JPS60216532A - Aluminum electrolytic condenser - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an aluminum electrolytic capacitor used in electronic equipment.

Conventional Structure and Problems Conventionally, this type of aluminum electrolytic capacitor has been structured as shown in FIG. That is, a high-purity aluminum foil is roughened and an insulating oxide film is formed by anodizing to form a dielectric material, and a separator is interposed between the dielectric material and the opposing cathode foil made of a conductive metal, and the material is wound. This constitutes a capacitor element 1, and the capacitor element 1 is impregnated with an electrolyte and stored in a case 2.
The gap between the case 2 and the case 2 is filled with a fixing material 3 such as atactic polyglobulene, and the open end of the case is sealed with a sealing body 6 having an external lead terminal 4. Further, an anode internal lead 6 is connected to the anode foil, and a cathode internal lead 7 is connected to the external terminal 4 from the cathode foil.

The electrolyte for such aluminum electrolytic capacitors contains boric acid and solvents such as ethylene glycol and glycerin.

A solution containing an inorganic acid such as adipic acid, an organic acid, an ammonium salt thereof, and various additives as necessary is used. In this way, the electrolyte for aluminum electrolytic capacitors generally consists of a mixture of several to nearly ten types of chemicals, and each of these chemicals contains a small amount of chlorine ions. It may be included as an impurity.

Furthermore, the sealing body 6 may also contain chlorine ions as impurities, and these impurity chlorine ions accumulate and move onto the anode internal lead θ, causing defects in the oxide film on the anode internal lead θ. This caused corrosion and failure of aluminum electrolytic capacitors.

Purpose of the Invention The present invention eliminates such conventional drawbacks, and aims to provide an aluminum electrolytic capacitor that does not suffer from corrosion defects even if a small amount of chlorine ions are scattered inside the aluminum electrolytic capacitor. It is.

Structure of the Invention In order to achieve this object, the present invention is to apply a resin material in which 1 to 30% by weight of a hydrotalcite compound is dispersed on the anode internal lead of an aluminum electrolytic capacitor.

With this configuration, some of the chlorine ions that exist inside the aluminum electrolytic capacitor are incorporated into the crystal structure of the hydrotalcite compound, and free chlorine ions no longer exist in the system, making it possible to create an aluminum electrolytic capacitor that does not suffer from corrosion defects. can be provided. This utilizes the property of the hydrotalcite compound dispersed in the coating resin material to absorb chlorine ions.The uptake of chlorine ions by the hydrotalcite compound will be explained below.

When the chlorine ion is, for example, hydrochloric acid, the chloride ion is incorporated into the crystal structure of the hydrotalcite compound according to the reaction formula shown below.

My, 6M2(OH), 3Co3-3. rsH20+
2HcIl→My4.6A12(oH)13C1!2・
mH2O+H20+C02 The chlorine ion-type hydrotalcite compounds thus generated have a temperature around the operating temperature of aluminum electrolytic capacitors (usually 86°C to 106°C).
In this case, C1'' is not eliminated.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below. The structure of the aluminum electrolytic capacitor is substantially the same as that shown in FIG. 1, and therefore will not be described here.

Capacitor element 1 for rated value 250V470#F is 60
Add 50 PPm of hydrochloric acid to Mp 4.6A12 (OH)1aCOs ・3-5
H2O table wasalel hydrotalcite compound 15
A coating resin material made of atactic polypropylene dispersed in weight percent is applied and cured on the anode internal lead 6, and the case 2 is sealed to form a completed aluminum electrolytic capacitor.
A no-load storage test was conducted at ℃ for 1000 hours.

After the test, all aluminum electrolytic capacitors were disassembled, the applied resin material was collected, and this resin material was melted while being kept at about 200° C., and separated from the hydrotalcite compound. Thermal analysis of the spent idrotalcite compounds thus obtained was conducted. The results are shown in Figure 2. For comparison, Figure 3 shows the results of thermal analysis of the hydrotalcite compounds before the test. Comparing these analysis charts, as shown in the chart in Figure 2,
Weight loss and endothermic reaction due to elimination of chlorine are observed.

Next, as another example, 60 PPm of hydrochloric acid was added to 100 capacitor elements 1 with a rated value of 250 V and 470 μF, and this was divided into two, and 60 pieces were added to the product of the present invention.
p4.5A12(OH)13CO3-3,5H20 is expressed... A coating resin material made of atactic polypropylene in which 16% by weight of idrotalcites is dispersed is coated on the anode internal lead 6 and cured. Case 2 The completed aluminum electrolytic capacitor was sealed and subjected to a rated voltage application test at 106°C. On the other hand, similar tests were conducted on the remaining 50 conventional aluminum electrolytic capacitors using a resin material that does not contain hydrotalcite compounds. After the test, all products were disassembled and visually inspected for corrosion. As shown in the table below, the conventional product had 4 corrosion defects, and the product of the present invention had 0.

The following margin high-temperature load test Note that in the conventional product that caused corrosion failure, the corrosion point occurred on the internal lead of the anode. This is thought to be because free chlorine ions (C1-) migrated onto the anode internal lead due to the load test.

As described in detail, according to the present invention, an aluminum electrolytic capacitor without corrosion defects can be obtained by simply applying a resin material containing a hydrotalcite compound dispersed on the anode internal lead. Its industrial value is great.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional aluminum electrolytic capacitor, FIG. 2 is a thermal analysis chart of a salt ion type hydrotalcite compound, and FIG. 3 is a thermal analysis chart of a hydrotalcite compound. DESCRIPTION OF SYMBOLS 1... Capacitor element, 2... Case, 3... Fixing material, 4... External lead terminal, 6... Sealing body, 6... Anode internal lead, 7... Cathode internal lead. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 (M%zAblJIH1t ClraHyg) Temp
・(@O) 3rd aI CM%HAItC (JNIBCO3・3.5t4tO)
Temp, t'cJ

Claims (3)

[Claims] (1) A capacitor element made by winding an anode foil with an anode internal lead coated with a resin material containing a hydrotalcite compound and a cathode foil with a cathode internal lead together with a separator and impregnating it with an electrolytic solution is cased together with a fixing material. An aluminum electrolytic capacitor whose open end is sealed with a sealant. (2) Hydrotalcite compounds are added to the resin material for coating.
The aluminum electrolytic capacitor according to claim 1, wherein the aluminum electrolytic capacitor contains up to 30% by weight. (3) The aluminum electrolytic capacitor 0 according to claim 1, wherein the hydrotalcite compound is 1,6p42(OR)13CO3·3.6m0.