JP2009094473A - Chip type solid electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a chip type solid electrolytic capacitor used for various electronic equipment compact. <P>SOLUTION: The chip-type solid electrolytic capacitor comprises: an element stack of a plurality of flat plate type elements 1 provided with positive electrode portions 3 at both ends and also provided with a negative electrode portion 4 between the positive electrode portions 3; an positive conductive member 5 joined to the lowest stage of the element stack; an external package 6 covering the element stack in a state where respective end surfaces of the positive electrode portions 3 of the element stack are exposed on opposite end surfaces and the negative conductive member 5 is exposed on a bottom surface; a base electrode 7 connected to the positive electrode portions 3 of the element stack exposed on the opposite end surfaces of the external package 6; and an external electrode 9 formed on the base electrode 7, the base electrode 7 comprising a zinc layer formed by cold spraying. Consequently, the number of components and the assembly man-hour can be decreased to make the chip-type solid electrolytic capacitor low-cost and compact, and respective electrodes are led out by the shortest distances to reduce ESL. <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.

  5 (a) and 5 (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-mounted solid electrolytic capacitor in which the anode terminal portion 16c 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 16c 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-mentioned problems, the present invention provides an element laminate in which a plurality of flat elements each having an anode electrode portion at both ends and a cathode electrode portion provided between the anode electrode portions are laminated, and the element laminate. The cathode conductive member joined to the bottom surface of the cathode electrode portion of the lower element and the end surfaces of the anode electrode portion of the element laminate are exposed to the opposing end surfaces, and the cathode conductive member is exposed to the bottom surface. The valve action of the exterior body made of an insulating resin that covers the element laminate and is embedded between the elements of the anode electrode portion, and the anode electrode portion of the element laminate that is exposed on the opposing end surfaces of the exterior body, respectively. A diffusion layer is formed on the metal foil, and includes a base electrode made of a non-valve metal formed on the diffusion layer and an insulating resin embedded between the elements, and an external electrode formed on the base electrode It is a configuration.

  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 that exposes the anode electrode part by covering the element laminate in which the flat elements are laminated with the insulating resin, and each valve action metal of the anode electrode part. 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, it is possible to reduce the number of parts and the number of assembly steps, thereby reducing the cost and the size.

  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 the 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. It is possible to obtain the effect that a further reduction in ESR can be realized.

(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 forms a dielectric oxide film layer by roughening the surface of an anode body 2 made of an aluminum foil (thickness: 0.1 mm) which is a valve action metal. After that, an insulating resist portion (not shown) is provided, and the anode electrode portion 3 is separated at both ends so that a cathode forming portion (not shown) is disposed between the anode electrode portions 3. A cathode electrode part 4 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 forming part, thereby forming a longitudinal electrode A plate-like element 1 (vertical and horizontal: 5.6 × 3.4 mm) in which an anode electrode portion 3 is provided at both ends and a cathode electrode portion 4 is provided between the anode electrode portions 3 is configured.

  5 is the cathode electrode of the lowermost element 1 of the element stack in which a plurality of the elements 1 are arranged in the same direction (four in the present embodiment, but the present invention is not limited thereto). It is a cathode conductive member joined to the bottom surface of the part 4, and is constituted by a copper plate or the like.

  Reference numeral 6 denotes an exterior body made of an insulating resin that integrally covers the element laminate to which the cathode conductive member 5 is bonded, and an end face of the anode electrode portion 3 of the element laminate is provided on the opposite end face of the exterior body 6. Are exposed, and the bottom surface of the cathode conductive member 5 is exposed on the bottom surface of the outer package 6.

  Reference numeral 7 denotes a pair of base electrodes that are connected to the anode electrode portions 3 exposed on the opposing end faces of the outer package 6 so as to cover the end faces, and the base electrodes 7 are made of a zinc layer. is there.

  Reference numeral 8 denotes a pair of intermediate electrodes respectively formed on the surface of the base electrode 7, and the intermediate electrode 8 is formed using a conductive silver paste.

  Reference numeral 9 denotes a pair of external electrodes respectively formed on the surface of the intermediate electrode 8, and the external electrodes 9 are formed using molten solder plating.

Next, the manufacturing method of the chip-type solid electrolytic capacitor according to this embodiment configured as described above will be described. First, as shown in FIG. After the cathode conductive member 5 made of a copper plate is joined to the bottom surface of the cathode electrode portion 4 of the element 1 at the lowest stage of the element laminate, the end surfaces of the anode electrode portions 3 are exposed to the opposite end surfaces, In a state where the bottom surface of the cathode conductive member 5 is exposed, the element laminate is integrally covered with an exterior body 6 made of an insulating resin. 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 7 is formed so as to be connected to the pair of anode electrode portions 3 exposed at the opposing end faces of the outer package 6 and to cover the entire end faces. The base electrode 7 is formed by forming an intermetallic-bonded zinc layer formed by causing zinc particles, which are non-valve action metals, to collide with an end face of an 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, the base electrode 7 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 6a with the aluminum in the anode electrode part 3. At the same time, it is in a state of being bitten into the surface of the insulating resin of the exterior body 6. 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 7 formed by the high-speed particle collision technique is configured such 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.

In addition, the formation of the base electrode 7 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 exterior body 6 at a speed of 200 m / s or higher and a speed of sound or lower. However, since the opposite end surface of the exterior body 6 is exposed from the side end surface of the anode electrode portion 3 and its area is as small as about 0.3 mm ² , zinc is used at supersonic speeds exceeding the sound speed. When the cold spray method in which the particles collide is used, the zinc particles scrape off the side end surface portion of the anode electrode portion 3, the diffusion layer 6a is not formed, and the zinc layer as the base electrode 7 is not uniformly laminated. On the other hand, when zinc particles are collided at a speed of less than 200 m / s, a zinc layer is formed, but the impact of the collision is weak, so the diffusion layer 6a 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 6 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 6a of aluminum and zinc particles, thereby forming a uniform zinc layer.

  Subsequently, intermediate electrodes 8 are formed on the surfaces of the pair of base electrodes 7 respectively. In addition, although the electroconductive silver paste was used as this intermediate electrode 8, this invention is not limited to this, The paste using the nickel-coated copper-nickel alloy particle or the copper particle, and the silver plating particle | grains For example, an inexpensive one can be used.

  Subsequently, external electrodes 9 are respectively formed on the surfaces of the pair of intermediate electrodes 8. In addition, although the molten solder plating was used as this external electrode 9, 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 has an end face collecting electrode formed by directly forming an electrode on each end face of the anode electrode portion 3 of the element laminated body in which flat elements are laminated. As a result, it is possible to reduce the number of parts and the number of assembling steps, thereby reducing costs and downsizing, and to obtain a special effect of reducing the ESL by pulling out each electrode at the shortest distance.

  Furthermore, the base electrode 7 connected to the anode electrode part 3 has a structure in which a metal-bonded non-valve metal layer is formed by a high-speed particle collision technique, so that the oxide film layer formed on the surface of the anode electrode part 3 is destroyed. As a result, it is possible to form aluminum and a diffusion layer 6a 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 7 is formed on the entire end face so as to be connected to the anode electrode portion 3 exposed at the opposing end face of the exterior body 6, and the intermediate electrode 8 is formed on the base electrode 7. However, the present invention is not limited to this, and the intermediate electrode 8 is eliminated, and the external electrode 9 is formed on the base electrode 7. It can also be formed directly.

  Specific examples will be described below.

(Example)
After roughening the surface of an aluminum foil (thickness: 0.1 mm) that is a valve metal foil to form a dielectric oxide film layer, an insulating resist portion is provided on both ends of the surface, and both ends are anode electrode portions. The anode electrode part is separated as a cathode forming part, and a conductive polymer layer made of polypyrrole by an electrolytic polymerization method, a cathode made of a carbon layer and a silver paste layer are formed on the dielectric oxide film layer of the cathode forming part. The cathode electrode part was formed by successively laminating layers, thereby obtaining a flat element (vertical and horizontal: 5.6 × 3.4 mm) provided with an anode electrode part and a cathode electrode part in the longitudinal direction.

  Next, four elements are stacked so that the anode electrode portions are arranged in the same direction to form an element laminate, and both end surfaces of the anode electrode portion are exposed, and the upper surface of the element and the anode electrode portion The element was covered with an insulating resin to obtain an outer package. The bottom surface of the cathode electrode portion of the outer package is exposed.

  Next, zinc particles (average particle size 10 μm) are 150 m / s, 200 m / s, 250 m / s, 300 m / s, by a high-speed particle collision technique on both end surfaces of the outer electrode body where the opposing anode electrode portions are exposed. Collisions were performed at a collision speed of 350 m / s and 400 m / s 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 2V 120 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. 5 was produced (rated 2V 120 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 less than the speed of sound. 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, 10 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 10, the anode electrode portion 3 and the cathode electrode portion 4 have substantially the same thickness. In the present embodiment, an epoxy resin is used as the resin layer 10, 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 10 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. Since the gap is eliminated between the anode electrode portions 3 when the element laminate is formed by the configuration in which the thicknesses are substantially the same, the exterior laminate 6 is covered by covering the element laminate integrally with an insulating resin. At the time of molding, 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.

  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 (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 Cathode conductive member 6 Exterior body 7 Base electrode 8 Intermediate electrode 9 External electrode 10 Resin layer

Claims (4)

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, anode electrodes are provided at both ends in the longitudinal direction, and a cathode is provided between the anode electrodes. Separated so that the forming portion is disposed, a solid electrolyte layer made of a conductive polymer, a cathode layer made of a carbon layer and a silver paste layer are sequentially laminated on the dielectric oxide film layer of the cathode forming portion. Capacitor element having a cathode electrode part formed by the above, an element laminate in which a plurality of capacitor elements are laminated in the same direction, and a cathode conductive material bonded to the bottom surface of the cathode electrode part of the lowermost element of the element laminate Members,
Each end face of the anode electrode portion of the element laminate is exposed to the opposite end face, and the element laminate is covered with the cathode conductive member exposed to the bottom, and embedded between the elements of the anode electrode portion. An exterior body made of an insulating resin;
A diffusion layer is formed on each valve action metal foil of the anode electrode portion of the element laminate exposed on the opposing end surfaces of the exterior body, and formed on the diffusion layer and an insulating resin embedded between the elements. A chip-type solid electrolytic capacitor comprising a base electrode made of a non-valve metal and an external electrode formed on the base electrode. 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.

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