JPH11121284A - Method for manufacturing solid electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a solid electrolytic capacitor, in which the number of defective products due to defective ESR characteristic is reduced and yield is improved by thinly applying a highly viscous silver paste to the carbon layer of a capacitor element through an immersion method. SOLUTION: In a method for manufacturing a solid electrolytic capacitor, which includes the steps of forming a condenser element 11 by forming a chemical film 2, a solid electrolytic layer 3, and a carbon layer 4 on an anode 1 made of a valve action metal, covering the carbon layer 4 of the capacitor element 11 with a silver paste 51, and silver-soldering a lead frame 6 to a silver paste layer 5, the carbon layer 4 is covered with the silver paste 51 by immersing the capacitor element 11 in the silver paste 51, while oscillating relatively the silver paste 51 and the capacitor element 11 and by pulling out the condenser element 11 in the direction of oscillation.

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 solid electrolytic capacitor, characterized in that a high-viscosity silver paste is efficiently and thinly applied to a capacitor element.

[0002]

2. Description of the Related Art The body (10) of a solid electrolytic capacitor is shown in FIG.
As shown in (1), a capacitor element (11) is produced by forming a chemical conversion film (2), a solid electrolyte layer (3), and a carbon layer (4) on an anode body (1) made of a valve action metal. The carbon layer (4) of the device was covered with a silver paste (51), and FIG.
As shown in FIG. 3, a lead frame (6) is bonded to the silver paste layer (5) with a silver adhesive (52), and the whole is covered with a resin outer shell (7) as shown in FIG. Go and it is completed.

However, the completed solid electrolytic capacitor E
There was a problem that the characteristics of SR (equivalent series resistance) were poor, many defective products were produced, and the yield was poor. As a result of repeated tests, the applicant found that the cause of the above-mentioned poor ERS characteristics was that when the capacitor body (10) was bonded to the lead frame (6), the silver paste layer (51) and the silver adhesive (52) It was concluded that the conductivity of the film deteriorated.

[0004] This is for the following reason. Silver paste
It comprises silver, a binder, and a solvent (volatile component) for dissolving the binder. Here, the binder is a resin component such as an epoxy resin. The solid electrolytic capacitor is required to be miniaturized in use, and therefore, the silver paste (51) is coated as thinly as possible. In order to make the silver paste layer (5) thin, the viscosity of the silver paste (51) is reduced, and the silver paste (5) is immersed in the capacitor element (11).
1) need to be applied. In order to reduce the viscosity of the silver paste (51), it is necessary to increase the ratio of the solvent in the silver paste (51). When the ratio of the solvent is high, the silver and the binder are easily separated, the binder as a resin component is exposed on the surface of the silver paste, and the contact resistance with the silver adhesive (52) increases.

When a silver paste (51) having a low solvent ratio and thus a high viscosity was applied to the capacitor element (11), the defect of the ESR characteristics was greatly reduced, and the yield was remarkably improved.
However, a silver paste having a high viscosity adheres too thickly by application by immersion, which hinders minimization of a finished product. Brushing is not practical in terms of spots and productivity.

In view of the above problems, the present invention provides a solid electrolytic capacitor capable of improving the yield by applying a high-viscosity silver paste to a capacitor element by an immersion method to reduce the rate of discharge of defective products due to poor ESR characteristics. This clarifies the manufacturing method.

[0007]

According to the method of manufacturing a solid electrolytic capacitor of the present invention, a conversion film (2), a solid electrolyte layer (3) and a carbon layer (4) are formed on an anode body (1) made of a valve metal. To produce a capacitor element (11), covering the carbon layer (4) of the capacitor element with a silver paste (51), and bonding a lead frame (6) to the silver paste layer (5) with silver. In the method of manufacturing a solid electrolytic capacitor including a carbon paste (51), the carbon layer (5) is coated with a silver paste
(51) While oscillating the capacitor element (1) relatively, the capacitor element (11) is immersed in the silver paste (51), and the capacitor element (11) is pulled out in the direction of the vibration. I do.

Specifically, the viscosity of the silver paste (51) is 5
0 to 300 poise.

The amplitude of the vibration may be 0.2 to 2 times the length of the capacitor element in the vibration direction.

[0010] More specifically, the frequency is 20-100H.
z may be used.

[Operation and Effect] Due to the relative vibration between the silver paste and the capacitor element (11), the effective viscosity of the silver paste (51) decreases near the surface of the capacitor element (11). Therefore, even the silver paste (51) having a high viscosity can be thinly applied to the capacitor element (11). As in the case where a silver paste having a low viscosity was applied to the capacitor element (11), the poor yield due to poor conductivity was significantly improved. Further, since the silver paste (51) can be applied to the capacitor element (11) by an immersion method, the productivity is excellent.

[0011]

Embodiments of the present invention will be described below. As shown in FIG. 1, the body of the solid electrolytic capacitor
(10) is a dielectric conversion coating on the surface of the anode body (1) formed by a valve metal such as Ta, Al, Nb by electrolytic oxidation treatment.
(2) to form a solid electrolyte layer (3) comprising an inorganic solid electrolyte of MnO ₂ or an organic solid electrolyte such as a conductive polymer on the dielectric conversion coating (2);
(3) A carbon layer (4) and a silver paste layer (5) formed by covering the carbon layer (4).

The solid electrolytic capacitor of the present embodiment comprises a lead wire (60) of an anode of a capacitor element (11) and a silver paste layer.
(5), lead frames (6) and (61) are attached respectively, and the capacitor body (10) and a part of the lead frames (6) and (61) are covered with resin by injection molding. Shell (7)
And the lead frame (6) (6) exposed from the outer shell (7).
1) is folded along the outer shell (7), and then is subjected to an aging process to complete the process.

In the embodiment, a Ta sintered body is used for a valve metal as an anode, and polypyrrole as a conductive polymer is used for a solid electrolyte layer (3) as a cathode. The feature of the present invention resides in the step of coating the carbon layer with a silver paste, and the other steps are known in, for example, Japanese Patent Application Laid-Open No. 8-148392, and will not be described.

FIG. 4 shows a silver paste on the capacitor element (11).
(51) shows an application device (8) for coating;
(8) is a tank (82) having a top opening connected to the vibration device (81).
And a jig (87) for dipping the capacitor element (11) in the silver paste (51) in the tank (82).

The vibrating device (81) pivotally connects an elevating shaft (83) projecting downward on the lower surface of the tank (82) to an eccentric position of a rotary plate (85) through a link (84), and rotates the shaft. Motor on plate (85)
(86). The vibration device is not limited to this, and an electromagnetic device may be used. Silver paste (51) is 50
A material having a high viscosity of about 300 poise is used.

The vibrating device (81) vibrates the tank (82), that is, the silver paste (51) in the vertical direction, and the capacitor element (11) attached to the jig (87) with the lead wire (60) facing upward. To
It is immersed to the base end side of the lead wire (60) and pulled up just above, that is, in the direction along the vibration direction of the silver paste (51). here,
The length of the vibration element of the capacitor element (11) was about 3.0 mm. The amplitude of the vibration device in this case was 1.5 mm, but the effect does not change even if the amplitude is increased by a certain amount or more.
(See Table 3). Rather, if the amplitude is too large, the silver paste tank
(82) depth required, silver paste accordingly (51)
It is not economical because the required amount increases. Further, when the amplitude is increased, the power consumption of the vibrating device is increased, which is not economical.

Due to the vibration of the silver paste (51), the effective viscosity of the silver paste (51) decreases near the surface of the capacitor element (11). Therefore, even the silver paste (51) having a high viscosity can be thinly applied to the capacitor element (11).

A silver paste having a small viscosity is used for a capacitor element.
As in the case of coating (11), poor yield due to poor ESR characteristics could be significantly improved. In addition, silver paste (51)
Can be applied to the capacitor element (11) by an immersion method, so that the productivity is excellent.

Example Silver paste Viscosity 200 poise binder Epoxy resin Solvent n-butyl carbitol Silver content 82 wt% Non-volatile components (silver + binder etc.) 91 wt% Silver paste coating apparatus Frequency of tank 30 Hz Amplitude 1.5 mm As the silver paste (51), the same silver paste (52) as a result of bonding the capacitor element (11) to the lead frame (6) was used. It may be different from the silver adhesive (52) by adjusting the viscosity to be easy to use in the range of -300 poises.

Under the above conditions, the capacitor element (11) whose outer surface is covered with the carbon layer (4) is immersed in a tank (82) containing the silver paste (51) and immediately pulled up in the direction along the vibration direction. Was. In the capacitor element (11), a silver paste layer (5) having a carbon layer (4) with an average thickness of about 40 μm was formed.

The ESR of the capacitor body 10 on which the silver paste layer 5 was formed was 20 to 35 mΩ. The ESR after bonding the frame was 25 to 50 mΩ. If the ESR of the completed product in FIG. 3 is 80 mΩ as the border line, the higher one is a defective product, and the lower one is a good product, the yield is about 90%.

COMPARATIVE EXAMPLE Silver paste Viscosity 10 poise binder Epoxy resin Solvent n-butyl carbitol Silver content 65 wt% Non-volatile component (silver + binder etc.) 72 wt% When the completed solid electrolytic capacitor was manufactured, the yield was 30%.

The following table shows the relationship between the viscosity of silver paste and ESR, the relationship between frequency and average film thickness, and the relationship between amplitude and film thickness.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

When the viscosity of the silver paste was 50 to 300 poise, the yield of the completed solid electrolytic capacitor could be 80% or more.

The thickness of the silver paste layer (5) is from 40 to 200
μm is desirable, and the frequency of the silver paste (51) is 20 to 10
If it is 0 Hz, it falls within this range. In addition, silver paste (5
If the amplitude of 1) is 0.6 to 6 mm, it falls within this range.
This amplitude corresponds to 0.2 to 2 times the length of the capacitor element (11) in the vibration direction of the silver paste (51).

In practicing the present invention, the tank containing the silver paste (51) is stopped, and while vibrating the capacitor element (1), the capacitor element (1) is extracted from the tank of the silver paste (51) in the direction along the vibration direction. Is also good. The present invention is not limited to the configuration of the above embodiment, and various modifications can be made within the scope of the claims.

[Brief description of the drawings]

FIG. 1 is a sectional view of a capacitor element before a lead frame is attached.

FIG. 2 is an explanatory view of mounting a lead frame.

FIG. 3 is a cross-sectional view of the completed solid electrolytic capacitor.

FIG. 4 is an explanatory diagram of a silver paste coating device.

[Explanation of symbols]

 (1) Anode body (10) Capacitor body (11) Capacitor element (2) Chemical conversion film (3) Solid electrolyte layer (4) Carbon layer (5) Silver paste layer (6) Lead frame (7) Outer shell (8) Silver paste coating equipment (81) Vibration equipment

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yutaka Takeya 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (4)

[Claims] 1. A capacitor element (11) is produced by forming a chemical conversion film (2), a solid electrolyte layer (3), and a carbon layer (4) on an anode body (1) made of a valve metal. A method for manufacturing a solid electrolytic capacitor, comprising a step of coating a carbon layer (4) of an element with a silver paste (51) and bonding a lead frame (6) to the silver paste layer (5) with silver. Coating on carbon layer (5) with silver paste
While oscillating the (51) and the capacitor element (11) relatively, immersing the capacitor element (11) in the silver paste (51) and pulling out the capacitor element (11) in the direction of the vibration is performed. To manufacture solid electrolytic capacitors. 2. The method according to claim 1, wherein the viscosity of the silver paste is 50 to 300 poise. 3. The method for manufacturing a solid electrolytic capacitor according to claim 1, wherein the amplitude of the vibration is 0.2 to 2 times the length of the capacitor element in the vibration direction. 4. The method for manufacturing a solid electrolytic capacitor according to claim 1, wherein the frequency is 20 to 100 Hz.