JPH08321331A - Method of joining electric wires - Google Patents

Abstract

PURPOSE: To get favorable metallic junction having the electric wires clearable of pollution and low in contact resistance. CONSTITUTION: The metallic powder 3 of any one of copper, nickel, tungsten, and molybdenum 70-200mesh in grain diameter being the hard conductive powder harder than soft copper is applied in advance onto pressure bonding part of a cable, before pressure-bonding the pressure bonding part of the cable 2 composed of a plurality of element wires 1 consisting soft copper by means of a crimp-style terminal, and then the crimp-style terminal is pressure-bonded by a pressure bonder. Accordingly, since the metallic powder 3 bites in the element wire 1 at the time of pressure bonding, and the polluted film 4 on the surface of the cable 2 is broken, stable polluted film removal effect and excellent performance reproducibility at mass production can be obtained. Moreover the pressure at pressure bonding concentrates on the metallic powder 3, and even with low pressure, the metallic powder 3 bites in the element wire 1 enough, so even in case that quenching shock, mechanical vibration, or the like adds to the crimp-style terminal or the cable, favorable electric connection can be kept.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric wire joining method for crimping a crimp portion of an electric wire composed of a plurality of wires with a crimp terminal.

[0002]

2. Description of the Related Art In recent years, the performance of automobiles and general industrial equipment has been improved, which is considered to be the result of the application of various sensors. Along with this, the number of signal circuits for passing minute voltages and currents has increased, and the processing capability of the CPU for processing the information of these signal circuits to control the system has also improved.

However, when the number of parts handling such minute voltages and currents increases, the contact resistance and instantaneous interruption of the connection parts of electric wires and the like, which have not been a problem in the past, are greatly increased, which is why In addition to the conventional crimping method, ultrasonic welding method and resistance welding method have begun to be used as a method for joining electric wires, and tin-plated electric wires have been used in the conventional mechanical crimping method.

[0004]

However, in the case of welding,
Tear strength is lower than mechanical crimping, so it is necessary to devise a method to protect the welded part. Furthermore, if the wire is thin, there is a problem that the damage during welding is large and the mechanical strength of the welded part is reduced. .

In addition to the natural oxide film on the surface of the electric wire, there are some organic compound coatings such as plasticizers and lubricants that are attached when the vinyl chloride or the like is coated and extruded. An organic film is formed on the surface of the electric wire. In order to eliminate the adverse effects of these contaminated coatings (oxide coating + organic coating), a plurality of grooves are formed on the inner surface of the crimp terminal in the direction orthogonal to the direction of the wire to form protrusions called serrations. It is considered to break through the contaminated film by serration to remove the contamination of the electric wire and to obtain good metal joining, but in this case, the edges of the serration become gentle with the abrasion of the molding die of the crimp terminal, The effect of breaking through the contaminated coating on the surface of the wire is weakened.

Further, a method of applying a conductive paste prepared by dissolving a powder of a noble metal, copper, carbon or the like in an organic resin to an electric wire and press-bonding the same has been considered, but in this case, the contact resistance when the resin is hardened or the contact resistance increases. Since gas is released due to evaporation of the resin or decomposition of the resin in a high temperature environment, the released gas reacts with the components in the ambient atmosphere and adheres to the pressure-bonded portion, forming a film and increasing contact resistance, Depending on the type of organic substance, there is a problem that the resin of the connector housing may be melted or damaged.

Therefore, the present invention has been made in order to solve the above-mentioned problems, and enables to effectively remove the contaminated film on the surface of the electric wire without lowering the mechanical strength. The purpose is to

[0008]

According to the first aspect of the present invention,
When crimping a crimp portion of an electric wire composed of a plurality of strands with a crimp terminal, a hard conductive powder harder than the strand material is applied to the crimp portion.

Further, as described in claim 2, it is also effective to suspend a hard conductive powder, which is harder than the wire material, in an organic solvent which is volatile at room temperature and attach it to the crimp portion. Is.

Further, as described in claim 3, it is desirable that the particle diameter of the hard conductive powder is 70 to 200 mesh.

[0011]

In the invention of claim 1, when the hard conductive powder harder than the wire material is applied to the crimping portion of the electric wire,
When the crimp terminal is crimped, the hard conductive powder bites into the element wire and breaks through the contaminated coating on the wire surface, so the wire contamination is removed and good metal joining is obtained, and the pressure applied during crimping is small. Since it concentrates on the hard conductive powder, the hard conductive powder bites into the wire even with a low pressure, and even if cold shock or mechanical vibration is applied to the crimp terminal or wire, good electrical connection with low contact resistance can be achieved. Can be kept.

Further, since the hard conductive powder is applied, a stable effect of removing the contaminated film can be obtained, and the performance reproducibility during mass production is excellent.

Further, as described in claim 2, even if a hard conductive powder which is harder than the wire material is suspended in an organic solvent which is volatile at room temperature is attached to the crimping portion, By the same operation as in the case of the described invention, the contamination of the electric wire is removed and a good metal joint is obtained.

By the way, when the particle diameter of the hard conductive powder is set to 70 to 200 mesh as described in claim 3, the hard conductive powder is distributed in the gap between the individual wires as in the case where the hard conductive powder is coarser than 70 mesh. It does not easily get in and does not fall off before crimping. As with hard conductive powder finer than 200 mesh, the effect of the wedge driven between each wire or between the wire and crimp terminal is weakened and the contact resistance is reduced. There is no inconvenience of not contributing to the reduction.

At this time, in the invention according to claim 1, 2 or 3, when the wire is made of annealed copper or copper alloy, the hard conductive powder is made of metal powder of copper, nickel, tungsten or molybdenum. When the wire is made of stainless steel, the hard conductive powder is preferably made of metal powder of nickel, tungsten, or molybdenum, and when the wire is made of nickel or nickel alloy, it is hard conductive. It is desirable that the powder is made of a metal powder of either tungsten or molybdenum, and if the wire is made of aluminum or an aluminum alloy, the hard conductive powder is copper or a copper alloy or nickel or a metal powder of tungsten or molybdenum. It is desirable to consist of

In the invention according to claim 1, 2 or 3, when the wire is made of annealed copper, stainless steel, nickel or aluminum, the hard conductive powder is titanium,
It is desirable to use a conductive ceramic powder of a nitride compound of a refractory metal such as tantalum or nickel, or a carbon compound or a boron compound.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Explaining one embodiment of the present invention, as shown in FIG. 1, a crimp portion of an electric wire 2 constituted by a plurality of strands 1 made of, for example, annealed copper is crimped by a crimp terminal (not shown). Prior to the above, a metal powder 3 of copper or nickel, tungsten, or molybdenum having a particle size of 70 to 200 mesh, which is a hard conductive powder harder than annealed copper, is applied to the crimping portion of the electric wire 2 and then by a crimping machine. Crimp the crimp terminals.

As described above, the metal powder 3 is applied to the crimp portion of the electric wire 2.
When the crimp terminal is crimped, the metal powder 3 bites into the element wire 1 when the crimp terminal is crimped, and the contamination coating 4 on the surface of the wire 2 is pierced, so that the contamination of the wire 2 is removed. It is possible to obtain a stable contamination film removal effect, it is possible to obtain good metal joining by contact between fresh metals, and moreover, as in the case of forming serration on the inner surface side of the crimp terminal as in the conventional case, The effect of removing the contaminated film due to the abrasion of the serration edge accompanying the abrasion of the molding die of the crimp terminal is not deteriorated, and the stable effect of the contaminated film removal and the excellent performance reproducibility during mass production can be obtained.

Further, the metal powder 3 which has a small pressing force at the time of pressure bonding
Since the metal powder 3 sufficiently penetrates into the wire 1 even with a low pressing force, a good electrical connection can be maintained even when a thermal shock or mechanical vibration is applied to the crimp terminal or the electric wire 2.

By the way, using a 1.25 sq electric wire 2 composed of 50 annealed copper wires 1 having a wire diameter of 0.18 mm, a crimp terminal composed of brass, and a metal powder 3 composed of 80-mesh copper powder, cold-heat shock resistance is used. A test was conducted, and an initial contact resistance value before the start of the test and a contact resistance value after endurance after repeating thermal shock for 300 cycles at -40 to 120 ° C for 30 minutes each as one cycle were measured. It came to be shown in. For comparison, FIG. 2 also shows similar data obtained by the conventional crimping method.

As is clear from the results shown in FIG. 2, when the copper powder which is harder than the wire material is applied as the metal powder 3 in this way, the contact resistance values at the initial stage and after the endurance test become lower than those of the conventional ones. It can be seen that the change in the contact resistance value between the initial stage and the endurance is smaller than that of the conventional one, and the stability in the endurance test is remarkably increased.

Further, since only the wire 1 and the metal powder 3 are present in the crimping portion, there is an increase in contact resistance and gas under a high temperature environment as in the case of using a conductive paste made of a conventional organic resin. There is no inconvenience due to release.

By the way, the particle size of the metal powder 3 is 70 to 20.
When the mesh size is 0 mesh, as in the case where the particle size is coarser than 70 mesh, the metal powder 3 does not easily enter the gaps between the individual wires 1 and does not fall off before crimping. In addition, there is no inconvenience that the effect of a wedge driven between the wires 1 or between the wires 1 and the crimp terminals during crimping is weakened and does not contribute to reduction of contact resistance.

Therefore, according to the above embodiment, there is no reduction in the mechanical strength of the joint portion as in the case of conventional welding, and the metal powder which is a hard conductive powder harder than the wire material in the crimping portion of the electric wire 2. When 3 is applied, when the crimp terminal is crimped, the metal powder 3 bites into the wire 1 and the contamination coating 4 on the surface of the wire is pierced, so that the contamination of the wire can be removed and the contact resistance is good. It is possible to obtain a stable metal joint, and also to obtain a stable contamination film removing effect and excellent performance reproducibility during mass production.

Further, the metal powder 3 having a small pressure force at the time of pressure bonding
Since the metal powder 3 fully digs into the wire 1 even with a low pressure, it is possible to maintain a good electrical connection even when a thermal shock or mechanical vibration is applied to the crimp terminal or the wire 2. is there.

In the above embodiment, the case where the wire 1 is made of soft copper and the metal powder 3 of copper, nickel, tungsten or molybdenum, which is harder conductive powder than this, is applied, is explained. The wire 1 may be a copper alloy, and when the wire 1 is made of stainless steel, either nickel, tungsten or molybdenum may be used as the metal powder 3 which is a hard conductive powder. When is made of nickel or nickel alloy, either tungsten or molybdenum may be used as the metal powder 3 which is hard conductive powder, and when the wire 1 is made of aluminum or aluminum alloy, it is hard conductive powder. Any one of copper, copper alloy, nickel, tungsten, or molybdenum as the metal powder 3 Or it may be used, the same effect as the above embodiments be any combination can be obtained.

When the wire 1 is made of annealed copper, stainless steel, nickel or aluminum, the hard conductive powder is either a nitride compound of a refractory metal such as titanium, tantalum, nickel or a carbon compound or a boron compound. The same effect as that of the above-described embodiment can be obtained by using the conductive ceramic powder.

Further, the wire is made of stainless steel on the outside of the conductor.
It may be a composite wire plated or clad with nickel, aluminum or the like.

By the way, as another embodiment, prior to crimping the crimp terminal, a metal powder 3 which is harder than the material of the wire 1 is added to an organic solvent having volatility at room temperature, such as ethanol or positive propyl alcohol or isopropyl alcohol.
A suspension of hard conductive powder such as or conductive ceramic powder may be attached to the crimping portion of the electric wire 2 to remove the contamination of the electric wire and to have a low contact resistance as in the case of the above embodiment. It is possible to obtain excellent metal bonding.

[0030]

As described above, according to the invention of claim 1, since the hard conductive powder harder than the wire material is applied to the crimping portion of the electric wire, the wire of the hard conductive powder is applied to the wire at the time of crimping. It is possible to break through the contaminated film on the wire surface by biting into the wire, and it is possible to obtain a good metal joint with low contact resistance by removing the wire contamination. Moreover, a stable contaminant film removal effect and excellent performance reproduction during mass production are possible. It is possible to obtain the property, and the concentrated pressure applied to the hard conductive powder at the time of crimping allows the hard conductive powder to bite into the wire sufficiently with a low pressure. Even when applied to an electric wire, good electrical connection can be maintained, and it is extremely suitable for joining a terminal-electric wire or an electric wire-electric wire of a wire harness in automobiles and general industrial equipment.

Further, as described in claim 2, even if a hard conductive powder which is harder than the wire material is suspended in an organic solvent which is volatile at room temperature is attached to the crimping portion, As in the case of the described invention, the contamination of the electric wire can be removed to obtain a good metal joint with low contact resistance.

Further, according to the third aspect of the present invention, when the particle diameter of the hard conductive powder is 70 to 200 mesh, the hard conductive powder has gaps between the individual wires as in the case where the particle diameter is coarser than 70 mesh. It does not easily get in and does not fall off before crimping, and as in the case where the grain size is finer than 200 mesh, the effect of the wedge driven between the wires or between the wire and the crimping terminal is weakened and the contact resistance is reduced. There is no inconvenience of not contributing to the reduction.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a diagram showing a measurement result of contact resistance in one example.

[Explanation of symbols]

 1 Elementary wire 2 Electric wire 3 Metal powder (hard conductive powder)

Claims (9)

[Claims] 1. An electric wire joint, characterized in that, when crimping a crimp portion of an electric wire composed of a plurality of strands with a crimp terminal, a hard conductive powder harder than the strand material is applied to the crimp portion. Method. 2. When crimping a crimp portion of an electric wire composed of a plurality of strands with a crimp terminal, a hard conductive powder harder than the strand material is suspended in an organic solvent which is volatile at room temperature. An electric wire joining method characterized in that it is attached to a crimping portion. 3. The particle diameter of the hard conductive powder is 70 to 200.
The electric wire joining method according to claim 1 or 2, which is a mesh. 4. The wire is made of annealed copper or copper alloy,
4. The electric wire joining method according to claim 1, wherein the hard conductive powder is made of a metal powder of copper, nickel, tungsten, or molybdenum. 5. The electric wire joining method according to claim 1, wherein the wire is made of stainless steel, and the hard conductive powder is made of metal powder of nickel, tungsten, or molybdenum. 6. The electric wire joining method according to claim 1, wherein the wire is made of nickel or a nickel alloy, and the hard conductive powder is made of a metal powder of either tungsten or molybdenum. 7. The wire according to claim 1, wherein the wire is made of aluminum or aluminum alloy, and the hard conductive powder is made of metal powder of copper, copper alloy, nickel, tungsten, or molybdenum. 3. The electric wire joining method described in 3. 8. The conductive wire is made of annealed copper, stainless steel, nickel or aluminum, and the hard conductive powder is conductive of any one of a nitride compound of a refractory metal such as titanium, tantalum, nickel or a carbon compound or a boron compound. The electric wire joining method according to claim 1, wherein the electric wire joining method comprises ceramic powder. 9. The organic solvent is ethanol, orthopropyl alcohol or isopropyl alcohol, and the organic solvent is 2, 3, 4, 5, 6, 7 or 8.
The electric wire joining method described.