JP2002299150A - Electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of the irregularity being easily generated in a contact resistance and an applied pressure in the tip shape of an unworked lead wire, when the lead wire is resistance-welded to a metal film formed on a substrate and that the diameter of the lead wire requires a special working operation, when an electronic component is to be miniaturized. SOLUTION: The tip of the lead wire is worked, in advance to be spherical by electrical discharging operation. Even when the contact resistance of the lead wire bumped to the metal film or its bumped angle is deviated from 90 deg. with respect to the surface of the metal film, the contact resistance, and the applied pressure are stabilized because the tip is spherical.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component for connecting a substrate and a lead wire via a metal film, and more particularly to a method of forming a tip of a lead wire into a spherical shape by electric discharge in advance and then performing resistance welding to the metal film. Things.

[0002]

2. Description of the Related Art When a conventional electronic component is used in a high temperature environment of 300 ° C. or more in a radial component, the heat resistance cannot be satisfied by soldering. Therefore, a method of resistance welding a lead wire to a metal film deposited on a substrate is used. There is. In this case, when two welding electrodes are applied to the lead wire and a current is applied while pressing the lead wire on the surface of the metal film, Joule heat is generated due to contact resistance between the metal film and the lead wire. The lead wire and a part of the metal film are welded by the Joule heat to form an alloy layer.

Therefore, in order to improve the reliability of resistance welding, it is desirable to keep the contact resistance between the metal film and the lead wire constant and to keep the pressure of the lead wire against the surface of the metal film constant.

In addition, since two welding electrodes must be applied to the side surfaces of the lead wires, the lead wires must be horizontal with respect to the substrate. Therefore, the lead wire must be L-shaped in advance or the lead wire must be bent after welding.

[0005]

In the conventional processing, since the metal film and the lead wire must be welded horizontally, the lead wire must be L-shaped in advance or the lead wire must be bent after welding. L-shaped processing of a lead wire is an obstacle to miniaturization of components, and processing of a lead wire after welding lowers the reliability of a joint.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a radial component used in a high-temperature environment of 300 ° C. or higher, in which when a metal film and a lead wire are welded, the tip of the lead wire is previously formed into a spherical shape by electric discharge. Since this can be perpendicularly welded to the metal film while chucking it with the positive and negative electrodes, the processing accuracy is increased.

When a lead wire is connected to a metal film, the tip of the lead wire is formed into a spherical shape by electric discharge in advance, so that not only the contact resistance is stabilized, but also the contact angle deviates from 90 degrees with respect to the metal film surface. However, since the tip is spherical, the contact resistance and pressure are stable. Therefore, stable welding strength can be obtained.

[0008]

The present invention has been made as a result of the finding that the spherical portion formed at the tip of the lead is reliably brought into contact with the metal film and can be welded with stable contact resistance.

[0009]

FIG. 1 is a diagram showing an embodiment of the present invention. At the tip of the lead wire 3 on the electrode of the substrate, a spherical portion 1.5 to 2 times the wire diameter is formed by discharge. Next, the tip of the lead wire was pressed against the surface of the metal film 2 deposited on the substrate 1 while applying pressure and resistance welding was performed by applying a current.

[0010]

As described above, according to the present invention, a stable welding strength can be easily obtained by forming the tip of the lead wire into a spherical shape in advance and performing resistance welding.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Metal film 3 Lead wire

Claims (2)

[Claims] When a lead wire is connected to a substrate via a metal film, the tip of the lead wire is previously processed into a spherical shape by electric discharge,
Electronic components resistance welded to a metal film. 2. The radial electronic component according to claim 1, wherein a lead wire is connected to the metal film in a vertical direction.