JPH0364015A - Manufacture of solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain a solid electrolytic capacitor with improved leakage current characteristics and without any reduction in capacity by using acryl resin as an insulation resin and by drying it at a specified temperature. CONSTITUTION:An external lead-out lead 3 which is a metal wire such as tin plating copper wire is welded to an anode tab 6 and acryl resin is clad to a lead-out lead part,. thus preventing adhesion of a semiconductor layer and/or a conductive layer to be formed at a later process. Further, acryl resin which is clad to the lead-out lead part is dried at a specified temperature, hopefully a temperature which is approximately 10deg lower than the melting point of acryl resin or higher, thus enabling acryl resin clad to the lead-out lead to contract and eliminating pin holes generated within the clad acryl resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application J] The present invention relates to a method for manufacturing a solid electrolytic capacitor, and particularly to a method for manufacturing a solid electrolytic capacitor that has good leakage current characteristics and can achieve high capacity. 2. Description of the Related Art A solid electrolytic capacitor has a structure in which a semiconductor layer and a conductor layer are sequentially formed on a valve metal such as aluminum, tantalum, or niobium, which has dielectric oxide film layers on two surfaces. In general, an anode lead is an external lead wire that is led out from the element of a solid electrolytic capacitor to the outside.
This lead wire consists of a lead-out lead portion that is fixed to the valve metal directly or via an anode tab. Therefore, although the anode lead is substantially drawn out from the valve metal, only a part of the lead part of the anode lead has a dielectric oxide film layer on the surface, so the other part has a semiconductor layer and / Or the structure is such that if even a portion of the conductor layer adheres, a short circuit will occur. In order to prevent such short circuits, an insulating resin is applied to the lead portion to prevent the semiconductor layer and/or the conductive layer from directly adhering to the lead portion. Generally, such insulating resins include epoxy resin, modified fluororesin,
Thermosetting resins such as silicone resins and elastic resins such as polybutadiene are known. [Problem to be Solved by the Invention 1] The above-mentioned insulating resin may cause problems if the degassing is insufficient during application or the application method during application is insufficient.
It is not uncommon for pinholes to form, resulting in short circuits when depositing semiconductor and/or conductor layers. Furthermore, if the viscosity of the insulating resin is insufficiently controlled when applying it, the insulating resin may seep into the position where the semiconductor layer is to be formed, resulting in an unexpected decrease in capacity. [Means for Solving the Problems J] As a result of intensive research in order to solve the above-mentioned problems, the present inventors used acrylic resin as the insulating resin, and further, dried this insulating resin at a predetermined temperature. By doing so, the inventors discovered that a solid electrolytic capacitor with good leakage current (hereinafter referred to as LC) characteristics and no decrease in capacity could be produced, and the present invention was completed. That is, the present invention provides a solid electrolytic capacitor in which a dielectric oxide film layer, a semiconductor layer formed by chemical deposition, and a conductive layer are sequentially formed on the surface of an anode body made of a valve metal on which an anode lead is provided. In the manufacturing method, a drawer lead portion of the anode drawer lead is coated with acrylic resin;
Thereafter, the acrylic resin is dried at a predetermined temperature to produce a solid electrolytic capacitor. The present invention will be explained in detail below. As the valve metal used as the anode body of the solid electrolytic capacitor in the present invention, any metal having a valve effect can be used, such as aluminum, tantalum, titanium, and alloys using these as substrates. Foil or a sintered body is used for these anode bodies. The dielectric oxide film layer provided on the surface of the valve metal may be an oxide layer of the valve metal itself provided on the surface portion of the valve metal, or a dielectric oxide layer provided on the surface of the valve metal. Although the layer may be made of another dielectric oxide, it is particularly preferable to use a layer made of an oxide of the valve metal itself. In either case, a conventionally known method such as an anodization method using an electrolytic solution can be used to provide the oxide layer. In Figure 1, a dielectric oxide film layer (not shown) is shown on the surface.
A flat anode tab 6 made of a valve metal such as aluminum is caulked to a valve metal foil 4 having a valve metal foil 4. An external lead 3 made of a metal wire such as a tin-plated copper wire is welded to the anode tab 6.
is led out from the right end of the anode tab 6. The drawer lead portion 2 includes the anode tab 6, and the anode tab 6 is attached to the valve metal foil 4! Refers to the surrounding area where A is attached. This drawer lead part 2 is covered with acrylic resin 5, and the im drawer lead l is composed of the drawer lead part 2 and the external drawer lead 3. In FIG. 2, an external lead 3 is directly welded to the valve metal foil 4 instead of the anode tab 6 of FIG. The part of the external drawer lead 3 connected to this valve metal foil 4 and the part of the valve metal foil 4 around it are called a drawer lead part 2, and this drawer lead part 2 is covered with an acrylic resin 5. ing. Although a valve metal foil is used as the anode body in FIGS. 1 and 2, a sintered body may also be used. The anode lead l is connected to the valve metal foil 4, but generally, after forming a dielectric oxide film layer on the surface of the valve metal foil 4, it is directly connected to the valve metal by caulking, welding, etc. Therefore, it is industrially easier to form the dielectric oxide layer by breaking it. Therefore, in order to repair the broken dielectric oxide film again, it is re-formed by a method such as the anodic chemical formation method described above. Since a portion of the drawer lead portion 2 is made of valve metal, a dielectric oxide film layer is also formed on the surface of the portion of the drawer lead portion 2 during this re-formation. Further, in the present invention, the valve metal itself may be used as an anode lead. In this case, the ゛F conductor layer described later is a valve metal having a dielectric oxide film layer other than the portion predetermined as the anode lead. Formed on metal. As described above, the anode lead is only necessary as an electricity introduction part in order to store charge on the dielectric oxide film layer, and there are no particular limitations on its eaves shape, size, connection position, etc. Next, in the present invention, an acrylic resin is coated on the above-mentioned lead-out lead portion to prevent adhesion of a semiconductor layer and/or a conductive layer to be formed in a later step. Furthermore, the acrylic resin adhered to the drawer lead portion is dried at a predetermined temperature, preferably at a temperature that is approximately 10 degrees lower than the melting point of the acrylic resin. The drying time cannot be specified because it varies depending on the type, concentration, and amount of acrylic resin applied, but it is generally several tens of minutes or more. It goes without saying that the upper limit of the drying temperature of the acrylic resin is the decomposition point of the acrylic resin. Typical examples of acrylic resins include polyacrylic acid, poly-4-biphenylacrylate, poly-t-butyl acrylate, polycesium acrylate, polypentachlorophenylacrylate, polyferrocenylmethyl acrylate, polymagnesium acrylate, poly-3,
5-dimethyladamantyl acrylate, polybotacium acrylate, polysodium acrylate, polyadamantyl methacrylate, poly-t-butyl methacrylate, poly-4-cyanomethylphenyl methacrylate, poly-4-cyanoethyl methacrylate, polyferrocenyl ethyl methacrylate, poly Methacrylic acid, polymethylchloroacrylate, polymethylfluoroacrylate. Polymethyl methacrylate, polyethyl methacrylate, poly-2-naphthyl acrylate. Polyisobutyl chloroacrylate, poly-2-chloroethyl methacrylate, poly-2-cyanoethyl methacrylate, poly-4-methoxycarbonylphenyl methacrylate, poly-3,3-dimethyl-2-butyl methacrylate, polybutyl cyanoacrylate, polycyclohexyl chloro Acrylate, polyethyl chloroacrylate, polyphenyl methacrylate, poly-2-butylphenyl acrylate, poly-4-7-butylphenyl acrylate, poly-4-methoxycarbonylphenyl acrylate, polycyclohexyl methacrylate, polyethyl methacrylate, poly- 1, l, l-
Trifluoro-2-propyl methacrylate, poly-2-
Hydroxypropyl methacrylate, polyisopropyl methacrylate, polypropyl chloroacrylate, polymethylfluoromethacrylate, etc. are used. Incidentally, an appropriate solvent is added to the acrylic resin to adjust the viscosity before use. The semiconductor layer used in the present invention is formed on the conductive oxide film layer described above by a chemical precipitation method. As a chemical precipitation method, for example, a semiconductor layer consisting of lead dioxide or lead dioxide and 6M lead acid is deposited by a chemical precipitation method as described in JP-A No. 62-256423, JP-A No. 63-51621, etc. This method is preferred because the solid electrolytic capacitor produced has good high frequency performance. In addition, a method of forming a conductive polymer compound such as polyaniline or polypyrrole as a semiconductor layer by vapor phase polymerization using an oxidizing agent and an organic acid (Japanese Unexamined Patent Publication No. 62-47109) and a method containing thallium ions and persulfate ions are also available. Is it possible to chemically precipitate thallium oxide as a semiconductor layer from the reaction mother liquor? P. (Japanese Unexamined Patent Publication No. 62-98715) is also an example. Next, for the conductor layer formed on the semiconductor layer, a conventionally known conductive paste such as silver paste is used. The element of the solid electrolytic capacitor configured in this way is, for example, a resin mold, a resin case, a metal exterior case,
It can be made into a general-purpose capacitor product for various uses by resin dipping and laminate film exterior. [Function] When an acrylic resin is applied to the drawer lead portion of the anode drawer lead and then dried at a predetermined temperature, the acrylic resin adhered to the drawer lead portion shrinks. As a result, pinholes that occur in the deposited acrylic resin can be eliminated, and the resin that originally flowed to the position where the semiconductor layer should be formed on the dielectric oxide film layer can be returned to the desired position. can. Therefore, it is possible to prevent defects in LC characteristics due to adhesion of semiconductor layers and/or conductor layers, and to produce a solid electrolytic capacitor without a decrease in capacity. [Example 1] The present invention will be described below with reference to Examples and Comparative Examples. Example: 40μF/cr with dielectric oxide film layer on the surface
An aluminum flat plate with a tin-plated copper wire connected to n'' aluminum etched foil was caulked as an anode tab, and the lead-out leads were coated with the acrylic resin shown in Table 1 and dried at each temperature for about 30 minutes. Next, the etching foil coated with the acrylic resin described above was placed in a mixed solution of a 2.4 mol/e aqueous solution of lead acetate trihydrate and a 4.0 mol/2 aqueous solution of ammonium persulfate up to the surface to which the acrylic resin was applied.
'C for 30 minutes. After the resulting semiconductor layer made of lead dioxide and fM lead acid was sufficiently washed with water, a semiconductor layer was formed using silver paste and sealed with epoxy resin to produce a solid electrolytic capacitor. Comparative Example A solid electrolytic capacitor was produced in the same manner as in the example except that an epoxy resin, a silicone resin, a modified fluororesin, and a polybutadiene resin were used instead of the acrylic resin in the example. Table 1 summarizes the type of resin and drying temperature in each Example and Comparative Example, and Table 2 shows the performance value of the average of 20 points for each of the elements fabricated in each Example and Comparative Example. be. (Leaving space below) Table 1 Table 2 A direct line at tOV in Table 2 [Effect of the invention J] After connecting the anode lead to the valve metal and covering the lead part of the anode lead with acrylic resin, the acrylic resin Since the solid electrolytic capacitor is dried at a predetermined temperature, a solid electrolytic capacitor with good LC characteristics can be produced without a decrease in capacity.

[Brief explanation of drawings]

FIG. 1 is an explanatory view showing an example of an anode lead for explaining the present invention, and FIG. 2 is an explanatory view showing the other side of the anode lead. l...-1 Anode drawer lead 2...Drawer lead part 3...External drawer lead 4...Valve metal foil 5...Acrylic Resin 6... Anode tab

Claims (1)

[Claims] 1. In the method for manufacturing a solid electrolytic capacitor, a dielectric oxide film layer, a semiconductor layer formed by a chemical deposition method, and a conductive layer are sequentially formed on the surface of an anode body made of a valve metal in which an anode lead is provided. Apply acrylic resin to the drawer lead part of the anode drawer lead, and then
A method for manufacturing a solid electrolytic capacitor, which comprises drying this acrylic resin at a predetermined temperature.