JPH0474849B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing a multilayer capacitor.

BACKGROUND ART In recent years, film capacitors are becoming smaller and more laminated, and in the manufacturing method of this laminated capacitor, as shown in FIG. A thick protective film 2 is placed at the beginning and end of the winding of the capacitor base material (metalized film 3, dielectric film 4).
The common method is to wind the After winding a predetermined number of turns, a metallized silicone 6 is applied to the end face of the base capacitor for drawing out external electrodes, and heat treatment is performed to stabilize the characteristics. that time,
The band tightening method is used because the method of tightening a metal band 7 on the outside of the base capacitor and heat treating it provides much more stable characteristics than heat treating it in a free state. After the heat treatment has been completed, the band 7 and drum 1 are removed from the base capacitor, and the capacitor is cut to a predetermined capacitance to produce a multilayer capacitor element. After attaching terminals to the element, it is inserted into a case and potted with sealing resin to create the desired multilayer capacitor.

Problems to be Solved by the Invention However, among the above-mentioned manufacturing methods, stabilizing the characteristics by tightening metal bands before heat treatment can reduce the decrease in capacity during service life, and reduce the electrical withstand voltage after cutting. However, due to the management of the band tightening pressure, the generation of gaps between the base capacitor and the metal band due to burrs on the metallicon 6, and the thermal expansion of the metal band 7 due to heat,
This does not necessarily mean that the base capacitor is tightened with little variation.

Means for Solving the Problems Therefore, in order to eliminate the above-mentioned drawbacks, the present invention has been developed by winding the base material (metallized film, dielectric film) of the base capacitor, and then winding the paper. This method is characterized in that a metallized silicone is applied to the end face of the capacitor, heat treated, and then cut to form a capacitor element.

Effect According to the above method, during heat treatment, the diameter of the metal drum increases due to thermal expansion.
Furthermore, since the base material is a thermoplastic plastic film, a force of thermal contraction acts toward the center of the drum, but the thickness of the film, that is, the thickness of the base capacitor, expands thermally. At that time, the paper wrapped at the end of the base capacitor has an extremely small coefficient of thermal expansion compared to metals and plastics, so
The mother capacitor is sandwiched between a metal drum and paper.
Tightens evenly. Also, since metallicon is applied after the paper is wound, unlike metal bands, it is not affected by metalliconburi. Furthermore, after heat treatment,
The desired multilayer capacitor element can be made by cutting the base capacitor without removing the band, and the process can be simplified.

In addition, if the winding is uniform and strong, there will be less loosening of the element when cutting the mother capacitor, and the cut surface will be firmly fixed, allowing voltage to be applied to the cut surface and restoring electrical insulation. When this happens, there is less self-healing and less damage to the element. In addition, regarding changes in characteristics during life, if the film layers are tightly tightened evenly, the gap layer between the film layers becomes smaller, and the amount of air that causes oxidation of the vapor-deposited metal, which is the electrode of the capacitor, can be reduced. . As a result, the capacitance change during life is reduced.

Example Examples of the present invention will be described below.

In Fig. 1, 1 is a metal bobbin, a protective film 2 is wound around the metal bobbin 1, and a double-sided metallized film 3 (a polyester film with a thickness of 5 μm is used) and a dielectric film (a polyester film with a thickness of 5 μm are used).
5 μm polypropylene film) 4 is wound alternately, and after this winding, a 50 μm thick paper 5 is wound 10 times to form a base capacitor. Next, a metallicon 6 for electrode extraction is applied to the end face, heat treated at 120℃ for 10 hours, and then cut and divided into 10μF
The element is made and sealed with resin to make a multilayer capacitor. This multilayer capacitor has a voltage of 250VAC
Figure 3 shows the change in capacitance over time when . From this Figure 3, the capacity reduction of the example product is -1.5% after 1000 hours, while that of the conventional product is -2.3%. It has been demonstrated that the tightness between the film 3 and the dielectric film 4 is strengthened, the interlayer gap layer is reduced, and as a result, the oxidation of the vapor-deposited metal, which is the capacitor electrode, is reduced and a decrease in capacity is prevented. FIG. 4 shows the rate of change in capacitance when a voltage is applied to recover the electrical insulation of the cut surface after cutting. With conventional products, when a voltage is applied, large self-healing occurs at the cut surface, a large inrush current flows, and the contact between the metallcon and the vapor-deposited electrode melts due to Joule heat, separating the capacitor electrodes and reducing the capacitance accordingly. ing. On the other hand, the product of this example has less capacity reduction and less variation.

Effects of the Invention As described above, the present invention provides uniform winding and
Moreover, since the winding is tightened more tightly, it has a great effect in reducing the rate of change in capacitance at withstand voltage after cutting and reducing the decrease in capacitance during service life, among other capacitor characteristics. Furthermore, there is no need for the conventional process of tightening metal bands, making it possible to provide a more rational construction method.

[Brief explanation of drawings]

Figure 1a is a perspective view of a base capacitor in the manufacturing process of a multilayer capacitor showing an embodiment of the present invention, Figure 1b is a perspective view of a capacitor element obtained by cutting the base capacitor, and Figure 2a is a conventional Fig. 2b is a perspective view of a capacitor element obtained by cutting the multilayer capacitor, and Fig. 3 shows capacitance changes during the life of the capacitors according to the embodiment and the conventional example. FIG. 4 is a diagram showing the capacitance change rate before and after the cut-off withstand voltage of the same capacitor. 1...Metal bobbin, 3...Double-sided metal film,
4...Dielectric film, 5...Paper.

Claims (1)

[Claims] 1. Wrap paper around the end of the winding of a base capacitor obtained by winding metallized films together or a metallized film and a dielectric film around a bobbin, and heat-treat the end face of the base capacitor after applying metallic contact for drawing out electrodes. A method for manufacturing a multilayer capacitor that is cut to form a capacitor element.