JPH0794363A - Structure of surface-mount solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To enable a solid electrolytic capacitor such as a tantalum solid electrolytic capacitor or the like to be lessened in equivalent series resistance (ESR) on high frequencies and manufacturing cost. CONSTITUTION:A lead terminal 4 is fixed to anode rods 3a and 3b which protrude from the end face 2a of a chip piece 2 of a capacitor device 1, a cathode side electrode film 5 is formed on the other end face 2b of the chip piece 2 opposed to the end face 2a provided with the anode rods 3a and 3b or on a base adjacent to the end face 2b, and the other surface of the chip piece 2 is covered with an insulating film 6, and moreover the chip piece 2 of the capacitor device 1 is so formed as to be recessed or protrudent in cross section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a solid electrolytic capacitor such as a tantalum solid electrolytic capacitor which is constructed so that it can be mounted on a printed circuit board by soldering. is there.

[0002]

2. Description of the Related Art Conventionally, a surface mount type solid electrolytic capacitor of this type has a chip piece made of a sintered body and protruding from the chip piece, as described in, for example, JP-A-60-220922. After arranging a capacitor element consisting of an anode rod and a pair of left and right lead terminals so that the anode rod in the capacitor element is connected to one lead terminal and the chip piece to the other lead terminal respectively, The whole capacitor element is packaged in a thermosetting synthetic resin mold part, both lead terminals protruding from this mold part are bent along the lower surface of the mold part, and the two lead terminals are used to form a surface. It was configured to implement.

The storage capacity of this type of solid electrolytic capacitor is proportional to the volume of the chip piece of the capacitor element, while the equivalent series resistance (ESR) at high frequencies of the solid electrolytic capacitor is the surface area of the chip piece of the capacitor element. Is inversely proportional to.

[0004]

However, in the conventional solid electrolytic capacitor, since the chip piece in the capacitor element is formed in a rectangular column shape having a quadrangular cross section or a cylindrical shape having a circular cross section, Although its volume can be increased, its small surface area allows
Since the equivalent series resistance (ESR) at high frequencies in the solid electrolytic capacitor cannot be lowered, it cannot be used in a place where the characteristics in the high frequency region pose a problem.

Moreover, in the conventional solid electrolytic capacitor, as described above, the pair of left and right lead terminals are used, and the solid electrolytic capacitor is packaged in the mold portion to form the surface mounting type. In addition to the need for two lead terminals, the step of connecting the capacitor element to both lead terminals and the step of forming the molding part are required, which not only significantly increases the manufacturing cost but also There is also a problem that a defective connection frequently occurs at a connecting 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 all at once.

[0007]

In order to achieve this technical object, the present invention provides an anode rod projecting from one end face of a sintered chip piece in a capacitor element, and both ends of which are substantially the same as the bottom surface of the chip piece. Secure the lead terminals bent in parallel,
While forming a cathode-side electrode film on at least the other end surface on the opposite side of the anode rod or the bottom surface near the other end surface of the surface of the chip piece, the other surface of the chip piece is covered with an insulating coating, and The chip piece of the capacitor element is formed to have a concave cross section or a convex cross section from one end surface to the other end surface.

[0008]

[Operation] With this structure, the chip piece of the capacitor element can be protected by the insulating film, but the lead terminal fixed to the anode rod protruding from the chip piece and the capacitor The cathode side electrode film formed on at least the other end surface of the chip piece of the element enables surface mounting by soldering to a printed circuit board or the like.

Moreover, by forming the chip piece of the capacitor element in a concave cross section or a convex cross section from one end surface to the other end surface, the surface area of the chip piece can be remarkably increased.

[0010]

Therefore, according to the present invention, the equivalent series resistance (ESR) at high frequency can be made much lower than that of the conventional solid electrolytic capacitor, and the characteristic in the high frequency region becomes a problem. In addition to the need for a lead terminal on the cathode side,
Since the molding process of the molding part is not required, the manufacturing process is simplified and the manufacturing cost can be significantly reduced.

Further, by directly forming the cathode electrode film on the chip piece of the capacitor element, there is an effect that it is possible to almost completely eliminate the connection failure on the cathode side as in the conventional case.

[0012]

Embodiments of the present invention will be described below with reference to the drawings of FIGS. In the figure, reference numeral 1 indicates a capacitor element, which is a chip piece 2 obtained by sintering metal powder such as tantalum, and a pair of left and right anode rods 3a protruding from one end surface 2a of the chip piece 2, Three
The chip piece 2 is formed in a concave cross section from one end face 2a to the other end face 2b.

Both anode rods 3 in the capacitor element 1
Both end portions 4a and 4b are provided on the lower surface of
A lead terminal 4 made of a metal plate formed by bending the bottom surface (to be exact, a bottom surface of an insulating film 6 to be described later) in
On the one side or both of the other end face 2b and the bottom face near the other end face 2b of the tip piece 2, while the cathode side electrode film 5 is formed by metal plating or the like (however, the drawings are The other end surface 2b of the surface of the chip piece 2
(The case where the cathode side electrode film 5 is formed on the entire surface near the side is shown).

Further, a portion of the surface of the chip piece 2 excluding 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 in the capacitor element 1 is
The lead terminal 4 fixed to both anode rods 3a and 3b protruding from the chip piece 2 and the other end surface 2 of the chip piece 2 can be protected by the insulating film 6.
b and the cathode side electrode film 5 formed on either or both of the bottom surfaces near the other end surface 2b, surface mounting can be performed on a printed circuit board or the like by soldering.

Further, since the chip piece 2 of the capacitor element 1 is formed in a concave cross section from the one end surface 2a to the other end surface 2b, the surface area of the chip piece 2 can be remarkably increased. The chip piece 2 in the capacitor element 1 is not limited to the concave cross section as in the above-described embodiment, but may be formed in the convex cross section as shown in FIG. The surface area can be greatly increased. Also,
The number of anode rods may be one.

[Brief description of 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 in FIG.

FIG. 4 is a left side view of FIG.

5 is a cross-sectional view taken along line VV of FIG.

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.

[Explanation of symbols]

 1 Capacitor element 2 Chip piece 2a One end surface of chip piece 2b Other end surface of chip piece 3a, 3b Anode rod 4 Lead terminal 5 Cathode side electrode film 6 Insulating film

Claims (1)

[Claims] 1. A lead terminal having both ends bent substantially parallel to the bottom surface of the chip piece is fixed to an anode rod projecting from one end surface of the sintered chip piece of the capacitor element, and the surface of the chip piece is fixed. While forming a cathode side electrode film on at least the other end surface on the side opposite to the anode rod or on the bottom surface near the other end surface, the other surface of the chip piece is covered with an insulating coating, and the chip in the capacitor element is further formed. A structure of a surface mount type solid electrolytic capacitor, wherein the piece is formed in a concave cross section or a convex cross section from one end surface to the other end surface thereof.