JPS61100919A - Driving electrolytic liquid for aluminum electrolytic capacitor - 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] Industrial Application Field The present invention prevents corrosion and disconnection inside the capacitor caused by penetration of the halogenated hydrocarbon into the capacitor when the aluminum electrolytic capacitor is cleaned with a halogenated hydrocarbon solution. This invention relates to an electrolytic solution for driving aluminum electrolytic capacitors.

Conventional technology In the past, when aluminum electrolytic capacitors were immersed in a halogenated hydrocarbon solution for cleaning during the solder flux removal process used when inserting them into a printed circuit board, the halogenated hydrocarbon that had penetrated into the capacitor was decomposed. The generated chlorine ions caused many corrosion and disconnection accidents. In order to prevent these accidents, countermeasures such as coating the capacitor sealing part with resin have been conventionally taken, but this increases cost and is not sufficiently effective.

Problems to be Solved by the Invention In view of the above-mentioned problems, the present invention aims to provide a driving electrolyte for an aluminum electrolytic capacitor that can actually prevent corrosion accidents by improving the driving electrolyte.

Means for Solving the Problems In order to achieve this object, the present invention uses polyhydric alcohols such as ethylene glycol and propylene glycol, or water as a solvent, and uses boric acid, monocarboxylic acid, dicarboxylic acid, phosphorus, etc. In an electrolytic solution containing one or more of acids or salts thereof as a solute, 0.
The electrolytic solution is made by adding 5 to 5.0 wt% of nitrocatechol.

Working Nitrocatechol contains nitrogen as a constituent element with an independent pair of electrons, thereby making it an electron donor. On the other hand, the aluminum surface has the property of being an electron acceptor, and the aluminum surface adsorbs nitrocatechol. In particular, since nitrocatechol is adsorbed on the aluminum surface by protonated nitro groups, corrosion caused by chlorine ions is significantly inhibited, and corrosion accidents caused by chlorine ions of aluminum electrolytic capacitors can be reliably prevented.

The amount of nitrocatechol added above is 0.5 to the driving electrolyte.
~5. If it is within the range of Q at %, it is effective and practically sufficient. In practice, it is recommended to add nitrocate to the drive electrolyte (less than 1.5 wt%, corrosion accidents cannot be reliably prevented;
If the amount exceeds 5.0 wt%, the capacitance reduction rate and tan δ change rate are large in high temperature life characteristics.

Therefore, the appropriate amount of nitrocatechol to be added is 0.5 to 5.0 wt% based on the driving electrolyte.

EXAMPLE The composition of the electrolytic solution for driving an aluminum electrolytic capacitor according to the present invention is shown in the table.

Table (unit: t%) Sample number 4.5.6 of the electrolyte in the table is the electrolyte of the present invention, 1
．． 2.3 shows an electrolyte for comparison.

Using the driving electrolyte for aluminum electrolytic capacitors with the composition shown in the table, aluminum electrolytic capacitors with a rating of 50 WV-1 μF were used, 1.1.1 50 samples each were soaked in trichloroethane vapor for 10 minutes. 8
The characteristics when the rated voltage is continuously applied at 5°C are
It is shown in Figs.

In other words, Figure 1 shows the relationship between application time and explosion-proof valve operation.
Figure 2 shows the relationship between application time and capacitance change rate, Figure 3 shows the relationship between application time and tanδ, and Figure 4m shows the relationship between application time and leakage current in curve diagrams. After applying the rated voltage for 1000 hours, each sample was disassembled, and the capacitors with symbols A and B showed significant corrosion, and the internal pressure increased due to corrosion, causing the explosion-proof valve to operate. No corrosion was observed in capacitors with symbols C, D, E, and F.

In addition to the above-mentioned examples, polyhydric alcohols such as propylene glycol or those to which water is added are used as the solvent, and one or more of boric acid, monocarboxylic acid, dicarboxylic acid, phosphoric acid, or their salts are used as the solute. A similar effect was obtained by using an electrolytic solution containing nitrocatechol. The nitrocatechol may be a mixture of 3-nitrocatechol/L/ and 4-nitrocatechol.

Effects of the Invention As detailed above, the drive electrolyte of the present invention containing nitrocatechol maintains extremely stable characteristics even after cleaning with halogenated hydrocarbons in aluminum electrolytic capacitors, making it a highly reliable electrolytic capacitor. is obtained,
It has great industrial and practical value.

[Brief explanation of the drawing]

Figure 1 is an application time vs. explosion-proof valve operation characteristic diagram for an aluminum electrolytic capacitor, Figure 2 is an application time vs. capacitance change rate characteristic diagram for the same capacitor, and Figure 3 is an application time vs. capacitance change rate characteristic diagram for the same capacitor.
The tan δ characteristic diagram and FIG. 4 are the application time-leakage current characteristic diagram of the same capacitor. A, BSC: sample for comparison

Claims (2)

[Claims] (1) Polyhydric alcohols such as ethylene glycol and propylene glycol or water added thereto are used as the solvent, and boric acid, monocarboxylic acid, dicarboxylic acid, phosphoric acid, or one or more of these salts are used as the solute. An electrolytic solution for driving an aluminum electrolytic capacitor, characterized in that 0.5 to 5.0 wt% of nitrocatechol is added to the electrolytic solution. (2) Nitrocatechol is 3-nitrocatechol, 4-nitrocatechol
The electrolytic solution for driving an aluminum electrolytic capacitor according to claim 1, characterized in that the electrolytic solution is at least one kind of nitrocatechol.