JPH0146966B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in composite electrical contact materials for inlay-type bending springs.

The first composite electrical contact material for inlay-type bending springs, which are generally used for connector contacts, micromotor brushes, relay spring contacts, etc.
As shown in the figure, between a contact metal 1 mainly made of Au or an Au alloy and a spring base metal 2 made of phosphor bronze or a Cu alloy such as Be-Cu, to which this contact metal 1 is inlay-fitted, there is a contact metal 1 made mainly of Ni or Ni. A composite electric contact material 4 for a bending spring is used, which has an intermediate layer 3 made of an alloy. In this composite electric contact material 4 for bending springs, the reason why the intermediate layer 3 is provided between the contact metal 1 and the springy base metal 2 is that when the contact metal 1 and the springy base metal 2 are directly joined. This is because, since they are joined in a heated state, Cu contained in the springy base metal 2 will diffuse into the contact metal 1, resulting in a decrease in the corrosion resistance and electrical conductivity of the contact metal 1.

By the way, this composite electrical contact material 4 for bending springs
is used as a composite electrical contact 5 for a spring by rolling it to a desired thickness, cutting it to a predetermined length, and then bending it by 180 degrees at the contact metal 1 as shown in Fig. 2. However, in the rolled state, the elongation rate is particularly low due to work hardening, so if the contact metal 1 is bent as described above, cracks will occur at the peripheral edge and the bent surface of the contact metal 1.

For this reason, conventionally, low-temperature heat treatment is performed immediately after the rolling process is completed, if necessary. However, since the temperature is as low as several 100 degrees Celsius, the contact metal 1 and the spring base metal 2 are sufficiently annealed, but the intermediate layer 3 is mainly made of Ni or Ni alloy, so it is not annealed at this temperature. As a result, when the contact metal 1 is bent into the shape shown in FIG. 2, cracks appear at the peripheral edge of the contact metal 1 and the intermediate layer 3, and in some cases, the contact metal 1 peels off or falls off. There was a drawback.

The present invention has been made to eliminate such drawbacks, and when bent into the shape shown in FIG. 2, cracks do not occur in the peripheral edge and the intermediate layer of the contact metal 1, and the contact metal does not peel off. It is an object of the present invention to provide a composite electrical contact material for a bending spring that will not fall off or fall off.

The composite electrical contact material for bending springs of the present invention is the first
Contact metal 1 made of Au or Au alloy as shown in the figure
Ag or
This is characterized by the provision of an intermediate layer 3 made of an Ag alloy.

Composite electrical contact material 4 for bending springs of the present invention
As mentioned above, Ag or Ag alloy is used instead of Ni or Ni alloy, which has been conventionally used as the material for the intermediate layer 3, so Ag or Ag alloy is not used during heat bonding.
Although some diffusion occurs to the boundary of the contact metal 1 made of Au or Au alloy, it can prevent the spring base metal 2 made of Cu alloy from diffusing into the contact metal 1, and even if it diffuses, the amount is extremely small and the amount of diffusion is very small at the contact point. It does not reduce the corrosion resistance and electrical conductivity of the metal 1, and therefore does not impede the contact performance of the contact metal 1. On the other hand, the peripheral wall portions of the inlaid contact metal 1 and intermediate layer 3 are also diffusion bonded to the spring base metal 2, but since they do not become contact surfaces when bent, there is no problem even if they are diffused. Furthermore, after rolling or subsequent low-temperature annealing, an Au-Ag diffusion layer is formed at the boundary between the contact metal 1 and the intermediate layer 3, and an Ag-Cu diffusion layer is formed at the boundary between the intermediate layer 3 and the spring base metal 2. Even if the Ag or Ag alloy used as the intermediate layer 3 is bent into the shape shown in Fig. 2 after being cut to a predetermined length, there will be no cracks in the Ag or Ag alloy used as the intermediate layer 3, and the contact metal 1 will not peel or fall off. There is nothing to do.

Next, in order to clarify the effectiveness of the composite electric contact material for bending springs according to the present invention, a comparison between specific examples and conventional examples will be described.

〔Example〕

Contact metal 1 made of Au-10w/oAg with a width of 3 mm and a thickness of 15μ as shown in Fig. 1, and a contact metal 1 made of Ag with a width of 3 mm.
25 mm wide and 3 mm thick, the spring base metal 2 made of phosphor bronze has a groove 3 mm wide and 100 μ deep in the longitudinal direction at the center of the upper surface. After joining them together, they were heated and pressure welded at 580°C to form a composite electrical contact intermediate material for a bending spring, and then this intermediate material was rolled to make a width of 25 mm, a total thickness of 0.2 mm, and a thickness of contact metal 1 of approximately 1 μm. Composite electrical contact material 4 for bending springs was created. This was then applied in an _N2 atmosphere at 250
A low temperature annealing treatment was performed at ℃.

[Conventional example]

Except for using Ni as the intermediate layer 3, a composite electrical contact material 4 for a bending spring having the same dimensions and the same shape as in the example was obtained under the same conditions.

The composite electric contact materials 4 for bending springs of the embodiment and the conventional example were cut into lengths of 5 mm, and each of the 30 cut pieces was bent by 180 degrees at the contact metal 1 to form a spring as shown in FIG. When a composite electrical contact 5 for a spring was prepared and the occurrence of cracks in the intermediate layer 3 was investigated, it was found that there were no cracks at all in the intermediate layer 3 of the composite electrical contact 5 for a spring obtained from the electrical contact material 4 for a bending spring of the example. This did not occur and there was no peeling of the contact metal, whereas the composite electrical contact 5 for springs obtained from the conventional composite electrical contact material 4 for bending springs
Cracks occurred in 14 out of 30 cases in the intermediate layer 3, and in some cases the contact metal 1 had peeled off, and in some cases the contact metal 1 was on the verge of peeling off. None of the inlay boundary parts of the composite electrical contact 5 that had peeled off or was about to peel off were bonded.
It should be noted that there was no part of the boundary portion of the spring composite electrical contact 5 of the example that was not bonded.

As detailed above, the composite electrical contact material for bending springs according to the present invention uses Ag or Ag alloy for the intermediate layer between the contact metal and the base metal, so it is particularly suitable for low-temperature annealing after rolling. sufficiently diffused,
As a result, cracks do not occur at the peripheral edge of the contact metal 1 and the intermediate layer during the bending process after cutting, and therefore the contact metal does not peel or fall off. Even when Ag sulfurizes, it moves along the surface of Au or Au alloy, so the sulfide film on the sides does not thicken and does not peel off.
The sulfide film that moves and spreads on the surface of Au or Au alloys is extremely thin and does not interfere with conduction, so when used in connector contacts, micromotor brushes, relay spring contacts, etc. This provides high reliability.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a composite electrical contact material for a bending spring, and FIG. 2 is a perspective view of a composite electrical contact material for a spring. 1...Contact metal, 2...Spring base metal, 3
...Intermediate layer, 4...Composite electrical contact material for bending springs, 5...Composite electrical contact for springs.

Claims (1)

[Claims] 1. In a composite electrical contact material for an inlay type bending spring, a contact metal made of Au or an Au alloy and a spring base metal made of a Cu alloy in which this contact metal is inlay-fitted are made of Ag or an Ag alloy. 1. A composite electrical contact material for a bending spring, characterized in that the contact metal and the intermediate layer of this material are diffusion bonded to the spring base metal by low-temperature annealing treatment.