Solid electrolytic capacitor and its manufacturing method

Details Solid electrolytic capacitor and its manufacturing method Solid electrolytic capacitor and its manufacturing method

2002-06-18

2004-04-13

Nguyen, Ha Tran (Department: 2812)

Metal working

Barrier layer or semiconductor device making

Barrier layer device making

C361S523000, C361S528000, C361S535000, C361S540000

Reexamination Certificate

active

06719813

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a solid electrolytic capacitor provided with a solid electrolyte layer formed of a conductive polymer, and its manufacturing method.
BACKGROUND OF THE INVENTION
FIG. 2
shows a cross-sectional view of a prior art solid electrolytic capacitor. It is to be noted that a thickness of each of respective layers in FIG.
1
and
FIG. 2
is exaggerated for the purposes of illustration.
In
FIG. 2
, valve metal
13
provided with a roughened surface layer
14
formed by an etching process is divided into an anode lead out area
12
and a capacitor element area
11
by means of a resist
19
applied onto the roughened surface layer
14
.
The capacitor element area
11
is formed on a surface of the roughened surface layer
14
first by depositing dielectric oxide layer
15
by anodization and then a solid electrolyte layer
16
, a carbon layer
17
and a silver paint layer
18
in succession. A lead terminal (not shown in
FIG. 2
) is connected to the anode lead out area
12
and the capacitor element area
11
, respectively, thus completing a capacitor element. Then, the entire capacitor element is encapsulated in a packaging resin by resin molding.
It is known that there are a method of electrolytic oxidation polymerization and a method of chemical oxidation polymerization in forming the solid electrolyte layer
16
. When the method of electrolytic oxidation polymerization is employed, a manganese dioxide layer is formed in advance on the dielectric oxide layer
15
and the solid electrolyte layer
16
is deposited on the manganese dioxide layer. When the method of chemical oxidation polymerization is employed, the solid electrolyte layer
16
is formed directly on the dielectric oxide layer
15
.
With a solid electrolytic capacitor as shown in
FIG. 2
, valve metal
13
provided with roughened surface layer
14
is divided into an anode lead out area
12
and a capacitor element area
11
by a resist
19
. However, solid electrolyte layer
16
is likely to creep to the anode lead out area
12
from the capacitor element area
11
through gaps between the resist
19
and the roughened surface layer
14
, often resulting in causing defective insulation or an electrical break-down.
In order to address the problem, such attempts as increasing the pattern width of resist
19
, adopting a material having good adhesion to the valve metal
13
and the like have been made. However, it is not easy to obtain good results for many production lots and achieving a low defective insulation rate constantly, and it has been a big problem in view of costs.
The present invention aims to address the foregoing problem and to provide a solid electrolytic capacitor and its manufacturing method, in which the probability of the conductive polymer layer to reach the anode lead out area and cause defective insulation or an electrical breakdown is remarkably reduced. In addition, the present invention provides a solid electrolytic capacitor and its manufacturing method, which do not worsen a good productivity so far enjoyed, while solving the foregoing problem.
SUMMARY OF THE INVENTION
A solid electrolytic capacitor of the present invention comprises:
(A) a capacitor element comprising:
a dielectric oxide layer formed on a roughened surface layer on a part of an outer surface of an anode body made of a valve metal;
a solid electrolyte layer formed on the dielectric oxide layer;
a cathode formed of a conductor layer disposed on the solid electrolyte layer, and
an anode lead out area on a remaining part of the outer surface of the anode body;
(B) lead terminals connected to the cathode and the anode lead out area of the capacitor element; and
(C) a packaging resin encapsulating the capacitor element with parts of the respective lead terminals exposed outside.
The solid electrolytic capacitor of the present invention is characterized in having a first separation strip and a second separation strip formed on a part of the roughened surface layer and also having an insulating material applied onto the respective surfaces of the first and second separation strips. According to the present invention, a solid electrolyte layer does not extend to the anode lead out area to cause defective insulation, thereby allowing the probability of an electrical breakdown to be reduced remarkably. Moreover, the present invention does not require the use of special jigs and processes and provides a solid electrolytic capacitor without worsening the productivity so far enjoyed.


REFERENCES:
patent: 4520430 (1985-05-01), Long et al.
patent: 5019949 (1991-05-01), Ikeda et al.
patent: 5168434 (1992-12-01), Kobayashi
patent: 5198967 (1993-03-01), Kuranuki et al.
patent: 6229687 (2001-05-01), Wada et al.
patent: 6293974 (2001-09-01), Kobatake et al.

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