JPS5851408B2 - 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 250μ, but as shown in Figure 1, the diameter of the lead wire of the capacitor element is 0.5
~1. Since OrILm is thick, 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, the thickness of the plastic film on the inner surface that is fused to the lead wire should be at least as thick as the radius of the lead wire to prevent gaps from forming at the fused portion of the lead wire. The purpose of the present invention is to provide a method for manufacturing a capacitor that is small, easy to mass-produce, and inexpensive, which has good airtightness and prevents contact between the metal foil and the lead wire.

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

That is, as shown in FIGS. 2 and 3, the lead wire 11
A laminate film 13 is placed above and below the capacitor element 12 to which the capacitor element 12 is attached.

The laminate film 13 is made of polypropylene, polyamide, polyester, polyvinylidene fluoride, polyvinylidene chloride, polycarbonate, ionomer, polysulfone, polytetrafluoroethylene, polyethylene naphthalate,
Aluminum is placed between two plastic films of the same or different types, such as polybutylene terephthalate, polyphenyline oxide, polyvinyl fluoride, polyvinyl chloride, polyvaraxylene, ethylene-vinyl acetate copolymer, vinylon, etc. , the thickness of the plastic film 15 on the inner surface which is bonded to the lead wire 11 by interposing a metal foil 14 such as tin, is set to a thickness equal to or larger than the radial dimension of the lead wire 11, that is, 250 mm.
Set to ~1000μ.

The thickness of the plastic film 16 on the outer surface is 10 mm.
It may be about 250 μm.

Then, the capacitor element 12 is loaded between the two upper and lower laminate films 13 with the thick plastic film 15 facing each other, and the capacitor element 12 is sealed by heat sealing with a heating device such as a hot plate or an indenter. The exterior is formed by heat sealing and then cooling.

The thickness of the plastic film 15 on the inner surface that is fused to the lead wire 11 is greater than or equal to the radial dimension of the lead wire 11,
That is, the radius of the lead wire 11 is approximately 0.25 to 0.5
By setting the thickness of the plastic film 15 on the inner surface to 250 to 100 μm, the lead wire 11
A gap between the fused parts is completely eliminated, and contact between the metal foil 14 and the lead wires 11 or a short circuit between the lead wires 11 via the metal foil 14 can be completely prevented.

If the thickness is less than the radial dimension of the lead wire 11, the metal foil 14 and the lead wire 11 may come into contact depending on the melting state of the plastic film 15 on the inner surface.
The thickness shall be greater than or equal to the radial dimension of.

As shown in FIG. 4, at least one laminate film 13 may be thermoformed in advance into a shape capable of accommodating the capacitor element 12, and then heat-sealed.

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 heat sealing of the laminate film 13 in the present invention, hot plate solubility (temperature 120 to 180°C, time 2 to 7 seconds) is used.
, ion pulse welding (temperature 120~180℃, time 2~
8 seconds), ultrasonic welding (frequency 15-30KHz, load 1
0 to 20 kg/c1111 time 1 to 10 seconds) or high frequency welding (frequency 10 to 70 MHz, load 2 to 15 kg
/cyyt, 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 15, 16 and the metal foil 14 can be laminated by heat-sealing or bonding with adhesive, or by dropping heated and molten materials on both sides of the metal foil 14 in a shower set or in the form of a band, and then rolling this with a rolling roller. They are integrated by passing through a stretching roller, or by applying heated and molten 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 moisture absorption, there is little deterioration in characteristics due to moisture absorption, and the sealing performance is excellent, and short circuits due to contact between the metal foil 14 and the lead wire 11 are completely eliminated.

As described in detail above, the present invention is applicable to the case where a laminate film with metal foil interposed between two plastic films is placed above and below a capacitor element to which lead wires are attached, and the laminate film is heat-sealed. By making the plastic film on the inner surface that is fused to the metal foil at least as thick as the radius of the lead wire, there is no gap in the fused portion of the lead wire, resulting in good airtightness and a seal between the metal foil and the lead wire. It is possible to provide a method for manufacturing a capacitor that is small, easy to mass-produce, and inexpensive, while preventing contact between the two.

[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 lead wire of the capacitor shown in FIG. 2. 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 another embodiment; FIG.
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...
... Metal foil, 15 ... Inner plastic film, 16 ... Outer plastic film.

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. 2. A method for manufacturing a capacitor, characterized in that the thickness of the plastic film on the inner surface that is fused to the lead wire is at least as thick as the radius dimension of the lead wire, and heat-sealed. 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.