C3 varies. Can be kept on.

  Next, a manufacturing method of the multilayer solid electrolytic capacitor according to this embodiment will be described.

  First, an anode element 1 made of a thin aluminum plate whose surface is electrochemically roughened is anodized by applying a predetermined voltage in an aqueous solution of ammonium adipate, and a dielectric film which is an oxide film layer on the surface 2 is formed. Next, after the anode element 1 on which the dielectric film 2 is formed is cut into a flat plate shape, an insulating resin is applied around an appropriate position so as to be wound in the circumferential direction to form a scooping prevention material 7, and the anode portion It is divided into a region to be 6 and a region to be the cathode part. Next, the end face portion where the anode element 1 is exposed by the cutting is again subjected to anodizing treatment by applying a predetermined voltage in an aqueous solution of ammonium adipate to form the dielectric film 2 on the cut surface. Thereafter, the solid electrolyte layer 3, the carbon layer 4, and the silver layer 5 are sequentially formed on the surface of the dielectric film 2 to constitute the cathode portion, thereby completing the capacitor elements C1, C2, and C3.

  Subsequently, as shown in FIG. 4, the cathode parts of the capacitor elements C1, C2, and C3 produced by the above method are connected with the conductive paste 12, and the capacitor elements C1, C2, C3 is laminated to produce a laminate 8. And the produced laminated body 8 is arrange | positioned on the anode terminal 9 and the cathode terminal 10. FIG.

  Thereafter, in order to resistance-weld the anode parts 6 of the capacitor elements C1, C2, and C3 and the anode part 6 and the anode terminal 9 of the capacitor element C1, each anode part 6 and anode terminal 9 of the capacitor elements C1, C2, and C3. Is sandwiched between a disk-shaped upper rotating electrode 14 and a disk-shaped lower rotating electrode 15 for resistance welding, and as shown in FIG. 5, the anode portions 6 and the anode terminals 9 of the capacitor elements C1, C2, and C3 are in close contact with each other. Let At this time, the outer peripheral curved surface of the upper rotating electrode 14 is in contact only with the central portion in the width direction of the anode portion 6 of the uppermost capacitor element C3 (see FIG. 5B). The contact width (w2) between the upper rotary electrode 14 and the anode portion 6 of the capacitor element C3 is shorter as the diameter of the upper rotary electrode 14 is smaller.

  Subsequently, in the state shown in FIG. 5, a predetermined pressure is applied to each anode part 6 and anode terminal 9 of the capacitor elements C1, C2, and C3, and a current is allowed to flow. Thereby, as shown in FIG. 6, the center part in the width direction of each anode part 6 of the capacitor elements C1, C2, and C3 is softened and crushed. On the other hand, both end portions in the width direction of the anode portion 6 of the capacitor element C2 (C3) are lifted from the anode portion 6 of the capacitor element C1 (C2) as shown in FIG. Therefore, an accommodation space is formed between the anode portion 6 of the capacitor element C2 and the anode portion 6 of the capacitor element C1, and between the anode portion 6 of the capacitor element C3 and the anode portion 6 of the capacitor element C2. As the current continues to flow, the central portion in the width direction of each anode portion 6 of the capacitor elements C1, C2, and C3 starts to melt. By solidifying the molten metal, the anode portions 6 of the capacitor elements C1, C2, and C3 and the anode portion 6 of the capacitor element C1 and the anode terminal 9 are joined. In addition, since the molten metal (molten metal 13) that does not directly contribute to the bonding remains in the accommodation space, it leaks out to the periphery of the anode portion 6 and places other than the welded portions of the capacitor elements C1, C2, C3 and the anode terminal 9 It will not adhere to.

  Finally, the laminated body 8 is sealed with the exterior resin 11 except for the lower surfaces (connection surfaces with external circuits) of the anode terminal 9 and the cathode terminal 10, so that the laminated solid electrolytic capacitor as shown in FIG. Complete.

  Table 1 shows that a storage space is formed between the anode portions 6 by using the multilayer solid electrolytic capacitor (Examples 1 to 32) according to the present embodiment manufactured by the above method and the upper rotating electrode having a large diameter. It is the table | surface which compared and evaluated the number of inferior goods of the conventional multilayer solid electrolytic capacitor (conventional example) which was made not to be performed. In the evaluation, 1000 multilayer solid electrolytic capacitors according to each of the examples and the conventional examples were manufactured, and the number of defective defective solid electrolytic capacitors was measured in the appearance inspection after welding. The number of defective products is the number of stacked solid electrolytic capacitors in which the molten metal 13 leaks out around the anode portion 6 and adheres to places other than the welded portion of the capacitor element and the anode terminal 9.

In Table 1, “diameter” is the diameter of the upper rotating electrode 14, and “contact width” is the width (w 2 in FIG. 5B) where the upper rotating electrode 14 and the uppermost anode portion 6 are in contact with each other. is there. “Θ _T ” in Table 1 is an angle formed by a plane passing through the center of the uppermost anode portion 6 in the width direction and the tip of one end in the width direction and a plane parallel to the anode terminal 9. The “overlapping number” in Table 1 is the number n of the welded anode portions. In each of the embodiments and the conventional example, the capacitor elements are laminated in the same direction, and therefore the number n of the welded anode portions is the same as the number m of the capacitor elements laminated.

As is clear from Table 1, it can be seen that no defective product was generated in Examples 1 to 32. This is because the diameter of the upper rotating electrode 14 is reduced to shorten the contact width (w2) between the upper rotating electrode 14 and the uppermost anode portion 6, and the anode portion 6 is welded only at the center in the width direction. It is considered that a housing space was formed between the anode parts 6 and the molten metal 13 generated during welding remained there. That, theta _T is attached to the 5 ° or more and 70 ° if included in the scope of the following, where the non-welded portions of the capacitor element and the anode terminal 9 by the molten metal 13 leaks around the anode part 6 Can be surely prevented. On the other hand, in the conventional example, since the accommodation space is not formed between the anode portions 6, the molten metal 13 having nowhere to leak leaks out around the anode portions 6 and is located in places other than the welded portions of the capacitor elements and the anode terminals 9. It is thought that it adhered.

  Of the two anode parts 6 that are stacked adjacent to each other, a plane passing through the width direction center and the width direction end of the upper anode part 6, and the width direction center and the tip of the width direction end of the lower anode part 6 Is not necessarily equal between the anode portions 6 but is preferably within a certain range. That is, when the overlapping number n is 5 or less, θ is preferably 5 ° or more and 40 − {(n−2) × 10} ° or less. If θ is included in the above range, the molten metal 13 can be retained in the accommodation space even if the size of the accommodation space varies. Therefore, θ is 5 ° ≦ θ ≦ 40 ° when the number n of superpositions is 2, 5 ° ≦ θ ≦ 30 ° when the number n of superpositions is 3, and 5 ° when the number n of superpositions is 4. When ≦ θ ≦ 20 ° and the number of overlapping n is 5, it is preferable that 5 ° ≦ θ ≦ 10 °.

  As mentioned above, although the example of preferable embodiment of the multilayer type solid electrolytic capacitor and its manufacturing method which concern on this invention has been demonstrated, this invention is not limited to these structures.

  For example, in the above embodiment, the capacitor elements are stacked in the same direction, but the capacitor elements may be stacked so that the protruding directions of the anode portions 6 are alternately reversed.

  In the above embodiment, the anode parts 6 and the anode part 6 and the anode terminal 9 are welded by resistance welding, but may be welded by a welding method other than resistance welding such as laser welding or ultrasonic welding. .

  Moreover, in the said embodiment, although the disk shaped rotating electrode was used for the lower electrode, you may use a flat electrode.

  Furthermore, in the said embodiment, when welding the anode parts 6 and the anode parts 6 and the anode terminal 9, the accommodation space which can hold | maintain the molten metal 13 is formed. The housing space may be formed before welding by using a capacitor element having a U-shaped or V-shaped cross section as shown in FIG.

C, C1 to 3 Capacitor element 1 Anode element 2 Dielectric film 3 Solid electrolyte layer 4 Carbon layer 5 Silver layer 6 Anode portion 7 Scatter preventive material 8 Laminate 9 Anode terminal 10 Cathode terminal 11 Exterior resin 12 Conductive paste 13 Melting Metal 14 Upper rotating electrode 15 Lower rotating electrode

Claims (6)

A plate-like anode element made of a valve metal has m capacitor elements each having an anode portion on one side and a cathode portion made of a dielectric film, a solid electrolyte layer and a cathode lead layer on the other side (where m is 2 or more) A laminated solid electrolytic capacitor in which a laminated body is formed by stacking, and the anode parts of the laminated body are overlapped and welded onto a lead terminal,
When the direction from the anode part to the cathode part is the longitudinal direction and the direction orthogonal to the longitudinal direction is the width direction, n superimposed anodes (where n is an integer of 2 or more and m or less) The two anode parts, which are superposed adjacent to each other in the vertical direction, are welded to each other at the center in the width direction, and the upper anode part is lifted from the lower anode part at both ends in the width direction to form an accommodation space. And
A multilayer solid electrolytic capacitor, wherein molten metal generated from the two anode parts when the two anode parts are welded is accommodated in the accommodation space.   2. The multilayer solid electrolytic capacitor according to claim 1, wherein the housing space is formed between all the anode portions included in the n anode portions. N is 5 or less,
A plane passing through the widthwise center of the lower anode part and the widthwise end of the lower anode part, and a plane passing through the widthwise end of the upper anode part and the upper anode part where the two anode parts are welded. 3. The multilayer solid electrolytic capacitor according to claim 1, wherein the formed angle is 5 ° or more and 40 − {(n−2) × 10} ° (where n ≦ 5) or less.   The cross-sectional shape in the width direction of the upper anode portion is a U-shape or V-shape bent away from the lower anode portion as it goes from the center portion in the width direction to both ends in the width direction. The multilayer solid electrolytic capacitor according to any one of claims 1 to 3, wherein: A plate-like anode element made of a valve metal has m capacitor elements each having an anode portion on one side and a cathode portion made of a dielectric film, a solid electrolyte layer and a cathode lead layer on the other side (where m is 2 or more) An integral number of layers) to form a laminated body, and stack the anode parts of the laminated body to weld on the lead terminal,
When the direction from the anode part to the cathode part is the longitudinal direction and the direction orthogonal to the longitudinal direction is the width direction, n superimposed anodes (where n is an integer of 2 or more and m or less) Welding two anode parts stacked adjacent to each other vertically in the central part in the width direction,
A laminated solid characterized in that the upper anode part is lifted from the lower anode part at both ends in the width direction to form an accommodation space, and molten metal generated from the two anode parts is accommodated in the accommodation space. Manufacturing method of electrolytic capacitor. The n anode parts and the lead terminals are sandwiched between a lower electrode and a disk-shaped upper electrode disposed to face the lower electrode, and the n anode parts are welded on the lead terminals. A method for producing a multilayer solid electrolytic capacitor according to claim 5,
The n anode portions are arranged on the lead terminal, an outer peripheral curved surface of the upper electrode is brought into contact with the central portion in the width direction of the anode portion located on the uppermost side among the n anode portions, and the lead Welding the n anode parts on the lead terminals by applying a predetermined pressure and applying a current to the n anode parts and the lead terminals with the lower electrode in contact with the terminals. A method for producing a multilayer solid electrolytic capacitor, characterized in that:

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