JP2001102252A - Method of manufacturing solid electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized chip capacitor having large capacitance. SOLUTION: In a method of manufacturing a solid electrolytic capacitor, in which a capacitor element 2 having an anode lead 11 led out at one end thereof, and a cathode formed on the outer peripheral surface is resin-sealed, in order to improve the volume ratio of the capacitor element to a capacitor finished product, the capacitor element 2 is bonded on the inner surface of a circuit board 3 which has a positive electrode and negative electrode both on the inner and outer surfaces thereof and the electrodes having the same polarity are connected to each other via through-holes, so that the negative electrode on the surface and the cathode of the capacitor element 2 are electrically connected, and after the anode lead 11 of the capacitor element 2 is connected to the positive electrode, the outer surface of the circuit board 3 is exposed and the capacitor element 2 is resin-sealed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a chip-type solid electrolytic capacitor, and more particularly to a method for manufacturing a chip capacitor in which the volume ratio of a capacitor element to a finished capacitor is improved.

[0002]

2. Description of the Related Art As shown in FIG. 3, a solid electrolytic capacitor is made of a dielectric material such as a sintered body (for example, a tantalum sintered body) made of a valve metal having an anode lead (11) led out at one end. A film, a solid electrolyte layer, a carbon layer, and a silver paste layer are sequentially formed to complete the capacitor element (2). Next, the two lead frames (21) (2
Of 2), one lead frame is welded to the anode lead (11), and the other lead frame (22) is adhesively connected to the silver paste layer with the silver adhesive (4). Next, the capacitor element (2) is resin-sealed by transfer molding or the like so that the leading ends of the lead frames (21) and (22) are exposed. Finally, the lead frames (21) and (22) led out of the exterior resin (6) are bent to predetermined dimensions to form a plus electrode and a minus electrode, thereby completing the capacitor.

[0003]

In the method according to the prior art, the anode lead (11) and the lead frame are provided on the plus side.
The welding margin (23) for connection with the (21) needs to be provided, and the lead frame (21) must have a bending margin (24) on the minus side. For example, in the case of a capacitor having a length of 7.3 mm and a width of 4.3 mm (hereinafter, referred to as "D case"), the thickness L1 and L2 of the plus side and minus side exterior resin (6) are about 1 respectively. It was .8 mm. Conventionally, it is necessary to bend the lead frames (21) and (22) outside the exterior resin (6), and the length of the exterior resin (6) after molding is 7.
It was necessary to mold the lead frame (21) to be smaller than 3 mm by the thickness of the lead frame (21) (see FIG. 3).

In the above example, the exterior resin (6) after molding is used.
Is molded to 7.1 mm in length. Therefore, in the method according to the prior art, the volume ratio of the capacitor element to the completed capacitor product (hereinafter simply referred to as “volume ratio”) cannot be sufficiently large, and the volume ratio is about 20.4% as shown in Table 1 below. Was stopped at Table 1 shows an example in the case of a capacitor having a height of 1.8 mm in the D case. The present invention
An object of the present invention is to solve the above problem and provide a small and large-capacity chip capacitor by improving the volume ratio.

[0005]

[Table 1]

[0006]

According to the method for manufacturing a solid electrolytic capacitor of the present invention, an anode lead (11) is led out at one end and a capacitor element (2) having a cathode formed on the outer peripheral surface is sealed with a resin. In the method of manufacturing an electrode capacitor, the capacitor element (2) is adhered to the inner surface of a circuit board (3) having a positive electrode and a negative electrode on both the inner and outer surfaces, respectively, and having the same polarity through a through hole, thereby forming a negative electrode. After electrically connecting the electrode and the cathode of the capacitor element (2) and bonding the anode lead (11) of the capacitor element (2) to the brass electrode,
It is characterized in that the outer surface of the circuit board (3) is exposed and resin sealing is performed on the capacitor element (2).

[0007]

[Function and effect] Circuit board (printed circuit board)
By bonding the capacitor element (2) to (3),
Since the volume ratio can be increased, a small-sized and large-capacity capacitor can be obtained. Also, since the conventional lead frame (21) can be omitted, the equivalent series resistance (ESR)
Capacitor with a small size can be manufactured. Furthermore, the lead frame (21) conventionally used becomes unnecessary, and the labor of joining and bending the lead frame (21) can be omitted.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIG. 10, an anode lead (11) is led out at one end of a solid electrolytic capacitor, and a capacitor element (2) having a cathode formed on the outer peripheral surface is subjected to resin sealing. I have. The capacitor element (2) forms a dielectric oxide film on the surface of a valve metal such as tantalum (Ta), aluminum (Al), niobium (Nb), and titanium (Ti) by a method such as anodic oxidation. After a polymer organic semiconductor such as polypyrrole, polythiophene, or polyaniline is formed on the film as a solid electrolyte, a carbon layer and a silver paste layer are sequentially formed to complete the process. A silver paste layer (not shown) serves as a cathode. Since the capacitor element (2) can be manufactured by a known technique (for example, JP-A-8-148392 (H01G9 / 00)), the description of the method of manufacturing the capacitor element itself is omitted. In the following examples, a tantalum sintered body (1) was employed as a valve metal and polypyrrole was employed as a solid electrolyte.

Example 1 A tantalum sintered body (1) is shown in FIG.
As shown at 0, the anode lead (11) is a flat rectangular parallelepiped, and the anode lead (11) is led out in the longitudinal direction from one end face orthogonal to the longitudinal direction.
When manufacturing the capacitor, first, as shown in FIG.
(3) is prepared. This embodiment is an example of manufacturing a D-case capacitor, and FIG. 4 shows one circuit board.
(3) shows a layout for manufacturing 360 (30 × 6 × 2) capacitors. The circuit board (3) has a thickness of 0.
A 2 mm glass cloth / epoxy resin copper-clad laminate was used.

FIGS. 5 and 6 show patterns of the circuit board (3) used in this embodiment. Here, the capacitor element (2)
The surface to be bonded is defined as the inner surface, and the opposite surface is defined as the outer surface. The inner positive electrode (31) is the outer positive electrode.
(31) and the inner negative electrode (32) are the outer negative electrode.
(32) and are electrically connected to each other by through holes (33). FIG. 5 shows the pattern of the electrodes on the inner surface, and FIG. 6 shows the pattern of the electrodes on the outer surface. Further, all the negative electrodes (32) of the circuit board (3) are electrically connected as shown in FIGS. This is for convenience in aging described later.

Next, the anode lead (1) of the capacitor element (2)
1) is connected to the plus electrode (31) on the inner surface of the circuit board (3), and the outer peripheral silver paste layer is connected to the minus electrode (32) on the inner surface of the circuit board (3). At this time, the outer silver paste layer (cathode) of the capacitor element (2) is adhesively connected directly to the negative electrode (32) of the circuit board (3) using a silver adhesive (4), and the anode lead (1) is formed.
1) is a fixed length, bent to about 90 degrees, and then a plus electrode (31)
Is connected by using a silver adhesive (4). Next, an exterior resin (6) such as an epoxy resin is applied from above the circuit board (3) so that the height is constant. In the present embodiment, the coating was performed such that the height of the exterior resin (6) was about 1.6 mm. Then 15
The exterior resin (6) is cured by placing it in a curing oven at 0 ° C. for 30 minutes.

Next, before cutting the circuit board (3) into product units, aging is performed for the purpose of reducing leakage current by applying a DC voltage to each capacitor.
Since the positive electrode (31) is independent of each other, it is necessary to connect it to each capacitor. However, since the negative electrode (32) is common, there is an advantage that it is sufficient to connect the power supply to one place. Finally, the chip capacitor is cut into a predetermined size by dicing to complete the chip capacitor (40).

In the present invention, a conventional lead frame is used.
Since (21) is not used, the length L1 of the exterior resin (6) on the minus side can be reduced from the conventional 1.8 mm to 0.5 mm.
Since it is not necessary to bend the lead frames (21) and (22) outside the exterior resin (6), the overall length of the exterior resin (6) is set to 7.
Capacitor element can be molded 0.2mm longer than conventional 3mm
(2) The overall length was increased by 1.5 mm. The relationship (length direction) is summarized in Table 2 below.

[0014]

[Table 2]

Looking at the height direction, FIG.
As described above, the thickness of the lead frame (22) covering the upper surface of the capacitor element (2) and the thickness of the lead frames (21) and (22) bent so as to be in contact with the lower surface of the exterior resin (6) become unnecessary. . Therefore, the height of the capacitor element (2) can be increased by 0.3 mm as compared with the conventional case. Table 3 summarizes this relationship. In the width direction, the relationship between the width of the exterior resin (6) after molding and the width of the capacitor element (2) is the same as in the related art.

Example 2 In Example 2, as shown in FIG. 11, an anode lead (11) was led out to one side of a flat rectangular parallelepiped tantalum sintered body (1) along the thickness direction of the sintered body. ing. From the formation of the dielectric oxide film on the tantalum sintered body (1),
The formation of the polypyrrole layer, the carbon layer and the silver paste layer can be performed by a known technique in the same manner as in Example 1 described above.
The capacitor element (2) is completed. However, anode lead (11)
No silver paste layer is formed in the vicinity of the base.

The patterns on the inner and outer surfaces of the circuit board (3) used in this embodiment are as shown in FIGS. The capacitor element (2) is adhesively connected to the inner surface of the circuit board (3) in the same manner as described above. At this time, as shown in FIG.
(11) is inserted halfway into the through hole (33) of the circuit board (3) and is connected in the through hole (33) by the silver adhesive (4). The portion of the surface of the capacitor element (2) from which the anode lead (11) is led out, except for the vicinity of the base of the anode lead (11), is provided with a silver adhesive (4) on the circuit board. (3) It is adhesively connected to the negative electrode (32) on the inner surface. Next, the capacitor element (2) is sealed with an exterior resin (6) such as an epoxy resin. The steps after sealing the exterior resin (6) are the same as those in the first embodiment.

In the second embodiment, since the length L2 of the conventional exterior resin (6) on the plus side can be reduced to 0.5 mm from 1.8 mm in the conventional case, the capacitor element (2) can be further improved compared to the first embodiment. Has been increased by 1.3 mm. (See Table 2). The height direction and the width direction are the same as those in the first embodiment (see Table 3 below).

[0019]

[Table 3]

The volumes and volume ratios of the capacitor elements (2) used in Examples 1 and 2 are as shown in Table 4 below.

[0021]

[Table 4]

In the first embodiment, the volume ratio is set to about 1.8 in the related art.
In the second embodiment, the magnification can be increased to about 2.34 times. As described above, according to the present invention, it is understood that the volume ratio can be increased, and a small-sized and large-capacity capacitor can be realized.

Embodiment 3 Regarding the pattern on the outer surface, the pattern can be divided into several parts. In this embodiment, each of the plus side and the minus side is divided into six (see FIG. 9). Electrodes are formed by forming solder balls on each pattern.

As described above, in the present invention, the volume ratio can be increased by adhesively connecting the capacitor element (2) to the circuit board (3), so that a small-sized and large-capacity capacitor can be obtained. . Also, lead frame (21)
Therefore, it is possible to manufacture a capacitor having a small equivalent series resistance (ESR). Further, since the conventional lead frame (21) can be omitted, as shown in FIG. 12, when the capacitor (40) is provided on the mounting circuit board (41), the soldering areas (42) on both sides of the capacitor (40) are used. (42)
Is unnecessary, and the mounting density of electronic components on the mounting circuit board (41) can be improved, which can contribute to miniaturization of electronic devices (see FIG. 13).

The present invention is not limited to the configuration of the above embodiment, and various modifications are possible within the scope of the claims.

[Brief description of the drawings]

FIG. 1 is a sectional view of a solid electrolytic capacitor according to Embodiment 1 of the present invention.

FIG. 2 is a sectional view of a solid electrolytic capacitor according to Embodiment 2 of the present invention.

FIG. 3 is a cross-sectional view of a conventional solid electrolytic capacitor element.

FIG. 4 is a layout diagram of the circuit board 3;

FIG. 5 is a pattern diagram of an inner surface according to the first embodiment.

FIG. 6 is a pattern diagram of an outer surface according to the first embodiment.

FIG. 7 is a pattern diagram of an inner surface according to the second embodiment.

FIG. 8 is a pattern diagram of an outer surface according to the second embodiment.

FIG. 9 is a pattern diagram according to a third embodiment.

FIG. 10 is a perspective view of a tantalum sintered body in Example 1.

FIG. 11 is a perspective view of a tantalum sintered body in Example 2.

FIG. 12 is a diagram of mounting a capacitor on a mounting circuit board according to the related art.

FIG. 13 is a diagram of mounting a capacitor on a mounting circuit board according to the present invention.

[Explanation of symbols]

 (1) Sintered tantalum (2) Capacitor element (3) Circuit board (4) Silver adhesive (6) Outer resin (11) Anode lead (21) Lead frame (31) Positive electrode (32) Negative electrode (33 ) Through-hole (40) Capacitor

Claims (5)

[Claims] 1. A method for manufacturing a solid electrode capacitor in which an anode lead (11) is led out at one end and a resin is sealed to a capacitor element (2) having a cathode formed on an outer peripheral surface, wherein a positive electrode is provided on both inner and outer surfaces. The capacitor element (2) is adhered to the inner surface of the circuit board (3) having a negative electrode and having the same polarity conducted through holes, and the negative electrode on the surface and the cathode of the capacitor element (2) are electrically connected. After connecting and bonding the anode lead (11) of the capacitor element (2) to the brass electrode, exposing the outer surface of the circuit board (3),
(2) A method for manufacturing a solid electrolytic capacitor, wherein resin sealing is performed. 2. The method for manufacturing a solid electrolytic capacitor according to claim 1, wherein the pattern of the plus electrode and the minus electrode on the outer surface of the circuit board is divided into two or more. 3. The method according to claim 1, wherein the valve metal constituting the capacitor element is a sintered body. 4. The method for manufacturing a solid electrolytic capacitor according to claim 1, wherein the anode lead is inserted into a through hole of the circuit board. 5. An aging process is performed before the circuit board (3) to which the capacitor element (2) is adhesively connected and resin-sealed is cut into individual size capacitors. 5. The method for manufacturing a solid electrolytic capacitor according to any one of 4.