JP2003213488A - Electric contact member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve corrosion and abrasion resistances even when the plating layer of Au or an Au alloy is made thinner on an electric contact point or a connector member of which the electrically contacting surface of the electric contact point or connectors is plated with Au or Au alloy. <P>SOLUTION: In the electrical contact member which is composed of a conductive base metal having the electrically contacting surface plated with Au or an Au alloy, a PdCo alloy plating layer is interposed between the base metal and the Au or Au alloy plating layer. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric contact member obtained by plating an electric contact surface of a conductive base metal with Au or an Au alloy.

[0002]

2. Description of the Related Art In the case of electrical contacts and connectors, plating of Sn, Ag, Au, Pd, etc. or their alloy plating is performed on the surface of a conductive base metal for the purpose of improving wear resistance, corrosion resistance or conductivity. It has been subjected. Among them, hard Au or Au alloy plating is applied to parts that require particularly high reliability, and AuF / PdNi (Au flash-plated PdN that has even better wear resistance than these is used.
i alloy plating) has also come to be adopted as standard specifications for electrical contacts and connectors.

[0003]

Au or Au alloy plating is expensive, and AuF / PdNi is also expensive. Therefore, cost reduction by thinning the film is desired,
In the case of hard Au plating, there is a problem that if the plating thickness is too thin, the number of pinholes increases, so the corrosion resistance decreases, and in AuF / PdNi plating, there is a problem that the wear resistance decreases in proportion to the film thickness when the film thickness is reduced. Yes, it results in the loss of that quality.

An object of the present invention is to solve such a problem, and to reduce the thickness of Au or Au alloy plating layer,
Further, it is to obtain an electrical contact member having excellent corrosion resistance and wear resistance even if the alloy plating layer containing Pd is thinned.

[0005]

According to the present invention, there is provided an electrical contact member comprising an electrically contacting surface of an electrically conductive base metal plated with Au or an Au alloy, and the base metal and Au or Au alloy plating. There is provided a member for electrical contact characterized in that a PdCo alloy plating layer is interposed between the layers. Further, the present invention relates to an electrical contact member obtained by plating an electrical contact surface of a conductive base metal with Au or an Au alloy, wherein a Ni plating layer and a PdCo alloy are provided between the base metal and the Au or Au alloy plating layer. Plating layer,
The present invention provides a member for electrical contact, characterized in that a Ni plating layer is provided on the metal side of the base material. In any case, the Au or Au alloy plating layer can be subjected to a sealing treatment on the outermost surface thereof.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION When Au or Au alloy plating is applied as a surface treatment for electrical contacts and connectors, hard Au plating (for example, AuCo plating) is used from the viewpoint of cost reduction.
If the plating thickness is reduced, pinholes increase and corrosion resistance decreases. The reduction in corrosion resistance due to this thinning can be suppressed to some extent by a sealing treatment (also called lubrication treatment) that fills the pinholes, but its effect is insufficient and it is necessary to suppress corrosion due to local battery formation. . Pd
Corrosion resistance is improved by Ni alloy plating and then hard Au plating, but wear resistance deteriorates when the film thickness is reduced. In this case, even if the outermost surface is lubricated, it is insufficient to improve the wear resistance, and basically it is necessary to increase the hardness of the plating film to reduce the wear amount. It is considered that the plating does not sufficiently enhance the hardness.

However, instead of PdNi alloy plating,
It has been found that when the hard Au plating is performed after the PdCo alloy plating is applied, both the corrosion resistance and the wear resistance are improved.

The present invention has been made on the basis of this finding, and has corrosion resistance and heat resistance with respect to the electric contact surface of the base metal (copper or copper alloy, iron or iron alloy, etc.) that constitutes the electric contacts and the connector. In order to apply Au or Au alloy plating to give the following, after applying PdCo alloy plating,
Au or Au alloy plating is applied. As a result, sufficient corrosion resistance can be maintained even if the plating thickness of Au or Au alloy plating is reduced, and an electrical contact surface with extremely excellent wear resistance can be obtained.

At that time, it is desirable to apply a dull Ni plating to the base metal as a base treatment, then apply a PdCo alloy plating as an intermediate plating layer, and form an Au or Au alloy plating layer as an upper plating on it. A plating layer having good adhesion can be obtained by the base treatment of this Ni plating.

Generally, in order to improve the corrosion resistance of the plated surface,
It is effective to reduce the potential difference between the plating layer and the material or between the plating layer and the plating layer. From this point of view, a PdNi alloy plating layer is interposed as an intermediate plating layer and AuF plating / PdNi plating / Ni plating / rather than the structure of Au plating / Ni plating / Cu material.
The corrosion resistance is better when the structure is made of Cu material. However, in the latter case, improvement in wear resistance cannot be expected when the film is thinned (for example, Comparative Example 2 described later). However, when the PdCo plated layer is interposed as the intermediate plated layer, the corrosion resistance is the same as when the PdNi plated layer is interposed, but the wear test results described below show that the wear resistance is about twice or more. I found out.

Therefore, PdCo is used as the intermediate plating layer.
When alloy plating is adopted, equivalent wear resistance characteristics can be obtained with a film thickness of 1/2 compared with the case of PdNi alloy plating, and yet corrosion resistance is not deteriorated.
It was found to have an economic effect of reducing the metal cost by half. Further, various tests were performed for Co weight% and film thickness in the PdCo alloy plating as the intermediate plating layer. As a result, the Co weight% was in the range of 5 to 60 weight%, and the film thickness was 0.05 μm or more. Alternatively, it was found that it can sufficiently contribute to the improvement of the corrosion resistance and wear resistance of the Au alloy plated product. The film thickness of the PdCo alloy plating as the intermediate plating layer contributes to the improvement of wear resistance as it becomes thicker, but considering productivity and cost, it is up to about 2.0 μm, preferably 0.02 to 0.5 μm.
It is good to be about m.

For the purpose of the present invention, the film thickness of Au or Au alloy plating as the upper layer plating formed on the PdCo alloy plating layer is preferably as thin as possible.
It is preferable to adjust the thickness to less than or equal to μm, preferably 0.02 to 0.10 μm.

The lubrication treatment (sealing treatment) performed after the Au or Au alloy plating of the upper layer has some effect on the improvement of corrosion resistance and wear resistance, although it depends on the use environment.

[0014]

[Example] [Example 1] In this example, by electrolytic plating,
Pure copper plate that has been degreased and activated (25 mm x 50 mm x
0.3mmt), 2μm matte Ni plating as lower layer plating, 0.4μm PdC as intermediate plating
O alloy plating (Co: 30% by weight), and Au flash plating of 0.1 μm as an upper layer plating were sequentially formed, and finally lubricated. The composition of the plating bath for each electrolytic plating and the lubricating treatment liquid are as follows.

"Matte Ni plating bath" Nickel sulfamate (as Ni): 100 g / L Nickel chloride: 15g / L Boric acid: 30 g / L

"PdCo alloy plating bath" (the following 7 kinds of reagents manufactured by Lucent Technologies were mixed in the following quantitative ratio) Pd PCl Make-up, Pd as metal: 30 g / L PCl Cobalt Make-up, Co as metal: 8 g / L PCl Conducting Salt: 40 g / L PCl Additive: 20 mL / L Additive IV: 10 mL / L PCl Ligand: 150 mL / L Additive M2C: 1 mL / L

[0017] "Au flash plating bath" (AuCo alloy plating bath: Nippon Kojundo Chemical Co., Ltd.) The following three kinds of reagents manufactured by the above were mixed in the following quantitative ratios) Bath salt for construction bath Aurobrite BA: Standard concentration Aurobrite BB (as Co) for building bath: 200ppm Potassium cyanide potassium (as Au): 6 g / L

[0018] "Lubrication bath" (Chemical Electronics Co., Ltd. reagent below) KD-Au100W: 200mL / L

The electroplating conditions for each of the above are as follows. pH Bath temperature (° C) Current density (A / dm ² ) Film thickness (μm) Matte Ni plating 4.0 50 4 2 PdCo alloy plating 7.2 50 4 0.4 AuCo alloy plating 4.0 50 0.1 0.1

The treated product thus obtained was subjected to the following chemical resistance test, thermal stability test and abrasion resistance test.

"Chemical resistance test": JIS H for specimens
A nitric acid exposure test according to 8616 was performed, and the contact resistance value after standing for 2 hours at 25 ° C was measured. The contact resistance was measured by the four-terminal method under a measurement load of 25 g, and the voltage (IR voltage) appearing in the measured section was measured while applying a constant current to the measured section. The chemical resistance was evaluated by the amount of change (ΔmΩ) in the contact resistance value at 25 ° C. for 2 hours with respect to the contact resistance value (initial value) at the start of the nitric acid exposure test. The higher ΔmΩ indicates the poorer chemical resistance. "Thermal stability test": Specimen at 960 at 150 ° C in air
The contact resistance value after holding for a period of time was measured, and the amount of change (Δ
It was evaluated by mΩ). The contact resistance was measured as in the chemical resistance test. The higher ΔmΩ indicates the poorer chemical resistance. "Abrasion resistance test": A copper pin having a diameter of 5 mm is plated under the same conditions as the test piece. The pin is erected vertically on the surface of the test piece, and with the load of 100 g applied in the axial direction of the pin, the tip of the pin is reciprocated on the surface of the test piece in the same orbit and scratched. At that time, the round trip distance of the pin tip is 1
With a constant 2.5 mm, reciprocate at a frequency of 0.5 Hz (30 cycles / minute) and measure the number of cycles until the base metal (copper plate) of the test piece is visible. The larger the number of cycles, the better the wear resistance.

The chemical resistance, thermal stability and wear resistance of the treated products evaluated in this way are summarized in Table 1, all of which are good.

Example 2 The treatment and test of Example 1 were repeated except that the PdCo alloy plating had a plating thickness of 0.2 μm. The chemical resistance, thermal stability and wear resistance of the obtained treated products are summarized in Table 1.

[Example 3] Example 3 except that the "PCl Cobalt Make-up, Co as metal" in the PdCo alloy plating bath was changed from 8 g / L to 16 g / L and the plating thickness was 0.2 μm. The treatment of 1 and the test were repeated. Table 1 shows the chemical resistance, thermal stability and wear resistance of the obtained treated products.
The summary is shown in.

[Comparative Example 1] As an intermediate plating, 0.4 μ
The treatment and test of Example 1 were repeated except that the PdCo alloy plating having a thickness of 0.4 μm was replaced with the PdNi alloy plating having a thickness of 0.4 μm (Ni: 20 wt%). Table 1 shows the chemical resistance, thermal stability and wear resistance of the obtained treated product. The PdNi alloy plating was performed using the following bath under the following conditions.

"PdNi alloy plating bath" (the following four types of reagents manufactured by Lucent Technologies were mixed in the following quantitative ratio) Pd M2 Make-up, Pd as metal: 20 g / L Ni M2 Make-up, Ni as metal: 10g / L Conducting Salt # 5: 50g / L Buffer M2 Salt: 10g / L

"Electrolytic conditions" for PdNi alloy plating: bath p
H = 7.5, bath temperature = 40 ° C., current density = 4 Adm ² , plating thickness = 0.4 μm

[Comparative Example 2] The thickness of the PdNi alloy plating was
The treatment and test of Comparative Example 1 were repeated except that the thickness was changed to 0.2 μm. Table 1 shows the chemical resistance, thermal stability and wear resistance of the obtained treated product.

Comparative Example 3 The same process as in Example 1 was repeated except that PdCo alloy plating was not performed. That is, the same copper plate surface was plated with 2 μm of dull Ni as in Example 1, directly coated with Au hard plating, and finally lubricated (sealed). However,
The thickness of the Au hard plating (AuCo alloy plating) increased from 0.1 μm (Example 1) to 0.5 μm.
Table 1 shows the chemical resistance, thermal stability and wear resistance of the obtained treated product.

[0030]

[Table 1]

As can be seen from the results in Table 1, in addition to the chemical resistance being improved by applying PdCo alloy plating as the intermediate plating, the wear resistance is also improved. Especially, compared with the conventional PdNi alloy plating as the intermediate plating, the wear resistance is remarkably good.

[0032]

As described above, according to the present invention,
Since the PdCo alloy plating is applied and then the Au or Au alloy plating is applied, it is possible to provide an electrical contact member having excellent corrosion resistance and wear resistance even if the Au or Au alloy plating layer is thinned.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01H 1/02 H01H 1/02 E 1/04 1/04 E H01R 13/03 H01R 13/03 DF term (reference) 4K024 AA03 AA11 AA12 AA24 AB02 AB03 BA02 BA09 BB09 BB10 DB10 GA03 GA04 GA16 4K044 AA02 AA06 AB10 BA06 BA08 BB03 BB04 BC01 BC02 BC11 BC14 CA18 CA59 5G050 BCA03 AA11 A02 A09 29

Claims (3)

[Claims] 1. Au on the electrically contacting surface of a conductive base metal.
Alternatively, an electrical contact member obtained by applying Au alloy plating, wherein a PdCo alloy plated layer is interposed between the base metal and Au or Au alloy plated layer. 2. Au on the electrically contacting surface of the conductive substrate metal.
Alternatively, in a member for electrical contact obtained by applying Au alloy plating, a Ni plating layer and a PdCo alloy plating layer are interposed between the base metal and Au or Au alloy plating layer, with the Ni plating layer being the base metal side. A member for electrical contact characterized by the above. 3. The member for electrical contact according to claim 1, wherein the outermost surface of the Au or Au alloy plating layer is lubricated.