JP6362171B2 - Airtight terminal and aluminum electrolytic capacitor using the airtight terminal - Google Patents

Description

  The present invention relates to an airtight terminal used for an electric / electronic device and an aluminum electrolytic capacitor using the airtight terminal.

  A typical hermetic terminal used for a crystal resonator includes a base made of Kovar material (alloy of iron: 54%, nickel: 28%, cobalt: 18%), a lead made of Kovar material, and a base and a lead. It includes a sealed insulating glass and an iron cap that is press-fitted and fixed to the base. A pair of through holes are formed in the base, and the leads are electrically insulated and hermetically sealed by glass so as to penetrate the through holes. In such airtight terminals, electrolytic plating such as solder alloy plating, tin plating, nickel plating, gold plating, etc. is usually applied to the entire surface of the airtight terminals to ensure solderability of the outer leads when mounted on a printed circuit board. The As an electrolytic plating method, a barrel plating method in which a large number of hermetic terminals are housed in a liquid barrel, the barrel is immersed in a plating bath, the barrel is rotated, and a large number of hermetic terminals are plated at once. Is adopted. Moreover, as a method of performing selective plating separately on the base and the lead, such as solder alloy plating, nickel plating, and gold plating, for example, a manufacturing method described in Patent Document 1 has been proposed.

  On the other hand, there is an aluminum electrolytic capacitor as a passive component constituting an electronic circuit. The aluminum electrolytic capacitor is composed of an aluminum foil for a cathode, an electrolytic solution, and capacitor paper using an oxide film formed on the surface of a high-purity aluminum foil for an anode as a dielectric. In particular, a device in which an anode foil and a cathode foil are opposed to each other and a capacitor paper is inserted between both electrodes and wound into a cylindrical shape is called an element. In this state, since the capacitance is very small, when electrolytic paper is impregnated with capacitor paper, the anode foil surface and the cathode foil surface are electrically connected, and the aluminum oxide film on the anode foil surface is used as a dielectric. A capacitor element having a large capacitance can be obtained. (Refer nonpatent literature 1) This electrolyte solution has played the role of the true cathode, and if the polar solvent of electrolyte solution dries up, an aluminum electrolytic capacitor will become a lifetime. In general, an aluminum electrolytic capacitor belongs to a class having the shortest lifetime among components constituting an electronic circuit, and therefore, in recent years, its lifetime has been increased.

  A conventional cylindrical aluminum electrolytic capacitor has a configuration in which a disk-shaped rubber packing is inserted into an opening of a cylindrical case, and the circumference of the case opening is caulked uniformly to seal. Recent electronic circuits are often mounted in narrow gaps in machinery, and in addition to conventional cylindrical aluminum electrolytic capacitors, non-cylindrical irregular package shapes such as flat aluminum electrolytic capacitors with low height Things are increasing. Aluminum electrolytic capacitors using these irregularly shaped packages have a square or elliptical shape at the bottom of the case, making it difficult to seal the case end evenly like conventional disc-shaped rubber packings. ing. Further, the rubber packing is weak against changes with time, and is poor in both airtightness and heat resistance, so it is difficult to cope with a long life of parts.

  As part of extending the life of aluminum electrolytic capacitors, if an airtight terminal can be used in the package that houses the capacitor element, it is possible to prevent electrolyte from drying up, and the case can be easily press-fitted and sealed to the shape of the bottom of the case. It is very convenient because it is not affected. However, conventional hermetic terminals that can be press-fitted and sealed are made by applying an electroplating coating of soft metal such as solder plating, tin plating, nickel plating, gold plating to the base material of iron or iron-base alloy. When the conventional plating film is kept in contact with the electrolytic solution for a long period of time, the dissimilar metal constituting the plating metal or the base metal gradually dissolves in the electrolytic solution and contaminates the capacitor, which cannot be used. It is conceivable to apply aluminum base metal base material and lead material to hermetic terminals, but there is no glass material whose expansion coefficient matches that of aluminum, and high-temperature process where glass sealing of hermetic terminals reaches about 1,000 ° C. For this reason, it was avoided because the aluminum material was dissolved, and it was difficult to put it to practical use.

JP 2004-342649 A

“Aluminum Electrolytic Capacitor Technical Note CAT.1101G”, Nichicon Corporation, 2014, p. 1

  The object of the present invention is to solve the above-mentioned problems, and to realize an airtight terminal in which the terminal metal or the base metal does not contaminate the electrolytic solution even if it is in contact with the electrolytic solution of the aluminum electrolytic capacitor for a long time. It is in.

  In order to achieve the above object, the present invention provides a base terminal and an inner lead surface inside a package in a hermetic terminal in which leads are hermetically sealed with insulating glass so as to penetrate through holes formed in a metal base. The desired surface of the outer lead exposed outside the package is not covered with the aluminum plating layer.

  According to the present invention, it is possible to provide a hermetic terminal excellent in airtightness and reliability without the elution of different metals from the base and inner leads to the electrolyte.

  Furthermore, the inner lead of the hermetic terminal of the present invention is electrically connected to a capacitor element made of an aluminum foil for an anode having an oxide film formed on its surface, electrolytic paper impregnated with an electrolyte, and an aluminum foil for a cathode. An aluminum electrolytic capacitor in which an aluminum case to be covered is hermetically pressure-bonded to a base can be provided.

  In order to realize such a selective plating coating, an airtight terminal in which a lead penetrating a through hole formed in a metal base is hermetically sealed with an insulating glass is prepared, and an inner lead of the airtight terminal and The base is partially immersed in a molten aluminum bath and then lifted, and only the inner leads and the surface of the base are subjected to molten aluminum plating. Thereafter, the hermetic terminal is formed by connecting an aluminum foil for an anode having an oxide film formed thereon, an electrolytic paper impregnated with an electrolytic solution, and an aluminum foil for a cathode to an inner lead, and electrically connecting the capacitor element to the aluminum lead. The case is press-fitted into the base and crimped to assemble the aluminum electrolytic capacitor.

  In addition, as another means for realizing selective plating, an airtight terminal in which a lead penetrating a through hole formed in a metal base is hermetically sealed with insulating glass is prepared, and the entire airtight terminal is melted. Immerse it in an aluminum bath and lift it up, apply molten aluminum plating to the entire surface of the lead and base, then immerse only the outer lead of the lead in an aluminum corrosive solution to peel off the aluminum plating layer of the outer lead exposed outside the package Is. Thereafter, the hermetic terminal is formed by connecting an aluminum foil for an anode having an oxide film formed thereon, an electrolytic paper impregnated with an electrolytic solution, and an aluminum foil for a cathode to an inner lead, and electrically connecting the capacitor element to the aluminum lead. The case is press-fitted into the base and crimped to assemble the aluminum electrolytic capacitor.

  Further, as another means, a base and a lead are prepared by dipping and lifting the entire surface of the metal base and at least the inner side of the lead in a molten aluminum bath, and applying the molten aluminum plating only to the base and the inner lead side, This is sealed with a low softening temperature glass below the melting temperature of aluminum plating, and the lead penetrating the through hole formed in the metal base is hermetically sealed with the insulating glass. Thereafter, the hermetic terminal is formed by connecting an aluminum foil for an anode having an oxide film formed thereon, an electrolytic paper impregnated with an electrolytic solution, and an aluminum foil for a cathode to an inner lead, and electrically connecting the capacitor element to the aluminum lead. The case is press-fitted into the base and crimped to assemble the aluminum electrolytic capacitor.

  According to the present invention, the thick film plating coating of aluminum can be selectively performed on the base of the hermetic terminal and at least the exposed surface of the inner lead. The aluminum plating layer applied to the inner lead preferably has an aluminum purity of 99.5% or more, and preferably has an aluminum purity of 99.8% or more in order to prevent local battery corrosion from being accelerated by voltage load. Should be used. Conventionally, molten aluminum coatings that have been used exclusively for construction materials such as coastal buildings, bolts and nuts, and piping materials for ships, can produce relatively thick aluminum coatings, but they have many surface irregularities. The variability is large and the aluminum purity is low. In order to improve this, it is preferable to use a high-purity ceramic material that does not react with molten aluminum as the tank wall material of the molten aluminum bath.

  As described above, according to the present invention, since the aluminum plating layer is coated on the base of the hermetic terminal and at least the exposed portion of the inner lead, the dissimilar metal from the inner lead even if it contacts the electrolytic solution of the aluminum electrolytic capacitor. The contamination of the electrolyte due to the above can be suppressed, and since there is no aluminum plating layer on the desired surface of the outer lead, the object of securing the solderability of the outer lead portion can also be achieved. In addition, since the aluminum plating layer applied to the base is a soft metal, cold press-fitting of the aluminum case can be used for sealing the capacitor element, and complicated processes such as caulking and bonding are not required.

  Further, the electrolytic corrosion of the lead is prevented by using an aluminum plating layer having an aluminum purity of 99.5% or more, preferably 99.8% or more. This has the effect of suppressing the progress of the local cell reaction of the anode lead that is particularly loaded with a voltage load.

  With this configuration, a compression seal of the airtight terminal can be applied, so that high airtightness and high reliability can be exhibited, and it is possible to prevent the electrolyte from drying up and to greatly extend the life of the aluminum electrolytic capacitor.

The airtight terminal 10 which concerns on this invention is shown, (a) is a top view, (b) is front sectional drawing cut | disconnected along DD of (a), (c) shows a bottom view. The aluminum electrolytic capacitor 20 which concerns on this invention is shown, (a) is a top view, (b) is front sectional drawing cut | disconnected along DD of (a), (c) shows a bottom view. The process flow figure which showed the manufacturing method of the airtight terminal which concerns on this invention, and the aluminum electrolytic capacitor using this airtight terminal is shown, (a) is the process flow figure 30 of the airtight terminal 10, and the process flow figure 30 of the aluminum electrolytic capacitor 20 (B) is a process flow diagram 40 of the hermetic terminal 10 and a process flow diagram 40-2 of the aluminum electrolytic capacitor 20, and (c) is a process flow diagram 50 of the hermetic terminal 10 and process flow of the aluminum electrolytic capacitor 20. FIG. 50-2 is shown.

  Hereinafter, an airtight terminal, an aluminum electrolytic capacitor, and a manufacturing method thereof according to the present invention will be described with reference to the drawings.

  The invention according to claim 1 of the present invention comprises, as shown in FIG. 1, a metal base 11 made of steel or an iron alloy and a steel or iron alloy penetrating a through hole formed in the base 11. In the airtight terminal in which the lead 12 and the lead 12 and the base 11 are hermetically sealed with an insulating glass 13, the base 11 is plated on the base surface, and the lead 12 is plated with aluminum on at least the surface of the inner lead 12-1 inside the package. The lead 12 is an airtight terminal 10 in which a predetermined surface of the outer lead 12-2 exposed to the outside of the package is not covered with an aluminum plating layer.

  As shown in FIG. 2, the invention according to claim 2 of the present invention is an electrolysis in which the inner lead 12-1 according to claim 1 is impregnated with an aluminum foil for an anode having an oxide film formed on the surface thereof, and an electrolytic solution. This is an aluminum electrolytic capacitor 20 in which a capacitor element 15 made of paper and an aluminum foil for cathode is electrically connected, and an aluminum case 16 covering the capacitor element 15 is airtightly pressure-bonded to a base 11.

  The aluminum plating layer of the hermetic terminal 10 of claim 1 and the aluminum electrolytic capacitor 20 of claim 2 according to the present invention preferably has an aluminum purity of 99.5% or more, preferably 99.8% or more. As a result, electrolytic corrosion of the lead can be prevented, and in particular, there is an effect of suppressing the progress of the local battery reaction of the anode lead on which the voltage load is applied.

  The method of applying an aluminum plating layer to the hermetic terminal 10 of claim 1 and the aluminum electrolytic capacitor 20 of the present invention is not limited to a specific method as long as a high-purity aluminum film can be applied to at least the inner lead. For example, the following manufacturing methods of claims 3 to 8 can be suitably used for the aluminum film construction method.

  The invention according to claim 3 of the present invention penetrates through a metal base made of steel or an iron alloy and a through hole formed in the base, as shown in a process flow diagram 30 of FIG. A component transfer step 31 in which a lead and an insulating glass tablet that seals the lead and the base are combined and set in a sealing jig, each component set in the sealing jig is passed through a heating furnace, and the lead and base This is a method for producing the hermetic terminal 10 comprising a glass sealing step 32 for sealing the substrate with insulating glass, and a hot dipping step 33 in which the inner lead and base of the hermetic terminal sealed with glass are dipped in a molten aluminum bath.

  The hermetic terminal 10 manufactured by the method of the process flow diagram 30 is subjected to hot dip aluminum plating only on the surfaces of the inner lead and the base.

  The invention according to claim 4 of the present invention is for an anode in which an oxide film is formed on the inner lead of the hermetic terminal according to claim 3 as shown in a process flow diagram 30-2 of FIG. An element mounting step 34 for electrically connecting a capacitor element made of an aluminum foil, an electrolytic paper impregnated with an electrolytic solution, and an aluminum foil for a cathode, and a press-fitting step 35 for press-fitting an aluminum case covering the capacitor element into a base are assembled. This is a method for manufacturing the aluminum electrolytic capacitor 20.

  In the invention according to claim 5 of the present invention, as shown in a process flow diagram 40 of FIG. 3 (b), a metal base made of steel or an iron alloy and a through hole formed in the base are penetrated. A component transfer step 41 in which a lead made of steel or an iron alloy and an insulating glass tablet for sealing the lead and the base are combined and set in a sealing jig, and each component set in the sealing jig is used in a heating furnace. A glass sealing step 42 in which the lead and the base are sealed with insulating glass, a hot-dip plating step 43 in which the entire glass-sealed hermetic terminal is immersed in a molten aluminum bath, and the entire surface of the lead and base The outer lead aluminum is exposed to the outside of the package by immersing only the outer lead of the molten aluminum plating in an alkaline aluminum corrosion solution. It is a manufacturing method of the hermetic terminal 10 made of plating peeling step 44 for separating the beam plating layer.

  The airtight terminal 10 manufactured by the method of the process flow chart 40 is once applied to the entire surface of the lead and the base, and then hot-dip aluminum plating is performed, and the plating layer of the outer lead is peeled off, so that only the surface of the inner lead and the base is removed. Hot dip aluminum plating is applied.

  The invention according to claim 6 of the present invention is for an anode in which an oxide film is formed on the inner lead of the hermetic terminal according to claim 5 as shown in a process flow diagram 40-2 of FIG. An aluminum foil, an electrolytic paper impregnated with an electrolytic solution, an element mounting step 45 for electrically connecting a capacitor element made of an aluminum foil for cathode, and a press-fitting step 46 for press-fitting an aluminum case covering the capacitor element into a base are assembled. This is a method for manufacturing the aluminum electrolytic capacitor 20.

  According to the seventh aspect of the present invention, as shown in a process flow diagram 50 of FIG. 3 (c), the entire surface of the metal base made of steel or iron alloy and at least the inner of the lead made of steel or iron alloy are provided. A part plating step 51 in which a base and a lead are prepared by immersing the side in a molten aluminum bath and drawing the base and the inner lead only on the base and the inner lead side. The plated lead is used as a through hole in the plated base. A component transfer step 52 in which the lead and the insulating glass tablet made of low softening temperature glass for sealing the base are combined and set in the sealing jig, and each component set in the sealing jig is put into the heating furnace. An airtight terminal comprising a glass sealing step 53 in which the lead and the base are sealed with insulating glass at a temperature not higher than the melting temperature of aluminum plating. 0 method of manufacturing. In addition, you may add the plating peeling process 51-2 to the above-mentioned process flowchart 50 for the purpose of removing the unnecessary part aluminum plating film as needed.

  The hermetic terminal 10 manufactured by the method of the process flow chart 50 is obtained by performing hot-dip aluminum plating on a predetermined surface of a lead and a base, and then sealing both with glass, so that only the surface of the inner lead and base is hot-plated with aluminum. The airtight terminal 10 to which is applied.

  According to an eighth aspect of the present invention, there is provided an anode aluminum foil having an oxide film formed on the inner lead of the hermetic terminal 10 according to the seventh aspect, an electrolytic paper impregnated with an electrolytic solution, and an aluminum foil for a cathode. This is a method of manufacturing the aluminum electrolytic capacitor 20 assembled in the element mounting step 54 for electrically connecting the capacitor elements, and the press-fitting step 55 for press-fitting the aluminum case covering the capacitor elements into the base.

  The molten aluminum bath used in the invention of claims 3 to 8 of the present invention has a wall surface selected from a high purity alumina material, magnesia material, zirconia material, graphite material, or silicon carbide material at least in contact with the molten aluminum. What was made is suitable. A zirconia material or a silicon carbide material is particularly desirable. The temperature of the molten aluminum bath is preferably in the range of 670 to 700 ° C. as the working temperature. Furthermore, by covering the top surface of the molten aluminum solution with an aluminum reducing inorganic molten salt selected from alkali halides, metal halides, phosphates and borates to prevent air contact, voids and icicles can be reduced. The uniformity of the film thickness is also good, which is preferable. When the inorganic molten salt is used, it is preferable to provide a washing step using water or a polar solvent as a cleaning agent after the hot dipping step and the component plating step.

  The present invention can be used for an aluminum electrolytic capacitor package used in an electric / electronic device.

10 ... Airtight terminal,
11 ... Base,
12 ... Lead,
12-1 ... Inner lead,
12-2 ... Outer leads,
13: Insulating glass,
14 ... Aluminum plating layer,
15: Capacitor element,
16 ... Aluminum case,
20 ... Aluminum electrolytic capacitor,
30, 30-2, 40, 40-2, 50, 50-2 ... process flow diagram 51 ... component plating process,
31, 41, 52 ... component transfer process,
32, 42, 53 ... Glass sealing step,
33, 43 ... hot dipping process,
44, 53-2 ... plating peeling process,
34, 45, 54 ... element mounting process,
35, 46, 55 ... press-fitting process.

Claims (4)

In a hermetic terminal in which leads are hermetically sealed with insulating glass so as to penetrate through holes formed in a metal base, an aluminum plating layer is formed on both the entire surface of the base and at least the inner lead surface inside the package. A hermetic terminal characterized in that the desired surface of the outer lead exposed to the outside of the package is not coated with an aluminum plating layer. The hermetic terminal according to claim 1, wherein the insulating glass is glass sealed at a temperature equal to or lower than a melting temperature of the aluminum. Prepare a hermetic terminal in which the lead penetrating the through hole formed in the metal base is hermetically sealed with insulating glass, and immerse the whole hermetic terminal in a molten aluminum bath and lift it up. subjected to molten aluminum plating on the surface and then the production method of the hermetic terminal, characterized in that stripping the aluminum layer of the outer lead which is exposed by immersing only in an aluminum etchant lead outer lead outside the package. A capacitor element made of an aluminum foil for an anode having an oxide film formed on its surface, electrolytic paper impregnated with an electrolytic solution, and an aluminum foil for a cathode is electrically connected to the inner lead inside the package of the hermetic terminal according to claim 3 , A method of manufacturing an aluminum electrolytic capacitor assembled by press-fitting an aluminum case covering a capacitor element into a base.

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