JPH0519942Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a so-called film capacitor using a metallized plastic film, and particularly to a small chip-type capacitor without an exterior.

[Conventional technology]

Usually, film capacitors are of the type in which the metal vapor deposited portion of the wound body is sprayed with metal (metallicon), and then the leads are taken out and resin-dipped or resin-molded.

[Problem that the invention attempts to solve]

In recent years, as integrated circuits have progressed, demands for miniaturization of electronic components have become stricter. A leadless chip structure is preferred as a type that is small and suitable for integrated circuits. To achieve this, it is sufficient to eliminate the exterior and provide a structure in which the terminals are provided directly on the wound body.

As a countermeasure to the above, two of the present inventors proposed a capacitor having the structure shown in FIG. 3a in Utility Model Application No. 61-91954. This capacitor (hereinafter referred to as a conventional example) has electrode terminals 2 directly provided at both ends of the winding end of a flat wound body 1 of metallized plastic film in contact with metal vapor deposited parts. This capacitor is manufactured by the process shown in FIG. 3b. A flat rolled body 1 formed by winding and pressing a metallized plastic film is masked with a masking tape 3 except for the winding end, and a high melting point metal is sprayed to form an electrode part 4. Next, after impregnating with resin, the resin on the electrode part 4 is removed by brushing, and then the electrode part 4 is plated in a plating solution to form the electrode terminal 2, thereby completing the electrode terminal 2.

Although the above-mentioned capacitor is the smallest form of a film capacitor, it has the following problems when soldered to the land of a printed circuit board. In the step shown in FIG. 3b, since masking is performed in close contact with the flat surface, the electrode portion 4 formed at the winding end is formed inside the periphery of the winding end. Therefore,
As shown in Figure 4b, the finished product is attached to the printed circuit board 5.
When soldering to the capacitor, the capacitor is mainly supported with its flat surface in contact with the printed circuit board 5, and a gap is likely to be formed between the land 6 and the electrode terminal 2 of the capacitor. In particular, the surface of the wound body 1 is uneven due to resin impregnation, and when flattened by applying pressure, the flat surface may have a curvature, so that the gap in the electrode terminal 2 becomes significant.

In this way, if there is a gap between the land 6 of the printed circuit board 5 and the electrode terminal 2 of the capacitor and they are not in direct contact with each other, the solder may get to the bottom of the capacitor during the soldering process, causing the solder to contact the electrode terminal 2. is not performed well, resulting in poor yield.

An object of the present invention is to provide a chip-type film capacitor which has been structurally improved so as to eliminate the above-mentioned drawbacks and improve solderability to a printed circuit board.

[Means for solving problems]

The chip-type film capacitor of the present invention consists of a metal vapor-deposited portion at the end of the winding end of a flat wound body of metallized plastic film (including a wound body cut into a rectangular or cubic shape in the direction of the winding axis). A capacitor element having a plate-shaped electrode portion formed by thermally spraying a high melting point metal in contact with the capacitor element, the electrode portion protruding from at least one oblique plane of the wound body, is immersed in a plating solution after resin impregnation treatment. , the electrode portion is plated to serve as an electrode terminal of the device.

[Effect]

When this capacitor is mounted on a printed circuit board, as shown in FIG. Since they are in direct contact, there is no problem mentioned above and the solderability is good.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. FIG. 1a is a perspective view of the embodiment, in which plate-shaped (rectangular in this example) electrode terminals 11 are provided at both ends of the wound body 1. There is a height difference l between the lower end of the electrode terminal 11 and the flat surface of the wound body 1. Even if l is about 0.1 mm, the purpose of the present invention can be met. Further, in the embodiment shown in FIG. 1A, the electrode terminals 11 protrude from both flat surfaces of the wound body 1, but they may protrude from one flat surface. Moreover, instead of being square, it may have a shape with curvature on both sides as shown in FIG. 1b.

The manufacturing process of the above embodiment will be explained. First, a roll of metallized plastic film is pressed,
The rolled body 1 has a flat shape. A high-melting point metal is thermally sprayed in contact with the metal vapor deposited portions appearing at each end of the winding opening to form a plate-shaped electrode portion 10 (in FIG. 1, this portion is plated to form an electrode terminal 11). At this time, a jig is used so that the spray can be applied only to the end of the roll. FIG. 2a is an exploded perspective view of the jig, showing a frame 12a that presses and holds the rolled body 1;
12b, and frames 13a, 13b overlapping the ends of frames 12a, 12b are shown.
FIG. 2b is an enlarged cross-sectional view showing the state in which the jig is used.
2b and fix the rolled body 1, and then overlap the ends on the frames 12a and 12b to fix the frame 1.
Combine 3a and 13b. At this time, the distance l between the peripheral edge of the wound body 1 and the inner edges of the frames 13a and 13b is selected so as to provide a gap between the electrode terminal 11 of the completed product and the flat surface of the wound body 1.

With the wound body 1 inserted and held in the jig, a high melting point metal is thermally sprayed. As the high melting point metal, for example, Zn and a high melting point solder alloy are thermally sprayed in this order. Once the thermal spraying on one end is completed, the frames 13a, 13b
The other end is then removed and the other end is thermally sprayed. In this way, the plate-shaped electrode part 10
The capacitor element with the formed capacitor element is immersed in a low-viscosity thermosetting resin, impregnated under reduced pressure, and then taken out, and the excess resin adhering to the element surface is removed and hardened. Next, the resin of the electrode parts 10 at both ends is brushed to expose the metal surfaces, and then the plating process is performed. Plating is an electrolytic barrel plating process in which solder, silver, or tin plating is applied to a copper or nickel base. In this way, the film capacitor shown in FIG. 1 is completed, in which the electrode portion is the terminal portion itself and is not packaged.

The present invention is intended to improve the solderability of a capacitor to a printed circuit board as described in the conventional Utility Model Application No. 61-91954. In order to verify the degree of improvement, we used a sample according to the present invention and a conventional sample with a flat area of 4.5 mm x 6.5 mm and a height of 2.3 mm.
A 0.22μF (50V rating) chip-type film capacitor is used as a printed circuit board with a land size of 3.0mm x 2.5mm.
It was mounted using solder reflow at a peak temperature of 220°C. According to visual soldering inspection, there were 0 out of 40 defective products in the inventive sample and 3 out of 40 in the conventional sample.

In the embodiments described above, capacitors were fabricated from individual turns of metallized plastic film. As a modified embodiment, it can be manufactured by cutting out a rectangular cubic shape in the direction of the winding axis from a wide winding body. In this case, a plurality of laminates can be obtained, but since a metal short circuit occurs on the cut surface of the film inside the wound body by cutting, a DC voltage is applied to the metal vapor deposited parts at both ends to blow off the metal at the short-circuited part. It is necessary to keep it.

[Effect of idea]

As explained in detail above, the capacitor of the present invention has the same advantages as conventional products as follows. That is, since it does not have an exterior and the electrode portion directly serves as a terminal portion, it is the smallest film capacitor and the cost is also the lowest.

Although there is no exterior, the resin impregnation treatment ensures moisture resistance. Although plating is performed by immersing the element in a plating liquid, since the resin impregnation process is performed, the plating liquid does not enter the inside of the element, and there is no deterioration in insulation due to this. In addition, since the electrode part has a sprayed metal layer of a high-melting point metal with a melting point of 270°C or higher, the reliability of the element will not deteriorate under both reflow and flow soldering conditions when attached to a printed circuit board.

Furthermore, as a difference from conventional products, the electrode part is formed by thermal spraying, is plate-shaped, and has a part that is in contact with the winding end of the winding body and protrudes from at least one oblique plane thereof. For this reason, when mounting a capacitor between the lands of a printed circuit board, the electrode terminals (terminals are formed by processing the plating that is easy to solder on the electrode parts) directly contact the lands, and the wound body and the printed circuit board are in direct contact with each other. Not in contact. Therefore, the solder does not flow into the element and has good solderability.

[Brief explanation of drawings]

Fig. 1 is a perspective view of an embodiment of the present invention, Fig. 2 is a perspective view of a jig used for metallization to form an electrode part, and a sectional view of the jig in use, and Fig. 3 shows the element shape and manufacturing process of a conventional example. 4 are diagrams showing the embodiment and the conventional example arranged on a printed circuit board. 1... Winding body, 10... Electrode portion, 11... Electrode terminal, 12a, 12b, 13a, 13b... Frame of jig.

Claims (1)

[Scope of Claim for Utility Model Registration] Metal vapor-deposited portion at the winding end of a flat wound body of metallized plastic film (including a flat wound body cut out into a rectangular or cubic shape in the direction of the winding axis) A chip-type film capacitor in which a plate-shaped electrode portion protruding from at least one flat surface of the wound body is formed by thermal spraying and plating with a high-melting point metal in contact with the flat wound body, A chip-type film capacitor characterized by having a resin-impregnated layer formed before treatment.