JPS6233733B2 - - Google Patents

Description

[Detailed description of the invention]

In the present invention, a composite film is used to connect the inner and outer leads of a capacitor element by interposing a separator in which both sides of a metal film are impregnated with a driving electrolyte (hereinafter referred to as paste) between the electrodes. The present invention relates to a composite film-clad electrolytic capacitor in which the ends of the composite film are thermocompression bonded. Conventional electrolytic capacitors are generally constructed by impregnating a wound capacitor element with paste with a separator between electrode foils, building it in a metal case, passing an external lead through the opening, and sealing it with rubber sealing packing. has been done. In such electrolytic capacitors, the outer case and the sealing body serve to prevent moisture and other harmful substances from entering the capacitor from entering the capacitor, and to prevent the paste contained inside from evaporating and diffusing. Recently, equipment has become smaller and thinner, and electrolytic capacitors are also required to develop products with a different shape than before to fit the storage space of parts.In response to this demand, plastic laminate film is used as the exterior of electrolytic capacitors for sealed exteriors. It was developed to This electrolytic capacitor can have any external shape such as sheet, square, round, oval, concentric, triangular, etc., and is extremely effective in making devices smaller and thinner by making effective use of space. However, in electrolytic capacitors using such a film exterior, the leads drawn out from the capacitor element and the solderable materials such as tin, zinc, copper, nickel, solder, etc., and the plating of these materials are used for mounting on the printed circuit board of the device. Leads must be used, and if these metals come into close contact with the capacitor element or paste adheres to them, the electrodes of the capacitor are made of aluminum, so electrochemical reactions between dissimilar metals can cause the electrodes to deteriorate. They also have drawbacks such as the metal moving onto the electrodes, resulting in a shot state, and reactions such as melting of the electrodes and leads, resulting in gas generation and disconnection, resulting in defects such as the inability to function as a capacitor. For this purpose, the internal lead drawn out from the electrode can only be made of aluminum, which is the same material as the electrode. However, it is difficult to solder aluminum, and in fact it is impossible to solder it. If it is absolutely necessary, it is necessary to use aluminum solder and perform ultrasonic welding or solder plating to aluminum, which is extremely difficult and has poor workability. Also, in the case of plating, there are disadvantages such as the lead becomes brittle, it takes time, and the plating can cause shoots at the parts where it comes into contact with the exterior. On the other hand, it is naturally possible to use aluminum for the internal leads and weld them with solderable external leads, but as mentioned above, it is not possible to insert the welded part inside where it contacts the capacitor element. Another option is to expose the welded part to the outside, but this is not good for the appearance, and the welded part may be damaged by force from the outside, or the internal lead of the ribbon-shaped aluminum plate or square bar may be soldered to the internal lead. Solder-plated plates and round tin bars that can be attached,
If the plated iron wire is welded, it can be inserted up to the welded part up to the hole in the printed circuit board, but it is impossible to go beyond that, and even if it is inserted, it cannot be soldered. A conventional example of a film-clad electrolytic capacitor is shown in a perspective view in FIG. FIG. 2 shows a sectional view taken along line XX' in FIG. 1. As shown in the figure, an internal aluminum lead 3, a solderable external lead 5, and an exterior composite film 1
It was welded outside. In the figure, 2 indicates a thermocompression sealing portion, 4 indicates a lead connection portion, and 8 indicates a capacitor element. FIG. 2 shows an internal aluminum lead 3 plated with a metal that can be soldered externally. 6 can be soldered with a matsuki lead. As mentioned above, these methods have various problems. The present invention eliminates the conventional drawbacks, and the welded part of the inner lead and the outer lead is provided in the part of the exterior composite film that does not touch the capacitor element, so that external force does not directly reach the welded part, and the sealing part of the lead wire is The purpose is to obtain a composite film-clad electrolytic capacitor with excellent airtightness. The present invention will be explained based on the drawings. FIG. 4 shows a perspective view of a composite film-clad electrolytic capacitor (hereinafter simply referred to as an electrolytic capacitor) of the present invention, and FIG. 5 shows a sectional view taken along the line Y--Y' in FIG. 4. In the figures, the same reference numerals as in FIGS. 1 to 3 indicate the same parts and parts. The present invention connects a solderable external lead 5 to an internal lead 3 as shown in FIGS. 3 are sandwiched by thermocompression to form a thermocompression sealing part 2-1, and further the solderable external lead 5 and the lead connection part 4 of the internal lead 3 are covered with an exterior composite film to cover the solderable external lead 5. The ends are tightly sealed by thermocompression clamping, and a thermocompression sealing part 2 is provided. Next, embodiments of the present invention will be described and compared with conventional electrolytic capacitors. The composite film material for the composite film exterior thin capacitor is made of aluminum foil laminated with polyethylene terephthalate on one side and ionomer resin on the other side, and the ionomer resin side is used as the thermocompression bonding surface. Product rating is 16W.V1000μ
F, a comparative product with the shape shown in Figure 1 and dimensions 30
It has a rectangular shape of mm x 49 mm and is 1.5 mm thick. CP wire (iron core copper coated tin wire) with a diameter of 0.6 mm is welded to the internal aluminum lead plate to serve as the external lead. As an example of the present invention, a CP wire with a diameter of 0.6 mm is internally welded as an external lead with the same rating and the shape shown in Figure 4, 38 mm x 49 mm in dimensions, 1.5 mm thick, and tightly sealed by thermocompression at the end of the composite film. I used the one I made. In addition, it has the same rating as the conventional product, lead wire in the same direction, aluminum cylindrical case, rubber seal, 0.6 mm diameter.
Use a CP wire lead with external dimensions of 12.5 mm and diameter of 25 mm. As representative examples of various comparative tests, the results of a solder heat resistance test and a salt spray test, both of which are highly effective in the present invention, are shown below. The number of tests was 30 each. As a solder heat resistance test, due to recent mounting technology, when the printed circuit board is a through-hole type, the solder may rise to the base of the leads, so a test was performed by immersing the base of the leads in molten solder at 350°C for 5 seconds. Judgment was made based on the airtightness of the sealing part and changes in initial characteristics. As shown in Table 1, all initial characteristic changes were passed and there were no problems; however, it was observed that the lead clamping and tightly sealed portions of the outer film were almost open due to heat. As an airtightness test, the capacitor was immersed in ethylene glycol for 10mm.
Judgment was made based on the generation of bubbles 5 minutes after reducing the pressure to Hg. All of these test items were checked to ensure that no air bubbles were generated by reducing the pressure before testing. When the airtightness of the sealing part deteriorates and bubbles are generated, the paste inside the capacitor evaporates and harmful substances enter from the outside, which shortens the life of the capacitor and significantly reduces its reliability. As shown in Table 1, in the product of the present invention, the lead portion is double sealed, so there is no problem with airtightness, the reliability is high, and the effect is extremely large.

[Table] Next, the lead portion was tested for corrosion using a salt spray test. The test conditions were based on JIS-C-5028, and the evaluation was made by spraying 5% salt water by weight at 35±2°C on each of 30 test pieces for 48 hours. Rust formation at the cut end of the lead is excluded from the judgment. As shown in Table 2, all of the composite film-clad capacitors with external lead connections and the shape shown in Figure 1 were found to have rust and corrosion, whereas all of the products of the present invention had rust and corrosion. is not recognized. This is a feature of the product of the present invention in which the lead connection portion is not exposed.

[Table] Since the present invention has the above configuration,
There is no need for the internal capacitor element to come into contact with a metal other than the aluminum of the solderable external lead, which eliminates the problem of not being able to operate as a short capacitor, etc., as mentioned earlier, and it can also be soldered to a printed circuit board. Since the external lead portion is fixed, no external stress is applied to the welded connection between the internal lead and the external lead, so the connection does not break. No stress is applied to internal elements and no changes in characteristics occur. Furthermore, it is also possible to prevent moisture from adhering to the welded portion of the lead due to cleaning or the like and causing breakage due to an electrochemical reaction. In addition, it not only has excellent quality characteristics, but also has a lead connection part inside, and has an excellent appearance and high commercial value.
On the other hand, in manufacturing, there is no need to perform soldering, etc., and it is only necessary to connect to solderable leads by welding, etc., and the shape can be freely changed to ribbon-shaped internal leads, round bars, or various other shapes. There are also advantages such as the ability to simply connect and use leads suitable for mounting. Furthermore, in terms of quality, the least reliable part of the sealed part in a composite film-wrapped capacitor is the part where the leads are sandwiched and tightly sealed, and in the present invention, this unreliable part is double-tightly sealed to ensure airtightness. This results in a capacitor with high cost and high reliability. Furthermore, since the lead connection portion is not exposed, it can be easily assumed that the device is extremely stable against cleaning and humidity after being attached to a printed circuit board. In addition, since the connection part is located inside, stress is not concentrated on the connection part and breakage does not occur due to vibrations, etc. The composite film capacitor of the present invention is extremely thin and can be made into any shape in various aspects. Moreover, it is highly reliable, suitable for mounting, and has great value for industrial use.

[Brief explanation of the drawing]

Figures 1 and 2 are a perspective view and a sectional view of a conventional composite film-clad electrolytic capacitor, Figure 3 is a perspective view of the same conventional example as Figure 1, and Figure 4 is a composite film-clad electrolytic capacitor of the present invention. A perspective view, FIG. 5 is a cross-sectional view taken along the line Y--Y in FIG. 4 of the present invention, and FIG. 6 is a perspective view of the electrolytic capacitor shown in FIGS. 4 and 5 of the present invention, with a part cut out. The figure shows. 1: Exterior composite film, 2, 2-1: Thermocompression sealing part, 3: Internal lead, 4: Lead connection part,
5: External lead, 6: Metsuki lead, 8: Capacitor element.

Claims (1)

[Claims] 1 Cover the capacitor element with a composite film consisting of a metal film and a plastic film laminated on both sides of the metal film, and bond the composite film by thermocompression to tightly sheath the capacitor element, and attach the aluminum internal lead drawn out from the capacitor element to the A composite film is used to clamp and tightly seal the aluminum internal lead, and a solderable external lead is welded to the aluminum internal lead. A composite film exterior electrolytic capacitor characterized by a sealed welded part of the solderable external lead.