JP3506738B2 - Structure of surface mount type solid electrolytic capacitor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface of a solid electrolytic capacitor such as a tantalum solid electrolytic capacitor which can be mounted on a printed circuit board or the like by soldering. The present invention relates to a structure of a mounting type solid electrolytic capacitor. 2. Description of the Related Art Conventionally, a surface mount type solid electrolytic capacitor of this kind has been disclosed in, for example, Japanese Patent Application Laid-Open No. 60-220922 and the like. A capacitor element comprising an anode bar protruding from one piece is disposed between a pair of left and right lead terminals such that the anode rod of the capacitor element is connected to one lead terminal and the chip piece is connected to the other lead terminal. After that, the entire capacitor element is packaged in a thermosetting synthetic resin molded part, and both lead terminals projecting from the molded part are bent so as to be along the lower surface of the molded part. It was configured to be surface-mounted by terminals. The storage capacity of this type of solid electrolytic capacitor is proportional to the volume of the chip of the capacitor element, while the equivalent series resistance (ESR) of the solid electrolytic capacitor at high frequency is the surface area of the chip of the capacitor element. Is inversely proportional to [0004] However, in the conventional solid electrolytic capacitor, the chip piece of the capacitor element is formed in a rectangular column shape with a rectangular cross section or a column shape with a circular cross section. Therefore, although its volume can be increased, due to its small surface area,
Since the high-frequency equivalent series resistance (ESR) of the solid electrolytic capacitor cannot be reduced, it cannot be used in places where the characteristics in the high-frequency region pose a problem. In addition, as described above, the conventional solid electrolytic capacitor uses a pair of left and right lead terminals and is packaged in a molded portion, so that it is configured as a surface mount type. In addition to the necessity of two lead terminals, the process of connecting the capacitor element to both the lead terminals and the process of molding the molded part are required, so that not only the manufacturing cost is greatly increased, but also in the capacitor element. There is also a problem that a connection failure frequently occurs in a connection portion between the chip piece and the other lead terminal. An object of the present invention is to provide a structure of a solid electrolytic capacitor which solves these problems at once. In order to achieve this technical object, the present invention provides a capacitor element comprising a pair of left and right anode rods projecting from one end face of a sintered chip piece.
A narrow metal plate lead terminal is placed on both anode rods.
This is fixed so that it extends in the direction transverse to the axis of the pole.
The both ends in the longitudinal direction of the lead terminal of the
While being bent substantially parallel to the bottom surface of the chip piece, a cathode-side electrode film is formed at least on the other end face opposite to the anode rod or on the bottom face near the other end face of the surface of the chip piece, while the other surface of the chip piece is Covered with an insulating film,
Further, the anode in the chip piece of the capacitor element
Cross-section in the direction perpendicular to the axis of the rod is
The portion of the surface between the two anode rods
Formed concavely from one end face to the other end face
Or, in the upper surface of the chip piece,
Depress the outer part than the part between the poles, and
Is formed in a convex shape from one end face to the other end face . ". [0008] With this configuration, while the chip piece in the capacitor element can be protected by the insulating film, the lead terminal fixed to the anode rod protruding from the chip piece. And the cathode-side electrode film formed on at least the other end surface of the chip piece of the capacitor element, it is possible to perform surface mounting by soldering on a printed circuit board or the like. Moreover, since the chip piece of the capacitor element is formed in a concave or convex cross section from one end face to the other end face, the surface area of the chip piece can be significantly increased. Therefore, according to the present invention, the equivalent series resistance (ESR) at a high frequency can be made much lower than that of a conventional solid electrolytic capacitor, and the characteristics in the high frequency region are problematic. In addition to the fact that a lead terminal is not required on the cathode side,
Since no molding step is required, the production process is simplified and the production cost is greatly reduced. In addition, by forming the cathode electrode film directly on the chip piece of the capacitor element, there is also an effect that almost no connection failure occurs on the cathode side as in the prior art. An embodiment of the present invention will be described below with reference to FIGS. In this figure, reference numeral 1 denotes a capacitor element. The capacitor element 1 includes a chip piece 2 obtained by sintering a metal powder such as tantalum, and a pair of left and right anode rods 3a, 3
b, and the chip piece 2 has the upper surface
The portion between the anode rods 3a and 3b is recessed, and the chip
2 in the direction perpendicular to the axis of the anode rods 3a and 3b.
The cross section becomes concave from one end face 2a to the other end face 2b.
It is formed as follows. Both anode rods 3 in the capacitor element 1
a, metal plate lead terminals 4 on the lower surfaces of
The anode rods 3a and 3b are melted so as to extend in the transverse direction.
The lead terminal 4 in the longitudinal direction.
Connect both ends 4a, 4b to the bottom surface (positive
Specifically, it is folded substantially parallel to the bottom surface of the insulating film 6 described later).
On the other hand, the cathode-side electrode film 5 is formed on one or both of the other end face 2b and the bottom face near the other end face 2b of the chip piece 2 by metal plating or the like. The case where the cathode-side electrode film 5 is formed on the entire surface near the other end surface 2b is shown). Further, a portion of the surface of the chip piece 2 other than the cathode-side electrode film 5 is covered with an insulating film 6 such as an epoxy resin. With this configuration, the chip piece 2 of the capacitor element 1 is
A lead terminal 4 fixed to both anode rods 3a and 3b protruding from the chip piece 2 while being protected by the insulating film 6, and the other end face 2 of the chip piece 2
The surface mounting by soldering to a printed board or the like can be performed by using the cathode-side electrode film 5 formed on one or both of the bottom surface b and the other end surface 2b. Further, since the chip piece 2 of the capacitor element 1 is formed in a concave cross section from one end face 2a to the other end face 2b, the surface area of the chip piece 2 can be significantly increased. Note that the chip piece 2 of the capacitor element 1 is not limited to being formed in a concave cross section as in the above-described embodiment, but as shown in FIG. 7, the upper surface is located between the two anode rods 3a and 3b.
The outer portion of the chip piece 2
The cross section perpendicular to the axis of both anode rods 3a, 3b is one end face 2.
Even if it is formed in a concave shape from a to the other end surface 2b, the surface area of the chip piece 2 can be greatly increased.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of a solid electrolytic capacitor according to an embodiment of the present invention. FIG. 2 is a plan view of FIG. FIG. 3 is a sectional view taken along line III-III of FIG. 2; FIG. 4 is a left side view of FIG. FIG. 5 is a sectional view taken along line VV of FIG. 1; FIG. 6 is an overall perspective view. FIG. 7 is a perspective view of a solid electrolytic capacitor according to another embodiment of the present invention. [Description of Signs] 1 Capacitor element 2 Chip piece 2a One end face 2b of chip piece The other end face 3a, 3b of chip piece Anode bar 4 Lead terminal 5 Cathode side electrode film 6 Insulating coating

Claims (1)

(57) [Claims 1] A pair of anode rods protruding from one end surface of a sintered chip piece in a capacitor element ,
Connect the narrow metal plate lead terminals to both anode rods
This lead is fixed so that it extends in the direction transverse to the axis.
End of the chip terminal at the bottom of the chip piece.
And forming a cathode-side electrode film on at least the other end surface opposite to the anode bar or the bottom surface near the other end surface of the surface of the chip piece, while insulating the other surface of the chip piece from the other. Covered with a coating,
The axis of the anode bar in the chip piece of the capacitor element
The cross section in the direction perpendicular to the line is
Then, depress the part between the anode rods and place it on the chip.
From one end face to the other end face, or
Is between the two anode bars on the upper surface of the chip piece.
Depress the outer part than the part and
A structure of a surface mount type solid electrolytic capacitor characterized by being formed in a convex shape from one end surface to the other end surface .