JPH0945587A - Electrolytic capacitor driving electrolyte and electrolytic capacitor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic capacitor driving electrolyte and an electrolytic capacitor using it capable of suppressing deformation of external appearance due to thermal stress during the mounting and thus capable of improving the soldering failure during the mounting. SOLUTION: An electrolytic capacitor driving electrolyte obtained by dissolving an organic acid as an electrolyte in a solvent containing 1,3-dialkyl-2- imidazolidinoe (where the carbon number of the alkyl group is not less than 2), and an electrolytic capacitor using it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic capacitor driving electrolytic solution used in an electrolytic capacitor and an electrolytic capacitor using the electrolytic solution.

[0002]

2. Description of the Related Art As a conventional electrolytic capacitor driving electrolytic solution, there is known an electrolytic solution in which an ammonium salt of boric acid or adipic acid is dissolved as an electrolyte in an ethylene glycol solvent.

As an electrolytic solution having excellent low-temperature characteristics, a solution obtained by dissolving an organic acid, an inorganic acid or a salt thereof as an electrolyte in a solvent such as γ-butyrolactone having a low viscosity at low temperature is used. , An electrolytic solution using diethylamine salt as an electrolyte (Japanese Patent Laid-Open No. 54-1024)
Etc. are known. Further, an electrolytic solution using a quaternary ammonium salt of maleic acid or citraconic acid as an electrolyte (Japanese Patent Publication No. 3-6646) or an electrolytic solution using a quaternary ammonium salt of aromatic carboxylic acid as an electrolyte (Japanese Patent Publication No. 3-8092).
No.) are also known.

Further, as an electrolyte solvent having a high boiling point,
An electrolytic solution using 1,3-dimethyl-2-imidazolidinone (JP-A-6-5471) is known.

[0005]

However, an electrolytic solution in which an ammonium salt of boric acid or adipic acid is dissolved as an electrolyte in an ethylene glycol solvent, or a triethylamine salt, a diethylamine salt, or a quaternary ammonium salt in γ-butyrolactone. The boiling point (heat resistance) of the solvent is not sufficient in the electrolyte solution in which is dissolved as an electrolyte. Therefore, when electrolytic capacitors using these electrolyte solutions are used as surface mounting components, heat treatment conditions (solder There is a problem in that the appearance may be deformed due to an increase in the internal pressure depending on the mounting temperature and the time of passing through the reflow furnace, and as a result, defective soldering may occur during mounting.

The present invention solves the above-mentioned conventional problems, and can suppress the external deformation of the electrolytic capacitor due to thermal stress during surface mounting, and thereby improve the soldering failure during mounting. An object of the present invention is to provide an electrolytic solution for driving an electrolytic capacitor and an electrolytic capacitor using the electrolytic solution.

[0007]

In order to achieve the above object, the electrolytic solution for driving an electrolytic capacitor of the present invention comprises 1,3-dialkyl-2-imidazolidinone (provided that the alkyl group has 2 or more carbon atoms). The organic acid salt is dissolved as an electrolyte in a solvent containing the electrolytic capacitor of the present invention, and the electrolytic solution for driving the electrolytic capacitor is used.

[0008]

In the electrolytic solution for driving the electrolytic capacitor of the present invention described above, 1,3-dialkyl-2-imidazolidinone having a high boiling point (however, the alkyl group has 2 or more carbon atoms) is used as a solvent, The electrolytic solution is less likely to vaporize even in the atmosphere, which suppresses the rise in internal pressure.Therefore, when an electrolytic capacitor using this electrolytic solution was used as a surface-mounted component, thermal stress was applied during surface mounting. In this case, it is possible to suppress the appearance deformation of the electrolytic capacitor, and it is possible to improve the soldering failure at the time of mounting.

[0009]

Embodiments of the present invention will be described below.

The basis of the present invention is 1,3-dialkyl-2.
An electrolytic solution for driving an electrolytic capacitor, wherein an organic acid salt is dissolved as an electrolyte in a solvent containing imidazolidinone (where the alkyl group has 2 or more carbon atoms).

Examples of the tertiary amine used in the electrolytic solution of the present invention include trialkylamines [trimethylamine, dimethylethylamine, methyldiethylamine, triethylamine, dimethyl n-propylamine, dimethylisopropylamine, methylethyl n-propylamine, Methylethylisopropylamine, diethyl n-propylamine, diethylisopropylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, tritert-butylamine, etc.] and phenyl group-containing amines [dimethylphenylamine, methylethylphenyl] Amine, diethylphenylamine, etc.].

Of these, preferred is a trialkylamine having high conductivity, and more preferred is one selected from the group consisting of trimethylamine, dimethylethylamine, methyldiethylamine and triethylamine, which have particularly high conductivity. That is all.

Examples of the quaternary ammonium used in the electrolytic solution of the present invention include tetraalkylammoniums [tetramethylammonium, trimethylethylammonium, dimethyldiethylammonium, methyltriethylammonium, tetraethylammonium, trimethyln-propylammonium and trimethyl. Isopropyl ammonium, dimethyl ethyl n-propyl ammonium, dimethyl ethyl isopropyl ammonium, methyl diethyl n-propyl ammonium, methyl diethyl isopropyl ammonium, triethyl isopropyl ammonium, triethyl n-propyl ammonium, tetra n-propyl ammonium, tetraisopropyl ammonium, tetra n- Butyl ammonium, tetra te
rt-butylammonium, etc.] and phenyltrialkylammonium [trimethylphenylammonium,
Dimethylethylphenylammonium, triethylphenylammonium, etc.].

Among these, trialkylammonium having a high electric conductivity is preferable, and trimethylammonium, trimethylethylammonium, dimethyldiethylammonium, methyltriethylammonium and tetraethylammonium having a particularly high electric conductivity are more preferable. It is one or more selected from the group consisting of.

Examples of compounds having an alkyl-substituted amidine group used in the electrolytic solution of the present invention include imidazole compounds, benzimidazole compounds, and alicyclic amidine compounds (pyrimidine compounds, imidazoline compounds). Specifically, 1,8-diazabicyclo [5,4,0] undecene-7,1,5-diazabicyclo [4,3,0] nonene having high conductivity and capable of providing a low-loss electrolytic capacitor is provided. -5,1,2-dimethylimidazolinium, 1,2,4-trimethylimidazoline, 1
-Methyl-2-ethyl-imidazoline, 1,4-dimethyl-2-ethylimidazoline, 1-methyl-2-heptylimidazoline, 1-methyl-2- (3'heptyl) imidazoline, 1-methyl-2-dodecylimidazoline ,
1,2-Dimethyl-1,4,5,6-tetrahydropyrimidine, 1-methylimidazole and 1-methylbenzimidazole are preferred.

An example of a quaternary salt of a compound having an alkyl-substituted amidine group used in the electrolytic solution of the present invention is one having 1 carbon atom.
Examples thereof include imidazole compounds, benzimidazole compounds and alicyclic amidine compounds (pyrimidine compounds, imidazoline compounds) quaternized with an alkyl group or an arylalkyl group of -11. Specifically, it is possible to provide an electrolytic capacitor having high conductivity and low loss. 1
-Methyl-1,8-diazabicyclo [5,4,0] undecene-7, 1-methyl-1,5-diazabicyclo [4,3,0] nonene-5,1,2,3-trimethylimidazolinium, 1,2,3,4-tetramethylimidazolinium, 1,3-dimethyl-2-ethyl-imidazolinium, 1,3,4-trimethyl-2-ethylimidazolinium, 1,3-dimethyl-2 -Heptylimidazolinium, 1,3-dimethyl-2- (3'heptyl) imidazolinium, 1,3-dimethyl-2-dodecylimidazolinium, 1,2,3-trimethyl-1,4,5,5
6-tetrahydropyrimidinium, 1,3-dimethylimidazolium and 1,3-dimethylbenzimidazolium are preferred.

Examples of organic acids used in the electrolytic solution of the present invention include polycarboxylic acids (2 to 4 valent): aliphatic polycarboxylic acids [saturated polycarboxylic acids such as oxalic acid and malonic acid,
Succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,6-decanedicarboxylic acid, 5,6-decanedicarboxylic acid: unsaturated polycarboxylic acids such as maleic acid, fumaric acid, Icotanic acid]; aromatic polycarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid; alicyclic polycarboxylic acids such as tetrahydrophthalic acid (cyclohexane-1,2-dicarboxylic acid, etc.) , Hexahydrophthalic acid; alkyl (C1 to C3) or nitro substitution products of these polycarboxylic acids such as citraconic acid, dimethylmaleic acid, nitrophthalic acid (3-nitrophthalic acid, 4-nitrophthalic acid); and sulfur-containing Polycarboxylic acids such as thiopropionic acid; monocarboxylic acids; aliphatic monocarboxylic acids Boric acid (C1 to C30) [Saturated monocarboxylic acid such as formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, lauric acid, myristic acid, stearic acid Acid, behenic acid: unsaturated monocarboxylic acid such as acrylic acid, methacrylic acid, oleic acid]; aromatic monocarboxylic acid such as benzoic acid, o-nitrobenzoic acid, p
-Nitrobenzoic acid, cinnamic acid, naphthoic acid; oxycarboxylic acids such as salicylic acid, mandelic acid, resorcinic acid and the like. Among these, maleic acid, phthalic acid, adipic acid and benzoic acid, which have high electric conductivity and are thermally stable, are preferable.

The ratio of the organic acid and the base constituting the electrolytic solution is usually 4 to 11, preferably 6 in terms of the pH of the electrolytic solution.
~ 9. Outside this range, the spark voltage of the electrolytic solution decreases.

The electrolytic solution of the present invention may contain water if necessary. Its content is usually less than 5%, based on the weight of the electrolyte. More preferably, it is less than 1%. When the water content is 5% or more, the solder heat resistance is significantly lowered due to the influence of the boiling point and vapor pressure of water.

The electrolytic solution of the present invention contains 1,3-dialkyl-2-imidazolidinone [wherein the alkyl group has 2 carbon atoms for the purpose of improving low temperature characteristics and discharging voltage.
Other organic solvent compatible with the above] may be mixed as an auxiliary solvent.

As the secondary solvent, a polyhydric alcohol solvent;
Ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, glycerin,
Polyoxyalkylene polyol, lactone solvent; γ
-Butyrolactone, γ-valerolactone, δ-valerolactone, 3-methyl-1,3-oxazolidin-2-one, 3-ethyl-1,3-oxazolidin-2-one,
Amide-based solvent; N-methylformamide, N-ethylformamide, N, N-dimethylformamide, N-methylacetamide, ether-based solvent; methylal, 1,2
-Dimethoxyethane, 1-ethoxy-2-methoxyethane, 1,2-diethoxyethane, nitrile solvent; acetonitrile, 3-methoxypropionitrile, furan solvent; 2,5-dimethoxytetrahydrofuran, 2-imidazolidinone System solvent; 1,3-dimethyl-2-imidazolidinone alone or a mixed solvent of two or more thereof.

In the case of the mixed solvent system, the content of the sub-solvent is
It is preferably 20 parts or less with respect to 100 parts of 1,3-dialkyl-2-imidazolidinone (where the carbon number of the alkyl group is 2 or more). If the content of the subsolvent exceeds 20 parts, the boiling point of the electrolytic solution is affected by the subsolvent, and a sufficient effect cannot be obtained.

If desired, the electrolytic solution of the present invention may be mixed with various additives. As additives, phosphorus compounds [phosphoric acid, phosphoric acid ester, etc.], boric acid compounds [boric acid, complex compounds of boric acid and polysaccharides (mannite, sorbite, etc.), boric acid and polyhydric alcohols (Ethylene glycol, glycerin, etc.)], and nitro compounds [p-nitrobenzoic acid, p-nitrophenol, etc.]. The addition of these additives may increase the spark voltage of the electrolytic solution, which may be preferable.

The content of the electrolyte in the electrolytic solution of the present invention is usually 1 to 70% by weight, preferably 5 to 40% by weight, based on the weight of the electrolytic solution. Outside this range, the electrical conductivity will be significantly reduced.

Next, specific examples of the present invention will be described, but the present invention is not limited thereto. Hereinafter, all parts are parts by weight.

Table 1 shows the 1,3-dialkyl-groups of the present invention.
1,3-di (n-propyl) -2-, which is a typical example of 2-imidazolidinone [wherein the alkyl group has 2 or more carbon atoms]
It shows the results of measuring the boiling points of imidazolidinone and a conventional electrolyte solvent.

[0027]

[Table 1]

As is clear from this (Table 1), 1,3-di (, which is a typical example of 1,3-dialkyl-2-imidazolidinone of the present invention [where the alkyl group has 2 or more carbon atoms]] It can be seen that n-propyl) -2-imidazolidinone has a higher boiling point than the solvent of the conventional electrolytic solution. In addition, the molecular weight of the alkyl group on the nitrogen atom is larger (for example, isopropyl group, n-butyl group, tert group).
-Butyl group etc.), the thermodynamic energy of the solvent molecule is increased, and the boiling point is further increased, and it is considered that the same effect can be obtained.

Table 2 shows the compositions of the electrolytic solutions of Examples 1 to 6 of the present invention and Conventional Examples 1 to 3.

[0030]

[Table 2]

A surface mount type aluminum electrolytic capacitor (rated voltage 4V-electrostatic capacity 220 μF, size; φ) using the electrolytic solutions of Examples 1 to 6 and Conventional Examples 1 to 3 of the present invention.
6 mm × L5.5 mm) was prepared. Butyl rubber (JIS-A hardness: 85 degrees) of peroxide persulfur was used as the sealing rubber. 100 aluminum electrolytic capacitors were mounted on each epoxy substrate (thickness: 2 mm) and passed through a solder reflow furnace. The number of appearance deformations at this time is shown in (Table 3). Further, FIG. 1 shows the relationship between the passage time of the reflow furnace and the surface temperature of the epoxy substrate when passing through the solder reflow furnace. The surface temperature of the epoxy substrate is measured indirectly from the electromotive force of a thermocouple bonded on the epoxy substrate.

[0032]

[Table 3]

As is clear from this (Table 3), the aluminum electrolytic capacitors using the electrolytic solutions of Examples 1 to 5 of the present invention are compared with the aluminum electrolytic capacitors using the electrolytic solutions of Conventional Examples 1 to 3. Thus, it is clear that there is no external deformation of the electrolytic capacitor due to thermal stress during surface mounting, and soldering failure during mounting can be improved.

[0034]

As described above, the electrolytic capacitor driving electrolytic solution of the present invention uses 1,3-dialkyl-2-imidazolidinone [where the alkyl group has 2 or more carbon atoms] as a solvent. This 1,3-dialkyl-2-imidazolidinone [however, the number of carbon atoms in the alkyl group is 2 or more] has a high boiling point, so that the electrolytic solution is less likely to vaporize even in a high temperature atmosphere, which suppresses an increase in internal pressure. Therefore, when an electrolytic capacitor using this electrolytic solution is used as a surface mount component, it is possible to suppress the appearance deformation of the electrolytic capacitor even if thermal stress is applied during surface mount, and Therefore, the soldering failure at the time of mounting can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a passage time of a reflow furnace and a surface temperature of an epoxy substrate when passing through a solder reflow furnace.

Claims (8)

[Claims] 1. An electrolytic solution for driving an electrolytic capacitor, wherein an organic acid salt is dissolved as an electrolyte in a solvent containing 1,3-dialkyl-2-imidazolidinone [where the alkyl group has 2 or more carbon atoms]. 2. 1,3-dialkyl-2-imidazolidinone [wherein the alkyl group has 2 or more carbon atoms] is 1,3-diethyl-2-imidazolidinone, 1,3-di (n-propyl). The electrolytic solution for driving an electrolytic capacitor according to claim 1, which is -2-imidazolidinone. 3. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the organic acid of the organic acid salt is a carboxylic acid. 4. The carboxylic acid is one or more selected from the group consisting of maleic acid, phthalic acid, adipic acid, benzoic acid, and alkyl- or nitro-substituted compounds of these compounds. The electrolytic solution for driving the electrolytic capacitor described in 1. 5. One or more selected from the group consisting of ammonium, a tertiary amine, a quaternary ammonium, a compound having an alkyl-substituted amidine group, and a quaternary salt of a compound having an alkyl-substituted amidine group as a base of the organic acid salt. The electrolytic solution for driving an electrolytic capacitor according to any one of claims 1 to 4. 6. The quaternary salt of a compound having an alkyl-substituted amidine group is at least one selected from the group consisting of imidazole compounds, benzimidazole compounds and alicyclic amidine compounds (pyrimidine compounds, imidazoline compounds). 5. An electrolytic solution for driving an electrolytic capacitor according to any one of 5. 7. An electrolytic capacitor using an electrolytic solution for driving an electrolytic capacitor, wherein an organic acid salt is dissolved as an electrolyte in a solvent containing 1,3-dialkyl-2-imidazolidinone [wherein the alkyl group has 2 or more carbon atoms]. . 8. The electrolytic capacitor according to claim 7, wherein the electrolytic capacitor is a surface mount component.