JPS5851409B2 - Capacitor manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a capacitor which is packaged by heat sealing a plastic film.

In general, an aluminum case or a plastic molded case is often used as the exterior of a capacitor, but as the performance of plastic films has improved recently, a method has been proposed in which the capacitor element is directly wrapped in a metal-plastic laminate film and heat-sealed.

The thickness of each plastic film used for the laminate film is usually within the range of 10 to 250 μm, but as shown in FIG.
Since it is as thick as ~1.0 mm, a gap 3 is likely to occur at the fused portion between the laminate film 2 and the lead wire 1 when heat sealing is performed.

In addition, a laminate film in which a metal foil such as aluminum is interposed has a drawback that contact between the metal foil and the lead wire 1 or a short circuit between the lead wires 1 via the metal foil is likely to occur.

The present invention was made in view of the above-mentioned circumstances, and consists of arranging a laminate film with a metal foil interposed in between, such as plastic film-metal foil-plastic film, above and below a capacitor element to which lead wires are attached. When heat-sealing the laminate film, at least the width of the metal foil on the side where the lead wires are fused is made narrower than the width of the plastic film to prevent the metal foil from being exposed from the end surface of the plastic film, thereby creating a gap at the fusion portion of the lead wires. It is an object of the present invention to provide a method for manufacturing a capacitor that is small, easy to mass-produce, and inexpensive, with good airtightness and prevention of contact between metal foil and lead wires.

An embodiment of the present invention will be described below with reference to the drawings.

That is, as shown in FIG. 2, laminate films 13 are placed above and below the capacitor element 12 to which the lead wires 11 are attached.

The laminate film 13 is made of polypropylene, polyamide, polyester, polyvinylidene fluoride, polyvinylidene chloride, polycarbonate, ionomer, polysulfone, polytrifluoroethylene, polytetrafluoroethylene, polyethylene naphthalate, polybutylene terephthalate, polyphenyline. A metal foil such as aluminum or tin is placed between two plastic films 14 of the same or different types of plastic films such as oxide, polyvinyl fluoride, polyvinyl chloride, polyparaxylene, ethylene-vinyl acetate copolymer, vinylon, etc. The width of the metal foil 15 on at least one end surface, that is, the side of the fused portion of the lead wire 11 is made narrower than the width of the plastic film 14.

In this case, the width of the metal foil 15 is 1.5 mm larger than the width of the plastic film 14 because the size of the fused portion is about 1 to 4 mm.
Make it narrower by ~5mm.

Furthermore, the metal foil 15 can be applied to a lead wire reflection direction type capacitor without any problem by narrowing not only the fused portion side of the lead wire 11 but also both end faces.

Then, the capacitor element 12 with the lead wire 11 attached thereto is loaded between the laminate films 13 facing each other vertically, and the capacitor element 12 is sealed by heat sealing with a heating device such as a hot plate or an indenter. It is cooled to form an exterior.

By making the width of the metal foil 15 narrower than the width of the plastic film 14 at least on the fused portion side of the lead wire 11 and heat-sealing it, the gap that occurs at the fused portion of the lead wire 11 is completely eliminated, and the gap between the metal foil 15 and the lead wire is 11 or a short circuit between the lead wires 11 through the metal foil 15 can be completely prevented.

If the width dimension difference between the metal foil 15 and the plastic film 14 is less than 1.5 mm, the end face of the metal foil 15 may be exposed at the fused portion and come into contact with the lead wire 11, so it should be set to at least 1.5 mm. I have to throw it.

However, if the width dimension difference exceeds 5 mm, the area near the fused portion will be the same as that of a laminate film heat-sealed with just the plastic film 14, and the moisture-proofing effect of interposing the metal foil 15 will be reduced, so it is set within 5 mm. I have to do it.

As shown in FIG. 3, the laminate film 13 is coated with a plastic film 16 on the inner surface, preferably having a thickness of 250 to 100 mm, which is equal to or larger than the radius of the lead wire 11.
0μ) is more effective in preventing the occurrence of gaps at the fused portion of the lead wire 11 and preventing short circuits.

Further, as shown in FIG. 4, at least one laminate film 13 is thermoformed in advance to form the capacitor element 12.
It is also possible to process it into a shape that can accommodate it and then heat seal it.

Furthermore, as shown in FIGS. 5 and 6, a laminate film 13 may be wound around the outer periphery of the capacitor element 12, and one side and both end surfaces may be heat-sealed.

In the present invention, the laminate film 13 is heat-sealed by hot plate welding (temperature 120-180°C, time 2-7 seconds).
, impulse welding (temperature 120-180℃, time 2-8
seconds), ultrasonic welding (frequency 15-30 KHz, load 10-20 kg/c111 time 1-10 seconds) or high frequency welding (frequency 10-70 MHz, load 2-15 kg
/cyd, time 1 to 7 seconds).

If the laminate film 13 is subjected to secondary processing such as electron beam irradiation, corona discharge treatment, and biaxial stretching before lamination, mechanical and thermal properties can be improved and heat sealing can be performed efficiently. .

The plastic film 14 and the metal foil 15 may be laminated by heat-sealing or bonding with an adhesive, or by dropping heated and molten materials on both sides of the metal foil 15 in the form of showers or strips, which are then stretched using a rolling roller. They are integrated by passing through a roller, or by applying heated and melted material with a roller.

Next, Table 1 shows an example of comparison between the embodiment of the present invention and a conventional reference example.

As is clear from Table 1, all of the examples of the present invention have a smaller capacitance change rate after the humidity test than the conventional reference examples, and a gap occurs at the fused portion between the lead wire 11 and the laminate film 13. It can be seen that since there is no deterioration of characteristics due to moisture absorption, the sealing performance is excellent, and short circuits due to contact between the metal foil 15 and the lead wire 11 are completely eliminated.

As described in detail above, the present invention provides a method for disposing a laminate film with a metal foil interposed between two plastic films above and below a capacitor element to which lead wires are attached, and heat-sealing the laminate film. By making the width of the metal foil on the lead wire fusion part side narrower than the plastic film width so that the metal foil is not exposed from the edge of the plastic film, there is no gap in the lead wire fusion part, which improves airtightness. It is possible to provide a method for manufacturing a capacitor that is small, easy to mass-produce, and inexpensive, while preventing contact between a metal foil and a lead wire.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a lead wire fusion part of a capacitor according to a conventional method, FIG. 2 is a sectional view showing a capacitor according to an embodiment of the present invention, and FIG. 3 is a sectional view showing a capacitor according to another embodiment of the present invention. 4 is a sectional view showing such a capacitor; FIG. 4 is a perspective view showing a heat sealing method according to another embodiment of the present invention; FIG. 5 is a perspective view showing a heat sealing method according to yet another embodiment;
The figure is a perspective view showing a capacitor obtained by the method of FIG. 5. 11... Lead wire, 12... Capacitor element, 13... Laminate film, 14...
...Plastic film, 15...Metal foil.

Claims (1)

[Claims] 1. A capacitor in which a laminate film with a metal foil interposed between two plastic films is placed above and below a capacitor element to which a lead wire is attached, and the laminate film is heat-sealed to provide an exterior packaging. In the manufacturing method of the capacitor, the width of the metal foil at least on the fused portion side of the lead wire is narrower than the width of the plastic film, and the end face of the plastic film is heat-sealed so that the metal foil is not exposed. Production method. 2. The method of manufacturing a capacitor according to claim 1, wherein the laminate film is previously thermoformed into a shape capable of accommodating a capacitor element, and then heat-sealed. 3. The method of manufacturing a capacitor according to claim 1, wherein the outer casing is formed by wrapping a laminate film around the outer periphery of the capacitor element and heat-sealing it.