JPH061749B2 - Film capacitor manufacturing method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a film capacitor having a metallized film as a dielectric, and more particularly to a method of drawing external electrodes.

2. Description of the Related Art In recent years, the development of small and highly reliable electronic components has been remarkable. In particular, precision welding technology has come to be positioned as an important processing technology in the development of electronic parts.

In a film capacitor, after winding or laminating a metallized film, a conductive layer is formed by metal spraying on both edge portions where the opposing internal electrodes (usually a metal vapor deposition film) extend, and the conductive layer is provided with external electrodes. A method of manufacturing a film capacitor, which is obtained by resistance welding a lead wire or a lead frame to be formed and, if necessary, applying an outer package, is known.

Hereinafter, with reference to the drawings, a conventional film capacitor and a method of drawing out external electrodes will be described by taking a laminated film capacitor as a representative.

However, the same applies to the wound film capacitor.

FIG. 3 is an enlarged view of a part of a cut surface of a conventional laminated film capacitor, showing its configuration. In FIG. 3, 1 is a dielectric film, 2 and 3 are dielectric films 1.
The internal electrode 4 deposited on the insulating layer 4 is an insulating part for insulating the internal electrodes 2 and 3, 5 is a protective film, and 6 is a conductive layer obtained by metal spraying.

FIG. 4 is a perspective view at the time of drawing out external electrodes in the conventional laminated film capacitor. In FIG. 4, 6
Is a conductive layer and has the same structure as in FIG. Reference numeral 7 is an external electrode, and 8 is a resistance welding electrode tip for welding the conductive layer 6 and the external electrode 7.

The external electrode extraction method of the conventional film capacitor is
As shown in FIG. 4, the conductive layer 6 and the external electrode 7 are energized while being adhered and pressed by the resistance welding electrode tip 8 to make the conductive layer 6
A method (resistance welding method) of welding the external electrode 7 is adopted.

Problems to be Solved by the Invention However, in the method as described above, as can be seen from FIGS. 3 and 4, the weakest point regarding the stability of the bonding state between the internal electrodes 2, 3 and the conductive layer 6 is: Usually, it is experimentally clear that there is mechanical damage due to the pressure applied during welding and thermal damage due to the heat generated during welding. The mechanical and thermal damage during welding applied to the joint part is It has been known that the dielectric loss tangent characteristic of (3) is deteriorated and the capacitance of the capacitor fluctuates in some cases.

Conventionally, as a means for reducing the damage at the time of welding, a thick dielectric film has been used and the number of protective films has been increased. Has become an obstacle. In addition, welding burrs during welding are also obstacles to the production of small film capacitors.

In view of the above problems, the present invention provides a method for drawing out an external electrode of a film capacitor, which does not cause damage to the film capacitor element during welding and generation of welding burrs.

Means for Solving the Problems In order to achieve this object, the method for producing a film capacitor element of the present invention is a method of temporarily welding a conductive layer of a film capacitor element and an external electrode by resistance welding, and then applying a laser beam. The external electrode is welded to the conductive layer of the film capacitor element by melting the conductive layer and the external electrode.

When the external electrode is brought into contact with the conductive layer of the working film capacitor and the resistance welding electrode tip pressurizes the external electrode to energize it,
The conductive layer and the external electrode are welded to each other due to resistance heating at the contact portion between the conductive layer and the external electrode. In this case, the applied pressure, applied current,
Energization time is related to welding strength and welding quality.

On the other hand, when the external electrode is brought into contact with the conductive layer and irradiated with a laser beam, the conductive layer and the external electrode are melted by the heat generated by the absorption of the laser beam. In this case, the contact state between the conductive layer and the external electrode is related to laser welding strength and laser welding quality.

In the present invention, first, the resistance welding electrode tip is about (200 g or less) necessary for the external electrode to contact the conductive layer,
The external electrode is pressurized and energized. At this time, the applied current and the applied time may be such that the external electrode is slightly welded to the conductive layer (the tensile shear strength is 500 g or less).

Next, when a laser beam is applied to the part where the conductive layer and the external electrode are temporarily welded, the part irradiated with the laser beam locally generates heat, and the conductive layer and the external electrode are melted. As a result, the welding of the external electrodes without damage to the film capacitor element and welding burrs is completed.

Embodiment One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing components when carrying out the method of the present invention. In FIG. 1, 6 is a conductive layer, 7 is an external electrode, 8 is a resistance welding electrode tip, and the above is the same as the configuration of FIG. 9 is a laser generator, 10 is an optical system,
Reference numeral 11 is a laser beam. The operation of the elements configured as described above will be described below.

First, in the resistance welding electrode tip 8, the external electrode 7 is the conductive layer 6
The external electrode 7 is pressurized and energized with a small force such that it contacts the.

Next, after the resistance welding electrode tip 8 is retracted, the laser beam 11 generated by the laser generator 9 passes through the optical system 10 and scans the range where the external electrode 7 is temporarily welded to the conductive layer 6. At this time, if the focused diameter of the laser beam 11 is larger than the welding range, scanning may not be performed.

Further, FIG. 2 is a diagram in which a part of the resistance welding electrode tip is in contact with the external electrode outside the contact range of the conductive layer and the external electrode, and all the constituent elements are the same as those in FIG. This is a method in which the external electrodes can be welded to a smaller film capacitor than the case shown in FIG. 1, which is more effective than the case shown in FIG.

As described above, according to the present embodiment, after the conductive layer and the external electrode are provisionally welded by the resistance welding method, the welding is performed by using the laser beam, so that the damage to the film capacitor element at the time of welding and the melting External electrodes can be welded without burr formation.

The laser beam in the present invention can be selected from YAG laser and Co ₂ laser for use. The selection of the laser depends on the combination of metals to be welded. For example, if the conductive material is zinc,
If the external electrode material is copper-based metal, multi-mode YA
G or Co ₂ lasers can be used.

In this case, the laser is selected so that the energy density of the laser beam is less than the evaporation energy density of the metal to be welded,
This can be done from the viewpoint that the distribution state is flat.

As described above, according to the present invention, after pre-welding the external electrode to the conductive layer by the resistance welding method, laser welding is performed, thereby causing damage at the time of welding to the film capacitor element and occurrence of welding burrs. Without the need to weld external electrodes,
Its practical effect is enormous.

[Brief description of drawings]

FIG. 1 is a block diagram showing the components of the essential part of the manufacturing method in one embodiment of the present invention, and FIG. 2 is another embodiment of the present invention in which a part of the resistance welding electrode tip is a conductive layer and an external electrode. Fig. 3 is a sectional view showing a state of being in contact with an external electrode outside the contact range of Fig. 3, Fig. 3 is a cross-sectional view showing the configuration by enlarging a part of a cut surface of a conventional film capacitor, and Fig. 4 is a conventional film capacitor. FIG. 7 is a perspective view showing a state when the external electrode is drawn out in FIG. 6 ... Conductive layer, 7 ... External electrode, 8 ... Resistance welding electrode tip, 9 ... Laser generator, 10 ... Optical system, 11 ...
… Laser light.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location H01G 4/30 311 E 8019-5E (72) Inventor Yuji Uesugi 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-55-102221 (JP, A) JP-A-55-58517 (JP, A) JP-A-57-49217 (JP, A) JP-A-60-148691 (JP, A)

Claims (1)

[Claims] 1. When connecting an external electrode to the conductive layer of a film capacitor element having conductive layers formed on both end surfaces, a laser is used after temporarily welding the conductive layer of the film capacitor element and the external electrode by resistance welding. A method of manufacturing a film capacitor, characterized in that the conductive layer and the external electrode are melted by using light.