JP2001015390A - Electric double layer capacitor and gasket thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure sufficient heat resistance event for reflow soldering with leadless solder. SOLUTION: The electric double layer capacitor 1 comprises a coin type case 2 comprising a dish-like case body 2a, an annular gasket 7 placed along the inner circumferential surface of the case body 2a, a cap 2b being applied airtightly to the case body 2a through the gasket 7, and a pair of polarizing electrodes 4, 5 disposed oppositely in the case 2 through a separator 3 while being impregnated with a specified electrolyte wherein the gasket 7 is composed of polyallyletherketone resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coin-type (or button-type) electric double-layer capacitor which is soldered to a circuit board by a reflow soldering method. It relates to a double-layer capacitor.

[0002]

2. Description of the Related Art As shown in FIG. 1, a coin-type electric double-layer capacitor 1 has a dish-shaped case body 2a whose peripheral edge is raised to a predetermined height, and a cap which is put on the case body 2a. 2b is provided. Stainless steel is used for both the case body 2a and the cap 2b.

[0003] In a case 2, sheet-shaped polarizable electrodes 4 and 5, which are arranged to face each other with a separator 3 interposed therebetween, are housed in a state where a predetermined electrolytic solution is impregnated therein. The polarizable electrodes 4 and 5 are fixed to the bottom of the case body 2a and the bottom of the cap 2b via conductive adhesives 6 and 6 such as adhesive silver, for example.

A gasket 7 as a sealing material is disposed on the inner peripheral surface of the case body 2a, and the opening edge of the case body 2a is swaged inward so that the case body 2a and the cap 2b are separated from each other. The space is hermetically sealed.

[0005]

By the way, in many cases, inexpensive polypropylene (PP) has been mainly used for gaskets in terms of cost. However, polypropylene has poor heat resistance. Therefore,
It has been difficult to solder the circuit board by the reflow soldering method.

That is, according to the reflow soldering method, it is exposed to a high temperature of 200 ° C. or more for several tens of seconds. However, in the case of a gasket made of polypropylene, the gasket may be thermally deformed or may be melted in an extreme case. Leakage occurs.

In order to prevent this, as one method, a coin-type electric double layer capacitor is surrounded by an outer case made of a heat-resistant resin. Not preferred. Further, even in this case, the deformation and melting of the gasket cannot be reliably prevented.

Therefore, as another method for enabling reflow soldering, polyphenylene sulfide (PPS) is used as a gasket material. Polyphenylene sulfide has better heat resistance than polypropylene. However, even with this resin, 240 ° C.
Liquid leakage sometimes occurred at some peak temperatures.

Particularly recently, lead-free solders have been used in conjunction with the deleading of solders. However, since lead-free solders generally have a melting point about 20 ° C. higher than lead-based solders, lead-free solders have been used. In the case of reflow by solder, higher heat resistance is required.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide an electric wire having a sufficient heat resistance against reflow soldering using lead-less solder. An object of the present invention is to provide a double-layer capacitor and its gasket.

That is, the present invention is characterized in that a gasket used for a coin-type electric double layer capacitor is formed of polyallyl ether ketone.

Further, the present invention provides a dish-shaped case main body, an annular gasket arranged along the inner peripheral surface of the case main body, and a cap hermetically covered on the case main body via the gasket. In the electric double-layer capacitor comprising a pair of polarizable electrodes, comprising a coin-shaped case consisting of, and disposed opposite to each other with a separator in the case, and impregnated with a predetermined electrolytic solution, The gasket is characterized by being formed of polyallyl ether ketones.

[0013] Polyallyl ether ketones are partially crystalline high-performance thermoplastic resins, and their structural formulas are represented by the following general formula (1) or (2).

Embedded image

[0014]

Embedded image

The polyallyl ether ketones are structurally polyether ketones, such as polyether ether ketone (PEEK) manufactured by Victrex.
Although it is a resin close to the above, it is particularly characterized by heat resistance, and is superior to PPS and polyetherketones when comprehensively judged on melting temperature, heat deformation temperature and continuous use temperature.

Incidentally, the continuous usable temperature of polyallyl ether ketone (for example, "Victrex PEK (trademark) polymer" manufactured by Victrex Corporation) having the structure represented by the general formula (1) is 260 ° C. Polyallyl ether ketone having a structure represented by the general formula (2) (for example, “Ultrapec (trademark)” manufactured by BASFAG) shows almost the same characteristics. Both polyallyl ether ketones can withstand even higher temperatures for a short time such as reflow soldering.

Polyallyl ether ketones are electrically insulating materials. It has good chemical resistance, is resistant to almost all organic and inorganic solvents, and does not dissolve in ordinary solvents even at high temperatures. Therefore, it is suitable as a gasket for electric double layer capacitors.

[0018]

Next, examples of the present invention and comparative examples will be described.

Example 1 Both a pair of polarizable electrodes were kneaded with 85% by weight of activated carbon, 6% by weight of carbon, and 9% by weight of polytetrafluoroethylene as a binder, spread out in a sheet shape, and formed into a disk having a diameter of 4 mm and a thickness of 1 mm. Punched out. One of the polarizable electrodes is fixed to the bottom of the case body via a conductive adhesive, and a polyallyl ether ketone represented by the general formula (1) (Victrex PEK (Victrex Corporation) Trademark)
A gasket made of polymer ") was placed. The other polarizable electrode was fixed to the bottom on the cap side with a conductive adhesive. Each polarizable electrode was sufficiently impregnated with an electrolytic solution (a solution of tetraethylammonium tetrafluoroborate dissolved in propylene carbonate at a rate of 1 mol / liter). And the glass fiber 10 between them
A cap was put on the case body with a 0% separator interposed, and the opening edge of the case body was swaged inward and sealed. In this way, 200 coin-type electric double layer capacitors rated at 2.5 V and 0.18 F were produced. Reflow soldering was performed on the 100 pieces under the following temperature conditions, and reflow soldering was performed on the remaining 100 pieces under different temperature conditions. Reflow soldering; preheating 150 ° C, 2 minutes, main heating 200 ° C or more (maximum temperature 240 ° C), 40 seconds. Reflow soldering: preheating 160 ° C, 2 minutes, main heating 200 ° C or more (maximum temperature 260 ° C), 65 seconds. As a result, the number of occurrences of liquid leakage was 0/100 in both cases of reflow soldering.

Example 2 A polyallyl ether ketone (BASFAG) represented by the general formula (2) was used for a gasket.
Company's “Ultrapec ™”),
In the same manner as in Example 1, 200 coin-type electric double-layer capacitors rated at 2.5 V and 0.18 F were produced. Then, reflow soldering was performed for 100 of them, and reflow soldering was performed for the remaining 100. As a result, the number of occurrences of liquid leakage was 0/100 in both cases of reflow soldering.

Comparative Example 1 200 coin-type electric double-layer capacitors rated at 2.5 V and 0.18 F were manufactured in the same manner as in Example 1 except that a polypropylene gasket was used. Then, reflow soldering is performed for 100 of them, and the remaining 100
Each piece was subjected to reflow soldering. As a result, the number of occurrences of liquid leakage was 100/100 in both cases of reflow soldering. That is, liquid leakage occurred in all 200 pieces.

Comparative Example 2 200 coin-type electric double-layer capacitors rated at 2.5 V and 0.18 F were produced in the same manner as in Example 1 except that a polyphenylsulfide gasket was used. And about 100 of them, reflow soldering is performed,
Reflow soldering was performed on the remaining 100 pieces. As a result, the number of occurrences of liquid leakage was 9/100 in reflow soldering, but the number of occurrences of liquid leakage was 87/100 in reflow soldering.

[0023]

As described above, according to the present invention,
By using a resin made of polyallyl ether ketone for the gasket of the coin-type electric double-layer capacitor, a coin-type electric double-layer capacitor that can be used by reflow soldering to a circuit board can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an internal configuration of a coin-type electric double-layer capacitor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Separator 2-3 polarity electrode 5 Case 5a Cap 5b Case main body 6 Gasket

Claims (6)

[Claims] A pair of coin-shaped cases, each of which is opposed to each other via a separator and is impregnated with a predetermined electrolytic solution, is provided in a coin-shaped case including a dish-shaped case main body and a cap put on the case main body. When accommodating the polarizable electrode and sealing the case body and the cap, in a gasket made of a synthetic resin material interposed therebetween, polyallyl ether ketones are used for the synthetic resin material. A gasket for an electric double layer capacitor, characterized in that the gasket is used. 2. A pair of coin-shaped cases each comprising a dish-shaped case main body and a cap put on the case main body, which are opposed to each other via a separator, and are impregnated with a predetermined electrolytic solution. A gasket made of a synthetic resin material interposed between the case body and the cap for housing the polarizable electrode and sealing the case body and the cap, wherein the synthetic resin material has the following general formula (1) A gasket for an electric double layer capacitor, wherein a polyallyl ether ketone having the structure shown in (1) is used. Embedded image 3. A pair of coin-shaped cases each comprising a dish-shaped case main body and a cap placed on the case main body and opposed to each other via a separator and impregnated with a predetermined electrolytic solution. A gasket made of a synthetic resin material interposed between the case body and the cap when the polarizer electrode is housed and the case body and the cap are sealed, wherein the synthetic resin material has the following general formula (2) A gasket for an electric double layer capacitor, wherein a polyallyl ether ketone having the structure shown in (1) is used. Embedded image 4. A coin type comprising: a dish-shaped case main body; an annular gasket disposed along an inner peripheral surface of the case main body; and a cap hermetically mounted on the case main body via the gasket. In an electric double layer capacitor comprising a pair of polarizable electrodes which are arranged opposite to each other via a separator in the case and are impregnated with a predetermined electrolytic solution, the gasket is made of poly An electric double-layer capacitor formed of allyl ether ketones. 5. A coin type comprising: a dish-shaped case main body; an annular gasket disposed along an inner peripheral surface of the case main body; and a cap hermetically covering the case main body via the gasket. In an electric double-layer capacitor comprising a pair of polarizable electrodes which are disposed opposite to each other via a separator in the case and are impregnated with a predetermined electrolytic solution, the gasket includes: An electric double layer capacitor formed of a polyallyl ether ketone having a structure represented by the following general formula (1): Embedded image 6. A coin type comprising: a dish-shaped case main body; an annular gasket arranged along an inner peripheral surface of the case main body; and a cap hermetically covered on the case main body via the gasket. In an electric double-layer capacitor comprising a pair of polarizable electrodes which are disposed opposite to each other via a separator in the case and are impregnated with a predetermined electrolytic solution, the gasket includes: An electric double-layer capacitor formed of a polyallyl ether ketone having a structure represented by the following general formula (2): Embedded image