JPH0579937U - Solid electrolytic capacitor - Google Patents

Abstract

(57) [Summary] [Structure] The solid electrolytic capacitor 7 is characterized in that the volume of the capacitor element 1 is 10% or less of the volume including the resin sheath 3. Further, in particular, the solid electrolytic capacitor is characterized in that a capacitor element is provided with an insulating layer having at least one of elasticity and water repellency. [Effect] Since the volume ratio of the capacitor element is set to 10% or less, it is possible to improve the deterioration of the characteristics of the leakage current and the capacity change rate due to pressurization and moisture absorption, and prevent the defect of the capacitor element exposed from the resin exterior. Further, by providing an elastic insulating layer on the capacitor element, it is possible to further improve the characteristic deterioration of the leakage current due to the pressurization. If the insulating layer has water repellency, deterioration of leakage current characteristics and the like due to moisture absorption can be further improved.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a solid electrolytic capacitor.

[0002]

[Prior Art]

 Solid electrolytic capacitors such as chip-type tantalum with a resin exterior are characterized by their small size and large capacitance. In order to bring out this feature, the volume of the capacitor element is made as large as possible with respect to the volume of the entire capacitor including the resin sheath, and is usually 15 to 30%.

[0003]

[Problems to be solved by the device]

 However, when the volume ratio occupied by the capacitor element is increased, the thickness of the resin outer casing is reduced, which causes the following characteristic problems. First, it becomes susceptible to mechanical stress. That is, when a capacitor is mounted on a printed wiring board or the like by an automatic machine, a force of 1 kg or more is usually applied to this capacitor. Then, this force is transmitted to the internal capacitor element, the oxide film is damaged, and the leakage current increases. By applying an insulating material having elasticity to the capacitor element, damage to the oxide film can be reduced. However, when the resin outer casing is thin, the capacitor element is exposed from the outer casing, but by applying an insulating material, it becomes easier to expose. Further, the resin exterior absorbs moisture from the outside air. Therefore, the deterioration of the capacitor element is accelerated, and its capacitance change and leakage current increase. There is a drawback that these increases become more significant as the resin sheath becomes thinner.

An object of the invention of claim 1 is to provide a solid electrolytic capacitor that can improve the above-mentioned drawbacks, improve characteristics such as leakage current, and prevent the capacitor element from being exposed from the exterior.

An object of the invention of claim 2 is to provide a solid electrolytic capacitor capable of further improving characteristics such as leakage current.

[0006]

[Means for Solving the Problems]

 In order to achieve the above object, the invention of claim 1 provides a solid electrolytic capacitor characterized in that the volume of the capacitor element is 10% or less of the volume including the resin exterior.

The invention of claim 2 provides a solid electrolytic capacitor according to claim 1, wherein the capacitor element is provided with an insulating layer having at least one of elasticity and water repellency. It is a thing. Silicon gel or silicone rubber is used for the insulator.

[0008]

[Action]

 By making the volume of the capacitor element 10% or less of the total volume including the resin sheath and making the resin sheath thicker, even if a force is applied to the capacitor, it is difficult to transmit to the capacitor element. Further, even if it absorbs moisture from the outside air, the thick exterior can reduce the influence on the capacitor element. Then, even if the position of the capacitor element is slightly changed, it becomes difficult to expose the capacitor element from the resin exterior. Furthermore, even if a layer of an insulator having elasticity and water repellency is provided on the capacitor element, the capacitor element is less likely to be exposed from the exterior, and the influence of external force and moisture absorption can be reduced.

[0009]

【Example】

 Hereinafter, the present invention will be described based on embodiments. Example 1 In FIG. 1, reference numeral 1 denotes a capacitor element, which is a compact formed by compression molding tantalum fine powder into a cylindrical shape and firing it in a vacuum to form an oxide film, a manganese dioxide layer, and a carbon. Layer and a silver paste layer are formed, and an anode lead wire 2 made of a tantalum wire is drawn out. Reference numeral 3 is a resin exterior covering the capacitor element 1. Reference numeral 4 denotes an anode terminal welded to the cathode lead wire 2, the tip of which is bent along the resin sheath 3 and pulled out. Reference numeral 5 denotes a cathode terminal soldered on the surface of the capacitor element 1, the tip of which is bent along the surface of the resin sheath 3 and led out. The volume of the capacitor element 1 is 10% or less of the total volume of the solid electrolytic capacitor 7 including the resin sheath 3.

Next, the volume ratio of the capacitor element 1 of Example 1 was changed, the characteristics were evaluated along with the conventional example and the comparative example, and the defect rate at which the capacitor element 1 was exposed from the resin sheath 3 was obtained. The tantalum solid electrolytic capacitor of the example has a rating of 6.3 V and 4.7 μF and dimensions of 3.2 mm length × 1.6 mm width × 1.6 mm thickness. The conventional example and the comparative example are manufactured under the same conditions except that the volume of the capacitor element is different from that of the example. The characteristic evaluation was performed on the following three points. i) Apply a 0.5φ metal rod to the top surface of the sample to apply pressure, and measure the pressure at which the leakage current exceeds the standard value of 0.5 μA. ii) Measure the capacity change rate and leakage current when the sample is left for 500 hours in an atmosphere of a temperature of 85 ° C. and a humidity of 85%. The number of samples is the same in all of the examples, the conventional examples and the comparative examples, the characteristic evaluation is 10 pieces each, and the exposure defect rate is 4000 pieces each. The measurement results are shown in Table 1.

[0011]

[Table 1]

As is clear from Table 1, according to Examples 1-1 to 1-3, since the sample broke when a force of 10 kg was applied, the leakage current was not less than the standard value of 0.5 μA. No pressure was required. On the other hand, in the conventional example 1 and the conventional example 2, 1.5-2. It was 0 kg, which was ⅕ or less of that of Example 1-1 to Example 1-3. The rate of change in capacity due to moisture absorption is 2% in Examples 1-1 to 1-3, which is 1/4 to 2/5 of 5% to 8% in Conventional Example 1 and Conventional Example 2. Is becoming Regarding the leakage current, the values of Example 1-1 to Example 1-3 are 0.2 to 0.3 μA, which is about 9.5, compared with 1.5 to 2.1 μA of the conventional example 1 and the conventional example 2. The size is up to 20%. Furthermore, the exposure failure rate of the capacitor element was 0% in Examples 1-1 to 1-3. On the other hand, in Conventional Example 1 and Conventional Example 2, the ratio was 2 to 10%.

Example 2 As shown in FIG. 2, the capacitor element 8 is covered with an insulating layer 9 having elasticity and water repellency. Then, the capacitor element 8 is covered with a resin sheath 10 to form a solid electrolytic capacitor 11.

Next, the characteristics of the second example and the conventional example were evaluated under the same conditions as in the first example. In addition, the number of samples was set to 2000, and the failure rate at which the capacitor element was exposed from the resin exterior was determined. The solid electrolytic capacitor of Example 2 has a rating of 10 V and 10 μF and dimensions of 3.4 mm length × 2.6 mm width × 1.9 mm thickness. The conventional example is manufactured under the same conditions as in Example 2 except that the capacitor element is not provided with an insulating layer and the volume ratio is different. The results are shown in Table 2.

[0015]

[Table 2]

As is clear from Table 2, Example 2-1 and Example 2-2 were broken when a force of 15 kg was applied, but the standard leakage current value was satisfied for the force up to this value. To do. On the other hand, Conventional Example 3 was 5 kg. The rate of change in capacity is 2% in both Example 2-1 and Example 2-2, which is 1/5 of 10% in the conventional example. The leakage current is 0.3 μA in both Example 2-1 and Example 2-2, which is 1/10 of 3.0 μA in Conventional Example 3.

[0017]

[Effect of the device]

 As described above, according to the invention of claim 1, since the volume ratio of the capacitor element is 10% or less, it is possible to improve the characteristics deterioration of the leakage current and the capacity change rate due to pressurization and moisture absorption, and the capacitor element is covered with the resin sheath. It is possible to obtain a solid electrolytic capacitor that can prevent defects exposed from the inside. According to the second aspect of the present invention, by providing the capacitor element with the elastic insulating layer, the deterioration of the characteristic of the leakage current due to the pressurization can be further improved, and the insulating layer further has the water repellency. If so, it is possible to obtain a solid electrolytic capacitor that can further improve deterioration of leakage current characteristics and the like due to moisture absorption.

[Brief description of drawings]

FIG. 1 shows a cross-sectional view of an embodiment of the invention of claim 1.

FIG. 2 shows a sectional view of an embodiment of the invention of claim 2.

[Explanation of symbols]

1, 8 ... Capacitor element, 3, 10 ... Resin exterior, 7,
11 ... Solid electrolytic capacitor, 9 ... Insulator layer.

Claims (2)

[Scope of utility model registration request] 1. A solid electrolytic capacitor in which a capacitor element is coated with a resin sheath, wherein the volume of the capacitor element is 10% or less of the volume including the resin sheath. 2. The solid electrolytic capacitor according to claim 1, wherein the capacitor element is provided with an insulating layer having at least one of elasticity and water repellency.