JP2008311615A - Aluminum electrolytic capacitor and manufacturing method thereof - Google Patents

Abstract

An object of the present invention is to provide an aluminum electrolytic capacitor that is practically reliable without leakage of electrolyte even when the pressure in a metal case increases.
A capacitor element 20 formed by winding an anode foil 21 and a cathode foil 22 connected to an external lead wire 29 with a separator 23 interposed therebetween, and a capacitor element 20 having the built-in capacitor element 20 therein. A bottom cylindrical metal case 24 and a sealing member 25 for sealing the opening of the metal case 24 by drawing the opening of the metal case 24 are provided. The external lead wire 29 has a tin plating 28a. The formed external terminal wire 28 is inserted into a hole 27 formed in the center of the round bar portion 26a of the aluminum wire 26, and the aluminum wire 26 and the external terminal wire 28 are joined by forming a tin-aluminum alloy layer 28b. This is an aluminum electrolytic capacitor.
[Selection] Figure 1

Description

  The present invention relates to an aluminum electrolytic capacitor used in various electronic devices and a method for manufacturing the same.

  Conventionally, an external lead wire used in this type of aluminum electrolytic capacitor has been manufactured by a method as shown in FIGS. That is, as shown in FIG. 4 (a), a voltage is applied to the aluminum wire 1 and the copper base tin-drawn iron wire (hereinafter referred to as CP wire) 2, and the round bar portion 1a of the aluminum wire 1 and the CP wire 2 are applied. Are brought into contact with each other to generate a spark 3 between the two 1a and 2 and further push the CP wire 2 into the melted portion of the aluminum wire 1 as shown in FIG. In this way, the external lead wire 4 was manufactured. The external lead wire 4 manufactured by such a manufacturing method includes an overlay portion 5 formed by welding in the vicinity of the joint between the round bar portion 1a of the aluminum wire 1 and the CP wire 2 as shown in FIG. Is formed.

  FIG. 5 shows an aluminum electrolytic capacitor using the external lead wire 4 shown in FIG. 4 (b). In FIG. 5, 6 is a capacitor element, and this capacitor element 6 includes an anode foil 7 and a cathode foil. 8 is wound by interposing a separator 9 therebetween. Reference numeral 10 denotes a metal case made of bottomed cylindrical aluminum containing the capacitor element 6. A sealing member 11 is disposed in an opening of the metal case 10, and the sealing member 11 is an opening of the metal case 10. The opening of the metal case 10 is sealed by drawing the portion so that the diameter is small. 4B, the external lead wire 4 shown in FIG. 4B connects the flat portion 1b of each aluminum wire 1 to the anode foil 7 and the cathode foil 8, respectively, as shown in FIG. The CP wire 2 is drawn to the outside so that the bar portion 1a penetrates the sealing member 11. In this case, the build-up portion 5 formed in the vicinity of the joint between the round bar portion 1a of the aluminum wire 1 and the CP wire 2 described above has a small diameter portion 10a by drawing of the opening of the metal case 10 due to its structure. The metal case 10 is located closer to the opening end.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP 2006-339185 A

  However, the external lead wire 4 in the above-described conventional aluminum electrolytic capacitor has a built-up portion 5 formed in the vicinity of the joint between the round bar portion 1a of the aluminum wire 1 and the CP wire 2 and the aperture of the opening of the metal case 10 Since it is located on the opening end side of the metal case 10 with respect to the small diameter portion 10a by processing, there is a problem that when the pressure in the metal case 10 rises, the electrolyte leaks. That is, when the aluminum electrolytic capacitor is soldered at the time of installation in an electronic device, the electrolytic solution present in the metal case 10 is vaporized by the temperature at the time of soldering and the pressure in the metal case 10 is increased. As shown, the sealing member 11 disposed in the opening of the metal case 10 is bent by the internal pressure. Due to this bending, the opening end side of the metal case 10 widens greatly in the hole 11a through which the round bar portion 1a of the aluminum wire 1 in the sealing member 11 passes. At this time, the built-up portion 5 formed in the vicinity of the joint portion between the round bar portion 1a of the aluminum wire 1 and the CP wire 2 is located closer to the opening end than the small-diameter portion 10a formed by drawing the opening portion of the metal case 10. Therefore, the contact portion between the round bar portion 1a of the aluminum wire 1 and the hole 11a of the sealing member 11 is reduced, and the electrolyte solution vaporized in the metal case 10 leaks from the reduced contact portion. Had. The leakage of the electrolyte greatly affects the life of the aluminum electrolytic capacitor.

  Further, the built-up portion 5 formed in the vicinity of the joint between the round bar portion 1a of the aluminum wire 1 and the CP wire 2 is made by melting aluminum, tin, copper, iron, etc., which are the materials used for them. Since they are joined, tin on the surface causes whiskers, which is a serious problem in practical use.

  The present invention solves the above-mentioned conventional problems, and an object thereof is to provide an aluminum electrolytic capacitor that is practically reliable without leakage of electrolyte even when the pressure in the metal case increases. To do.

  In order to achieve the above object, an aluminum electrolytic capacitor of the present invention comprises a capacitor element formed by winding an anode foil and a cathode foil, to which an external lead wire is connected, with a separator interposed therebetween, and the capacitor A bottomed cylindrical metal case containing the element, and a sealing member for sealing the opening of the metal case by drawing the opening of the metal case, and the external lead wire has a tin on its surface. It consists of a plated external terminal wire and a flattened aluminum wire with a portion of this external terminal wire inserted, and the portion of the external terminal wire inserted into the aluminum wire forms a tin-aluminum alloy layer Thus, an aluminum electrolytic capacitor joined to an aluminum wire is obtained.

  In addition, a capacitor element constituted by winding an anode foil and a cathode foil connected with external lead wires with a separator interposed therebetween is housed in a bottomed cylindrical metal case, In the method of manufacturing an aluminum electrolytic capacitor in which a sealing member is arranged in the opening and the opening of the metal case is drawn to perform sealing, the external lead wire is a hole in the center of one end surface of the aluminum wire. After inserting the external terminal wire with tin plating in the hole, resistance welding electrodes are placed symmetrically on the round bar part of the aluminum wire and heated by resistance, and the aluminum wire is heated by the heat generated in the aluminum wire This is a method of manufacturing an aluminum electrolytic capacitor in which a tin-aluminum alloy layer is formed and joined to the hole and the portion of the inserted external terminal wire.

  According to the aluminum electrolytic capacitor described above, the external terminal wire having a tin plating formed on the surface thereof is inserted into a hole formed in the central portion of the end surface of the aluminum wire, and a tin-aluminum wire is inserted into the hole of the aluminum wire and the inserted external terminal wire. By forming the alloy layer, it is possible to solve the problem that the electrolyte solution leaks without the junction between the round bar portion of the aluminum wire and the external terminal wire rising.

  In addition, since a tin-aluminum alloy layer is formed inside the aluminum wire, the welded portion between the aluminum wire and the external terminal wire is hardly exposed, so that whisker generation can be suppressed and the bonding strength is strong and reliable. High performance aluminum electrolytic capacitors can be obtained.

  Furthermore, resistance heating is performed by placing resistance welding electrodes symmetrically on the round bar portion of the aluminum wire in a state where the external terminal wire formed with tin plating is pushed into the hole formed in the center portion of the end surface of the aluminum wire and resistance heating. Since the aluminum wire can be heated uniformly, a tin-aluminum alloy layer is uniformly formed on the outer peripheral surface of the aluminum wire hole and the external terminal wire. An effect to be suppressed can be obtained.

(Embodiment 1)
Hereinafter, the first and second aspects of the present invention will be described in detail with reference to the first embodiment.

  FIG. 1 is a cross-sectional view of an aluminum electrolytic capacitor according to Embodiment 1 of the present invention. In FIG. 1, a capacitor element 20 is formed by winding an anode foil 21 and a cathode foil 22 with a separator 23 interposed therebetween, and the anode foil 21 and the cathode foil 22 of the capacitor element 20 are respectively drawn out to the outside. Lead wires 29 are connected, and external terminal wires 28 constituting the pair of external lead wires 29 are led out from the capacitor element 20.

  The capacitor element 20 is inserted into a bottomed cylindrical aluminum metal case 24 housed together with a driving electrolyte (not shown), and the outside of the pair of external lead wires 29 drawn out from the capacitor element 20. The opening end of the metal case 24 is sealed with a sealing member 25 having a through-hole through which the terminal wire 28 is inserted, and a drawing process 24 a is performed from the metal case 24 side of the sealing member 25, and the opening end of the metal case 24 is provided. Is a configuration in which the curl processing is performed.

  The present invention is characterized in that the lead wire 29 for external lead is connected to the aluminum wire 26 and the external terminal wire 28 constituting the lead wire 29, and the configuration will be described below with reference to the drawings.

  2A, 2B, 2C, and 2D sequentially show a method for manufacturing the external lead wire 29 according to the first embodiment of the present invention. First, as shown in FIG. 2 (a), a drilling shaft 30 is prepared for drilling the end face of the round bar portion 26a of the aluminum wire 26, and as shown in FIG. 2 (b), the aluminum wire A hole 27 as shown in FIG. 2C is formed by pushing the hole machining shaft 30 into the end face of the round bar 26a.

  Thereafter, as shown in FIG. 2 (d), the external terminal wire (copper base tin-drawn iron wire) 28 is pushed in along the hole 27 formed in the round bar portion 26a of the aluminum wire 26, and the round bar of the aluminum wire 26 is pressed. The resistance welding electrodes 31 are arranged on the left and right sides of the portion 26a, and electricity is supplied from a resistance welding machine to heat the round bar portion 26a of the aluminum wire 26. 27, tin of the external terminal wire (copper-based tinned iron wire) 28 melts to form an alloy layer with aluminum, and the aluminum wire 26 and the external terminal wire (copper-based tinned iron wire) 28 are connected.

  By connecting the round bar portion 26 a of the aluminum wire 26 and the external terminal wire (copper base tin-drawn iron wire) 28 in this way, an external lead wire 29 is configured.

  Here, the melting point of tin used for the external lead wire is 232 ° C., the melting point of aluminum is 660 ° C., the melting point of copper is 1083 ° C., and the melting point of iron is 1539 ° C.

  In the resistance welding, by arranging the resistance welding electrodes 31 symmetrically with respect to the round bar portion 26a of the aluminum wire 26, only the round bar portion 26a of the aluminum wire 26 can be heated uniformly. By setting the temperature of the round bar portion 26a to a temperature close to the melting point of aluminum, tin diffuses with aluminum and only a tin-aluminum alloy layer can be formed.

  The aluminum wire 26 has a flat portion 26b in addition to the round bar portion 26a, and is connected to the anode foil 21 or the cathode foil 22 by needle caulking, ultrasonic welding, cold welding or the like.

  The flattened portion 26b of the aluminum wire 26 is formed after connecting the external terminal wire (copper base tinned iron wire) 28, or formed before connecting the external terminal wire (copper base tinned iron wire) 28. Also good.

  The flattened portion 26b of the aluminum wire 26 can be formed by flattening a predetermined portion of the round bar portion 26a of the aluminum wire 26 by pressing, and further cutting the flat outer peripheral portion.

  Further, as the external terminal wire 28, a nickel-base tin-drawn copper wire can be used in addition to the copper-base tin-drawn iron wire.

  The aluminum electrolytic capacitor using the external lead wire 29 configured as described above solves the problem that the electrolyte leaks without the junction between the round bar portion 26a of the aluminum wire 26 and the external terminal wire 28 rising. Can do. In addition, since the tin-aluminum alloy layer is formed in the round bar interior 26a of the aluminum wire 26, whisker generation can be suppressed and a highly reliable aluminum electrolytic capacitor with high bonding strength can be obtained. .

  In addition, the resistance welding electrode 31 is symmetrical to the left and right of the round bar portion 26a of the aluminum wire 26 in a state where the external terminal wire 28 formed with tin plating is pushed into the hole 27 formed in the center of the round bar portion 26a of the aluminum wire 26. Is placed and resistance-heated to form a tin-aluminum alloy layer by the heat generated in the round bar portion 26a of the aluminum wire 26 so that the external terminal wire 28 can be joined to the aluminum wire 26. The aluminum alloy layer is uniformly formed on the outer peripheral surface of the external terminal wire 28, so that the effect of suppressing the occurrence of whiskers can be obtained without the build-up portion of the joint portion.

(Embodiment 2)
Hereinafter, the first aspect of the present invention will be described in detail with reference to the first embodiment.

  In the first embodiment, an aluminum electrolytic capacitor is obtained in the same manner as in the first embodiment except that the connection between the aluminum wire 26 of the external lead wire 29 and the external terminal wire 28 is connected by laser irradiation. It is.

  That is, the end face of the round bar portion 26a of the aluminum wire 26 is subjected to hole machining, and the external terminal wire (copper-based tin-drawn iron wire) 28 is pushed along the formed hole 27, as shown in FIG. A laser oscillator 32 is arranged on the round bar portion 26a of the aluminum wire 26, and the round bar portion 26a of the aluminum wire 26 is heated by laser irradiation. The iron wire 28 is melted to form an alloy layer with aluminum, and the aluminum wire 26 and the external terminal wire (copper base tin-drawn iron wire) 28 are connected.

  Here, since the alloy layer of tin-aluminum must be uniformly formed on the outer peripheral surface of the external terminal wire 28, it is preferable that laser irradiation is performed from above and below or from the left and right of the round bar portion 26a of the aluminum wire 26.

  The intensity of the laser irradiation is controlled such that the temperature of the round bar portion 26a of the aluminum wire 26 is a temperature below the melting point of aluminum. If the laser irradiation is too strong, the round bar portion 26a of the aluminum wire 26 is melted and the quality of the lead wire 29 for external lead is lost, or the tin-aluminum alloy layer is not uniformly formed, and the bonding strength is weakened.

  The temperature of the aluminum wire 26 is controlled by an infrared sensor or the like, and the information is fed back to the laser device to adjust the energy intensity of laser irradiation.

  As in the first embodiment, the aluminum electrolytic capacitor using the external lead wire 29 configured in this manner is electrolytic without causing the joint between the round bar portion 26a of the aluminum wire 26 and the external terminal wire 28 to rise. The problem of liquid leakage can be solved. In addition, since the tin-aluminum alloy layer is formed in the round bar interior 26a of the aluminum wire 26, whisker generation can be suppressed and a highly reliable aluminum electrolytic capacitor with high bonding strength can be obtained. .

  In each of the above embodiments, the aluminum electrolytic capacitor using the driving electrolytic solution has been described, but the present invention is not limited to this, for example, polypyrrole, polyethylenedioxythiophene, polyaniline, etc. instead of the driving electrolytic solution. Even in an aluminum solid electrolytic capacitor using the conductive polymer, an effect of suppressing the generation of whiskers is obtained.

  As described above, in the aluminum electrolytic capacitor of the present invention, the tin-plated external terminal wire is inserted into the hole formed in the central portion of the round bar of the aluminum wire, and the tin-aluminum is interposed between the aluminum wire and the external terminal wire. By forming and joining the alloy layer, it is possible to solve the problem that the electrolytic solution leaks without the joining portion of the round bar portion of the aluminum wire and the external terminal wire rising. Further, since the tin-aluminum alloy layer is formed inside the round bar of the aluminum wire, whisker generation can be suppressed, and an aluminum electrolytic capacitor with high bonding strength and high reliability can be obtained.

Sectional drawing which shows the whole structure of the aluminum electrolytic capacitor in Embodiment 1 of this invention Process drawing showing the manufacturing method of the external lead wire Sectional drawing which shows the connection method of the external extraction lead wire and aluminum wire in Embodiment 2 of this invention Process diagram showing a conventional method for manufacturing external lead wires for aluminum electrolytic capacitors Sectional view showing the overall structure of the aluminum electrolytic capacitor Sectional drawing which shows the whole structure of the state in which the pressure in a metal case rose in the aluminum electrolytic capacitor

Explanation of symbols

20 Capacitor element 21 Anode foil 22 Cathode foil 23 Separator 24 Metal case 24a Metal case drawing part 25 Sealing member 26 Aluminum wire 26a Aluminum wire round bar part 26b Aluminum wire flat part 28 External terminal line 29 External lead wire

Claims (3)

A capacitor element configured by winding an anode foil and a cathode foil connected with external lead wires with a separator interposed therebetween, a bottomed cylindrical metal case containing the capacitor element, and the metal A sealing member that seals the opening of the metal case by drawing the opening of the case. The external lead wire has an external terminal wire with a tin plating on the surface, and one of the external terminal wires. An aluminum electrolytic capacitor comprising a flattened aluminum wire having a portion inserted therein, wherein the portion of the external terminal wire inserted into the aluminum wire forms a tin-aluminum alloy layer and is joined to the aluminum wire. A capacitor element constituted by winding an anode foil and a cathode foil to which an external lead wire is connected with a separator interposed therebetween is housed in a bottomed cylindrical metal case, and an opening of the metal case In the method of manufacturing an aluminum electrolytic capacitor in which a sealing member is provided and sealing is performed by drawing the opening of the metal case, the external lead wire is provided with a hole at the center of one end surface of the aluminum wire. After pushing the external terminal wire with tin plating in the hole, resistance welding electrodes are placed symmetrically on the round bar part of the aluminum wire and heated by resistance, and the hole of the aluminum wire is generated by the heat generated in the aluminum wire And a method of manufacturing an aluminum electrolytic capacitor in which a tin-aluminum alloy layer is formed and joined to the portion of the inserted external terminal wire. The method for producing an aluminum electrolytic capacitor according to claim 2, wherein the aluminum wire is heated by laser irradiation instead of resistance heating to heat a round bar portion of the aluminum wire.

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