JPH021362B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an unpacked film capacitor having a foil-wrapped tab structure.

Conventionally, film capacitors have a foil-wrapped tab structure in which a dielectric film such as polyethylene terephthalate and an electrode foil such as aluminum are alternately overlapped and wound, and a lead wire is drawn out from the electrode foil in the middle of the winding process. The element is heated and pressed into a flat shape, and then impregnated and cured with a thermosetting resin such as epoxy, and then coated and cured.

This impregnation and coating process is as important as winding for a capacitor, and determines the quality of the capacitor, and the impregnation and coating are usually performed in a vacuum. This is to ensure that the impregnation sufficiently penetrates into the element to stabilize its characteristics, and to prevent defects due to the formation of pinholes due to air bubbles and the like.

The present invention proposes a capacitor that does not undergo vacuum impregnation with epoxy resin or vacuum packaging as in the past, and involves winding a dielectric film such as polyethylene terephthalate and an electrode foil such as aluminum foil. In film capacitor elements with a tab structure in which lead wires are drawn out from electrode foil in the middle, thermoplastic resin is coated on both or one side of the dielectric film, and at least on the lead wire lead-out portion on the coated surface, and at the edges. The narrow width is coated with a thermosetting resin in the longitudinal direction, then rolled up and heated and pressed into a flat shape.

In the capacitor according to the present invention, it is possible to obtain a so-called void-free film with good adhesion between the film and the electrode foil, and at the same time, at least the end face on the lead-out side is made strong, so the lead-out strength is increased and the leads are solidified. As a result, moisture absorption from the roots of the reeds is suppressed, resulting in even better moisture resistance. Also,
It is unique in that it utilizes the good moldability of thermoplastic resin and the heat deformation resistance of thermosetting resin to provide a function to protect internal thermal deformation, especially on the lead wire extraction side portion. Of course, it goes without saying that if the thermosetting resin coating is applied not only to the lead wire extraction side but also to other sides, the reliability will be improved accordingly. Further, in order to increase the mechanical strength of the outside of the element, it is desirable to directly wrap the element with the above-mentioned coated film. The base film is made of polyethylene terephthalate, etc., and the thermoplastic resin coated on it can be made of polyolefin, polystyrene, polycarbonate, or other resins, and the thermosetting resin is epoxy. There are also phenolic and phenolic resins, and these resins are
Since the composite dielectric material of film and resin affects the characteristics of the capacitor, a wide range of appropriate dielectric materials can be selected.

In this way, the present invention has good adhesion, is strong at least on the end face on the lead wire side, and is coated with both thermoplastic and thermosetting resins, resulting in pressure resistance, A stable capacitor with good performance such as moisture resistance, heat resistance, and earthquake resistance can be obtained. In addition, since vacuum impregnation and vacuum packaging are not required in the manufacturing process, part of the process is simplified, resulting in a capacitor that is inexpensive to manufacture.

To explain with figures, FIG. 1 is an explanatory diagram of the film of the present invention coated with a thermoplastic resin.
1 is a film, and 4 is a thermoplastic resin surface coated on the film. FIG. 2 is an explanatory diagram of the rolled capacitor of the present invention developed, and 2 is an electrode foil;
3 is a lead wire, and 5 is a thermosetting resin surface coated on 4. Figure 3 shows a film of the present invention coated with thermosetting resin not only on the lead-out side but also on both edges. FIG. 4 is a perspective view of a film capacitor with leads drawn in the same direction according to the present invention, and FIG. 5 is a perspective view of a film capacitor with leads drawn in opposite directions according to the present invention.

As explained above, the present invention enables the production of a film capacitor at a low cost that has excellent performance comparable to that of conventional capacitors, and is of great industrial value.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the film of the present invention coated with a thermoplastic resin, and FIG. 2 is an explanatory diagram of the rolled film capacitor of the present invention developed.
Figure 3 shows another example in which both edges of the film of the present invention are coated with thermosetting resin, and Figure 4 shows
FIG. 5 is a perspective view of a film capacitor with lead wires pulled out in the same direction according to the present invention. FIG. 5 is a perspective view of a film capacitor with lead wires pulled out in opposite directions according to the present invention. 1... Film, 2... Electrode foil, 3... Lead wire, 4... Thermoplastic resin coating surface, 5...
Thermosetting resin coating surface, 6...Film capacitor with lead wires drawn in the same direction, 7...Film capacitor with lead wires drawn in opposite directions.

Claims (1)

[Claims] 1. In a film capacitor element having a tab structure in which a dielectric film and an electrode foil are wound and a lead wire is led out from the electrode foil, both or one side of the dielectric film is coated with a thermoplastic resin, and the coated surface is further coated with a thermoplastic resin. A method for manufacturing a film capacitor, in which a thermosetting resin is coated in the longitudinal direction of the thin strip along the edge at least on the lead wire pull-out side, and then the wound element is heated and pressed into a flat shape.