JPS6016090B2 - How to pull out lead wires for plastic film capacitors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for drawing out lead wires from plastic film capacitors used as circuit elements in electronic circuits.

<Conventional technology> As shown in FIG. 1, a conventional capacitor element has a film (dielectric material) constituting the capacitor element 1, and ribbon-shaped metal foils serving as electrodes are attached to both sides of the film (dielectric material). By slightly shifting the metal foils in opposite directions, one side edge of each film is loosely exposed from both sides of the film, and the film is wound. Place the lead wire 3 on the welding electrodes 4, 4' and apply current while applying pressure to perform spot welding, or place the lead wire 3 on the electrodes 2, 2' as described above and separate the electrodes 2, 2'. The contact portion with the lead wire 3 was soldered.

Therefore, the method of drawing out the lead wire by spot welding is as follows:
A lead wire 3 is attached to the end of the laminate made by winding an extremely thin metal foil with a thickness of about 6 millimeters microns, which becomes the element electrodes 2 and 2', and is welded after applying pressure. However, since spot welding is used, the welding range is mainly limited to the area in contact with the welding electrodes, and therefore the welding strength between the element electrodes 2 and 2' and the lead wire 3 is low, and moreover, the strength tends to vary. There were drawbacks. In addition, the surface of the welded part is different due to the difference in capacitance of the capacitor, and as a result, the strength of the welded part is not constant in each case, making it even more difficult to control the quality of the welded part, which can lead to problems with product yield and variations in welded strength. There are performance issues and special consideration is required. In addition, in the case of spot welding, the welding electrode is severely worn out, which is a problem in the mass production process.

In addition to the spot welding described above, there is also a method of soldering, but in this case, at the same time as connecting the lead wire, the end face of the wound metal foil can be widely welded and integrated, improving performance and strength. Although it is possible to do so, the work efficiency is extremely poor, making it difficult to reduce costs.

In order to eliminate these drawbacks of the above example, there is a welding method using arc discharge as shown in FIG.

In this method, after the element constructed in the conventional example is supported by the capacitor holding mechanism 9, the capacitor element 1 is
A movable welding electrode 6 having a holding mechanism for the lead wire 3 is placed opposite to the welding position on the element electrode 2 exposed on the side surface of the electrode 2 by means of moving mechanisms 7 and 8. Another fixed welding electrode 5 is brought into contact at a distant position. When electricity is applied to both welding electrodes 5 and 6 to generate an arc discharge between a predetermined welding portion, that is, between electrode 2 and lead wire 3, the lead wire and electrode 2 become high temperature and melt.

Next, the movable welding electrode 6 that holds the lead wire 3 is moved to the moving mechanism 7.
When the welding power source is cut off while moving in the direction of the arrow by the action of , 8, the lead wire 3 is buried under pressure in the melted and softened electrode 2, and the welding electrode 6 adjusts the shape of the uncured welded part. It is formed as shown in FIG.

In FIG. 3, the welded part 1 and the electrode are completely melted and integrated, and are connected to the lead wire 3 with sufficient strength.

Further, the other end of the capacitor element 1 is also welded by the same method.

In such welding, it is possible to attach the lead wire 3 more strongly than in the conventional method. However, if we look closely at the cross section of the capacitor with the lead wire attached due to the arc discharge, as shown in Figure 4, the lead wire 3 is connected to the metal foil 11 melted by the arc discharge, that is, both the electrode 2 and the lead wire 3. is strongly pressed and embedded in the molten metal (mainly the alloy made of electrode 2) by the movable welding electrode 6 of the lead wire, but since the upper surface of the lead wire 3 is in contact with the welding electrode 6, heat dissipation is prevented. A void 12 is formed in the welded portion to allow for large and rapid cooling.

In this state, as shown in Figure 5, only the lower half of the IJ lead wire 3 is welded, and the welding strength F only covers the diameter of the lead wire, so welding cannot be said to be complete. Ta. <Problems to be Solved by the Invention> An object of the present invention is to solve the above-mentioned problems and to obtain an element in which the bonding strength between the lead wire and the electrode can be maintained sufficiently.

<Means for solving the problem> One fixed welding electrode of the two welding electrodes is brought into direct contact with the element electrode of the wound type capacitor, and the remaining movable welding electrode is placed in direct contact with the element electrode. A concave portion is provided on the surface to be welded, and the lead wire of the capacitor element is held facing the surface of the movable welding electrode across the concave portion without touching the electrode of the element, and then a constant voltage is applied between both the welding electrodes. As a result, the movable welding electrode is moved while causing an arc discharge between the movable welding electrode and the IJ lead wire, and when the lead wire comes into pressure contact with the electrode of the element, the discharge is stopped and welding is performed. Become.

<Function> By causing an arc discharge between the electrode exposed at the side end of the capacitor element and the wire held oppositely by a welded electrode at a certain distance above the electrode, the The heat generated melts both the lead wire and the electrode of the capacitor facing it, so the welding electrode is pressed against the electrode surface of the capacitor in this state and the power is cut off.

At this time, since the welding electrode has a recessed part, the metal melting area extends to the outside of the lead wire because there is less heat dissipation due to heat conduction, and the area of integration is widened and the strength is improved. <Embodiment> The embodiment of the present invention shown in FIGS. 6a, b, and c will be described in detail below. The lead wire 3 is attached to a part of the surface facing the element electrode of the movable welding electrode 6 that holds the lead wire. A recessed portion 13 having a dimension determined in proportion to the thickness of the recessed portion 13 is provided.

That is, a hemispherical depression 13 having a diameter A proportional to the thickness D of the lead wire is provided on the lower end surface 15 of the welding electrode 6 near the chuck portions 14 and 16 of the lead wire 3.

In this case, the most ideal range of A is 1. Mark~3. The proof that the mark is good is tied up.

Then, the lead wire 3 is held between the chuck parts 14 and 16 of the movable welding electrode 6 and made to face the electrode of the capacitor, and the other fixed welding electrode 5 is connected to the electrode 2 of the capacitor.
When the lead wire 3 and the electrode of the capacitor are connected to each other and current is applied for about 20 milliseconds, the arc generation time is about 8
When the two are brought close to each other while local heating is performed for milliseconds, the lead wire 3 is pressed against the welded part at the lower end surface 15 of the welding electrode 6, and is gradually embedded in the electrode part of the capacitor.

At this time, the cable wire 3 held on the lower surface of the movable welding electrode 6
Since there is a space around the lead wire 3 due to the recessed part 13, the metal melted by the arc discharge swells up to wrap around the entire circumference of the lead wire 3, and has a sufficient aging effect to ensure weld strength. Cool and solidify.

Therefore, the result of the above welding is as shown in Fig. 7, where the molten metal 11, in which the capacitor electrode 2 and the lead wire 3 are fused, completely wraps around the lead wire 3 and reaches the surrounding area in a gentle curve. .

Therefore, in this case, as shown in Figure 8, the distribution area of the weld strength F is much wider than in the conventional method, which not only improves the absolute value of the melt strength, but also reduces the variation, dramatically improving the quality. improves.

Moreover, FIG. 9 shows the electrode part of a capacitor obtained by demonstrating the method of the present invention, and the raised part 17 of welding is
It is desirable to provide the lead wire 3 of the capacitor element 1 at a portion where the strength is most required. Furthermore, Figure 6a
, b, c at the lower end surface 15 of the electrode 6.
Similar to the conventional product, no swelling occurs in the parts that do not face 3.

<Effects of the Invention> When a lead wire is attached by the method of the present invention, stable strength can be obtained for all possible combinations, such as changing the shape depending on the capacitance of the capacitor and the thickness of the lead wire.

In addition, it eliminates the occurrence of burrs due to the scattering of molten metal, and since the electrode surface of the capacitor is melted and integrated over a wide range, it has many excellent effects, such as further improving the nonconducting characteristics.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a device formed by conventional spot welding, Fig. 2 is a front view of a device formed by conventional arc welding, Fig. 3 is a perspective view of an element formed by conventional arc welding, and Fig. 4 is a part of the same as above. FIG. 5 is a partially enlarged view of the same as above; FIG. 6a is an enlarged side view of the welding electrode used in carrying out the method of the present invention; FIG. 6b is an enlarged perspective view of the recessed portion; FIG. FIG. 8 is a partially enlarged view of FIG. 7, and FIG. 9 is a perspective view of a capacitor element formed by the method of the present invention. 1... Capacitor, 2,2'... Electrode,
3... Lead wire, 5, 6... Welding electrode, 13... Recessed part. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 (0) Figure 6 (01 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] 1 One fixed welding electrode of the two welding electrodes is brought into direct contact with the element electrode of the wound capacitor, and the remaining one
A recessed portion is provided on a surface of each of the two movable welding electrodes facing the element electrode, and the lead wire of the capacitor element is held facing the surface of the movable welding electrode by straddling the recessed portion without touching the element electrode; By applying a constant voltage between both welding electrodes, arc discharge is caused between the movable welding electrode and the lead wire, and the movable welding electrode is moved together with the lead wire toward the element electrode surface. A method for drawing out a lead wire for a film capacitor, characterized in that the discharge is canceled when the wire comes into pressure contact with the element electrode surface, and a gentle bulge is formed on the outside of the lead wire corresponding to the depression.