JP2006176841A - Anode conducting wire for electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tantalum or niobium (Nb) anode conducting wire which can fulfill a function as a conducting wire for an entire anode body because a substantial contact area between an anode conducting wire and an anode body can be increased and smoothness at corners can be improved and consequently stable fixing on the anode body can be done. <P>SOLUTION: The anode conducting wire for an electrolytic capacitor is composed of tantalum or niobium material and has a tape-shaped form whose corners have a curved surface shape having a roundness. The tape-shaped form usually is 10 to 500μm in thickness and 0.5 to 5 mm in width, and further, a cross-sectional form in a width direction is, preferably, a quadrangle having a roundness at a corner, an ellipse or a deformed quadrangle having different r-values. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an anode lead for an electrolytic capacitor, and an anode for an electrolytic capacitor and an electrolytic capacitor using the same.

  Conventionally, an anode conductor (wire) is usually used for an electrolytic capacitor. In the case of a tantalum (Ta) conductor, two methods are common, and one is manufactured by a method of processing from a tantalum ingot. That is, the tantalum powder is melted to form an ingot, then forged and rolled, and then slitting or groove rolling is performed. Since the melting point of tantalum is 3000 ° C., most impurities are removed by evaporation. The other is a method in which tantalum powder is press-molded by powder metallurgy, a sintered body obtained by sintering is rolled, and then slitting or groove rolling is performed. Although this method does not dissolve, it is somewhat difficult in terms of purity, but has the advantage of easily controlling the characteristics by uniformly mixing the necessary additives. Although the tantalum anode conductor manufactured by such a method has a so-called round cross section, a flat strip (tape-shaped) conductor has recently been proposed for the purpose of increasing the contact area with the anode body. (Patent Document 1). However, such an improved conducting wire is not easy to fix to the anode body as compared with the round shape, and has a difficulty in formability. That is, burrs are likely to occur in the corner portion during slitting, and the improvement of the smoothness of the corner portion becomes a problem, and the improvement of the smoothness of the corner portion becomes a problem also in roll processing.

DE 10040853

  The present invention solves the above-mentioned problems, can increase the substantial contact area between the anode conductor and the anode body, and can improve the smoothness of the corner portion, and as a result, can be stably fixed to the anode body. Therefore, the present invention provides a tantalum or niobium (Nb) anode lead that can be sufficiently exerted.

The present invention provides the following inventions in order to solve the above problems.
(1) An anode lead for an electrolytic capacitor made of a tantalum or niobium material, having a tape-like shape, and having a curved surface with a rounded corner portion;
(2) The anode lead wire for electrolytic capacitors according to (1), wherein the cross-sectional shape in the width direction of the lead wire is an ellipse or a quadrilateral having rounded corners;
(3) The anode lead wire for an electrolytic capacitor according to (2), wherein the corners of each corner portion may have different radiuses;
(4) The anode conductor for an electrolytic capacitor according to any one of (1) to (3), wherein the cross section in the width direction has a thickness of 10 to 500 μm and a width of 0.5 to 5 mm;
(5) The anode lead for an electrolytic capacitor according to any one of (1) to (4), wherein the tantalum or niobium material contains 0.01 to 3 ppm of a rare earth element;
(6) The anode lead for an electrolytic capacitor according to (5), wherein the rare earth element is selected from one or more of yttrium, neodymium, or cerium;
(7) The anode lead for an electrolytic capacitor according to any one of (1) to (6), wherein the tantalum material further contains 10 to 500 ppm of one or more of tungsten, molybdenum, or niobium;
(8) The anode lead for an electrolytic capacitor according to any one of (1) to (6), wherein the niobium material further contains 10 or 500 ppm of one or more of tungsten or molybdenum;
(9) An electrolytic capacitor anode comprising the conductive wire according to any one of (1) to (8); and (10) An electrolytic capacitor comprising the electrolytic capacitor anode according to (9),
It is.

  According to the tantalum or niobium anode conductor of the present invention, the contact area with the anode body can be increased, and the smoothness of the corner portion can be improved. As a result, the entire anode body can be stably fixed to the anode body. The function as a lead wire can be fully exhibited.

  The anode conductor for an electrolytic capacitor of the present invention is made of a tantalum or niobium material, has a tape shape, and has a curved shape with a rounded corner portion. The tape shape varies depending on the application, but is usually 10 to 500 μm in thickness and 0.5 to 5 mm in width. And the cross section of this conducting wire in the width direction is usually a quadrilateral, and the corner portion needs to have a curved surface shape with a rounded shape. The corner portion is, for example, a four-corner portion when the cross section is a quadrilateral, and the curved surface shape can be freely formed with respect to each corner, so that one to four rounds can be given. The radius size of each corner is arbitrary, and may be the same radius value or different radius values. Usually, the radius value (curvature radius) is 0.01 mm or more and can be managed. Therefore, the lead wire of the present invention can adopt various shapes such as a quadrilateral having a round cross section in the width direction, an ellipse, and a deformed quadrangle with each round value changed. Further, the surface roughness of the portion having a curved surface shape can be arbitrarily selected from a general roll processing finish level to a surface having a small roughness by polishing, etching, or the like, if necessary.

  In the present invention, for example, the following method can be adopted to form a curved surface shape with a rounded corner.

When a tape-shaped conductor is manufactured by a rolling method, a coiled Ta or Nb foil is slit, and roll processing is performed using this to impart a radius to the corner portion of the tape-shaped conductor. In this case, a predetermined radius can be imparted by controlling the corner portion of the roll mold.

When manufacturing a tape-shaped lead wire by roll processing, a material that has been processed to a fine wire by forging and / or roll processing is given a round to the corner portion of the tape-shaped lead wire by final roll processing. Also in this case, a predetermined radius can be imparted by controlling the corner portion of the roll mold.

When manufacturing a tape-shaped conducting wire by roll processing, it is possible to give a radius to the corner portion of the tape-shaped conducting wire at the stage of processing to a fine wire by forging and / or roll processing and to control the dimensions in the final roll.

  In the present invention, a tantalum or niobium material used as a raw material for producing an anode lead for an electrolytic capacitor can be obtained by a conventional method. For example, a method for producing tantalum or niobium powder is a method of reducing a metal salt containing tantalum or niobium such as potassium tantalum fluoride or potassium niobium fluoride at a high temperature of 700 ° C. or higher using sodium, potassium, etc. in a diluted salt. Is common. Such diluted salts include potassium fluoride, potassium chloride, sodium chloride or mixtures containing them.

  The tantalum or niobium material of the present invention is usually obtained by adding a rare earth element to the tantalum or niobium material thus obtained. The rare earth element is preferably added alone or as an oxide. For example, when the raw material powders are blended, they can be weighed and blended together. Such rare earth elements include scandium (Sc), yttrium (Y) and lanthanoid 15 elements, ie, lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (atomic number 57-71) Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium ( Lu), and one or more of yttrium, neodymium, or cerium is preferably selected. The content of these rare earth elements is selected from 0.01 to 3 ppm, preferably 0.05 to 1 ppm. If it exceeds 3 ppm, there is a risk of increasing the leakage current of the capacitor, while it is less than 0.01 ppm. It is difficult to exert the effect of suppressing grain coarseness.

  In one aspect of the present invention, the tantalum material preferably further contains 10 to 500 ppm of one or more of tungsten, molybdenum or niobium in order to further improve the insert characteristics during press (pressurization) molding as will be described later. It is. Similarly, the niobium material preferably further contains 10 to 500 ppm of one or more of tungsten or molybdenum. The addition of these elements is preferably simple.

  The anode lead for an electrolytic capacitor according to the present invention can be suitably manufactured by such an ingot method or powder metallurgy method using such a tantalum or niobium material. For example, according to the ingot method, a tantalum or niobium powder containing 0.5 to 3 wt% of a rare earth element is preferably dissolved by electron beam melting to obtain an ingot. In the tantalum or niobium powder, the rare earth element content is from 0.5 to 3 wt% in consideration of conditions such as the melting temperature so that 0.01 to 3 ppm remains in the ingot because the rare earth element evaporates. Selected. Next, the resulting ingot is forged, rolled, and then slitted or groove-rolled to suitably comprise a tantalum or niobium material containing 0.01 to 3 ppm of rare earth elements, and the shape is a tape. A conducting wire can be obtained. Forging, rolling, slitting or groove roll processing itself can be performed by a conventional method. On the other hand, according to the powder metallurgy method, a tantalum or niobium powder containing 0.1 to 1 wt% of a rare earth element is preferably press-molded and then sintered to obtain a sintered body. In the tantalum or niobium powder, the rare earth element content is 0.1% in consideration of conditions such as the sintering temperature so that 0.01 to 3 ppm remains in the sintered body because the rare earth element evaporates during sintering. It is selected from ˜1 wt%. Next, the resulting sintered body is rolled, and then slitted or groove-rolled to obtain a conductive wire made of a tantalum or niobium material containing 0.01 to 3 ppm of rare earth elements and having a tape shape. it can. Rolling, slitting or grooving can be performed by a conventional method. The shape is preferably a quadrilateral cross section in the width direction.

  The conducting wire thus obtained is particularly suitable as an anode for an electrolytic capacitor, and an electrolytic capacitor anode can be prepared by a conventional method. By using the conductive wire of the present invention, high temperature embrittlement can be reduced, the substantial contact area with the anode body can be increased, and, surprisingly, the powder can be formed at the time of molding despite being in the form of a tape. Tantalum which can be fixed to the anode body stably, and as a result, the original characteristics of the conductor can be fully exhibited. Alternatively, a niobium anode lead can be provided.

  An electrolytic capacitor including such an electrolytic capacitor anode can be produced by a conventional method.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.
Example 1
After drying the reaction vessel made of nickel alloy at 130 ° C., using potassium fluoride as a diluting salt, the reaction vessel was dried and then filled into the reaction vessel from a dryer. Thereafter, the lid was closed and the gas was sufficiently replaced with argon gas. This was heated to 800 ° C. and dried, and then potassium tantalum fluoride was reduced using metallic sodium as a reducing agent. After cooling this, the lid was opened, the product was washed with water, and further washed with a mixed acid to obtain a tantalum powder.

After adding about 1 wt% of yttrium oxide to the tantalum powder, melting it with an electron beam at 3000 ° C. or higher to make an ingot, cutting and removing the surface of the ingot, press forging up to 30 mm, and then using a roll rolling machine, 0.15 mm Rolled to. Finally, it was cut to a predetermined width (2 mm) with a slitting machine to produce a tape-shaped conductor (cross section 0.15 × 2 mm). Roll processing was performed using this, and the radius shown in FIG. 1 was given to the corner portion of the tape-shaped conductor while controlling the corner portion of the roll mold. That is, FIG. 1 is a schematic sectional view of the tape-shaped anode lead (1), radius R ₁ of the four corner _portions, R _2, R ₃ and R ₄ were the same.
Tantalum powder and organic binder resin were mixed and filled into a mold of a pressure molding machine, and one end of the tape-shaped lead wire was inserted therein and pressure molded into a specific shape. Next, the organic binder resin is removed by heating at 400 ° C. in an argon stream, and further subjected to high-temperature heat treatment (about 1350 ° C.) in a high vacuum atmosphere furnace (˜ <10 ⁻⁵ Torr) to obtain a porous sintered body. Obtained. Insert properties and sintering properties were significantly improved. Subsequently, this porous sintered body was anodized in an aqueous phosphoric acid solution as an anode, and a dielectric film was formed on the surface. Thereafter, a solid electrolyte layer, a carbon layer and a metal layer were laminated on the dielectric film to obtain a solid electrolytic capacitor element.

  This capacitor element can be further connected to a lead frame by a conventional method and molded with a thermosetting synthetic resin to form a tantalum solid electrolytic capacitor.

  When the tape-shaped anode conductor of the present invention is used, the substantial contact area with the anode body can be increased, and the smoothness of the corner portion can be improved. As a result, the anode can be stably fixed to the anode body. The present invention provides a tantalum or niobium anode conductor that can sufficiently function as a conductor of the entire body.

The cross-sectional schematic of a tape-shaped anode conducting wire.

Explanation of symbols

  1 Tape-like anode conductor

Claims (10)

  An anode lead for an electrolytic capacitor, which is made of a tantalum or niobium material, has a tape shape, and has a curved shape with a rounded corner portion.   2. The anode lead for an electrolytic capacitor according to claim 1, wherein the cross-sectional shape in the width direction of the lead is an ellipse or a quadrangle having rounded corners.   The anode lead for an electrolytic capacitor according to claim 2, wherein each corner portion may have a different radius.   The anode conductor for an electrolytic capacitor according to any one of claims 1 to 3, wherein a cross section in the width direction has a thickness of 10 to 500 µm and a width of 0.5 to 5 mm.   The anode lead for an electrolytic capacitor according to any one of claims 1 to 4, wherein the tantalum or niobium material contains 0.01 to 3 ppm of a rare earth element.   The anode conductor for an electrolytic capacitor according to claim 5, wherein the rare earth element is selected from one or more of yttrium, neodymium, and cerium.   The anode lead for an electrolytic capacitor according to any one of claims 1 to 6, wherein the tantalum material further contains 10 to 500 ppm of one or more of tungsten, molybdenum or niobium.   The anode lead for an electrolytic capacitor according to any one of claims 1 to 6, wherein the niobium material further contains 10 or 500 ppm of one or more of tungsten or molybdenum.   An anode for an electrolytic capacitor, comprising the conducting wire according to claim 1.   An electrolytic capacitor comprising the anode for an electrolytic capacitor according to claim 9.

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