JPH01151228A - Manufacture of solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To enhance productivity by a method wherein low-viscosity silicone oil is penetrated into an electrode body where a dielectric layer, a semiconductor layer and a cathode layer have been formed one after another on an anode body having a valve-action metal wire and, after that, a connecting operation to a cathode extraction terminal is executed. CONSTITUTION:As shown in Figure a, electrode bodies 1 of a tantalum solid electrolytic capacitor welded to a stainless hoop 11 at equal intervals are immersed in silicone oil 12 as an undercoat agent; they are dried in a hot-blast furnace, a silicone film thickness on the surface of the dried electrode bodies is set to be 0.1mum or less. After a drying operation, a tantalum lead wire 2 and an anode extraction terminal 6 are bonded by a welding operation as shown in Figure b; the electrode body 1 and a cathode extraction terminal 5 are bonded by using a conductive adhesive 7; a transfer molding operation is executed by using an epoxy resin 4 as shown in Figure c; an outside extraction terminal 10 is bent along a molded resin; a manufacturing process is completed. By this setup, productivity of an undercoat process is enhanced; working efficiency can be enhanced sharply.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing solid electrolytic capacitors.

2. Description of the Related Art A conventional undercoated solid electrolytic capacitor, such as an eva-chip tantalum solid electrolytic capacitor, is generally produced by the method shown in FIG.

First, connect the electrode body 1 and the cathode lead terminal 6 with a conductive adhesive 7.
After joining the tantalum lead wire 2 and the anode lead terminal 6 by welding, a resin 3 such as epoxy as an undercoat agent is applied to the entire electrode body using a brush or the like. Thereafter, a resin sheath 4 was applied by transfer molding or in-die extrusion molding, and the external electrode lead terminals 10 were bent along the side surfaces 8 and bottom surface 9 of the resin sheath.

Problems to be Solved by the Invention These conventional undercoating agents are formed on the electrode body in a relatively thick film of about 10 to 500 μm, which increases the size of the electrode body. High assembly precision is required during resin molding.

Furthermore, in order to ensure electrical conductivity, an undercoat agent must be applied after bonding with the cathode lead terminal, so the only way to undercoat only the electrode body is by brushing or brush painting. did not become.

Therefore, undercoating is a well-known technique for improving moisture resistance, but the conventional manufacturing method is very disadvantageous in terms of construction method and productivity.

The present invention is intended to solve these problems, and aims to stabilize the quality of solid electrolytic capacitors and improve productivity.

Means for Solving the Problems The present invention solves these conventional problems, and includes a dielectric layer, a semiconductor layer,
Low-viscosity silicone oil is infiltrated into the electrode body in which cathode layers are sequentially formed, and then connection to the cathode lead terminal is made, and the film thickness of the silicone oil is 0.1 μm or less.

Function According to the present invention, the undercoat agent permeates into the interior of the electrode body, so that the undercoat film thickness on the surface of the electrode body is 0.1 μm or less, and an increase in the size of the electrode body can be prevented.

Further, in the step of applying the undercoat agent to the electrode body, a method of immersing the entire electrode body can be used, so that the work can be facilitated.

EXAMPLE Hereinafter, an example of the present invention will be explained using FIG. 1. As shown in FIG. 1B, electrode bodies 1 of a tantalum solid electrolytic capacitor welded to stainless steel hoops 11 at equal intervals are immersed in silicone oil 12, which is an undercoating agent.

The silicone oil used had a temperature of about 20 C depending on the diluent.
The viscosity was adjusted to p, s, and dried in a hot air oven at about 180°C for 90 minutes. The silicon film thickness on the surface of the electrode body after drying was about 0 to 06 μm.

Figure 2 is a simplified cross-sectional view of the surface of the electrode body.
There is a part on the convex part where the silicone oil coating 14 is not formed, and electrical conductivity is obtained in this part,
It has been confirmed that even if a silicone oil film is formed on the silver paint convex parts, if the film thickness in the concave parts is within 0.1 μm, the minimum film thickness on the convex parts will be 0.001 μm or less. It has also been confirmed that dielectric breakdown occurs at a DC voltage of about 1 to 3 V when the film thickness is 0.001/im or less. From the above, even if the connection to the cathode lead terminal is made after immersion in silicone oil, electrical conductivity can be ensured.

After drying, as shown in Figure 1, the tank! The relief wire 2 and the anode lead terminal 6 are joined by welding, the electrode body 1 and the cathode lead terminal 5 are joined by a conductive adhesive 7,
Transfer molding was performed using epoxy resin 4 as shown in FIG. 1C, and the external lead terminal 1o was bent along the mold resin to complete the process.

The rating of the completed chip tantalum solid electrolytic capacitor is 1
The following comparative test was conducted between the conventional method and the method of the present invention at 6V and 1.0 μF.

Table 1 compares the number of occurrences of defective electrode body exposure after exterior molding. In the conventional method, 5 out of 2561 cases occurred, but in the method of the present invention, 0 out of 2586 cases occurred.

Table 1 Figure 3 shows the electrical characteristics obtained by the humidity test. Figure 3a shows the capacitance change rate, Figure 3 shows the loss angle tangent, and Figure 3C shows the leakage current characteristics. Both have shown equivalent performance.

From the above results, it is clear that the method of the present invention is superior, as it has a significant effect on exposure defects and maintains the same performance as the conventional method in terms of electrical properties.

In addition, in improving the workability of undercoat treatment,
As shown in Figure a, several dozen electrode elements can be immersed at once, resulting in a significant improvement in work efficiency.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, by infiltrating the inside of the electrode body with low-viscosity silicone oil, it is possible to prevent an increase in the size of the electrode body, and to have a significant effect on reducing poor exposure. By making it possible to bond to the cathode lead terminal after coating, productivity can be greatly improved.

[Brief explanation of the drawing]

Fig. 1 is a schematic process diagram showing one embodiment of the manufacturing method according to the present invention, Fig. 2 is a cross-sectional view of the surface of the electrode body illustrating ensuring electrical conductivity after undercoating, and Fig. 3 is a conventional method and the present invention. FIG. 4 is a diagram illustrating moisture resistance characteristics in comparison with the methods of FIG. 1... Electrode body, 2... Tank lead wire, 4... Exterior resin, 5... Cathode lead terminal, 6... Anode lead terminal, 7... ... Conductive adhesive, 10... External electrode lead terminal, 12.
...Silicone oil, 13...Silver paint, 14
...Silicone oil I coating film. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 4
Figure (ku)

Claims (2)

[Claims] (1) Low viscosity silicone oil is infiltrated into the inside of the electrode body in which a dielectric layer, a semiconductor layer, and a cathode layer are formed on an anode body having a valve action metal wire, and then connection to a cathode lead terminal is made. A manufacturing method for solid electrolytic capacitors. (2) The thickness of the electrode body surface film of the infiltrated silicone oil is 0.
Claim 1 characterized in that the diameter is 1 μm or less.
Method for manufacturing solid electrolytic capacitors as described in Section 1.