JP4596939B2 - Manufacturing method of three-terminal solid electrolytic capacitor element - Google Patents

Description

  The present invention relates to a method for manufacturing a solid electrolytic capacitor element, and more particularly to a method for manufacturing a three-terminal solid electrolytic capacitor element that can realize low impedance in a wide frequency range and exhibits high noise removal characteristics.

  The driving frequency of the power supply is increasing as the electronic equipment becomes smaller, faster, and digitized. In addition, the importance of removing noise generated from a switching power supply or various electronic devices is increasing.

  Conventionally, electrolytic capacitors have been widely used for the purpose of removing noise generated from devices. As shown in FIG. 1, the noise can be removed by connecting a two-terminal capacitor in parallel between the power source and the device. However, this method can only remove noise having a frequency near the resonance point unique to each capacitor. In particular, in the high frequency region, the impedance increases due to the inductances L and L ′ of the anode and cathode lead wires, so a large number of various capacitors must be used in parallel to deal with a wide frequency region. There wasn't.

  On the other hand, a three-terminal capacitor shown in FIG. This capacitor reduces the inductance due to the anode lead wire in the high frequency region by making the anode plate a part of the circuit directly.

  Since the center conductor of the three-terminal capacitor becomes a part of the conducting wire, a structure in which the cathode completely covers the center conductor like the shield wire is preferable.

  Patent Document 1 discloses an element having such a structure and a manufacturing method thereof. According to this document, it is shown that the element exhibits a low impedance in a wide frequency range and can remove noise.

  As described above, since the three-terminal capacitor can be used in place of a part of the conductor of the circuit, downsizing and thinning are required.

  The manufacturing method disclosed in Patent Document 1 is useful because the anode lead portion can be prevented from being immersed in the cathode forming solution by making the element shape a special shape such as a U shape or a U shape. Although it is a method, since the shape is complicated, many materials are wasted and it is uneconomical.

  Moreover, patent document 2 can be illustrated regarding the manufacturing method of a solid electrolytic capacitor. The gist of the present invention is that a step of forming an insulating coating film on the valve metal surface on which the dielectric oxide film is formed, leaving a grid pattern, a step of forming a conductive precoat layer on the grid , A step of forming a polypyrrole film by electrolytic polymerization on the conductive precoat layer, a step of forming a cathode conductive layer with carbon and silver paste on the polypyrrole layer, a step of obtaining a capacitor element by separating for each grid and commercializing Is a method of manufacturing a solid electrolytic capacitor.

  In manufacturing the three-terminal solid electrolytic capacitor element, when the manufacturing method of Patent Document 2 is applied, there is a problem that leakage current failure frequently occurs due to mechanical stress when cutting around the cathode forming portion.

  Moreover, since the solid electrolyte layer is not formed on the cut cross section, the cathode forming portions on the front and back sides are not electrically connected, and the structure preferable as a three-terminal solid electrolytic capacitor element, that is, the outer periphery of the central conductor is a conductor. In order to obtain a structure covered with, a complicated process such as a process of conducting the cathode conductive layer on the front and back with a conductive paste or the like after applying the insulating resin again to the cut cross section is necessary.

JP 2003-1224066 A JP-A-5-159983

  In the manufacture of a small, elongated three-terminal solid electrolytic capacitor element, there are problems as described above, and a more preferable manufacturing method has been desired.

  Accordingly, an object of the present invention is to produce a small and long three-terminal type solid electrolytic capacitor element having a cathode conductive layer disposed on the outer periphery of a central conductor made of a valve metal through a dielectric oxide film with high productivity. It is to provide a method of manufacturing.

  The present invention provides a valve-acting metal foil on which a dielectric oxide film is formed, a step of providing through holes at regular intervals, a valve-acting metal foil sandwiched between adjacent through-holes, forming an anode lead portion and a cathode A capacitor element portion having a portion, affixed from the front and back of the valve-acting metal foil so as to cover the insulating tape with at least part of the anode lead-out portion and the through hole, Insulating tape pasted from the front and back is overlapped in the through-hole, and the insulating tape is crimped to the insulating tape at the overlapped position to insulate the through-hole cross section and the anode lead-out portion, the solid electrolyte in the cathode forming portion Including a step of forming a cathode conductive layer, a step of partially removing the insulating tape formed on the anode lead portion, and a step of cutting a portion where the cross-section of the through-hole is covered to separate each element. It is a manufacturing method of three-terminal type solid electrolytic capacitor element characterized.

  Moreover, the thickness of the said valve action metal foil is 0.15 mm or more and 1.0 mm or less, It is a manufacturing method of the three-terminal type solid electrolytic capacitor element characterized by the above-mentioned.

  Moreover, in the said manufacturing method, in the part which concerns on a through-hole inside from the through-hole end, the length of the part which overlaps the insulating tapes stuck from the front and back within a through-hole is 0.5 mm or more and 1.5 mm or less This is a method for manufacturing a three-terminal solid electrolytic capacitor element.

  The method for producing a three-terminal solid electrolytic capacitor element is characterized in that the step of forming the solid electrolyte includes a step of forming an electropolymerized polypyrrole after forming a conductive precoat layer.

  The conductive precoat layer includes a polypyrrole formed by gas phase chemical polymerization, and is a method for producing a three-terminal solid electrolytic capacitor element.

  In the manufacturing method, when the insulating tape formed on the anode lead portion is partially removed, a distance of 0.3 mm or more and 1.0 mm or less from the end of the cathode forming portion is set, and the insulating tape is removed. This is a method for manufacturing a three-terminal solid electrolytic capacitor element.

  The three-terminal solid electrolytic capacitor element obtained by the method of the present invention is excellent in leakage current characteristics. In addition, according to this manufacturing method, a three-terminal solid electrolytic capacitor element in which a cathode conductive layer is disposed on the outer periphery of a central conductor made of a valve metal via a dielectric oxide film can be manufactured with high productivity. .

  Examples of the valve action metal foil used in the present invention include metal foils that form a dielectric oxide film by oxygen oxidation by heating, oxidation treatment by chemicals, or anodic oxidation by applying a voltage in a liquid. A metal foil made of at least one of titanium, tantalum, niobium and niobium monoxide is preferable. Moreover, as a form of the valve action metal surface, a flat plate may be used, but a surface obtained by chemically or electrochemically etching the surface is preferable. Among these, an electrochemically etched aluminum foil (hereinafter abbreviated as “etched aluminum foil”) is most preferable in terms of price and workability. The thickness of the valve action metal foil is preferably thick to some extent because electricity flows through the central conductor. For example, in the case of etched aluminum foil, the electrical conductivity of aluminum is about 1/3 that of copper. Therefore, the thickness of the central conductor portion of etched aluminum foil is the minimum to replace a copper pattern having a thickness of 0.035 mm. 0.1 mm is necessary, and the thickness of the entire foil including the etching layer is preferably 0.15 mm or more. However, if it is too thick, workability such as drilling and cutting is deteriorated, and material is wasted. For this reason, 0.15 mm or more and 1.0 mm or less are suitable.

  First, a plurality of through holes are provided in the valve-acting metal foil using a punching die. FIG. 3 is a schematic perspective view showing a state in which a through hole is formed in the valve action metal foil. As shown in FIG. 3, through holes 12 are provided at regular intervals in the vertical and horizontal directions relative to the valve action metal foil 11. In the process of the present invention, since the foil is punched in a flat state, a special process for the mold for suppressing deformation of the foil is not required, and the mold can be easily repolished.

  Examples of the shape of the through hole 12 include a rectangle, a chamfered rectangle, and an oval as shown in FIG. In addition, the narrower the gap, the less waste of the material, but if it is too narrow, a conductive polymer or conductive paste film is formed in the through-hole when forming the solid electrolyte or the cathode conductive layer, which is inconvenient. Further, when punching, if the distance between two parallel sides is narrow, that is, if the mold becomes too thin, it is likely to be damaged. Considering these points, the interval between the parallel two sides of the through hole is appropriately 0.5 to 1.5 mm.

  Then, in order to form an oxide film in this through-hole cross section, it forms by a conventionally well-known method. A portion sandwiched between the long sides of the adjacent through holes is a capacitor element portion 21, a central portion is a cathode forming portion, and both ends thereof are anode lead portions.

  Next, the anode lead portion is covered with an insulating tape. FIG. 5 is a schematic perspective view of a valve-acting metal foil that has been subjected to insulation coating with an insulating tape, and a schematic cross-sectional view of the A-A ′ portion. The insulating tape 31 is stuck on both sides of the foil. As shown in FIG. 5, the covering form is affixed from both sides of the valve-acting metal foil by applying an insulating tape so as to cover the anode lead portion and a part of the through hole. The cross section of the through hole is covered by pressing the position where the insulating tapes on the front and back overlap in the through hole.

  As the insulating tape, a material using a silicone-based thermosetting adhesive, an acrylic rubber-based thermosetting adhesive, or the like for a substrate such as polyester, polyimide, polyphenylene sulfide, or the like can be used.

  If the length of the portion covering the through hole is too short, the cross section of the through hole is not sufficiently covered, and the valve metal foil of the anode lead portion and the conductive polymer layer may come into contact with each other, and the leakage current characteristics deteriorate. Sometimes. For this reason, it is appropriate to take a part covering 0.5 mm or more from the end of the through hole to the through hole side. If this part is too long, the material is wasted, so about 1.5 mm or less is preferable.

  Examples of the solid electrolyte layer include conventionally known organic solid conductors such as polyethylene dioxythiophene, polythiophene or a derivative thereof, polypyrrole or a derivative thereof, polyaniline or a derivative thereof, polyphenylene vinylene or a derivative thereof, and a TCNQ complex or a derivative thereof. In the method of forming a solid electrolyte layer, a method of forming a conductive precoat layer and then forming an electrolytic polymerization polypyrrole is preferable. The reason is that by forming a conductive precoat layer and then performing electropolymerization, polypyrrole grows and forms so as to surround the outer periphery of the valve action metal foil that is the central conductor.

  Examples of the conductive precoat layer include a method of immersing and drying in a solvent-soluble polyaniline or polythiophene derivative, a method of chemically polymerizing pyrrole, thiophene, or a derivative thereof. In the former immersion method, a precoat layer is formed. Therefore, many application times are required. On the other hand, the method based on chemical polymerization of pyrrole is preferable because a precoat layer suitable for electrolytic polymerization can be obtained in a small number of times. When chemically polymerizing polypyrrole as a precoat, a method of alternately immersing the valve metal foil in a solution containing an oxidizing agent and a solution containing a pyrrole monomer is common, but in this method, the chemical solution is contaminated. Therefore, by applying an oxidant solution to the valve action metal foil, or by immersing the valve action metal foil in the oxidant solution, and then contacting the valve action metal foil with pyrrole monomer vapor, by using a gas phase chemical polymerization method, Liquid contamination is minimized, and the amount of chemical liquid used can be reduced.

  After forming the solid electrolyte layer, a cathode conductive layer made of a conductive paste is formed by a conventionally known method such as a dipping method. Thereafter, since it is necessary to expose the anode lead portion for connecting the external anode terminal from the anode lead portion covered with the insulating tape, a part of the insulating tape is removed. FIG. 6 is a schematic perspective view after forming the cathode layer and exposing the anode lead portion, and a schematic cross-sectional view of the B-B ′ portion. A part of the insulating tape 31 is removed and the anode lead portion 42 is exposed. In this method, the insulating tape is dissolved or peeled off with a chemical, the method of mechanical peeling, the method of cutting with a blade such as a cutter, the method of cutting mechanically with a rotary tool such as a drill or a router, Examples include a method of cutting with a dicing saw, a method of grinding with a file, and a method of removing by burning or evaporating with a laser or heat. Among these, the method of cutting and removing with a dicing saw is preferable because it can be removed with high accuracy.

  Since the portion where the anode is exposed is too close to the solid electrolyte or the conductive paste layer formed in the cathode forming portion, the leakage current increases, so a separation distance of at least 0.3 mm is necessary. The length is not limited, but if it is too long, the material is wasted or the element shape becomes large.

  Thereafter, the individual elements are separated to complete the three-terminal solid electrolytic capacitor element of the present invention. FIG. 7 is a schematic perspective view showing a cutting part. When the individual elements are separated, it is preferable to cut the cutting portion 51 shown in FIG. In the lateral direction, the insulating tape is cut so as to cross the through hole at the portion where the insulating tape is applied to the through hole and is crimped.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1
A through hole was formed in a lattice shape with a punching die in an etched aluminum foil of 160 mm long × 160 mm wide × 0.15 mm thick formed with a dielectric oxide film. The shape of the through hole was a rectangle of 1 mm × 5 mm, and the interval between adjacent through holes was 1.5 mm in length, that is, the element cathode width of this example was 1.5 mm. The horizontal interval was 5 mm. The number of columns is 15. 900 elements were obtained from one sheet.

  An insulating tape having a width of 6 mm was attached to the valve action metal foil. The insulating tape used is a polyester base material using an acrylic rubber adhesive. This was affixed from both surfaces of the valve action metal foil so that 0.5 mm might be applied to a through-hole. The part hung on the through hole was pressure-bonded from above and below. This was immersed in a chemical conversion solution composed of a 1.5 g / L aqueous ammonium dihydrogen phosphate solution and energized to carry out a chemical conversion treatment.

  A conductive precoat layer was formed on the valve action metal foil by gas phase chemical polymerization of pyrrole. This operation was repeated 4 times.

  In order to repair the dielectric film damaged by the chemical polymerization, the valve action metal foil was immersed in a chemical conversion solution composed of 150 g / L aqueous solution of diammonium adipate and energized to perform a re-chemical conversion treatment. Next, a copper foil tape was stuck on the conductive precoat layer to form a feeding point for electrolytic polymerization.

  A polypyrrole layer was formed on the conductive precoat layer by immersing the sheet in an electrolytic polymerization solution in which pyrrole and a supporting electrolyte were dissolved, and applying current to the feeding point. Next, a carbon paste and a silver paste were sequentially applied as a cathode conductive layer.

  Finally, the insulating tape on the anode part was removed with a dicing saw to expose aluminum, and then the element was separated again with a dicing saw to complete a three-terminal solid electrolytic capacitor element. Table 1 shows the results of measuring the leakage current one minute after applying an electrostatic capacity at a frequency of 120 Hz, an equivalent series resistance at 100 kHz (hereinafter abbreviated as “ESR”), and a rated voltage of 6.3 V. Shown in

Comparative Example 1
As a comparison, an insulating tape was applied to the etched aluminum foil having a length of 160 mm × width of 160 mm × thickness of 0.15 mm at the same position as in the example, and a precoat layer was formed by chemical polymerization of polypyrrole.

  This was punched with a mold. The mold pushed the insulating tape portion, the sheet was greatly deformed, and workability was poor. As in the example, 900 elements were obtained from one sheet.

  The following steps were performed in the same manner as in Example 1 to complete a three-terminal solid electrolytic capacitor element. Table 1 shows the characteristics and workability results of the obtained elements. Capacitance and ESR were the same and both were good results as a capacitor, but the leakage current increased.

Comparative Example 2
Following the method of Patent Document 1, a curved element was fabricated. The number of elements obtained from etched aluminum foil having a length of 160 mm, a width of 160 mm, and a thickness of 0.15 mm was smaller than that of Example 1 and was about 500.

  Polyethylene dioxythiophene was formed as a solid electrolyte layer on each cut out portion of each element, and then a carbon paste and a silver paste were sequentially applied as a cathode conductive layer to complete a three-terminal solid electrolytic capacitor element. Table 1 shows the characteristics and workability results of the obtained elements. As shown in Table 1, the characteristics of the obtained device were the same as those in Example 1.

  By the production method of the present invention, a three-terminal solid electrolytic capacitor element having high noise removal performance at high frequency and low leakage current can be obtained with high productivity.

The circuit schematic diagram which uses a capacitor for noise removal. Schematic diagram of using a three-terminal capacitor to remove noise. The perspective schematic diagram which shows a mode that the through-hole was formed in the valve action metal foil. The shape schematic diagram of a through-hole. The perspective schematic diagram of the valve action metal foil performed to the insulation coating process by an insulating tape, and the cross-sectional schematic diagram of A-A 'part. The perspective schematic diagram after forming a cathode layer and exposing an anode extraction part, and the cross-sectional schematic diagram of a B-B 'part. The perspective schematic diagram which shows a cutting site | part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Valve action metal foil 12 Through-hole 21 Capacitor element part 31 Insulating tape 41 Capacitor element part 42 after cathode layer formation 42 Anode extraction part 51 Cutting part

Claims (3)

A step of providing through holes at regular intervals in a valve action metal foil having a dielectric oxide film formed and having a thickness of 0.15 mm to 1.0 mm, and a valve action sandwiched between adjacent through holes A metal foil is used as a capacitor element part having an anode lead part and a cathode forming part, and an insulating tape is applied from the front and back of the valve action metal foil so as to cover at least a part of the anode lead part and the through hole. In the part related to the inside of the through hole from the end, the insulating tape affixed from the front and back is overlapped with a length of 0.5 mm or more and 1.5 mm or less in the through hole, and the insulating tape is crimped at the overlapped position. A step of insulatingly covering the cross section of the through hole and the anode lead portion, a step of forming a solid electrolyte layer and then a cathode conductive layer on the cathode forming portion, and a separation distance of 0.3 mm or more and 1.0 mm or less from the end of the cathode forming portion. Placed, the step of partially removing the insulating tape formed on the anode lead-out portion, the through-hole cross section by cutting a portion covered, three-terminal solid state, characterized by comprising the step of disconnecting the individual elements Manufacturing method of electrolytic capacitor element. The method for producing a three-terminal solid electrolytic capacitor element according to claim 1 , wherein the step of forming the solid electrolyte includes a step of forming an electropolymerized polypyrrole after forming the conductive precoat layer. The method for producing a three-terminal solid electrolytic capacitor element according to claim 2 , wherein the conductive precoat layer contains polypyrrole formed by gas phase chemical polymerization.

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