JPS6025213A - Method of producing film capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method of manufacturing a film capacitor.

Conventional structure and its problems General Ni-film capacitors are made of polyester (PET).
, a dielectric such as polypropylene (PP) film and metal foil, or the surface of the dielectric itself is metallized, are wound and laminated, and then lead wires are pulled out and coated with epoxy resin or polybutadiene resin for moisture-proofing, insulation, etc. The exterior is coated with a thermosetting liquid resin (hereinafter referred to as resin) such as Particularly when moisture-proofing is desired, a method in which a large amount of resin infiltrates into the inside of a wound and laminated film capacitor element (hereinafter referred to as an element) by performing the exterior packaging in a vacuum (hereinafter referred to as a vacuum There is impregnation9).

Figure 1 (a) shows the process of the exterior packaging method, (b)
) is an Itf'r plane view of the packaged film capacitor. The process of the exterior packaging method consists of element 1 and resin 2f! : Place in vacuum state 3 (A-B), immerse element 1 in resin 2 (C), return vacuum state to atmospheric pressure D), lift element 1 from resin 2 (E), then heat cure side) It will be done as follows. In this case, the resin 2 "infiltrates" into the element 1 due to the pressure difference when the vacuum state in the packaging process is returned to atmospheric pressure, but the resin 2 and the element 1 form a single bay through the dielectric 1a.
Also, due to the interfacial resistance with the surface of the metal foil 1b, the penetration is not instantaneous and usually takes several tens of minutes. During this time, high moisture resistance can only be obtained by continuing the state (D), that is, the state in which the element 1 is immersed in the resin 2.

However, in general, due to the emphasis on productivity, the soaking time is insufficient, and as shown in FIG. The resin did not adhere to the ends of the l, and it was not possible to obtain high moisture resistance.

In order to compensate for the above-mentioned drawbacks, the packaging method shown in FIG. 2 has been used. FIG. 2(a) shows the entire process of the above-mentioned exterior packaging method (A-
After F), it is immersed in the resin 2 again at atmospheric pressure (G), pulled up (H), and then heated and cured (I). Figure 2 (
b) (I'i) A sectional view of a film capacitor packaged by this packaging method.

Since the resin 2a infiltrated by vacuum impregnation is heated and hardened without covering the entire surface of the dielectric 1a and the metal foil 1b, as in FIG. The resin 2b (hereinafter referred to as atmospheric impregnation) only slightly infiltrates into the inside of the element 1, and a gap 4 is created between the resin 2a and the resin 2a that has infiltrated by vacuum impregnation, and the moisture resistance is slightly lower than that of an exterior made only by vacuum impregnation. Although this was improved, the moisture resistance was not sufficient because moisture permeated more easily than when the resin was continuously infiltrated. In addition, heat curing twice (F, I
), leading to long lead times and high equipment costs.

OBJECT OF THE INVENTION An object of the present invention is to provide a method of manufacturing a highly reliable film capacitor with high moisture resistance without increasing lead time.

Structure of the Invention In order to achieve the above object, the structure of the present invention is to immerse a capacitor element placed in a vacuum state in a liquid resin placed in a similar vacuum state while maintaining the vacuum state, and maintain the immersion state. The device is returned to atmospheric pressure from the vacuum state while still being maintained, then removed from the resin, then immersed in the liquid resin again after a predetermined period of time without being heat-cured, taken out, and then heat-cured. be.

Figure 3(a) ld shows the exterior packaging process of this invention.
After carrying out steps (A-E) of the packaging process in Figure 1(a) in the same way, step (F) is omitted and the capacitor element 1 is immersed in the resin 2 again at atmospheric pressure for 3 to 10 minutes. G), lifting (H), and then heat curing (I).

According to this method, the resin can easily infiltrate into the inside of the element by pulling up the element after returning the pressure from the empty state to atmospheric pressure. In other words, after returning from a vacuum state to atmospheric pressure, the element is pulled up from the resin, thereby temporarily cutting off the supply of subsequent resin to the resin that is infiltrating, and allowing the resin adhering to the end of the element to infiltrate into the element. .

At this time, since the supply force of the resin following the infiltrating resin is cut off, the interfacial resistance between the resin, the dielectric material, and the metal foil decreases, and therefore the rate of infiltration of the resin into the element becomes faster. This allows the resin to penetrate in an extremely short time compared to the case where the resin is left in the immersed state and the resin is continued to be supplied.

Furthermore, the device is immersed in liquid resin again at atmospheric pressure, but in this case, the resin infiltrated by vacuum impregnation is attached to both ends of the device, the dielectric body, and the surface of the metal foil, and the molten resin that has not been heat-cured remains. Because of this condition, the resin that has entered through atmospheric impregnation immediately adheres to the surface, and as a result, no voids are created.

Therefore, the resin covers not only the entire surface of the dielectric and metal foil, but also the edges of the element, making it possible to create a capacitor with a high moisture-proofing effect in a short period of time. : Obtained by one heat curing.

FIG. 3(b) is a sectional view of a film capacitor after being packaged by the packaging method of the present invention. Resin 2 by vacuum impregnation
a and 2b due to air impregnation are the dielectric material 1 constituting the element l.
a and the metal foil 1b, and both ends of the element 10 are also completely covered.

Explanation of Examples FIG. 4 shows the time in which the puller 1 is pulled up after vacuum impregnation and immersed in the resin 2 again under atmospheric pressure in the casing, and the moisture resistance test ( 40℃, 95%.

The rate of change in capacitance after 500 hours is shown.

Also, when impregnated with Makabe, the degree is 5 rnmHf;' + 1
00 vmH? This is a comparison at +200 am HP.

According to t'LVC, the time from vacuum impregnation to pulling up and immersion in the resin again under atmospheric pressure is 3 minutes or more, the capacitance change rate in the moisture resistance test is small, and the degree of vacuum is 100tIun.
The rate of change in capacitance is small below Hy.

Further, if the time from vacuum impregnation to lifting and immersion in resin again at atmospheric pressure is I/'i 10 minutes or more, no further effect can be expected. It should be noted that if the degree of vacuum is less than 5 mH1;', the resin will boil, and the resin will adhere to unnecessary parts other than the element, which is unfavorable for work.

FIG. 5 shows a moisture resistance test of the capacitor of the present invention (40°C) conducted with 50 wHy of Makabe impregnation and 5 minutes from vacuum impregnation to immersion in resin again at atmospheric pressure.

95%, 500 hours) shows the rate of change in static t'tl jrx, and the horizontal axis shows the viscosity of the resin. According to this, the viscosity of commonly used resin is i0,000 cp.
No significant difference is observed below s.

Figure M6 compares the present invention with a conventional example. In other words, the element is made of epoxy resin for 50 +IIIH? The capacitor of the present invention was completed by vacuum impregnation, heat curing, and air impregnation after 5 minutes of lifting, and the capacitor of the present invention, which was completed by ladle and heating and curing. Capacitor moisture resistance test (4
0° C., 95%, 500 hours).

Here, the capacitor of the present invention has an extremely small rate of change in capacitance compared to conventional capacitors, and exhibits a sufficient moisture-proofing effect.

Effects of the Invention The film capacitor manufacturing method of the present invention has the effect that, compared to conventional packaging methods, highly reliable film capacitors with high moisture resistance can be manufactured without increasing the lead time. be.

[Brief explanation of drawings]

Figure 1 (a) is a process diagram of a conventional method, (b) is a cross-sectional view of a capacitor made by that method, Figure 2 (a) is a process diagram of another conventional method, and (b) is a process diagram of that method. 3(a) is a process diagram of the method of the present invention,
(b) is a cross-sectional view of an example of a capacitor made by this method, and FIG. 4 is a graph showing the relationship between the capacitance liquefaction rate and the time required for complete atmospheric impregnation after vacuum impregnation in moisture resistance test 2. Figure 5 is a graph showing the relationship between the capacitance change rate and resin viscosity in a moisture resistance test, and Figure 6 is a comparison of the capacitance change rate between the capacitor of this invention and a conventional capacitor in a humidity resistance test. This is the graph shown.

Claims (3)

[Claims] (1) A process of immersing a film capacitor element in a liquid resin under a vacuum atmosphere, and a process of removing the film capacitor element from the liquid resin after transferring it from a vacuum state to an atmospheric pressure state while maintaining the immersion state. , a process of immersing a film capacitor element in a liquid resin under atmospheric pressure before heat-curing the infiltrated resin, and a process of heat-curing the film capacitor element only after taking it out from the liquid resin. Production method. (2) The pressure of the vacuum surrounding air is 5 to 100 tnm I
19. The method for manufacturing a film capacitor according to claim 1, which is carried out within the scope of claim 19. (3) = h = a The second immersion operation of the film capacitor element is performed after the first removal from the liquid resin.
Claims (1) or (2) filed after 0 minutes
2. Method for manufacturing a film capacitor as described in Section 1.