Electricity: electrical systems and devices – Electrolytic systems or devices – Solid electrolytic capacitor
Reexamination Certificate
1999-11-04
2001-06-19
Dinkins, Anthony (Department: 2831)
Electricity: electrical systems and devices
Electrolytic systems or devices
Solid electrolytic capacitor
C361S524000, C361S528000
Reexamination Certificate
active
06249424
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a solid electrolytic capacitor, particularly a solid electrolytic multilayer capacitor, using an organic material such as an electrically conducting polymer, or an inorganic material such as a metal oxide, as the solid electrolyte. The present invention further provides a monolayer capacitor element for manufacturing a solid electrolytic multilayer capacitor.
2. Description of Related Art
In the manufacture of a solid electrolytic multilayer capacitor comprising the stacked monolayer of capacitor element using a conductive polymer (also called an electrically conducting polymer) or and the like, as the solid electrolyte therein, when the plural monolayer capacitor elements are stacked such that respective cathode areas are laid one on another to run parallel with each other, the anode areas must be bent so as to allow spot welding because each cathode area formed by providing a solid electrolyte layer and an electrically conducting layer in sequence has a thickness larger than that of the anode area. Due to this, stress concentrates in the vicinity of the boundary between the anode area and the cathode area of the monolayer capacitor element, and as a result, the capacitor performance deteriorates. Various attempts have been made to overcome this problem.
For example, in order to eliminate this difference between the thickness of the cathode area and the anode area, a method of inserting a metal sheet having a thickness corresponding to the space between respective anode areas of the plurality of monolayer capacitor elements during stacking of the monolayer capacitor elements (see, Japanese Unexamined Patent Application, No. Hei 5-205984), a method of forming an insulating resin layer in the space between respective anode areas and connecting those anode areas through a fine metal line or and the like, (see, Japanese Unexamined Patent Application, No. Hei 6-29163, and Japanese Unexamined Patent Application, No. Hei 6-84716) and a method of dividing a lead frame into pieces corresponding to respective anode area sites are known (see, Japanese Unexamined Patent Application No. Hei 4-167417).
SUMMARY OF THE INVENTION
However, these methods for eliminating the problem of the difference in the thickness so as to prevent the concentration of stress from occurring in the vicinity of the boundary between the anode area and the cathode area during stacking are disadvantageous due to the increase in the working steps and the rise in the cost for processing the materials, and the like. Furthermore, as a result of the increase in the working steps, the monolayer capacitor element is more frequently ruptured or reduced in the capability by the mechanical stress or and the like, during the handling, and this causes a decrease in the yield during manufacture of multilayer capacitors or deterioration in the capability.
The present invention has been created for solving these problems. The object of the present invention is to provide a high-performance and high-capacity solid electrolytic multilayer capacitor and prevent the reduction in yield in the manufacture of the multilayer capacitor by preventing the concentration of stress in the vicinity of the boundary between the anode area and the cathode area from occurring during stacking and thereby obtaining a multilayer capacitor excellent in yield and having superior capability. Furthermore, the present invention provides a monolayer capacitor element suitable for manufacturing the above-described solid electrolytic multilayer capacitor.
The monolayer capacitor element of the present invention is a monolayer capacitor element comprising an anode allocated to an end part of an anode substrate comprising a tabular valve-acting metal having formed on the surface thereof a dielectric oxide layer, and a cathode area formed by sequentially providing a solid electrolyte layer on the dielectric oxide layer exclusive of the anode area and thereon an electrically conducting layer, in which the thickness at the distal end part of the cathode area is larger than the thickness at the base part of the cathode area.
The solid electrolytic multilayer capacitor of the present invention is a solid electrolytic multilayer capacitor comprising a multilayer capacitor element obtained by stacking a plurality of monolayer capacitor elements, each of which comprises an anode allocated to an end part of an anode substrate further comprising a tabular valve-acting metal having a dielectric oxide layer formed on the surface thereof, and a cathode area formed by sequentially providing a solid electrolyte layer on the dielectric oxide layer exclusive of the anode area and thereon an electrically conducting layer, such that the anode areas aligned in the same direction are stacked and bonded onto a lead frame on the anode side and the cathode areas are stacked and bonded onto a lead frame in the cathode side by forming an electrically conductive adhesive layer so as to have an unfolded fan shape that widens from the anode area side toward the distal end of the cathode area, in which the periphery of the multilayer capacitor element is covered and sealed with an armoring resin.
In the above-described solid electrolytic multilayer capacitor, the electrically conducting adhesive layer is preferably formed in the range of 80% or less of the cathode area length from the distal end of the cathode area. Furthermore, the multilayer capacitor element is preferably obtained by stacking under pressure a plurality of monolayer capacitor elements.
Also, in the above-described solid electrolytic multilayer capacitor, the monolayer capacitor element is preferably a monolayer capacitor in which the thickness at the distal end of the cathode area is larger than the thickness at the base part of the cathode area. Furthermore, it is preferred that one cathode area and another cathode area of the monolayer capacitor elements in plurality or a cathode area and the lead frame in the cathode side are stacked and bonded by an electrically conducting adhesive layer, and that the thickness of the electrically conducting adhesive layer at the distal end part of the cathode is larger than that at the base part of the cathode area.
Furthermore, in the above-described solid electrolytic multilayer capacitor, the solid electrolyte layer is preferably formed using an electrically conducting polymer.
REFERENCES:
patent: 5005107 (1991-04-01), Kobashi et al.
patent: 5428500 (1995-06-01), Nishiyama et al.
patent: 5471365 (1995-11-01), Nakamura et al.
patent: 5621608 (1997-04-01), Arai et al.
patent: 5790368 (1998-08-01), Naito et al.
Ichimura Takashi
Minamida Wataru
Nitoh Hiroshi
Sakai Atsushi
Dinkins Anthony
Showa Denko K.K.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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