JP2005311014A - Niobium solid electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a niobium solid electrolytic capacitor capable of suppressing increase in ESR, even if the capacity of the capacitor is enlarged, by shortening the average path, from a dielectric coating up to the cathode drawer layer. <P>SOLUTION: A capacitor comprises an anode terminal (20) electrically connected to each anode lead component (1a) of a capacitor body (15), a cathode terminal (21) which is sandwiched by two capacitor bodies (15) and (15), and is allowed to be an electrically connected state, and exterior resin (7) constituted by covering and integrally molding the two capacitor bodies (15) and (15), the anode terminal (20), and the cathode terminal (21). Each of the parts of the anode terminal (20) and the cathode terminal (21) is exposed from the exterior resin (7). <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

 The present invention relates to a niobium solid electrolytic capacitor using a powder sintered body containing niobium or a niobium compound as a main component as an anode body.

  A solid electrolytic capacitor using a valve metal such as tantalum, niobium, or aluminum is known as shown in FIG. In this solid electrolytic capacitor, for example, an anode lead member (1a) made of tantalum and planted with tantalum powder is sintered as an anode body (1), and the anode body (1) is in an aqueous solution containing phosphoric acid or the like. Then, a dielectric film (2) is formed on the surface of the anode body (1) by anodic oxidation (hereinafter referred to as chemical conversion). Next, a cathode layer (3) made of a conductive inorganic material such as manganese dioxide or a conductive organic material such as a TCNQ complex salt or a conductive polymer is formed on the dielectric film (2), and a carbon layer (4), A metal paste layer (5) containing a metal such as silver or copper is sequentially formed to produce a capacitor body (15). Thereafter, a small amount of silver paste is dropped as a conductive adhesive (8) on a predetermined position of the cathode terminal (21), and the capacitor body (15) is placed thereon, and is thermally cured to form the capacitor body (15 ) And the cathode terminal (21) are electrically connected and fixed. On the other hand, the anode lead member (1a) and the anode terminal (20) are connected by welding. Thereafter, the capacitor body (15) is covered and sealed by injection molding of, for example, an exterior resin (7) with the anode terminal (20) and the cathode terminal (21) led out to the outside. The anode terminal (20) and the cathode terminal (21) led out to the outside are bent along the exterior resin (7) to complete a solid electrolytic capacitor (for example, Patent Document 1).

In recent years, while demands for miniaturization are increasing, demands for higher CPU speed, lower voltage, leveling voltage fluctuation, etc. have increased, and it is expected that capacitor capacity and equivalent series resistance (hereinafter referred to as ESR) will be reduced as much as possible. It has become. In order to increase the product of the capacitance of the capacitor and the rated voltage (hereinafter referred to as CV product), for example, a method of increasing the thickness of the element can be considered, but in this case, the average path from the dielectric film to the cathode lead layer becomes longer and ESR increases. Resulting in. That is, since the specific resistance of the lead frame is a metal, it is several μ to several tens μ [Ω · cm], whereas a solid electrolyte practically used for a solid electrolytic capacitor is several thousand μ to several thousand m [Ω · cm]. Therefore, the length of the solid electrolyte path is an important factor in capacitor performance. This problem is particularly problematic when using a niobium sintered body that is difficult to ensure sufficient thickness and uniformity of pores (hereinafter referred to as pores) between powders formed in the element among valve metals. Become. When niobium oxide, which has a weaker sintering power than niobium and is brittle, is used as the anode body, sintering is performed at a temperature 3 to 400 ° C. higher than that of niobium, so that the pores are further narrowed and the above problem becomes remarkable (for example, Patent Document 2). ).
Japanese Patent Laid-Open No. 10-64761 JP 2003-59763 A

  As a measure to solve this problem, as shown in FIG. 4, two capacitor bodies (15) formed up to the metal paste layer (5) are used in an overlapping manner (hereinafter, divided into two elements). A method of halving the average path to the metal paste layer (5) has been implemented. This is a method conceived from the fact that the metal paste layer (5) has conductivity close to that of metal. That is, the metal paste layer (5) consists of a kneaded metal powder (5a) such as silver and a resin (5b), and the specific resistance of the cured metal paste layer (5) is measured in the length direction of the film. In this case, the conductivity is close to that of metal at several tens of μ [Ω · cm]. However, as shown in FIG. 5, in actuality, a thin film of almost only resin (5b) is formed on the skin of the metal paste layer (5) during curing, and the ratio of the thickness direction of the metal paste layer (5) is reduced. The resistance is significantly higher than the measured value in the length direction. In the case of using the two-element structure as described above, a thin film of only the resin (5b) is connected to the outer skin by the conductive adhesive (8), and as a result, the ESR is reduced by halving the average path. There is a problem that the effect cannot be obtained sufficiently. This problem becomes prominent when the flake-like or flake-like metal powder (5a) is used, and is a major cause of an increase in ESR.

  In view of the above problems, the present invention provides a niobium solid electrolytic capacitor having a low ESR even when the average path from the dielectric film to the cathode lead layer is reduced and the capacity of the capacitor is increased.

 The present invention comprises an anode body (1) made of a powder sintered body containing niobium or a niobium compound as a main component, an anode lead member (1a), and a dielectric film (2) on the surface of the anode body (1). The capacitor body (15) is formed by forming the carbon layer (4) and the metal paste layer (5) on the capacitor element (10) on which the cathode layer (3) is formed. In a niobium solid electrolytic capacitor, the anode terminal (20) electrically connected to each anode lead member (1a) of the capacitor body (15) and the two capacitor bodies (15) (15) are sandwiched. And a cathode terminal (21) electrically connected to each other, and two capacitor bodies (15) and (15), an anode terminal (20), and a cathode terminal (21) are coated and packaged integrally. (7), wherein the anode terminal (20) and the cathode terminal (21) are partially exposed from the exterior resin (7). .

  Further, an anode body (1) made of a powder sintered body mainly composed of niobium or a niobium compound is provided with an anode lead member (1a), and a dielectric film (2), a cathode is formed on the surface of the anode body (1). In the niobium solid electrolytic capacitor comprising the capacitor element (10) formed with the layer (3), the carbon layer (4), and two capacitor elements (10) formed up to the carbon layer, the capacitor element (10 ) Formed on the surfaces of the anode terminal (20) electrically connected to each anode lead member (1a) and the two capacitor elements (10) (10) formed up to the carbon layer, and the two A metal paste layer (5) sharing one surface of the capacitor elements (10), (10), a cathode terminal (21) disposed in the shared metal paste layer (5), and two capacitor elements (10) (10), an anode terminal (20) and a cathode terminal (21) are coated and these are integrally molded Becomes because the fat (7), the anode terminal (20) and the cathode terminal (21) is characterized in that a portion of each exposed from the exterior resin (7).

  By using the present invention, there is no high resistance part by connecting thin film of resin only on the skin of the metal paste layer of two capacitor bodies, so niobium having a low ESR even when two capacitor bodies are connected in parallel A solid electrolytic capacitor can be provided.

  As the material of the anode body used in the present invention, a material mainly containing a niobium compound such as niobium or niobium oxide is used. For example, a mixture of niobium and niobium nitride is included. The anode lead member planted and sintered in these powders is used as an anode body, and the surface of the anode body is a dielectric film, a conductive inorganic material such as manganese dioxide, or a conductive material such as a TCNQ complex salt or a conductive polymer. A capacitor element having a solid electrolyte layer made of an organic material is used.

Examples of the present invention and comparative examples will be described below with reference to the drawings. Both the examples and comparative examples have a rated voltage of 10V. For the metal paste layers of the examples and comparative examples, those obtained by kneading a thin flake-like silver powder and a resin having a thickness of about one-tenth of the diameter were used.
(Example 1)
A longitudinal sectional view of a capacitor element according to the present invention is shown in FIG. Moreover, the longitudinal cross-sectional view of the niobium solid electrolytic capacitor in Example 1 is shown in FIG. An anode body (1) was prepared by sintering 29.5 mg of niobium powder having a CV product of 96000 μFV / g together with an implanted niobium wire having a diameter of 0.3 mm as an anode lead member (1a) into a rectangular parallelepiped having a thickness of 0.85 mm. This is formed in a phosphoric acid aqueous solution at 45 V to form a dielectric film (2), and then polypyrrole is polymerized and deposited on the inside and outside of the element to form a cathode layer (3) made of a solid electrolyte to form a capacitor element ( 10) was produced. Next, a carbon layer (4) was formed with carbon suspension water, and then a silver paste prepared by kneading silver powder and resin was applied and thermally cured to form a metal paste layer (5) to prepare a capacitor body (15).

Thereafter, the cathode terminal (21) is sandwiched between the two capacitor bodies (15) through the conductive adhesive (8) made of silver paste, and each metal paste layer (5) and the cathode terminal (21) are sandwiched. Are electrically connected and fixed. Next, each anode lead member (1a) led out from the capacitor main body (15) is welded to a predetermined position by resistance welding to the anode terminal. Thereafter, the exterior resin (7) is formed by injection molding, and the anode terminal (20) and the cathode terminal (21) are bent along the exterior resin (20), respectively, and the outer shape is 7.3 (length) × 4.3 ( A niobium solid electrolytic capacitor having a width (width) × 2.8 (thickness) mm was produced.
(Example 2)
Except that 47 mg of niobium powder having a CV product of 96000 μFV / g was sintered into a rectangular parallelepiped having a thickness of 1.3 mm, the outer shape 7.3 (length) × 4.3 (width) × was used in the same manner as in Example 1. A 3.8 (thickness) niobium solid electrolytic capacitor was produced.
(Example 3)
External form 10.0 (length) x 6.3 (width) x using the same method as in Example 1 except that 92 mg of niobium powder having a CV product of 96000 μFV / g was sintered into a rectangular parallelepiped with a thickness of 0.85 mm. A 2.8 (thickness) niobium solid electrolytic capacitor was produced.
Example 4
FIG. 3 shows a longitudinal sectional view of the niobium solid electrolytic capacitor in Example 4. An anode body (1) was prepared by sintering 29.5 mg of niobium powder having a CV product of 96000 μFV / g together with an implanted niobium wire having a diameter of 0.3 mm as an anode lead member (1a) into a rectangular parallelepiped having a thickness of 0.85 mm. This is formed in a phosphoric acid aqueous solution at 45 V to form a dielectric film (2) on the surface of the anode body (1), and then polypyrrole is polymerized and deposited inside and around the element to form a cathode layer (3) to form a capacitor element. (10) was produced. Next, a carbon layer (4) is formed with carbon suspension water on the surface of the capacitor element (10), and the two capacitor elements (10) and (10) having the carbon layer (4) are kneaded with silver powder and a resin. Immerse it in a silver paste bath made of material, sandwich the cathode terminal (21) between the two capacitor elements (10) and (10), and dry the cathode terminal (21) to the two capacitor elements (10) and (10). And a metal paste layer (5) in which the two capacitor elements (10) and (10) share one surface. Thereafter, the exterior resin (7) is formed by injection molding, and the anode terminal (20) and the cathode terminal (21) are bent along the exterior resin (7), respectively, and the outer shape is 7.3 (length) × 4.3 ( A niobium solid electrolytic capacitor having a width (width) × 2.8 (thickness) mm was produced.
(Comparative Example 1-1)
A capacitor body is prepared in the same manner as in Example 1, and the capacitor body is placed on the bent cathode terminal and electrically connected and fixed by a conductive adhesive. Next, the anode lead member led out from the capacitor body is welded to a predetermined position by resistance welding to the anode terminal. Thereafter, an exterior resin is formed by injection molding, and the anode terminal and the cathode terminal are bent along the exterior resin, respectively, so that the outer shape is 7.3 (length) × 4.3 (width) × 1.8 (thickness) mm. A niobium solid electrolytic capacitor was produced.
(Comparative Example 1-2)
A capacitor body is prepared in the same manner as in Example 1, the silver layers of the two capacitor bodies are connected with a conductive adhesive made of silver paste, and the two connected capacitor bodies are bent. It is placed on the cathode terminal and electrically connected and fixed by a conductive adhesive. Next, each anode lead member led out from the capacitor main body is welded to a predetermined position by resistance welding to the anode terminal. Thereafter, an exterior resin is formed by injection molding, and the anode terminal and the cathode terminal are bent along the exterior resin, respectively, so that the outer shape is 7.3 (length) × 4.3 (width) × 2.8 (thickness) mm. A niobium solid electrolytic capacitor was produced.
(Comparative Example 1-3)
A capacitor main body was prepared in the same manner as in Example 1 except that 59 mg of niobium powder having a CV product of 96000 μFV / g was sintered together with a planted niobium wire having a diameter of 0.3 mm into a rectangular solid having a thickness of 1.7 mm. Thereafter, the capacitor body is placed on the cathode terminal that has been subjected to the bending process, and is electrically connected and fixed by a conductive adhesive. Next, the anode lead member led out from the capacitor body is welded to a predetermined position by resistance welding to the anode terminal. Thereafter, an exterior resin is formed by injection molding, and the anode terminal and the cathode terminal are bent along the exterior resin, respectively, so that the outer shape is 7.3 (length) × 4.3 (width) × 2.8 (thickness) mm. A niobium solid electrolytic capacitor was produced.
(Comparative Example 2-1)
A capacitor body was prepared using the same method as in Example 2, and 7.3 (length) × 4.3 (width) × 2 using the same method as in Comparative Example 1-1 using the capacitor body. A niobium solid electrolytic capacitor of .8 (thickness) mm was produced.
(Comparative Example 2-2)
A capacitor body was prepared using the same method as in Example 2, and 7.3 (length) x 4.3 (width) using the two capacitor bodies and the same method as in Comparative Example 1-2. A niobium solid electrolytic capacitor of × 3.8 (thickness) mm was produced.
(Comparative Example 3-1)
A capacitor body was prepared using the same method as in Example 3, and 10.0 (length) × 6.3 (width) × 1 using the same method as in Comparative Example 1-1 using the capacitor body. A niobium solid electrolytic capacitor of .8 (thickness) mm was produced.

  After producing the niobium solid electrolytic capacitors of the above examples and comparative examples, aging treatment was performed, respectively, and then the capacitance and ESR at 100 kHz were measured. The results are shown in Table 1.

  The size of Example 1 corresponds to the dimension symbol “7343” defined in EIAJ-RC2378-101 (tantalum solid (conductive polymer) capacitor for surface mounting). For reference, the ESR standard at 100 μV / 10 V of the standard is 45 mΩ or less. The ESR value of 19 mΩ in Example 1 is parallel to the 36.8 mΩ of Comparative Example 1-1 produced by one capacitor body of Example 1, so that the achievement rate is 97 against the calculated value of 18.4 mΩ. %. On the other hand, in the comparative example 1-2 of the conventional product in which the metal paste layers of the two capacitor bodies are connected by the conductive adhesive, the achievement rate is only 73% because it is 25.2 mΩ. From this result, ESR was reduced by 25% compared to the conventional product by using the present invention. Moreover, the ESR value of the conventional product manufactured from one capacitor body as in Examples 1 to 3 is as large as 32.7 mΩ.

  In Example 2, the length and width are the same as those in Example 1, and the thickness is increased. Also in this case, since the 32.7 mΩ in parallel of Comparative Example 2-1 manufactured with one capacitor body of Example 2 is paralleled, the achievement rate of calculated value 16.4 mΩ is 95%. On the other hand, only 75% of the prior art in which the metal paste layers of the two capacitor bodies are connected by a conductive adhesive.

  In Example 3, the length and width are increased and the thickness is reduced. In this case, the absolute value of ESR is reduced, but the achievement rate is still high as 96% calculated from Comparative Example 3-1.

  In Examples 1 to 3 of the present invention using a niobium sintered body, a very high achievement rate was obtained for 95 to 97% of the calculated value and about 73% of the conventional product. As a result, ESR was reduced by 23 to 25% compared to the conventional product in which the metal paste layers of the two conventional capacitor bodies were connected by the conductive adhesive.

  This is because the ESR reduction effect by dividing the element into two elements that shorten the average path distance from the dielectric film to the cathode lead layer is more effective when niobium is used as the anode body than when other valve metal such as tantalum is used. It is extremely large, and the high resistance part is not formed by connecting the thin film of the skin resin only in the metal paste layer for connecting the two capacitor bodies with the conductive adhesive by dividing the element into two parts. This is thought to be because of a synergistic effect.

  In Example 4, the metal paste layer (5) sharing one surface of the two capacitor elements (10) and (10) formed with the carbon layer (4) is formed, and the shared metal paste layer (5) is formed. The cathode terminal (21) is arranged inside. By using this structure, there is no thin resin-only thin film that is easily formed on the surface of the skin in the metal paste layer (5), and a conductive adhesive is also used, so the ESR reduction effect is even greater than in Examples 1-3. Become.

  In the embodiment, the planted niobium wire is used as the anode lead member, but a tantalum wire may be used instead, and the niobium wire may be welded after the niobium powder is sintered. A plate material can also be used instead of the wire. Moreover, although the flake shaped thing was used as the shape of the metal powder used for a metal paste layer, the same effect can be acquired even if it uses a flake shaped thing.

  In the description in the metal paste layer, the resin-only thin film does not completely indicate the resin, but includes a resin that contains more resin than the metal powder.

It is a longitudinal cross-sectional view of the niobium capacitor element in this invention. 1 is a longitudinal sectional view of a niobium solid electrolytic capacitor in Example 1. FIG. 6 is a longitudinal sectional view of a niobium solid electrolytic capacitor in Example 4. FIG. FIG. 6 is a longitudinal sectional view of a solid electrolytic capacitor using a two-element splitting in a conventional product. It is an enlarged view of the connection part of the two capacitor | condenser main bodies in FIG. It is a longitudinal cross-sectional view of the conventional solid electrolytic capacitor.

Explanation of symbols

1 Anode body
1a Anode lead member 2 Dielectric coating 3 Cathode layer 4 Carbon layer 5 Metal paste layer
5a metal powder
5b Resin 7 Exterior resin 8 Conductive adhesive 10 Capacitor element 15 Capacitor body 21 Anode terminal 22 Cathode terminal

Claims (2)

An anode body (1) made of a powder sintered body mainly composed of niobium or a niobium compound is provided with an anode lead member (1a), and a dielectric film (2) and a cathode layer (on the surface of the anode body (1)). 3) A capacitor element (10) formed with a carbon layer (4) and a metal paste layer (5) to form a capacitor body (15), and niobium having two capacitor bodies (15) In solid electrolytic capacitors,
An anode terminal (20) electrically connected to each anode lead member (1a) of the capacitor body (15);
A cathode terminal (21) electrically connected between two capacitor bodies (15) (15);
Two capacitor bodies (15), (15), an anode terminal (20), and a cathode terminal (21) are coated with an exterior resin (7) formed by integrally molding them, and the anode terminal (20) and A niobium solid electrolytic capacitor, wherein each of the cathode terminals (21) is exposed from the exterior resin (7). An anode body (1) made of a powder sintered body mainly composed of niobium or a niobium compound is provided with an anode lead member (1a), and a dielectric film (2) and a cathode layer (on the surface of the anode body (1)). In a niobium solid electrolytic capacitor comprising a capacitor element (10) formed with 3), a carbon layer (4), and two capacitor elements (10) formed up to the carbon layer.
An anode terminal (20) electrically connected to each anode lead member (1a) of the capacitor element (10);
A metal paste layer (5) formed on the surfaces of the two capacitor elements (10) (10) formed up to the carbon layer and sharing one surface of the two capacitor elements (10) (10);
A cathode terminal (21) disposed in the shared metal paste layer (5);
Two capacitor elements (10), (10), an anode terminal (20), and a cathode terminal (21) are coated with an exterior resin (7) formed by integrally molding them, and the anode terminal (20) and A niobium solid electrolytic capacitor, wherein each of the cathode terminals (21) is exposed from the exterior resin (7).

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