JP2009076872A - Chip type solid electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the size of a solid electrolytic capacitor for use in various electronic devices. <P>SOLUTION: A chip type solid electrolytic capacitor includes: an external package 5 covering an element stack layering plate-like elements 1; a base electrode 6 connected to an anode electrode part 3 exposed on one end face of the exterior 5; an intermediate electrode 7 connected to the base electrode 6 and a cathode electrode part 4 exposed on another end face of the external package 5; and an external electrode 8 formed on the intermediate electrode 7, wherein the base electrode 6 is constituted of a zinc layer formed by high-speed particle collision techniques. Thus, since a dielectric oxide film layer formed on a surface of the anode electrode part 3 is destroyed and stuck to an anode body with a high strength, improvement in contact and reduction in connection resistance can be attained, thereby realizing low ESL and further, the solid electrolytic capacitor is reduced in size and cost by decreasing the number of components and the number of assembly steps. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a chip-type solid electrolytic capacitor that uses a conductive polymer as a solid electrolyte and is surface mountable among capacitors used in various electronic devices.

  Along with the increase in frequency of electronic equipment, capacitors that are one of the electronic components have been required to have better impedance characteristics in the high frequency range than before. Various solid electrolytic capacitors using a highly conductive polymer as a solid electrolyte have been studied.

  In recent years, a solid electrolytic capacitor used around a CPU of a personal computer has been strongly desired to be small in size and large in capacity. Further, in response to higher frequencies, lower ESR (equivalent series resistance), noise removal, There is a demand for low ESL (equivalent series inductance) excellent in transient response, and various studies have been made to meet such a demand.

  6 (a) and 6 (b) are a front sectional view and a side sectional view taken along line AA showing the structure of this type of conventional solid electrolytic capacitor. In FIG. Reference numeral 11 denotes a surface of an anode body 12 made of an aluminum foil which is a valve action metal to form a dielectric oxide film layer, and then an insulating resist portion 13 is provided to provide an anode electrode portion 14 and a cathode formation portion (not shown). The cathode electrode portion 15 is formed by sequentially stacking a solid electrolyte layer made of a conductive polymer, a cathode layer made of a carbon layer and a silver paste layer on the dielectric oxide film layer of the cathode forming portion. Thus, a flat element 11 having an anode electrode portion 14 and a cathode electrode portion 15 provided in the longitudinal direction is formed.

  16 is an anode comb terminal connected to the anode electrode portion 14 of the element 11, 16a is a plane portion provided on the anode comb terminal 16 and on which the anode electrode portion 14 is mounted, and 16b is bent at both ends of the plane portion 16a. A connecting portion formed by waking up, mounting the anode electrode portion 14 of the stacked element 11 on the plane portion 16a, folding the connecting portion 16b so as to be in close contact with the anode electrode portion 14, The tip portion of the connecting portion 16b and the anode electrode portion 14 of the element 11 are joined by laser welding.

  Reference numeral 17 denotes a cathode comb terminal connected to the cathode electrode portion 15 of the element 11, and 17a denotes a flat portion provided on the cathode comb terminal 17 on which the cathode electrode portion 15 is mounted. The flat portion 17a and the cathode electrode portion 15 and the cathode electrode part 15 of each element 11 are joined using the conductive adhesive 18.

  Reference numeral 19 denotes an insulating exterior resin that integrally covers the plurality of elements 11 in a state where parts of the anode comb terminal 16 and the cathode comb terminal 17 are exposed on the outer surface. The surface-mount type solid electrolytic capacitor in which the anode terminal portion 16d and the cathode terminal portion 17b are formed on the bottom surface portion by bending a part of the anode comb terminal 16 and the cathode comb terminal 17 along the exterior resin 19 to the bottom surface. Is configured.

  The conventional solid electrolytic capacitor configured as described above is stabilized by performing laser welding by simultaneously irradiating the tip of the connection portion 16b provided on the anode comb terminal 16 and the anode electrode portion 14 of the element 11 with laser light. The welding work can be performed.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP 2003-289023 A

  However, since the conventional solid electrolytic capacitor has a configuration using the anode comb terminal 16 and the cathode comb terminal 17 for laminating a plurality of elements 11 and integrally covering with the exterior resin 19, the number of parts and assembly Not only does the man-hour increase increase the cost, it is difficult to reduce the size, and further, due to the relationship between the lead-out distances and connection portions between the anode terminal portion 16d and the cathode terminal portion 17b, the ESL is naturally reduced. There was a problem that there was a limit.

  The present invention solves such a conventional problem, reduces the number of parts and the number of assembling steps, reduces costs and reduces the size, and realizes low ESR and low ESL by pulling out each electrode with the shortest distance. An object of the present invention is to provide a chip-type solid electrolytic capacitor.

In order to solve the above problems, the present invention provides an anode electrode portion and a cathode by providing an insulating portion at a predetermined position of an anode body made of a valve metal foil having a roughened surface and a dielectric oxide film layer formed thereon. The cathode electrode part is formed by sequentially laminating a solid electrolyte layer made of a conductive polymer, a cathode layer made of a carbon layer and a silver paste layer on the dielectric oxide film layer of the cathode forming part. Capacitor element, an element laminate in which a plurality of capacitor elements are laminated in the same direction, and the element laminate in a state where the end surfaces of the anode electrode portion and the cathode electrode portion of the element laminate face each other and are exposed. An exterior body made of an insulating resin that is covered and embedded between the elements of the anode electrode part;
A diffusion layer was formed on each valve action metal foil of the anode electrode portion of the element laminate exposed on one end face of the outer package, and formed on the diffusion layer and an insulating resin embedded between the elements. A base electrode made of a non-valve metal, an external electrode formed on the base electrode, and a cathode electrode portion surface and an insulating resin surface of the element laminate exposed on the other end face of the exterior body In this configuration, an intermediate electrode made of conductive fine particles and an external electrode formed on the intermediate electrode are used.

  Further, the base electrode made of the non-valve action metal has a metal-bonded non-valve action metal formed by colliding with the end face of the exterior body at a collision speed of the non-valve action metal particles of 200 m / s or more and a sound speed or less. It consists of layers.

  As described above, the chip-type solid electrolytic capacitor according to the present invention has an end face where an anode electrode portion is exposed by covering an element laminate in which flat elements are laminated with an insulating resin, and each valve metal of the anode electrode portion. Each valve action metal foil laminated by forming a diffusion layer on the foil and forming a base electrode made of a non-valve action metal on the diffusion layer and an insulating resin embedded between the elements. Since there is no contact interface between the electrode and the base electrode, the contact resistance can be made extremely low, and the adhesion strength of the base electrode can also be increased. The effect that it can further reduce is obtained.

  Further, by forming the end face current collecting electrode by directly forming the external electrode on each end face of the anode electrode portion and the cathode electrode portion, it is possible to reduce the number of parts and the number of assembly steps, thereby reducing the cost and the size. Is.

  Further, the base electrode formed on the end surface of the anode electrode portion is a non-valve metal-bonded non-valve metal particle formed by colliding with the end surface of the exterior body at a collision speed of non-valve action metal particles of 200 m / s or more and below the sound velocity. By forming the valve action metal layer, the valve action metal foil and the diffusion layer are formed without causing the destruction of the thin valve action metal foil or the loss of the insulating resin. It is also possible to form a non-valve metal layer that is deposited on the insulating resin buried between them and bonded to each other in a uniform and non-oxidized manner, so that a base electrode with extremely low contact resistance and high adhesion strength can be formed. Can be obtained, and an effect of further reducing the ESR can be obtained.

(Embodiment 1)
Hereinafter, the invention described in the first to third aspects of the present invention will be described using the first embodiment.

  1A and 1B are a perspective view showing a configuration of a chip-type solid electrolytic capacitor according to Embodiment 1 of the present invention, a front cross-sectional view showing a cross section taken along line AA, and FIGS. (C) is a perspective view, a front sectional view and a side view showing the state of the chip-type solid electrolytic capacitor before electrode formation, and FIGS. 3 (a) and 3 (b) show the base electrode of the chip-type solid electrolytic capacitor. It is the front sectional view and principal part expanded sectional view.

  1 to 3, reference numeral 1 denotes an element. The element 1 roughens the surface of an anode body 2 made of an aluminum foil (thickness: 0.1 mm) which is a valve action metal foil to form a dielectric oxide film layer. After the formation, an insulating resist portion (not shown) is provided and separated into an anode electrode portion 3 and a cathode forming portion (not shown), and a conductive polymer is formed on the dielectric oxide film layer of the cathode forming portion. The cathode electrode part 4 is formed by sequentially laminating and forming a solid electrolyte layer, a cathode layer made of a carbon layer and a silver paste layer, thereby forming a flat plate shape in which the anode electrode part 3 and the cathode electrode part 4 are provided in the longitudinal direction. Element 1 (vertical and horizontal: 5.6 × 3.4 mm) is configured.

  5 is an outer package made of an insulating resin integrally covering a plurality of element stacks (in the present embodiment, four elements in the present embodiment, but the present invention is not limited to this). Thus, the end surface of the anode electrode portion 3 and the end surface of the cathode electrode portion 4 of the element laminate are exposed at the opposing end faces of the outer package 5 that covers the element laminate as described above.

  Reference numeral 6 denotes a base electrode which is connected to the anode electrode portion 3 exposed on one end face of the outer package 5 so as to cover the end face, and the base electrode 6 is made of a zinc layer. .

  7 is formed so as to be connected to the cathode electrode portion 4 exposed on the opposite end surface of the outer package 5 so as to cover the end surface, and on the surface of the base electrode 6 formed on the anode electrode portion 3 side. The intermediate electrode 7 is formed using a conductive silver paste or the like.

  Reference numeral 8 denotes an external electrode formed on the surface of the intermediate electrode 7, and the external electrode 8 is formed by using molten solder plating or the like.

Next, a manufacturing method of the chip-type solid electrolytic capacitor having the above-described configuration according to the first embodiment will be described. First, as shown in FIG. 2, an anode electrode of an element laminate in which a plurality of elements 1 are laminated. The end face of the part 3 and the end face of the cathode electrode part 4 are covered with the exterior body 5 made of an insulating resin in a state where the end face is exposed to the opposing end face. The insulating resin of the outer package 5 is also embedded between the anode electrode portion 3 and the anode electrode portion 3 of the element 1. Further, as the insulating resin, an epoxy resin containing 80 to 90% of an inorganic filler made of silica (SiO ₂ ) is used, but the present invention is not limited to this.

  Subsequently, as shown in FIG. 3, the base electrode 6 is formed so as to be connected to the anode electrode portion 3 exposed on the opposite end face of the outer package 5 and to cover the entire end face. The base electrode 6 is formed by forming an intermetallic-bonded zinc layer formed by causing zinc particles, which are non-valve action metals, to collide with the end face of the exterior body at a collision speed of 200 m / s or more and a sound speed or less. The zinc layer is, for example, a system technology development research study 16-R-17 “Survey research report on innovative member creation using high-speed particle collisions” issued in March 2005 by the Japan Mechanical Systems Promotion Association. 3. “Summary”. Summary of research results, Chapter 1 High-speed particle collision technology, (3) Heavy film forming using high-speed particle collision, and technology introduced in the column of direct modeling technology, accelerating metal particles at supersonic speed By causing the metal particles to collide with the base material, the metal particles are melted by the energy of plastic deformation at the time of the collision, thereby causing the metal particles to adhere to the base material, and a strong adhesion strength can be obtained.

  In addition, since the base electrode 6 formed by the high-speed particle collision technique preferably uses zinc, brass, or copper which is a material having a corrosion potential close to that of the anode body 2 constituting the anode electrode portion 3. In this embodiment, zinc is used. As shown in the enlarged cross-sectional view of the main part of FIG. 3B, the zinc particles form the diffusion layer 5a with the aluminum of the anode electrode part 3. The outer body 5 is in a state of being bitten into the surface of the insulating resin. In addition, when the material which comprises the anode electrode part 3 is a tantalum, it is preferable to use copper and nickel which are materials with a corrosion potential close to tantalum.

  In addition, the base electrode 6 formed by the high-speed particle collision technique is configured so that the anode electrode portion 3 is made of aluminum which is a valve action metal. Therefore, it is necessary to use a non-valve action metal and to replace it with the non-valve action metal in order to prevent this. It is not limited to zinc.

The formation of the base electrode 6 by the high-speed particle collision technique is performed by causing the collision speed of zinc particles, which are non-valve action metals, to collide with the end surface of the outer package 5 at a speed of 200 m / s or higher and a speed of sound speed or lower. In this case, the opposite end surface of the outer package 5 is exposed at the side end surface of the anode electrode portion 3, and its area is extremely small, about 0.3 mm ² , so that it exceeds the speed of sound. If the cold spray method in which the zinc particles collide at the speed of sound is used, the zinc particles scrape off the side end surface portion of the anode electrode portion 3, the diffusion layer 5a is not formed, and the zinc layer as the base electrode 6 is also laminated uniformly. Disappear. On the other hand, when zinc particles collide with less than 200 m / s, a zinc layer is formed, but the impact of the collision is weak, so the diffusion layer 5a cannot be formed, and the chip type solid electrolytic capacitor has a low ESR. It is not preferable because it cannot be done. The average particle diameter of the zinc particles is preferably in the range of 5 to 30 μm.

  Furthermore, since the area of the anode electrode portion 3 exposed from the end face of the outer package 5 is small, the anode electrode portion 3 when the zinc particles collide with each other by embedding an insulating resin between the elements 1 of the anode electrode portion 3. The exposed portion of the anode electrode portion 3 can be maintained to form the diffusion layer 5a of aluminum and zinc particles, thereby forming a uniform zinc layer.

  Subsequently, an intermediate electrode 7 is formed so as to cover the entire end face while being connected to the cathode electrode portion 4 exposed on the opposite end face of the outer package 5, and on the surface of the base electrode 6. Also forms the intermediate electrode 7. In addition, although the electroconductive silver paste was used as this intermediate electrode 7, this invention is not limited to this, Cost etc., such as a paste using the silver-plated particle | grains which plated the copper-nickel alloy particle and copper particle, etc. Inexpensive ones can also be used.

  Subsequently, an external electrode 8 is formed on the surface of the intermediate electrode 7. In addition, although the molten solder plating was used as this external electrode 8, this invention is not limited to this, General plating may be sufficient.

  The chip-type solid electrolytic capacitor according to the present embodiment configured as described above is formed by directly forming electrodes on the end faces of the anode electrode portion 3 and the cathode electrode portion 4 of the element laminated body in which the flat element 1 is laminated. By configuring the end face collecting electrode, the number of parts and assembly man-hours can be reduced, cost reduction and downsizing can be achieved, and the low ESL can be achieved by pulling out each electrode at the shortest distance. It plays.

  Further, the base electrode 6 connected to the anode electrode portion 3 is formed by forming a metal-bonded non-valve metal layer by a high-speed particle collision technique, thereby destroying the oxide film layer formed on the surface of the anode electrode portion 3. As a result, it is possible to form aluminum and a diffusion layer 5a made of valve-acting metal foil, thereby attaching a non-valve action metal with high strength and preventing an oxide film layer from being formed on the exposed aluminum surface. In addition, it is possible to achieve a special effect that the high contact property and the connection resistance can be reduced and the ESR can be further reduced.

  In the present embodiment, the base electrode 6 is formed on the entire end face so as to be connected to the anode electrode portion 3 exposed on one end face of the outer package 5, and the intermediate electrode 7 is formed on the base electrode 6. However, the present invention is not limited to this, and the intermediate electrode 7 is eliminated, and the external electrode 8 is formed directly on the base electrode 6. It can also be formed.

  Specific examples will be described below.

(Example)
After forming a dielectric oxide film layer by roughening the surface of an aluminum foil (thickness: 0.1 mm) that is a valve action metal foil, an insulating resist portion is provided and separated into an anode electrode portion and a cathode formation portion, On the dielectric oxide film layer of the cathode forming portion, a conductive polymer layer made of polypyrrole by an electropolymerization method, a cathode layer made of a carbon layer and a silver paste layer are sequentially laminated to form a cathode electrode portion. A flat element (vertical and horizontal: 5.6 × 3.4 mm) having an anode electrode portion and a cathode electrode portion in the longitudinal direction was obtained.

  Next, an element laminate was formed by laminating four of the above elements, and an exterior body was obtained by covering the upper and lower surfaces of the element and between the anode electrode portion and the anode electrode portion with an insulating resin. The end face of the anode electrode portion and the end face of the cathode electrode portion of the outer package are exposed.

  Next, 150 m / s, 200 m / s, 250 m / s, and 300 m / s of zinc particles (average particle size of 10 μm) are applied to the end surface of the outer body facing the anode electrode portion on the opposite side by a high-speed particle collision technique. , 350 m / s, and 400 m / s, respectively, to form a base electrode (thickness: 5 μm). Thereafter, an intermediate electrode was formed using a conductive silver paste. Subsequently, a conductive silver paste was also used to form the cathode electrode portion exposed on the opposite end face of the outer package. Finally, an external electrode was formed on the surface of each intermediate electrode by using molten solder plating to produce a chip-type solid electrolytic capacitor (rated rating 6.3 V 47 μF).

(Comparative example)
In the above example, instead of the base electrode, a silver paste was applied to both end faces of the outer package, and then a chip-type solid electrolytic capacitor was produced by hot-dip solder plating as an external electrode. Further, as a conventional example, a chip-type solid electrolytic capacitor using a positive-cathode comb terminal shown in FIG. 6 was produced (rated 6.3 V 47 μF).

  For the chip-type solid electrolytic capacitors of the above Examples, Comparative Examples, and Conventional Examples, the characteristics of capacitance, ESR, ESL, and leakage current (LC) were measured. The results are shown in (Table 1).

  As is clear from the above (Table 1), the formation of the base electrode deteriorates the ESR characteristics when the collision speed of the zinc particles is less than 200 m / s, and the LC becomes supersonic when the collision speed exceeds 400 m / s and exceeds the sound speed. The preferred range is 200 m / s or more and the sound speed or less. By setting this range, the ESR characteristic, ESL characteristic, and LC characteristic can be reduced as compared with the comparative example and the conventional example.

(Embodiment 2)
The second aspect of the present invention will be described below with reference to the second embodiment.

  In the present embodiment, the configuration of the chip-type solid electrolytic capacitor described in the first embodiment with reference to FIGS. 1 to 3 is partially different, and other configurations are the same as those in the first embodiment. The same reference numerals are given to the same parts and the detailed description thereof is omitted, and only different parts will be described below with reference to the drawings.

  FIG. 4 is a front sectional view showing a state of the chip-type solid electrolytic capacitor according to the second embodiment of the present invention before electrode formation. In FIG. 4, 9 is formed on the surface of the anode electrode portion 3 of the element 1. It is an insulating resin layer. By providing this resin layer 9, the thickness of the anode electrode part 3 and the thickness of the cathode electrode part 4 are made substantially the same. In the present embodiment, an epoxy resin is used as the resin layer 9, but the present invention is not limited to this.

  In the chip-type solid electrolytic capacitor according to the present embodiment configured as described above, the insulating resin layer 9 is provided on the surface of the anode electrode portion 3 of the element 1, whereby the thickness of the anode electrode portion 3 and the cathode electrode portion 4 are reduced. With the configuration in which the thicknesses are substantially the same, there is no gap between the anode electrode portions 3 when the element laminate is formed. Therefore, the element laminate is integrally covered with the exterior body 5 made of an insulating resin. At this time, the anode electrode portion 3 is not deformed by the injection pressure of the resin, and there is an extraordinary effect that it becomes possible to perform molding with stable dimensional accuracy and quality.

(Embodiment 3)
The third aspect of the present invention will be described below with reference to the third embodiment.

  In the present embodiment, the configuration of the element laminate of the chip-type solid electrolytic capacitor described in the first embodiment with reference to FIGS. 1 to 3 is partially different, and other configurations are implemented. Therefore, the same portions are denoted by the same reference numerals and detailed description thereof is omitted, and only different portions will be described below with reference to the drawings.

  FIG. 5 is a front sectional view showing the structure of the chip-type solid electrolytic capacitor according to Embodiment 3 of the present invention. In FIG. 5, 10 is an insulating substrate disposed on the bottom surface of the element laminate, In the present embodiment, a glass epoxy substrate is used as the substrate 10, but the present invention is not limited to this.

  The chip-type solid electrolytic capacitor according to the present embodiment configured as described above has an insulating substrate 10 disposed on the bottom surface of the element stack, and thus has an insulating property that forms the outer package 5 on a small-sized product. It solves the problem that it is difficult to flow the resin uniformly and is likely to become unstable, and it has the special effect of making the wraparound of the resin uniform and performing molding with stable dimensional accuracy and quality. Is.

  The chip-type solid electrolytic capacitor according to the present invention has the effects of reducing costs and downsizing, and also realizing low ESL, and is useful as a capacitor in all fields.

(A) The perspective view which showed the structure of the chip-type solid electrolytic capacitor by Embodiment 1 of this invention, (b) Front sectional drawing in the AA line (A) The perspective view which showed the state before electrode formation of the chip-type solid electrolytic capacitor, (b) The front sectional view, (c) The side view (A) Front sectional view showing the base electrode of the chip-type solid electrolytic capacitor, (b) Enlarged sectional view of the main part Front sectional view showing a state before electrode formation of a chip-type solid electrolytic capacitor according to Embodiment 2 of the present invention Front sectional view showing the configuration of a chip-type solid electrolytic capacitor according to Embodiment 3 of the present invention (A) Front sectional view showing the configuration of a conventional solid electrolytic capacitor, (b) Side sectional view taken along the line AA.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Element 2 Anode body 3 Anode electrode part 4 Cathode electrode part 5 Exterior body 6 Base electrode 7 Intermediate electrode 8 External electrode 9 Resin layer 10 Substrate

Claims (5)

An insulating portion is provided at a predetermined position of an anode body made of a valve-acting metal foil having a dielectric oxide film layer formed by roughening the surface and separated into an anode electrode portion and a cathode forming portion. A capacitor element in which a cathode electrode portion is formed by sequentially laminating a solid electrolyte layer made of a conductive polymer on a body oxide film layer, a cathode layer made of a carbon layer and a silver paste layer, and the capacitor element in the same direction A plurality of stacked element laminates, and the element laminate is covered with each of the end surfaces of the anode electrode portion and the cathode electrode portion facing each other and exposed between the elements of the anode electrode portion. An exterior body made of an embedded insulating resin;
A diffusion layer was formed on each valve action metal foil of the anode electrode portion of the element laminate exposed on one end face of the outer package, and formed on the diffusion layer and an insulating resin embedded between the elements. A base electrode made of a non-valve metal, an external electrode formed on the base electrode,
A chip comprising an intermediate electrode made of conductive fine particles formed on the surface of the cathode electrode portion of the element laminate and the surface of the insulating resin exposed on the other end face of the outer package, and an external electrode formed on the intermediate electrode Type solid electrolytic capacitor. The base electrode made of a non-valve action metal is made of an inter-metal bonded non-valve action metal layer formed by colliding with the end face of the exterior body at a collision speed of non-valve action metal particles of 200 m / s or more and a sound speed or less. The chip-type solid electrolytic capacitor according to claim 1. 2. The chip according to claim 1, wherein an intermediate electrode is provided between a base electrode formed on the anode electrode portion of the element laminate exposed on one end face of the exterior body and an external electrode formed on the base electrode. Type solid electrolytic capacitor. The chip-type solid electrolytic capacitor according to claim 1, wherein an insulating resin layer is provided on the surface of the anode electrode portion. The chip-type solid electrolytic capacitor according to claim 1, wherein an insulating substrate is disposed on the bottom surface of the element laminate.

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