JPH0395908A - Electrode of smt film capacitor - Google Patents

Abstract

PURPOSE:To obtain strongly fitted electrodes by putting lead frames bent into a V-shape and having narrowed parts in the middle on metallicon electrodes made on winding sides of a film capacitor, and welding them by causing welding currents to flow. CONSTITUTION:Lead frames 3 are bent into V-shape groove by an opening angle within a range of 60 deg.-90 deg. for example, and have narrowed parts 3' in the middle of the two end edges parallel to the bent redgeline. The lead frames 3 are welded onto metallicon electrodes 2 by causing welding currents to flow touching a welding electrode to the ridgeline sections, in a situation that the narrowed parts 3' of the lead frames 3 are parted after the lead frames 3 are put on the metallicon electrodes 2 of a capacitor element 1 formed. As the edge sections of the frames 3 touch the metallicons when the frames 3 are put on the metallicons, because of the high current density at the narrowed parts 3' of the lead frames 3 and the V-shape groove of the frames 3 the current density at these sections is increased, and the temperature of the metallicons is raised quickly to the melting temperature.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to electrodes for SMT7 ilm capacitors.

<Prior art> According to the conventional electrode mounting structure 1 of a wound type capacitor, a plate-shaped terminal piece is brought into contact with the end face of a capacitor element, and a pair of welding electrodes is applied to the terminal piece and energized to connect the terminal piece and the capacitor element. There is a means to weld the end faces. For example, Japanese Patent Application Publication No. 48
-100650 or JP-A-62-183105 or l
See Yojitsu Publication No. 58-120638. The peel tensile strength of the conventional example is shown in the following table.

<Problems to be Solved by the Invention> However, in the above-mentioned example, since the terminal piece attached to the terminal piece of the capacitor element has a flat plate shape, the welding electrode is applied to the terminal piece and welding current is applied. In this case, it is not possible to increase the current density and, therefore, it is not possible to generate enough cold heat in a short time, resulting in poor workability and exposing the capacitor element to high temperature for a long time, which has a negative effect on the capacitor element. was there.

Furthermore, since the terminal pieces are 7 lats, if the end face of the capacitor element is not smooth, it may become a point contact, causing sparks and dielectric breakdown of the capacitor element, or even if the ends of the capacitor element are welded accurately, there may be surface contact. As is clear from the table above, there were drawbacks such as difficulty in exerting sufficient welding strength.

Therefore, the present invention eliminates the drawbacks of the above-mentioned conventional examples and provides an electrode with high mounting strength.

<Means for solving the problem> An electrode bent in a chevron shape and tapered in the middle is welded onto a metal rift electrode formed at the winding end of a film capacitor.

Effect> By passing welding current across the constricted part of the electrode attached to the metal rift electrode, the current density in the constricted part is increased and Joule heat is generated, and the Joule heat causes the electrode to bond with the welding current. Weld the metallikon electrode.

<Example> The present invention will be described in detail below with reference to an example shown in the drawings.As shown in FIG.
A metallicon electrode 2 made of an alloy of tin and zinc is formed in advance on the end surface of the winding, and a lead frame 3 formed as shown in FIG. 3 is placed on the metallicon electrode 2. Install by welding.

Therefore, the most important aspect of the present invention is the shape of the above-mentioned Lee 1'' frame 3, which is bent into a chevron-shaped groove shape with an opening angle θ within the range of 60 to 90 (°), and is bent to the peak of the chevron at this time. The height d of the lead frame 3 is set to 0.8 to 0.9 (m/m) (if it exceeds 1.0, there is a risk of sheet failure), and the middle of the two edges parallel to the bending ridge line of the lead frame 3 is set. 2.1-2.4 (+
N/m)
The dimensions are set so that the constricted portion 3 is approximately 70 to 80 (%) of the volume ratio of the pond portion.

In this case, in the above, Illgate is approximately 3 (m
／鞞）.

Lead frame constructed as described above: Ni: After being left still along the metallic electrode 2 of the formed capacitor element 1, the constricted portion 3 of the lead frame 3 is placed.
゛I! - The lead frame 3 is welded onto the metallic contact wire 2 as shown in FIG. 2 by abutting the welding electrode on the ridgeline part with the welding electrodes separated from each other and applying a welding current. At this time, each lead frame is individually contacted with a welding electrode, and the reference numeral 4 in the figure is a terminal plate.
The structure is such that a capacitor element or the like can be obtained by separating a plurality of base materials at the cutting portion 5.

Next, in order to weld the above-mentioned reel l'' frame 3, a wavy synchronous welding current of 2 to 3 c/s is passed.

The value of the current flowing through the constriction is determined by flowing a current that is 25 to 43 (%) higher than the current flowing through the connection between the welding electrode and the lead frame. Furthermore, as is clear from the time vs. temperature rise characteristic diagram in Figure 4, the lead frame of the present invention has a temperature rise that is extremely steep, whereas the lead frame A, which is shaped like a chevron groove, has an extremely steep rise in temperature. ,
In frame B, the temperature rise is slow, and as a result, the time it takes to reach the melting point MP of the metallicon electrode is at time t earlier than time L2 in lead frame B in lead frame A, which shortens the welding time. at the same time,
The welding work can be completed before the high temperature is transmitted to the pond and causes adverse effects.

The reason why a steep rise in temperature is obtained in this way is that by forming a constricted part 3' in a part of the lead frame 3, a high current density occurs in this part, and that the frame 3 is shaped like a chevron groove. As a result, when the frame 3 is placed opposite to the metallicon, the force f at the edge of the frame 3 comes into contact with the metallicon, so the current density is increased in this part, and it is assumed that the metallicon quickly reaches its melting temperature. It will be done. Furthermore, although the above embodiment illustrates the case where the lead frame is provided in the extending direction of the electrode plate, it can be implemented without any change even if the lead frame is formed parallel to the electrode plate as shown in Fig. 5. .

The electrodes of the capacitor according to the present invention were subjected to a peel tensile strength test, and the results are shown in the following table.

(Effects of the Invention) In the present invention, the lead frame is bent into a chevron groove shape and a constricted part is provided in the middle, so that the current density is increased at the constricted part and the edge part, and the temperature rise rate per hour is improved, allowing metallization to be performed at an early stage. Since the electrode is melted, the time required for welding is shortened, and the work is done in a short time, which reduces heat conduction and prevents thermal damage to other parts.Also, the engine part is welded with it biting into the metal rift. Therefore, as shown in the table, when compared to the value of the conventional example, the strength against separation is 2.9 times higher, and since the lead frame is bent in a chevron shape, the welding electrode acts strongly during welding. It maintains sufficient strength without causing deformation, and unlike conventional surface contact with the uneven surface of the metallcon, it is a line contact, so there is less discharge during welding, and This invention has many excellent and unique effects, such as eliminating the dielectric breakdown of capacitor elements caused by discharge.

[Brief explanation of drawings]

1 to 5 show embodiments of the present invention. Fig. 1 is an exploded perspective view of the main part, Fig. 2 is a perspective view showing the }8 contact state, Fig. 3 is an enlarged partial perspective view of the IJ-}'7 frame, and Fig. 4 is a graph showing time vs. temperature. Figure 5 is an exploded perspective view of the embodiment of the same pond. 1...
・Capacitor element 2...Metallicon 3.31・
...Lead frame, 3'...Neck part 4...Electrode plate

Claims (1)

[Claims] An SMT film characterized in that an electrode is bent into a chevron shape and has a thin constricted part in the middle on a metallicon electrode formed on a wound end face of a film capacitor, and is welded by passing a welding current. capacitor electrodes.