Electricity: electrical systems and devices – Electrolytic systems or devices – Solid electrolytic capacitor
Reexamination Certificate
2001-05-23
2002-05-21
Dinkins, Anthony (Department: 2831)
Electricity: electrical systems and devices
Electrolytic systems or devices
Solid electrolytic capacitor
C361S528000, C361S532000, C361S541000
Reexamination Certificate
active
06392869
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a solid electrolytic capacitor.
2. Description of the Prior Art
A solid electrolytic capacitor has a structure in which an anode is formed of a valve metal such as aluminum, tantalum, niobium, or the like; an oxide film as a dielectric layer is formed by anodizing the anode; and a solid electrolytic layer and a cathode layer are laminated on the dielectric layer in this order.
In recent years, with the demand for digitalization of a circuit and miniaturization of electronic equipment, there is an increasing demand for high-frequency response characteristics and miniaturization of electronic components. Also in a solid electrolytic capacitor, in order to meet such demands, low resistance of a conductor part such as a solid electrolytic layer, a cathode layer, and the like and miniaturization and large capacitance of a solid electrolytic capacitor is promoted.
For realizing miniaturization and large capacitance of a solid electrolytic capacitor, a laminated type solid electrolytic capacitor in which a plurality of capacitor units are laminated is proposed.
FIG. 13A
is a perspective view of a conventional solid electrolytic capacitor, and
FIG. 13B
is a cross-sectional view taken along line I—I in FIG.
13
A. In general, the electrolytic capacitor is produced as follows. First, a capacitor unit is formed by forming a dielectric layer
2
, a solid electrolytic layer
3
and a cathode layer
4
in this order on the predetermined surface of an anode layer
1
. Then, a plurality of capacitor units are laminated via a conductive adhesive
5
to form a unit laminate. Next, the anode lead portions
1
a
that are not covered with a solid electrolytic layer and the like are bundled and integrated into an anodic extraction terminal
13
by welding. Furthermore, a cathodic extraction terminal
9
is connected to a cathode layer
4
of the capacitor unit constituting the bottom layer of the laminate via a conductive adhesive
7
. Finally, a sealing body
8
is formed in a state in which the anodic extraction terminal
13
and the cathodic extraction terminal
9
are exposed to the outside.
In a solid electrolytic capacitor, further miniaturization and large capacitance are demanded. At the same time, in order to improve the high-frequency response characteristics of the products, the connection between conductors, in particular the connection between a valve metal as an anode and an anodic terminal, has further been demanded to have low resistance property and improved reliability.
JP 6 (1994)-84716 A discloses a method in which an anode of each capacitor unit is exposed to the outside of the sealing body respectively; a conductive layer formed of a thermal spraying layer, a sputtering film, a conductive resin, or the like is formed so as to cover the exposed portion; and anodes are electrically integrated via the conductive layer. According to this method, since the space necessary to integrate the anodes becomes smaller as compared with the capacitor shown in
FIGS. 13A and 13B
, it is possible to achieve further miniaturization and large capacitance. However, since an interface resistance between the anode and the conductive layer due to a natural oxide film formed on the surface of the valve metal is large, there are disadvantages in that connection with low resistance and high reliability cannot be obtained.
Furthermore, JP 8 (1996)-273983 A describes a method of forming a metal plating layer on the surface of each anode layer and connecting this respective metal plating layer to a further plating layer; and a method of connecting the individual metal plating layers to each other by soldering or welding. However, in the former method in which the anodes are connected to each other only by a plating layer, there is a problem in the reliability of the mechanical strength, etc. Furthermore, in a latter method in which a plating layer is connected by welding and the like, a thermal effect due to high temperature heating in welding is not negligible, thus deteriorating the quality of products. In addition, since the plating layer is generally thin, there is an industrial difficulty in connecting the extremely thin plating layers to each other by welding, that is, by fusing of metals.
SUMMARY OF THE INVENTION
Therefore, with the foregoing in mind, it is an object of the present invention to provide a solid electrolytic capacitor realizing miniaturization and large capacitance and capable of obtaining a low resistance and high reliability when electrically connecting anodes to each other.
In order to achieve the above-mentioned object, the first solid electrolytic capacitor of the present invention includes a laminate comprising a plurality of capacitor units, each capacitor unit comprising an anode made of a valve metal, a dielectric layer formed on the anode and a solid electrolytic layer formed on the dielectric layer; a sealing body for sealing the laminate; and an anodic conductive elastic body formed outside the sealing body and electrically connected to the anode; the anodes being electrically connected to each other via the anodic conductive elastic body; wherein a part of the anode is exposed to the outside of the sealing body, and the exposed portion of the anode is covered with a plating layer and electrically connected to the anodic conductive elastic body via the plating layer.
With such a configuration, since the space necessary for electric integration of the anodes can be reduced, it is possible to realize miniaturization and large capacitance of a solid electrolytic capacitor. Furthermore, since a plating layer is interposed between the anode and the anodic conductive elastic body, it is possible to suppress the increase of the interface resistance between the anode and the conductive elastic body due to a natural oxide film formed on the surface of the valve metal, and thus to realize the connection with low resistance and high reliability.
It is preferable that the first solid electrolytic capacitor further includes a cathode layer being laminated on the solid electrolytic layer.
Furthermore, the second solid electrolytic capacitor of the present invention includes a laminate comprising a plurality of capacitor units, each capacitor unit comprising an anode made of a valve metal, a dielectric layer formed on the anode, a solid electrolytic layer formed on the dielectric layer and a cathode layer formed on the solid electrolytic layer; a sealing body for sealing the laminate; and an anodic conductive elastic body formed outside the sealing body and electrically connected to the anode; the anodes being electrically connected to each other via the anodic conductive elastic body; wherein a part of the anode is exposed to the outside of the sealing body, and the exposed portion of the anode is covered with a plating layer and electrically connected to the anodic conductive elastic body via the plating layer.
With such a configuration, since the space necessary for electric integration of the anodes can be reduced, it is possible to achieve miniaturization and large capacitance of a solid electrolytic capacitor. Furthermore, since a plating layer is interposed between the anode and the anodic conductive elastic body, it is possible to suppress the increase of the interface resistance between the anode and the conductive elastic body due to a natural oxide film formed on the surface of the valve metal, and thus to realize the connection with low resistance and high reliability.
Furthermore, in the first and second solid electrolytic capacitors, it is preferable that the plating layer has a multi-layer structure. For example, by constituting the plating layer by a plurality of plating layers having a various kinds of materials, it is possible to compensate for respective defects in the properties of each plating material.
Furthermore, in the solid electrolytic capacitor, the plating layer includes at least one selected from the group consisting of a nickel plating layer, a copper plating layer
Igaki Emiko
Masumi Hideki
Nakada Yasuhiko
Nakagawa Keizou
Shimada Mikinari
Dinkins Anthony
Merchant & Gould P,C,
LandOfFree
Solid electrolytic capacitor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Solid electrolytic capacitor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Solid electrolytic capacitor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2829372