JPH0543467Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] This invention relates to an improvement in the sealing structure of an electrolytic capacitor, and particularly to a sealing structure that improves the life characteristics in a high temperature environment. [Prior Art] The sealing part of a normal electrolytic capacitor, especially a large electrolytic capacitor, is made by pasting an elastic insulating plate made of rubber or the like on the surface of a hard insulating plate made of a laminate of synthetic resin such as phenolic resin, and then attaching this to the capacitor element. The structure is such that it is attached to an exterior case that houses the camera, and the opening of the exterior case is crimped. Alternatively, a structure has been proposed in which the periphery of a heat-resistant synthetic resin is covered with a rubber groove ring having a U-shaped cross section, as described in Japanese Utility Model Publication No. 59-10751. However, impurities may be extracted from a hard insulating plate such as a phenol resin plate when it comes into contact with an electrolytic solution, causing corrosion of the electrolytic capacitor.
Therefore, as in the idea described in Japanese Utility Model Publication No. 52-2844, a three-layer sealing plate has a hard insulating plate with an elastic insulating plate on one side and a synthetic resin thin film layer made of polyethylene or polypropylene on the other side. is proposed. Such a sealing plate is made by forming a thin film layer of synthetic resin such as polyethylene on one side of a hard insulating plate such as phenolic resin by heat treatment, then bonding an elastic insulating plate such as rubber, and punching this to form the desired shape. It is formed into a shape. Therefore, the hard insulating plate and the electrolyte are separated by the synthetic resin thin film. [Problems to be solved by the invention] However, even with such a sealing structure, the peripheral end face of the sealing body is still exposed to the outside and comes into contact with the electrolyte, which may cause corrosion. In addition, in the process of manufacturing a sealing body, in the process of punching out a laminate in which an elastic insulating plate and a synthetic resin thin film layer are formed on a hard insulating plate surface made of phenolic resin, heat treatment is performed in advance to soften the laminate. I'm letting you do it. At this time, the higher the hardness of the hard insulating plate, the higher the temperature during the heat treatment. However, when a synthetic resin thin film such as polypropylene, which has poor heat resistance, is formed, the heat treatment temperature in the punching process is limited by the heat resistance temperature of the synthetic resin thin film.
Therefore, the hardness of the hard insulating plate is suppressed to a level low enough to obtain the minimum hardness required to maintain sealing performance due to constraints in the punching process. The hardness of this hard insulating plate affects the gas permeability of the sealing body and is also a factor that directly determines the life characteristics of the electrolytic capacitor. With conventional sealing structures using hard insulating plates with high gas permeability, it has been difficult to achieve sufficient life characteristics under conditions of use at high temperatures of 130° or higher. Furthermore, in a high operating temperature environment, the thin film layer of a synthetic resin such as polypropylene undergoes thermal changes, which may cause the hard insulating plate to come into contact with the electrolyte, causing corrosion. This idea prevents corrosion caused by the sealing body while
The aim is to improve life characteristics in high-temperature environments and to further downsize electrolytic capacitors. [Means for solving the problem] This invention consists of forming a synthetic resin thin film layer made of polyimide or aromatic polyamide on one surface of a hard insulating board, and covering the peripheral edge of the hard insulating board with an elastic insulator. It is characterized by the sealing body being attached to the opening of the exterior case and crimped. [Function] As shown in FIG. 1, the synthetic resin thin film layer 6 made of polyimide or aromatic polyamide with excellent heat resistance is attached to the hard insulating plate 5 made of phenolic resin or the like.
and electrolyte to prevent corrosion. Furthermore, since the peripheral edge of the hard insulating plate 5 is covered with the elastic insulator 7, the surface of the hard insulating plate 5, together with the synthetic resin thin film layer 6, directly faces the capacitor element 1. The hard insulating plate 5 and the electrolyte no longer come into contact with each other. Furthermore, since the polyimide or aromatic polyamide provided on one surface of the hard insulating board 5 has excellent heat resistance, the hard insulating board 5 can be heat-treated at high temperatures, resulting in a seal with high hardness, that is, low gas permeability. It becomes possible to manufacture the body 2. Moreover,
Polyimide or aromatic polyamide, which has excellent heat resistance, suppresses thermal changes to a minimum even when used in high-temperature environments. In addition, since a hard insulating board with high hardness can be obtained,
When forming a hard insulating board that has the same mechanical strength as a conventional hard insulating board, it can be formed thin. Next, we will show the results of a comparative test of the life characteristics of the electrolytic capacitor with the sealed structure of this invention and a conventional electrolytic capacitor. Comparison test is rated voltage 10WV capacitance 18000μF
An electrolytic capacitor was prepared, and as an example, a synthetic resin thin film layer made of aromatic polyamide was formed on one side of a hard insulating plate made of phenolic resin, and an elastic insulator made of elastic rubber was fitted around the periphery of the hard insulating plate. A sealed seal was attached. Further, as a conventional example, a synthetic resin thin film layer made of polypropylene was formed on one surface of a hard insulating plate, and a sealing body similar to that of the embodiment was attached. Ten of these electrolytic capacitors of the example and the conventional example were prepared, and while applying the rated voltage to five of each in a temperature environment of 130°C, the electrostatic capacitance of the other five was applied without applying any voltage. Changes in capacitance and loss angle tangent over time were measured. The average values are shown below.

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〔Example〕

Next, an embodiment of this invention will be explained according to the drawings. FIG. 1 is a partial sectional view showing a first embodiment of this invention. FIG. 2 is a partial cross-sectional perspective view showing the sealing body used in the first embodiment of this invention;
The figure is a partially sectional perspective view showing the sealing body used in the second embodiment, and FIG. 4 is a partially sectional view showing the third embodiment. The capacitor element 1, as shown in FIG.
While winding the bipolar electrode foil 10 and the electrolytic paper 11, a tab 12 for drawing out the electrode is formed from each electrode foil 10.
has been derived. After this capacitor element 1 is impregnated with an electrolytic solution, it is housed in a bottomed cylindrical outer case 4 made of aluminum or the like. Exterior case 4
A sealing body 2 for sealing the outer case 4 is provided in the opening of the
is placed. As shown in FIG. 2, a synthetic resin thin film layer 6 is formed on one surface of a hard insulating plate 5 made of phenolic resin or the like constituting the sealing body 2. As shown in FIG. When forming this synthetic resin thin film layer 6 on the hard insulating plate 5,
On one side of a hard insulating board made of phenolic resin,
A laminate is formed by heat-sealing polyimide, aromatic polyamide, or the like. Then, this laminate is heat-treated preferably at a temperature of 130°C or higher,
By punching the desired shape into a hard insulating board,
A hard insulating plate 5 having a synthetic resin thin film layer 6 provided on one surface is formed. The upper limit of the heat treatment temperature may be below the melting point or thermal decomposition point of the polyimide or aromatic polyamide. An elastic insulator 7 made of elastic rubber or the like and having a U-shaped cross section is disposed on the peripheral edge of the sealing body 2 to cover at least this peripheral edge. Further, an external connection terminal 3 consisting of a rivet portion and a lead portion passing through the sealing body 2 is fixed at a predetermined position of the sealing body 2, and a tab led out from the capacitor element 1 is attached to the tip of the rivet portion penetrating the sealing body 2. 1
2 are electrically connected. The sealing body 2 configured as described above is attached to the opening of the outer case 4 in which the capacitor element 1 is housed, and seals the electrolytic capacitor by crimping the open end of the outer case 4. In this embodiment, at least the portion of the sealing body 2 that comes into contact with the electrolyte is covered with a synthetic resin thin film layer 6 and an elastic insulator 7 to prevent corrosion of the electrolytic capacitor. Next, in the second embodiment, as shown in FIG. 3, a synthetic resin thin film layer 6 made of polyimide or aromatic polyamide is formed on one surface of a hard insulating plate 5 made of phenolic resin, etc., as in the first embodiment. On the other side of the sealing body 2,
An elastic insulator 9 made of elastic rubber is attached to cover this surface and the peripheral edge. The external connection terminal 3 penetrates both the hard insulating plate 5 and the elastic insulator 9 and is fixed to the sealing body 2. In this embodiment, the upper surface of the sealing body 2 is covered with an elastic insulator 9 in the same manner as the peripheral portion, and furthermore, at the joint between the external connection terminal 3 and the sealing body 2, the external connection terminal 3 is covered with an elastic insulator 9. Since it is fixed in such a way that it bites into, the sealing performance is even better than that of the first embodiment. Next, a third embodiment of this invention shown in FIG. 4 will be explained. In this embodiment, the sealing body 2
In this example, a synthetic resin thin film layer 6 made of polyimide or aromatic polyamide is formed on one surface of a hard insulating plate 5 made of phenolic resin in the same manner as in the first embodiment, and the peripheral edge of the hard insulating plate 5 is elastically insulated. body 7
It consists of a structure covered with This sealing body 2 is attached to the opening of the exterior case 4 as in the first embodiment, and subjected to a crimping process to seal the electrolytic capacitor. Then, the sealing body 2 is placed on the upper surface of this sealing body 2.
and a synthetic resin layer 8 covering the entire opening of the electrolytic capacitor. This synthetic resin layer 8 may be any resin that has excellent heat resistance and chemical resistance and also has excellent adhesion to the external connection terminals 3 even after solidification, and preferably silicone resin is suitable. Note that when covering the sealing portion of an electrolytic capacitor with silicone resin or the like, the adhesion to the elastic rubber is generally weak. Therefore, in this embodiment, the elastic insulator 7 of the sealing body 2 is arranged only at the peripheral edge of the hard insulating plate 5. According to this embodiment, the sealing performance of the electrolytic capacitor is further improved compared to the second embodiment, and the cleaning resistance is also improved, so that reliability is improved. Furthermore,
When coated with silicone resin, the silicone resin remains flexible even after solidification, so even if the external connection terminal 3 is bent, its adhesion will not be impaired. [Effects of the invention] As described above, this invention forms a synthetic resin thin film layer made of polyimide or aromatic polyamide on one surface of a hard insulating board, and covers the peripheral edge of the hard insulating board with an elastic insulator. Since the sealing body is attached to the opening of the exterior case and crimped, there is no contact between the electrolytic solution of the electrolytic capacitor and the hard insulating plate of the sealing body, thereby preventing corrosion. I can do it. In addition, the synthetic resin thin film layer made of aromatic polyamide or polyimide formed on one surface of the hard insulating board has excellent heat resistance, so it isolates the electrolyte from the hard insulating board without thermal change even in high operating temperature environments. do. In addition, the hard insulating board of the sealing body should be of high hardness.
That is, it becomes possible to use a material with low gas permeability. Therefore, compared to conventional sealed structures, it is possible to prevent deterioration of electrical characteristics, especially in high operating temperature environments, and improve life characteristics. Moreover, since a hard insulating board with high hardness can be obtained, when forming a hard insulating board that has the same mechanical strength as a conventional hard insulating board, the thickness of the hard insulating board can be made thinner, making the electrolytic capacitor smaller. can be achieved. As described above, this invention aims to improve the life characteristics of an electrolytic capacitor by improving the sealing structure, and also realizes miniaturization.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing an embodiment of this invention. Figure 2 shows the first embodiment of this invention.
Further, FIG. 3 is a partially sectional perspective view showing the sealing body used in the second embodiment, and FIG. 4 is a partially sectional view showing the third embodiment. 1... Capacitor element, 2... Sealing body, 3...
External connection terminal, 4... Exterior case, 5... Hard insulating plate, 6... Synthetic resin thin film layer, 7, 9... Elastic insulator, 8... Synthetic resin layer, 10... Electrode foil, 11
...Electrolytic paper, 12... tab.

Claims (1)

[Scope of utility model registration request] A synthetic resin thin film layer made of polyimide or aromatic polyamide is formed on one surface of a hard insulating plate, and a sealing body formed by covering the peripheral edge of the hard insulating plate with an elastic insulator is attached to the opening of the outer case. The sealed structure of an electrolytic capacitor is characterized by its tight seal.