JPH0232775B2 - SEKISOGATAFUIRUMUKONDENSANOSEIZOHOHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a multilayer film capacitor in which the means for forming a protective film layer is improved.

Generally speaking, in a laminated film capacitor constructed by cutting a base element wound around a large-diameter winding core in the radial direction, the metallized film functioning as a capacitance part is The strong adhesion to the metallicon electrode suppresses the tendency to separate due to stress, which means that the metallicon electrode and the metallized film do not separate when the lead wire is attached to the metallicon electrode, or even if there is no separation phenomenon, it is due to incomplete contact. This is an extremely important requirement in terms of preventing an increase in tanδ.

A technique disclosed in Japanese Unexamined Patent Application Publication No. 57-5320 that has attempted to meet such demands has been developed, namely, a technique in which a protective film is wound from side to side at the beginning and end of winding during the formation of a mother element to form a protective film layer. A capacitor element is formed by cutting a base element provided with a base element in the radial direction to form an uneven part on the end face of the protective film layer, or when winding the base element at the beginning and end of winding, a difference in width is formed in advance. A capacitor element is formed by winding protective films of the same width alternately, or by winding films of the same width in a staggered manner, and cutting the base element in the radial direction.By forming uneven portions on the end face of the protective film layer, Although there is a method to improve the adhesion with the metallized film electrode, as shown in FIG. This has drawbacks such as impairing the penetration of metallicon metal particles during the formation of the bent metallicon electrode 4, increasing tan δ and increasing capacity reduction over time due to incomplete contact. Therefore, it may be possible to reduce the bending of the end face of the metallized film by increasing the winding tension, but this increases the vibration noise when AC pulse voltage is applied, which poses a practical problem.

The present invention has been made in view of the above points, and as a means for forming a protective film layer, protective films of the same width, which are wider by the amount of the shift of the metallized films and have different heat shrinkage rates, are alternately laminated and heat-treated before forming the metallicon electrodes. By forming uneven steps on the end face of the protective film layer, bending of the end face during winding of the metallized film can be eliminated, and a multilayer film capacitor with improved adhesion to the metallicon electrode and less deterioration of characteristics can be obtained. The object of the present invention is to provide a method for manufacturing a multilayer film capacitor.

The present invention will be explained below with reference to Examples. That is, as shown in FIGS. 2 and 3, the large diameter winding core 1
1, a protective film 12 having a high heat shrinkage rate such as polyethylene, polystyrene, polypropylene, or vinyl chloride, and the same width as the film 12 and the same conditions as the film 12 having a high heat shrinkage rate such as polyester, polyamide, Teflon, or nylon. Then, a protective film 13 having a lower heat shrinkage rate than the film 12 is alternately wound so that both ends thereof are aligned, and a pair of metallized films 14 are alternately placed on top of the protective film 13, so that the displaced end faces are aligned with the protective films 12 and 1.
3. The protective film 12 with a high heat shrinkage rate and the protective film 13 with a low heat shrinkage rate are alternately wound on top of the protective film 12 with a high heat shrinkage rate and a protective film 13 with a low heat shrinkage rate in the same condition as described above so that both ends are aligned with both ends of the metallized film 14. Protective film layer 1 formed by winding it evenly
5 is formed. Next, as shown in FIGS. 4 and 5, the mother element 16 is heated, and the protective film layer 15 is formed by utilizing the different shrinkage rates of the protective film 12 with a high thermal contraction rate and the protective film 13 with a low thermal contraction rate. After forming uneven steps 17 on the end faces, metal spraying is applied to both end faces of the mother element 16 to form metallicon electrodes 18. Thus, the lead wire 20 is attached to the metallic electrode 18 of a multilayer capacitor element 19 which is formed by cutting the mother element 16 in the radial direction as shown in FIG.

According to the method for manufacturing a multilayer film capacitor configured as described above, the metallized film 14
Protective films 12 and 13 with different heat shrinkage rates are provided with no step on the end face of the protective film layer 15 during winding, eliminate bending of the shifted portion of the metallized film 14, and form the protective film layer 15 during the formation of the metallicon electrode 18.
Since the protective film layer 15 is formed by laminating alternately layers 15 and 15, the uneven steps 17 are provided on the end face, so that the winding tension of the metallized film 14 can be increased, and the adhesion between the metallized films 14 is improved. It is possible to improve the penetration of metallicon metal particles into the stepped part step and the uneven step 17 on the end face of the protective film layer 15, and simultaneously improve the adhesion between the multilayer capacitor element 19 and the metallicon electrode 18. As a result, the tan δ increases and the time elapses. Decrease in capacitance
It has the advantage of solving the drawbacks of conventional technology, such as increased vibration noise when AC or pulse voltage is applied, all at once.

Next, a comparison of characteristics between the present invention (A) and a conventional reference example (B) will be described using specific examples. First, the present invention
Let us describe the configuration of (A). In other words, a 25μ x 6.5mm wide polyester film was used as the protective film layer.
A pair of 6μ x 6mm wide metallized polyester films that are alternately laminated with 25μ x 6.5mm wide polystyrene films to a thickness of 0.5mm on one side, with a 0.5mm margin formed on one end surface as a capacitive part. The base element was heated at 140°C for 3 hours, and an Al metallicon electrode was formed. Reference example (B)
The structure is two 25μ x 6.0mm protective film layers.
It consists of 0.5mm thick polyester films stacked on one side with 0.5mm offset from each other, and a 6μ x 6mm wide metallized polyester film with a 0.5mm margin formed on one end as a capacitive part. Al metallicon electrodes are formed by stacking layers with a thickness of 1.0 mm with an offset of mm. The rating for both (A) and (B) is 250V.AC-0.01μF. However, when we measured the initial tan δ of the sample constructed as above, the results were as shown in Figure 7: 85°C, 160V.
Figure 8 shows the results of measuring the capacitance change rate with respect to time under AC application conditions.

As is clear from FIGS. 7 and 8, the present invention
It can be seen that (A) has smaller absolute values and variations in tan δ and less decrease in capacity than Reference Example (B).

As described above, according to the present invention, as a means for forming a protective film layer, protective films of the same width and having different heat shrinkage rates are laminated alternately by the difference between the pair of metallized films, and are heat-treated and protected before metallized electrode formation. By forming uneven steps on the end face of the film layer, bending of the end face during winding of the metallized film is eliminated, and a multilayer film capacitor with improved adhesion to the metallicon electrode and less deterioration of characteristics is obtained. It is possible to provide a method for manufacturing a multilayer film capacitor that is suitable for practical use.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway sectional view of a multilayer film capacitor obtained according to a conventional example, and Figs. 2 to 5 show an embodiment of the present invention, and Fig. 2 shows a state in which it is wound around a large diameter core. FIG. 3 is an enlarged sectional view of the section A in FIG. 6 is a perspective view showing a multilayer film capacitor obtained by cutting the base element shown in FIG. 4 in the radial direction, FIG. 7 is a tanδ characteristic diagram, and FIG.
The figure is a time-capacity change rate characteristic curve diagram. 11...Large diameter winding core, 12, 13...Protective film, 14...Metalized film, 15...Protective film layer, 16...Mother element, 17...Irregular steps,
18...Metallicon electrode.

Claims (1)

[Claims] 1. Protective films with the same width and different thermal shrinkage rates under the same heating conditions are alternately layered and wound around a large-diameter winding core, and a pair of metallized films are placed on top of them in a staggered manner so that the width becomes the same as that of the protective film. A protective film is alternately laminated and wound thereon in the same manner as above to form a mother element with protective film layers on both sides, and then the mother element is heat-treated to form a protective film on the end face of the protective film layer. 1. A method for manufacturing a multilayer film capacitor, which comprises forming uneven steps, forming metallicon electrodes on both end faces of a base element, and then cutting the base element in a radial direction.