JPH08138822A - Ultrasonic welding method - Google Patents

Abstract

PURPOSE: To obtain a ultrasonic welding method for damage reduction of a welded material and for improvement in joint strength. CONSTITUTION: After a copper powder 17 is provided in advance on a weld surface 16 of electric conductors 11 and 12 made of copper wires to be joined with each other, ultrasonic vibration energy is applied with a specified pressure. Thereby, ultrasonic welding is performed, and wire conductors 11 and 12 are joined with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for ultrasonically bonding various electric wires used in consumer electronic devices, automobiles and other industrial devices.

[0002]

2. Description of the Related Art Conventionally, in ultrasonic welding between metals, as shown in FIG. 2, in a state in which a predetermined pressure is applied to materials to be welded 1 and 2 such as electric wire conductors which are joined to each other,
By applying ultrasonic vibration energy, the materials to be welded 1 and 2 are joined together by sliding them at high energy.

Further, the contaminated coatings 3 and 4 such as oils and fats and oxide coatings are usually attached to the surfaces of the materials 1 and 2 to be welded. For this reason, the contaminated coatings 3 and 4 greatly contaminate the surface. In the case of the welding materials 1 and 2, the welding pressure, amplitude, time, etc. at the time of ultrasonic welding are increased to increase the energy for sliding between the materials 1 and 2 to be welded, and to increase the mechanical or frictional heat force. As a result, welding was performed while removing the contaminated coatings 3 and 4.

[0004]

However, according to the conventional method of increasing the pressing force, the amplitude, the time, etc. during the ultrasonic welding, the material to be welded is excessively increased by the pressing force, the amplitude, the time, etc. There is a drawback in that the deformation of the materials 1 and 2 itself is also increased, the damage to the materials 1 and 2 to be welded is increased, and as a result, the tensile strength of the welded portion is reduced.

Further, when the contaminated coatings 3 and 4 are removed by the pretreatment, the oxide coating cannot be removed only by the organic solvent, and in the case of acid cleaning, washing and drying are required, which is a problem. . Furthermore, there is a concern that the materials to be welded 1 and 2 themselves may be damaged by mechanical polishing.

In view of the above problems, it is therefore an object of the present invention to provide an ultrasonic bonding method for reducing the damage to the materials to be welded and improving the bonding strength.

[0007]

The technical means for achieving the above object is to apply ultrasonic vibration energy to a material to be welded made of metal materials to be bonded to each other under a pressurized condition. In the ultrasonic welding method of welding and joining the materials to be welded to each other, ultrasonic welding is performed after the metal powder is preliminarily interposed at the welding interface of the materials to be welded to be welded to each other.

Further, the metal powder may be the same kind of metal as the material to be welded, a metal having a hardness harder than the material to be welded, or a metal having a small standard potential difference with respect to the material to be welded.

[0009]

According to the present invention, at the initial stage of ultrasonic welding, the metal intervening at the weld interface due to the sliding force between the workpieces due to the pressing force acting on the workpiece and ultrasonic vibration energy. Since the powder breaks through the contaminated film adhering to the surface of the material to be welded and easily breaks, it is possible to easily join metals through the metal powder.

Therefore, even when the surface of the material to be welded is highly contaminated, the pressure, amplitude, and
It is not necessary to excessively increase the time, etc., and it is possible to reduce the damage to the materials to be welded and improve the joint strength.

When the metal powder is the same metal as the material to be welded, no problem occurs in the joined state.

Further, when the metal powder has a hardness higher than that of the material to be welded, the effect of removing the contaminated film is further improved.

Further, when the metal powder is a metal having a small standard potential difference with respect to the material to be welded, there is little potential difference with the material to be welded, and there is an effect of preventing corrosion.

[0014]

Embodiments of the present invention will now be described with reference to the drawings. In FIG. 1, 11 and 12 are electric wire conductors made of copper wires to be welded to each other, the surface of which is oil or grease. Contaminated coatings 13, 14 such as oxide coatings are present.

When performing ultrasonic welding, copper powder 17 as a metal powder is applied to the welding interface 16 of both wire conductors 11 and 12 by coating or the like, and then a predetermined pressing force is applied. , By applying ultrasonic vibration energy, they slide with each other at high energy.

In this case, the copper powder 17 present at the welding interface 16 is applied to the wire conductors 11 and 12 due to the pressing force applied to the wire conductors 11 and 12 and the sliding between the wire conductors 11 and 12.
Since the contaminated coatings 13 and 14 on the surface are pierced and easily destroyed, the electric conductors 11 and 12 can be joined to each other through the copper powder 17.

Therefore, even if the degree of contamination by the contaminated coatings 13 and 14 is large, the joining of metals can be easily obtained, so that the conditions such as the pressing force, the amplitude, and the time during ultrasonic welding are excessively increased. No need for wire conductor 11,
The damage of 12 can be reduced, and a good joining state of the metals can be obtained, and the joining strength between the electric wire conductors 11 and 12 can be improved.

In addition, each wire conductor 11 and 1 as metal powder
Since the copper powder 17 made of the same metal as 2 is used,
In the joined state, each wire conductor 11, 12 and the copper powder 17
There is no potential difference between them, there is no risk of adverse effects such as corrosion, and no trouble occurs.

In the above embodiments, the wire conductors 11 and 12 made of copper wire are shown as the material to be welded, but copper alloy, aluminum, iron alloy and other metals and alloy materials used for electric wires and electric circuits, etc. May be

Further, although the case where the same kind of metal powder as the material to be welded is used as the metal powder is shown, powder of a metal or alloy having a hardness higher than that of the material to be welded may be used. In this case, the contaminated coating 13, 1 made of metal powder
The removal effect of 4 is further improved. For example, when the material to be welded is copper, there is a copper alloy (for example, phosphor bronze, nickel silver, etc.) as the metal powder, and when the material to be welded is iron, there is nickel as the metal powder. If the material is aluminum,
Aluminum powder is an example of the metal powder.

On the other hand, the material to be welded (for example, the micro hardness 8
When powder of a metal or alloy (such as tin, solder or high-purity aluminum) whose hardness is softer than that of the wire conductors 11 and 12 of 0 to 100 Hv is used, the powder itself is easily deformed and spread. However, there is a drawback in that not only the effect of removing the contaminated coatings 13 and 14 is not obtained, but also the joining of the materials to be welded is hindered.

As the metal powder, the standard potential difference is small with respect to the material to be welded (preferably the potential difference is 0.2 V or less).
Powders of metals or alloys may be used. In this case, there is not much potential difference between the material to be welded and the metal of the metal powder, and it is possible to effectively prevent corrosion in a high humidity or water drop adhesion environment.

On the other hand, the use of metal powder (for example, nickel or copper) having a large standard potential difference with respect to the material to be welded (for example, aluminum) has a disadvantage that corrosion is promoted due to the mutual potential difference. is there.

As a concrete example of the present invention, for example, six electric wires each having a total cross-sectional area of 0.5 mm ² of a copper wire covered with a contaminated film such as oil and fat, an oxide film, etc. 1
In ultrasonic welding under the welding conditions of 000 N, amplitude of 35 μm, electric power of 1000 w, and time of 0.54 seconds, the conventional method had a tear strength of 27 N at the joint, but before welding, According to the method of the present invention in which copper powder is adhered to each wire, the tear strength of the joint portion is 34 N, and the tear strength is improved by about 26%.

Further, five electric wires each having a total cross-sectional area of 1.25 mm ² of copper wires covered with a contaminated film such as oil and fat or an oxide film were used, and the applied pressure was 1200 N, the amplitude was 45 μm, and the electric power was 1500 w. In the ultrasonic welding under the welding condition of 0.85 seconds in time, the conventional method had a tear strength of 50.3 N at the joint, but before welding, copper powder of 200 mesh was applied to each wire. According to the method of the present invention performed in the adhered state, the tear strength of the joint portion was 76.2 N, and the tear strength was improved by about 51%.

[0026]

As described above, according to the ultrasonic welding method of the present invention, after the metal powder is preliminarily interposed at the welding interface of the materials to be welded to each other, ultrasonic vibration energy is applied under pressure. It is a method of performing ultrasonic welding by joining and joining the materials to be welded together.Contaminating films such as fats and oxides that adhere to the surface of the materials to be welded are easily destroyed by the metal powder, and the joining of metals is done. It is easy to obtain, and it is not necessary to excessively increase the welding conditions even for a material to be welded with a large amount of surface contamination, and there is an advantage that damage to the material to be welded can be reduced and joint strength can be improved.

Further, when the metal powder is the same kind of metal as the material to be welded, there is an advantage that no trouble occurs in the joined state.

Further, when the metal powder has a hardness higher than that of the material to be welded, there is an advantage that the effect of removing the contaminated film is further improved.

Furthermore, in the case where the metal powder is a metal having a small standard potential difference with respect to the material to be welded, there is an advantage that there is not much potential difference between the metal powder and the material to be welded and there is a corrosion prevention effect.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an embodiment of the present invention.

FIG. 2 is a schematic explanatory view showing a conventional example.

[Explanation of symbols]

 11 Electric Wire Conductor 12 Electric Wire Conductor 13 Contamination Coating 14 Contamination Coating 16 Welding Interface 17 Copper Powder

Claims (4)

[Claims] 1. An ultrasonic bonding method for bonding ultrasonic welding energy to a material to be welded made of a metal material to be welded to each other under a pressure condition to weld the materials to be welded to each other. An ultrasonic welding method, characterized in that ultrasonic welding is performed after interposing metal powder in advance at a welding interface of materials to be welded to each other. 2. The ultrasonic bonding method according to claim 1, wherein the metal powder is the same kind of metal as the material to be welded. 3. The ultrasonic bonding method according to claim 1, wherein the metal powder is made of a metal having a hardness harder than that of the material to be welded. 4. The ultrasonic bonding method according to claim 1, wherein the metal powder is made of a metal having a small standard potential difference with respect to a material to be welded.