JP2020117770A - Terminal material for connector, and terminal for connector - Google Patents

Abstract

To provide a terminal material for a connector capable of improving abrasion resistance and heat resistance, and a terminal for connector.SOLUTION: A terminal material for a connector includes: a substrate at least the surface of which is composed of copper or a copper alloy; a nickel plating layer composed of nickel or a nickel alloy formed on the substrate; and a silver gold alloy plating layer formed on at least one part of the nickel plating layer, and constituting a surface layer where the content of Au in the silver gold alloy plating layer is 0.1 at% or more and 10 at% or less, and film thickness is 1 μm or more and 50 μm or less.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a connector terminal material and a connector terminal provided with a film that is useful for connecting electrical wiring of automobiles, consumer appliances, and the like.

2. Description of the Related Art Conventionally, connector terminals used for connecting electrical components of signal systems and power systems of automobiles, etc. are generally tin-plated on a base material made of copper or copper alloy and then subjected to reflow treatment. Terminals with a plated layer were often used. However, in recent years, the electrification rate of automobiles has increased, and the use of terminals plated with a noble metal, which is excellent in heat resistance and wear resistance and can flow a larger amount of current, has been increasing.

As such a connector terminal material required to have heat resistance and wear resistance, for example, as described in Patent Document 1, a base material made of copper or a copper alloy is subjected to silver plating using a cyan bath, A terminal material having a silver-plated layer is known.
Further, instead of this silver plating layer, a silver alloy plating layer containing antimony as described in Patent Document 2 or a silver tin alloy (Ag—Sn) plating layer as described in Patent Document 3 is used. Therefore, it has been proposed to harden the plating layer to improve wear resistance.

JP 2008-169408 A JP, 2009-79250, A JP, 2005-183216, A

However, in the terminal described in Patent Document 1, there is a problem that when heated, the crystal diameter of the silver plating layer becomes large and thus the hardness decreases. In order to suppress this decrease in hardness, it is conceivable to thicken the silver plating layer, but this leads to an increase in cost. On the other hand, as described in Patent Document 2, even in the case of a silver alloy plating layer containing antimony, although the initial hardness is high, the hardness is reduced by heating, and the antimony is concentrated and oxidized on the surface of the plating layer. This causes a problem that the contact resistance increases. Further, in the terminal material described in Patent Document 3, since the gold-tin alloy plating layer is too hard, when the base material on which the gold-tin alloy plating layer is formed is bent, cracks are generated in the plating layer and press working There is a problem that processing becomes difficult.

The present invention has been made in view of such circumstances, and an object thereof is to provide a connector terminal material and a connector terminal that can improve wear resistance and heat resistance.

The connector terminal material of the present invention includes a base material having at least a surface made of copper or a copper alloy, a nickel plating layer made of nickel or a nickel alloy formed on the base material, and at least a surface of the nickel plating layer. A silver-gold alloy plating layer which is formed in part and constitutes a surface layer, wherein the silver-gold alloy plating layer has an Au content of 0.1 at% or more and 10 at% or less and a film thickness of 1 μm or more and 50 μm or less. It is as follows.

Since the silver-gold alloy plating layer is formed on the surface, the surface can be hardened. If the film thickness of this silver-gold alloy plating layer is less than 1 μm, it is too thin and is likely to wear and disappear at an early stage, and under a high temperature environment, the nickel plating layer as a lower layer is oxidized and a contact resistance increases. There is no problem if the thickness of the silver-gold alloy plating layer exceeds 50 μm, but it is preferably 50 μm or less in terms of cost. Since silver and gold are solid solutions at all rates and do not form intermetallic compounds, they do not become excessively hard and cracks are less likely to occur during press working or the like. Further, even in a heating environment, coarsening of crystal grains and surface oxidation are less likely to occur, so that a decrease in hardness can be suppressed.
When the content of Au in the silver-gold alloy plating layer is 0.1 at%, the effect of hardening the surface is low. Although there is no problem even if the content of Au exceeds 10 at %, it is preferable to set it to 10 at% or less from the viewpoint of cost.
In addition, since the silver-gold alloy plating layer is laminated on the nickel plating layer formed on the base material, the adhesion between the nickel-plating layer and the silver-gold alloy plating layer is good and peeling is prevented even in a high temperature environment. It

The connector terminal material of the present invention includes a base material having at least a surface made of copper or a copper alloy, a nickel plating layer made of nickel or a nickel alloy formed on the base material, and at least a surface of the nickel plating layer. It has a silver plating layer formed on a part thereof and a silver-gold alloy plating layer which is formed on at least a part of the silver plating layer and constitutes a surface layer, and the silver plating layer has a thickness of 0. 0.5 μm or more and 50 μm or less, the silver-gold alloy plating layer has an Au content of 0.1 at% or more and 10 at% or less, and a film thickness of 0.05 μm or more and 50 μm or less.

Since the silver-gold alloy plating layer is formed on the surface, the surface can be hardened. If the film thickness of this silver-gold alloy plating layer is less than 0.05 μm, the wear resistance is reduced. In the case of this terminal material, since the silver-plated layer is interposed between the silver-gold alloy plated layer and the nickel-plated layer, even if the silver-gold alloy plated layer is thin, it has excellent wear resistance. There is no problem if the thickness of the silver-gold alloy plating layer exceeds 50 μm, but it is preferable to set it to 50 μm or less in terms of cost. Even if the film thickness is 50 μm, cracking is unlikely to occur during press working or the like. In addition, since the silver-gold alloy plating layer on the surface hardly causes coarsening of crystal grains and surface oxidation even under a heating environment, it is possible to suppress a decrease in hardness.
When the content of Au in the silver-gold alloy plating layer is 0.1 at%, the effect of hardening the surface is low. Although there is no problem even if the content of Au exceeds 10 at %, it is preferable to set it to 10 at% or less from the viewpoint of cost.
If the thickness of the silver plating layer is less than 0.5 μm, the effect of enhancing wear resistance is poor when the silver-gold alloy plating layer is thin, and there is no problem even if the thickness of the silver plating layer exceeds 50 μm. From the viewpoint of cost, it is preferably 50 μm or less.

In one embodiment of the connector terminal material, the nickel plating layer may have a film thickness of 0.5 μm or more and 5 μm or less.
When the thickness of the nickel plating layer is less than 0.5 μm, the heat resistance is lowered, and the Cu component may diffuse from the base material into the silver-gold alloy plating layer in a high temperature environment to increase the resistance value. If it exceeds 5 μm, cracks may occur during press working or the like.

A connector terminal of the present invention is a connector terminal made of the above connector terminal material, and the silver-gold alloy plating layer is formed on a surface of a contact portion with a counterpart connector terminal.
This connector terminal has excellent wear resistance because a hard silver-gold alloy plating layer is formed on the contact portion.

ADVANTAGE OF THE INVENTION According to this invention, the hardness of the surface of a connector terminal material and a connector terminal is high, abrasion resistance improves, and hardness fall is small even in a heating environment, and heat resistance is improved.

It is sectional drawing which shows typically the connector terminal material which concerns on 1st Embodiment of this invention. It is sectional drawing which shows typically the connector terminal material which concerns on 2nd Embodiment of this invention. 6 is a SIM image of a cross section of Sample 5. 6 is a SIM image of a cross section of Sample 23.

Embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment>
[Construction of connector terminal material]
The connector terminal material 1 of the first embodiment has a plate-shaped base material 2 having at least a surface made of copper or a copper alloy, and the entire surface of the base material 2 as shown in the schematic cross section of FIG. A nickel plating layer 3 made of nickel or a nickel alloy, and a silver-gold alloy plating layer 4 covering at least a part of the nickel plating layer 3 (left half in FIG. 1) and forming the outermost surface; Equipped with.
The base material 2 is not particularly limited in composition as long as it is made of copper or a copper alloy. Further, it may be formed of a plated material in which a copper plating layer made of copper or a copper alloy is applied to the surface of the base material. In this case, the base material may be a metal material other than copper.

The nickel plating layer 3 is coated by plating the base material 2 with nickel or a nickel alloy. The nickel plating layer 3 has a function of suppressing diffusion of the Cu component from the base material 2 into the silver-gold alloy plating layer 4 coated on the nickel plating layer 3. The thickness of the nickel plating layer 3 is preferably 0.5 μm or more and 5 μm or less. When the thickness of the nickel plating layer 3 is less than 0.5 μm, the Cu component diffuses into the silver-gold alloy plating layer 4 from the base material 2 made of copper or copper alloy in a high temperature environment and the silver-gold alloy plating layer 4 is formed. And the heat resistance may decrease, and if it exceeds 5 μm, cracking may occur during bending. The more preferable film thickness of the nickel plating layer 3 is 0.5 μm or more and 2 μm or less. The nickel plating layer 3 is not particularly limited in composition as long as it is made of nickel or a nickel alloy.

The silver-gold alloy plating layer 4 is located on the outermost surface of the connector terminal material 1, and after the nickel plating layer 3 is subjected to silver strike plating, it is coated thereon. The silver-gold alloy plating layer 4 has an Au content of 0.1 at% or more and 10 at% or less and a film thickness of 1 μm or more and 50 μm or less.
In this silver-gold alloy plating layer 4, since gold (Au) has a higher melting point than antimony (Sb), it is unlikely that antimony diffuses to the surface by heating and decreases in hardness. Further, since gold has a high electric conductivity, the electric resistance of the silver-gold alloy is also good. Furthermore, since a silver-gold alloy is less likely to be oxidized than pure silver (Ag), the contact resistance is less likely to be deteriorated by heating.

If the Au content of the silver-gold alloy plating layer 4 is 0.1 at %, the effect of hardening the surface is low. Although there is no problem even if the content of Au exceeds 10 at %, it is preferable to set it to 10 at% or less from the viewpoint of cost. The preferable Au content of the silver-gold alloy plating layer 4 is 0.5 at% or more.
Further, if the thickness of the silver-gold alloy plating layer 4 is less than 1 μm, it is too thin and easily wears and disappears at an early stage, and in a high temperature environment, the lower nickel plating layer 3 is oxidized and the contact resistance increases. Occurs. There is no problem if the thickness of the silver-gold alloy plating layer 4 exceeds 50 μm, but it is preferable to set it to 50 μm or less in terms of cost. Since silver and gold are solid solutions at all and do not form an intermetallic compound, they do not become excessively hard, and even if the film thickness is 50 μm, cracking is unlikely to occur due to pressing or the like. The preferable film thickness of the silver-gold alloy plating layer 4 is 2 μm or more and 10 μm or less. In addition, since it is a silver-gold alloy, it does not cause coarsening of crystal grains or surface oxidation even under a heating environment, can suppress the decrease in hardness, and has excellent heat resistance.

[Production method]
Next, a method for manufacturing the connector terminal material 1 will be described. The method for manufacturing the terminal material 11 for a connector includes a pretreatment step of cleaning a plate material made of copper or a copper alloy which is the base material 2, a nickel plating layer forming step of forming the nickel plating layer 3 on the base material 2, and a nickel plating layer. A silver strike plating step of performing silver strike plating on the plating layer 3, and a silver gold alloy plating layer forming step of forming the silver gold alloy plating layer 4 on the nickel plating layer 3 after performing the silver strike plating. Prepare

(Pretreatment process)
First, as the base material 2, a plate material made of copper or a copper alloy is prepared, and a pretreatment for cleaning the surface by performing degreasing, pickling, or the like on the plate material is performed. As described above, a base material may be formed by forming a copper plating layer made of copper or a copper alloy on a metal material other than copper.

(Nickel plating layer forming process)
Nickel or nickel alloy plating is applied to the surface of the base material 2 to form a nickel plating layer 3. For example, a nickel plating solution containing 300 g/L of nickel sulfamate, 30 g/L of nickel chloride, and 30 g/L of boric acid is used to perform nickel plating under conditions of a bath temperature of 45° C. and a current density of 3 A/dm ^2. To be done. The nickel plating forming the nickel plating layer 3 is not particularly limited as long as a dense nickel-based film can be obtained, and may be formed by electroplating using a known Watts bath.

(Silver strike plating process)
The nickel plating layer 3 formed on the base material 2 is subjected to activation treatment using a 5% by mass to 10% by mass aqueous potassium hydroxide solution on the portion where the silver-gold alloy plating layer 4 is formed, and then the nickel plating layer. Silver strike plating is applied on 3. This silver strike plating is performed to enhance the adhesion between the silver-gold alloy plating layer 4 formed on the nickel plating layer 3 and the nickel plating layer 3. The composition of the plating bath for applying this silver strike plating is not particularly limited, but for example, a plating bath comprising silver cyanide (AgCN) 1 g/L to 5 g/L and potassium cyanide (KCN) 80 g/L to 120 g/L. Is preferred. Then, using a stainless steel plate (SUS316) as an anode, this silver strike plating bath is subjected to silver plating for about 30 seconds under conditions of a bath temperature of room temperature (25° C. to 30° C.) and a current density of 1 A/dm ^2. Thereby, a silver strike plating layer is formed.

(Silver-gold alloy plating layer forming process)
After the silver strike plating step, silver-gold alloy plating is applied on the silver strike plating to form the silver-gold alloy plating layer 4. The composition of the plating bath for forming this silver-gold alloy plating layer 4 is not particularly limited, but for example, potassium silver cyanide (KAg(CN) ₂ ) 1 g/L to 5 g/L, silver cyanide (AgCN) A plating bath composed of 5 g/L to 15 g/L, potassium cyanide (KCN) 10 g/L to 30 g/L, potassium carbonate (KCO ₃ ) 10 g/L to 20 g/L, and an additive 5 ml/L is suitable. In the cyan bath, antimony should not be contained. Then, using a pure silver plate as an anode with respect to the silver plating bath, at a bath temperature of room temperature (25 ℃ ~30 ℃), 50 seconds under the conditions of a current density of ^{0.1A / dm 2 ~3A / dm 2} ~ The silver-gold alloy plating layer 4 is formed by plating for about 85 minutes.

In this way, the nickel plating layer 3 is formed on the surface of the base material 2, and the connector terminal material 1 having the silver-gold alloy plating layer 4 formed on a part of the surface of the nickel plating layer 3 is pressed or the like. Is performed to form a connector terminal in which the silver-gold alloy plating layer 4 is arranged in a portion used as a contact. In this case, in the connector terminal material, the portion where the silver-gold alloy plating layer 4 is formed is used so as to be arranged in the fitting portion (contact portion) with the mating terminal.
In this embodiment, since the silver-gold alloy plating layer 4 is formed on the surface, the surface can be hardened. The silver-gold alloy has a high melting point of gold and causes eutectoid gold, which is stable as a noble metal, and unlike silver which softens by heating, the hardness after heating is less likely to decrease. Further, since gold is a precious metal rather than silver, the surface is less likely to be oxidized and the contact resistance is good.
Further, since it is a silver-gold alloy, the connector is less likely to cause adhesion due to sliding, and wear resistance is improved.
Furthermore, since the silver-gold alloy plating layer 4 is laminated on the nickel plating layer 3 formed on the base material 2, and the nickel plating layer 3 and the silver-gold alloy plating layer 4 have good adhesion, the high-temperature environment Peeling is prevented even underneath.

<Second Embodiment>
[Construction of connector terminal material]
The connector terminal material 11 according to the second embodiment is different from the layer structure of the connector terminal material 1 according to the first embodiment in that the nickel plating layer 3 and the silver-gold alloy are used as shown in the schematic cross section in FIG. The silver plating layer 5 is formed between the plating layer 41 and the plating layer 41. That is, at least the surface of the plate-shaped base material 2 made of copper or copper alloy, the nickel plating layer 3 made of nickel or nickel alloy coated on the entire surface of the base material 2, and the surface of the nickel plating layer 3 At least a part of the silver plating layer 5 is covered, and a silver-gold alloy plating layer 41 which is formed on at least a part of the silver plating layer 5 and constitutes the outermost surface is provided.

In this case, the thickness of the nickel plating layer 3 is preferably 0.5 μm or more and 5 μm or less. When the thickness of the nickel plating layer 3 is less than 0.5 μm, Cu components diffuse from the base material 2 made of copper or copper alloy into the silver-gold alloy plating layer 41 via the silver plating layer 5 in a high temperature environment. Then, the resistance value of the silver-gold alloy plating layer 41 may be increased and the heat resistance may be lowered. If it exceeds 5 μm, cracks may occur during bending. The more preferable film thickness of the nickel plating layer 3 is 0.5 μm or more and 2 μm or less. The nickel plating layer 3 is not particularly limited in composition as long as it is made of nickel or a nickel alloy.
Further, the silver plating layer 5 has a film thickness of 0.5 μm or more and 50 μm or less, and the silver-gold alloy plating layer 41 has an Au content of 0.1 at% or more and 10 at% or less, but a film thickness of 0. It is not less than 05 μm and not more than 50 μm.

The silver plating layer 5 is preferably made of pure silver, but the Ag concentration may be 95% by mass or more. This is because if the Ag concentration of the silver plating layer 5 is less than 95% by mass, a large amount of impurities will be contained, and the silver plating layer will be alloyed and hardened, and may be cracked when bent by pressing or the like. This is because.
If the thickness of the silver plating layer 5 is less than 0.5 μm, the effect of enhancing wear resistance is poor when the silver-gold alloy plating layer 41 is thin, and there is no problem even if the thickness exceeds 50 μm. In terms of, 50 μm or less is preferable. A preferable film thickness of the silver plating layer 5 is 1 μm or more and 10 μm or less.

In this connector terminal material 11, since the silver plating layer 5 is formed between the nickel plating layer 3 and the silver-gold alloy plating layer 41, the thickness of the silver-gold alloy plating layer 41 is the same as that of the first embodiment. Even if it is thinner, excellent wear resistance can be exhibited, and the lower limit of the thickness of the silver-gold alloy plating layer 41 can be set to 0.05 μm. If the film thickness of the silver-gold alloy plating layer 41 is less than 0.05 μm, it is too thin and is likely to wear and disappear at an early stage. There is no problem if the thickness of the silver-gold alloy plating layer 41 exceeds 50 μm, but it is preferably 50 μm or less in terms of cost. Since the silver-gold alloy plating layer 41 is formed on the silver plating layer 5, a film thickness of 5 μm is sufficient. A preferable film thickness of the silver-gold alloy plating layer 4 is 0.1 μm or more and 5 μm or less.
If the Au content of the silver-gold alloy plating layer 4 is 0.1 at %, the effect of hardening the surface is low. Although there is no problem even if the content of Au exceeds 10 at %, it is preferable to set it to 10 at% or less in terms of cost. The preferable Au content of the silver-gold alloy plating layer 4 is 0.5 at% or more.

[Production method]
When manufacturing the connector terminal material 11 of the second embodiment, the pretreatment step, the nickel plating layer forming step, and the silver strike plating step are the same as those in the first embodiment. In the second embodiment, a silver plating layer forming step and a silver-gold alloy plating layer forming step are performed after the silver strike plating step.

(Silver plating layer forming process)
A silver plating step is performed on the silver strike plating layer to form the silver plating layer 5. The composition of the plating bath for forming this silver plating layer is not particularly limited, but for example, silver cyanide (AgCN) 30 g/L to 50 g/L, potassium cyanide (KCN) 120 g/L to 160 g/L, potassium carbonate (K ₂ CO ₃ ) 10 g/L to 20 g/L and 5 ml/L of additive. Then, using a pure silver plate as an anode for this silver plating bath, silver plating is applied for about 50 seconds to 85 minutes under conditions of a bath temperature of 25° C. and a current density of 2 A/dm ² to form a silver plating layer 5. To be done.

(Silver-gold alloy plating layer forming process)
In the silver-gold alloy plating layer forming step, a pure silver plate is used as an anode for the plating bath having the composition described in the first embodiment, the bath temperature is room temperature (25° C. to 30° C.), and the current density and the plating time are set. By adjusting, the silver-gold alloy plating layer 41 is formed. For example, the plating condition is about 53 seconds to 65 minutes under a current density of 0.5 A/dm ^{2 to} 3 A/dm ² .

In the connector terminal material 12 of this embodiment, the silver-gold alloy plating layer 41 is formed on the nickel plating layer 3 via the silver plating layer 5, so that the thickness of the silver-gold alloy plating layer 41 is reduced. If the silver-gold alloy plating layer 41 has a film thickness of 0.05 μm or more, good wear resistance can be exhibited.

<Other Embodiments>
Besides, the detailed configuration is not limited to the configuration of the embodiment, and various modifications can be made without departing from the spirit of the present invention.
In the first embodiment, the nickel plating layer 3 is formed on the entire surface of the base material 2, and the silver-gold alloy plating layer 4 is formed on at least a part of the nickel plating layer 3. In the second embodiment, The nickel plating layer 3 is formed on the entire surface of the base material 2, and the silver-gold alloy plating layer 4 is formed on at least a part of the nickel plating layer 3 via the silver plating layer 5. In contrast to these configurations, a configuration in which the silver-gold alloy plating layer 4 is formed on the entire surface of the nickel plating layer 3, or a silver plating layer 5 is formed on the entire surface of the nickel plating layer 3 and the entire surface of the silver plating layer 5 is formed. A configuration in which the silver-gold alloy plating layer 41 is formed may be used. Further, when the silver plating layer 5 is provided, the silver plating layer 5 may be formed on the entire surface of the nickel plating layer 3 and the silver-gold alloy plating layer 41 may be formed on a part of the silver plating layer 5. Is.
That is, the silver-gold alloy plating layers 4 and 41 may be formed at least at the portions arranged as the connector terminals at the contact portions with the mating terminals.

<First embodiment>
Prepare a 0.3 mm-thick base material made of a copper alloy plate, perform pretreatment to clean the surface by degreasing, pickling, etc. on this base material, and then apply nickel plating to the surface of the base material. Then, a nickel plating layer having a thickness of 2 μm was formed. Then, an activation treatment for cleaning the surface of the nickel plating layer is performed using a 5 mass% potassium hydroxide aqueous solution, and after this activation treatment, the base material coated with the nickel plating layer is subjected to silver strike plating. Then, a silver-gold alloy plating layer was formed on the silver strike plating layer by adjusting the current density and the plating time so that the film thicknesses shown in Table 1 were obtained.

The conditions of each plating are as follows.
(Nickel plating conditions)
・Plating bath composition Nickel sulfamate 300g/L
Nickel chloride 30g/L
Boric acid 30g/L
・Bath temperature 45°
・Current density 3 A/dm ²

(Silver strike plating conditions)
・Plating bath composition: 2 g/L of silver cyanide
Potassium cyanide 100g/L
・Anode SUS316
・Bath temperature 25℃
・Current density 1A/dm ²

(Silver-gold alloy plating conditions)
・Plating bath composition Potassium gold cyanide 3 g/L
Silver cyanide 10g/L
Potassium cyanide 20g/L
Potassium carbonate 15g/L
Additive 5ml/L
・Anode Pure silver plate・Bath temperature 25℃
・Current density 0.5 A/dm ^{2 to} 3 A/dm ²

In the comparative example, after nickel plating and silver strike plating were performed on the surface of the base material, bright silver plating was performed using Nisshin Bright N bath to which antimony made by Nikkosei Co., Ltd. was added. The composition of the plating bath is a standard composition, the bath temperature is 25° C., the current density is 1 A/dm ² , a pure silver plate is used as the anode, and a silver alloy plating layer (AgSb alloy layer) having a film thickness of 2.5 μm is formed. And Comparative Example 10. Moreover, what carried out pure silver plating instead of silver-gold alloy plating after silver strike plating (comparative example 11) was also produced.
Then, the following measurements and tests were performed on the samples of these Examples and Comparative Examples.

[Measurement of plating layer thickness]
The film thickness of the nickel plating layer and the film thickness of the silver-gold alloy plating layer (AgAu plating thickness) were manufactured by JEOL Ltd. after the silver-gold alloy plating layer was cross-section processed by FIB (focused ion beam device). It was measured by observing a cross section using an electron beam microanalyzer: EPMA (model number JXA-8530F). The measured value was the arithmetic average of 5 points.

[Measurement of Au content]
After performing the cross-section processing of the silver-gold alloy plating layer by FIB (Focused ion beam device), the Au content in the silver-gold alloy is electron beam microanalyzer manufactured by JEOL Ltd.: EPMA (model number JXA-8530F). The surface of each sample was measured by using an accelerating voltage of 10 kV and a beam diameter of 30 μm. The measured value was the arithmetic average of 5 points.

[Measurement of Vickers hardness]
Each sample before heating (initial) and each sample after heating at 150° C. for 240 hours was measured using a micro Vickers hardness tester HM-200 (manufactured by Mitutoyo Co., Ltd.) with a number of measurements N=10 and a load of 0. The Vickers hardness was measured under the condition of 0.005N. However, since the Vickers hardness of Samples 1 and 2 could not be measured as they were, a Vickers hardness of 2 μm was prepared without changing the Au content of the silver-gold alloy plating layer. It was measured.

[Measurement of hardness decrease]
The amount of decrease in hardness was calculated by subtracting the value of Vickers hardness after heating at 150° C. for 240 hours from the value of Vickers hardness before heating (initial) obtained by measuring Vickers hardness.

[Bending test]
Cut a test piece into a strip with a width of 10 mm so that the area between the contact planned part and the core wire contact part is 1:1 and bent so that the boundary between the contact planned part and the core wire contact part is the bent part. After performing 120° bending with a radius of 1.5 mm, bending back was performed. The surface of the bent outer peripheral portion of the sample was observed with an optical microscope (magnification: 50 times) to examine whether there was any abnormality. The plate thickness of the copper or copper alloy base material was 0.3 mm. The case where a state different from the flat plate state such as peeling, cracking, or cracking was observed in the bent back portion was designated as "B", and the case where no abnormality was observed was designated as "A".

[Measurement of contact resistance]
Each sample before heating and each sample after heating at 150° C. for 240 hours were cut into a test piece of 60 mm×10 mm, the flat plate sample was used as a substitute for the male terminal, and the flat plate sample was subjected to convex processing with a curvature radius of 1.0 mm. The sample thus obtained was used as a substitute for the female terminal. For the sliding test, a frictional wear tester (UMT-Tribolab) manufactured by Bruker AXS Co., Ltd. was used, and the convex surface of the female test piece was brought into contact with the horizontally mounted male terminal test piece, and the male terminal test piece was loaded. The contact resistance value when a load was applied from 0 N to 2 N at a speed of 1/15 N/sec was measured.

[Heat resistance peel test]
In the heat-resistant peeling test, after heating in an atmosphere heating furnace at 175° C. for 1000 hours, the cross-cut method described in JIS K5600-5-6 was used to test the film without peeling, and peeling off even with 1 mass in “A”. The item was designated as "B".
Table 1 shows the results of the above measurements and tests.

As can be seen from Table 1, a silver-gold alloy plating layer having a film thickness of 1 μm or more is formed on the nickel plating layer on the base material, and the Au content of the silver-gold alloy plating layer is 0.1 at% or more. Samples 2 to 6 and 8 to 10 had high Vickers hardness, little decrease in hardness after heating, no abnormalities such as peeling and cracks were observed in the bending test, and the contact resistance was good. In the heat-resistant peeling test, no peeling was observed between the nickel plating layer and the silver-gold alloy plating layer.

When the cross section of Sample 4 was observed with a scanning ion microscope (SIM), as shown in FIG. It was confirmed that the notation) was formed.

On the other hand, in sample 1, the silver-gold alloy plating layer had a thin film thickness of 0.8 μm, and thus the contact resistance after heating was high. In sample 7, the Au content in the silver-gold alloy plating layer was as low as 0.08 at %, so the Vickers hardness was low, and peeling was observed in the heat-resistant peeling test. The surface of Sample 11 is a silver antimony alloy plating layer, and the initial hardness is high, but the hardness decreases significantly after heating, and abnormalities such as peeling and cracks are observed in the bending test, and the contact resistance after heating is also large. Peeling was observed in the heating environment. The surface of Sample 12 was a pure silver plating layer, the hardness after heating was largely decreased, and peeling was observed in a heating environment.

<Second embodiment>
Prepare a 0.3 mm-thick base material made of a copper alloy plate, perform pretreatment to clean the surface by degreasing, pickling, etc. on this base material, and then apply nickel plating to the surface of the base material. Then, a nickel plating layer having a thickness of 2 μm was formed. Then, an activation treatment for cleaning the surface of the nickel plating layer is performed using a 5 mass% potassium hydroxide aqueous solution, and after this activation treatment, the base material coated with the nickel plating layer is subjected to silver strike plating. Then, the silver plating layer was formed on the silver strike plating layer, and the current density and the plating time were adjusted so that the film thicknesses shown in Table 1 were obtained to form the silver-gold alloy plating layer. The conditions of each plating layer other than the silver plating layer are the same as those in the first embodiment described above.

The silver plating conditions were as follows, and a silver plating layer having a film thickness of 2.5 μm was formed.
(Silver plating conditions)
・Plating bath composition Silver cyanide 40 g/L,
Potassium cyanide 120g/L
Potassium carbonate 15g/L
・Anode Pure silver plate・Bath temperature 25℃
・Current density 2A/dm ²

As a comparative example, the same samples as the samples 11 and 12 of the first embodiment were manufactured and used as samples 26 and 27, respectively.
For these samples, the film thickness of the plating layer, the Au content in the silver-gold alloy plating layer, the Vickers hardness and the hardness decrease amount, and the bending test were performed. The measuring method and the testing method are the same as those in the first embodiment.
The results are shown in Table 2.

As can be seen from Table 2, a silver-gold alloy plating layer having a film thickness of 0.05 μm or more and 50 μm or less is formed on the nickel plating layer on the base material via the silver plating layer. Samples 23 to 25 having an Au content of 0.1 at% or more have high Vickers hardness and little decrease in hardness after heating. In addition, no abnormality such as peeling or cracking was observed in the bending test, and the contact resistance was good.

When the cross section of Sample 23 was observed with a scanning ion microscope (SIM), as shown in FIG. 4, a nickel plating layer (denoted as Ni) and a silver plating layer (denoted as Ag) were formed on the base material (denoted as Cu). It was confirmed that the silver-gold alloy plating layer (denoted as AgAu) was sequentially formed.

On the other hand, Sample 21 had a thin silver-gold alloy plating layer of 0.02 μm, and Sample 22 had a low Au content in the silver-gold alloy plating layer of 0.08 at %, and thus had a low Vickers hardness. However, the contact resistance was good because the silver plating layer was formed. The surface of sample 26 is a silver antimony alloy plating layer, and the initial hardness is high, but the hardness after heating is largely reduced, and abnormalities such as peeling and cracks are observed in the bending test, and the contact resistance after heating is also large. became. The surface of the sample 27 was a pure silver plating layer, and the Vickers hardness was low.

1 Connector Terminal Material 2 Base Material 3 Nickel Plating Layer 4, 41 Silver Gold Alloy Plating Layer 5 Silver Plating Layer

Claims (4)

At least a surface of a base material made of copper or a copper alloy, a nickel plating layer made of nickel or a nickel alloy formed on the base material, and a surface layer formed on at least a part of the nickel plating layer. And a silver-gold alloy plating layer constituting the connector, wherein the silver-gold alloy plating layer has an Au content of 0.1 at% or more and 10 at% or less and a film thickness of 1 μm or more and 50 μm or less. For terminal material. A base material having at least a surface made of copper or a copper alloy, a nickel plating layer made of nickel or a nickel alloy formed on the base material, and a silver plating layer formed on at least a part of the nickel plating layer. And a silver-gold alloy plating layer that is formed on at least a part of the silver plating layer and forms a surface layer, and the silver plating layer has a film thickness of 0.5 μm or more and 50 μm or less, The silver-gold alloy plating layer has a Au content of 0.1 at% or more and 10 at% or less and a film thickness of 0.05 μm or more and 50 μm or less. The terminal material for a connector according to claim 1, wherein the nickel plating layer has a film thickness of 0.5 μm or more and 5 μm or less. A connector terminal comprising the connector terminal material according to any one of claims 1 to 3, wherein the silver-gold alloy plating layer is formed on a surface of a contact portion with a counterpart connector terminal. And connector terminals.