JP2020128575A - Terminal material for connector, terminal for connector, and method of producing terminal material for connector - Google Patents

Abstract

To provide a terminal material for a connector, capable of improving abrasion resistance, heat resistance and crack resistance, a terminal for a connector, and a method of producing a terminal material for a connector.SOLUTION: The terminal material for a connector according to the present invention, comprises a substrate at least whose surface layer is constituted of copper or a coper alloy, a silver layer comprising silver as its main component and at least coated on a part of the surface of the substrate, a silver-platinum alloy layer constituted of a silver-platinum alloy and at least coated on a part of the silver layer, with at least a part of the silver-platinum alloy layer being formed of an intermetallic compound of AgPt, the concentration of Pt not constituting the compound of Ag being 10 mass% or lower, and the film thickness of the intermetallic compound of AgPt being not smaller than 0.04 μm and not larger than 1.9 μm.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a connector terminal material provided with a coating useful for connecting electrical wiring of automobiles, consumer appliances, and the like in which slight sliding occurs, a connector terminal, and a method for manufacturing the connector terminal material.

2. Description of the Related Art Conventionally, a connector used for connecting electric wiring of an automobile or the like is known. To this vehicle-mounted connector (vehicle-mounted terminal), the contact piece provided on the female terminal is electrically connected by contacting the male terminal inserted in the female terminal with a predetermined contact pressure. The one with a terminal pair designed to be used is used. As such a connector (terminal), in general, a tin-plated terminal in which tin or tin is plated on a copper or copper alloy plate and which is subjected to reflow treatment is often used. However, in recent years, with the increase in current and voltage of automobiles, the use of terminals plated with a precious metal, which is capable of passing a larger amount of current and is excellent in heat resistance and wear resistance, is increasing.

As a plating for a vehicle-mounted terminal that is required to have such heat resistance and wear resistance, for example, a silver-plated terminal for a connector described in Patent Document 1 is known. In the silver-plated terminal for a connector described in Patent Document 1, the surface of a base material made of copper or a copper alloy is covered with a silver-plated layer, and the silver-plated layer is located on the lower layer side (base material side). And a second silver plating layer located on the upper side of the first silver plating layer, and the crystal grain size of the first silver plating layer is smaller than that of the second silver plating layer. Is also formed large. That is, in the configuration of Patent Document 1, by forming the crystal grain size of the first silver plating layer larger than the crystal grain size of the second silver plating layer, the Cu component from the base material becomes the second silver plating. It suppresses the diffusion into layers.

Further, in Patent Document 2, a silver or silver alloy layer having an antimony concentration of 0.1% by mass or less is formed on at least a part of the surface of a copper or copper alloy member as a base material. Discloses a copper or copper alloy member on which a silver alloy layer having a Vickers hardness of HV140 or more is formed as the outermost layer. Further, a nickel or nickel alloy layer is formed between the base material and the silver or silver alloy layer having an antimony concentration of 0.1% by mass or less. That is, in the configuration of Patent Document 2, the hardness is increased by adding antimony to the silver or silver alloy layer, and the wear resistance of the copper or copper alloy member is improved.

Further, Patent Document 3 discloses an electronic component having a silver-tin alloy plating film directly on a copper material or a copper plating film or via a nickel plating film as a base. The silver-tin alloy plating film of the electronic component described in Patent Document 3 has a film thickness of 0.1 to 100 μm, a Sn quality of 10 to 30 mass %, a micro Vickers hardness of Hv150 or less, and a heat treatment. The decrease in hardness due to (200° C.×1 hr.) is set to 20% or less of the hardness before heat treatment. That is, in the configuration of Patent Document 3, the silver-tin alloy plating film has the above-described configuration, thereby increasing hardness and improving wear resistance and heat resistance.

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

However, in the configuration of Patent Document 1, the surface of the base material is covered with a silver plating layer, and the silver plating layer has a large crystal grain size of silver and its hardness is lowered by heating, so that in a high temperature environment. Abrasion resistance decreases. In order to suppress this decrease in hardness, it is conceivable to increase the silver plating film thickness, but there is a cost problem. On the other hand, in the configuration of Patent Document 2, antimony is concentrated on the outermost surface of the plating layer by heating and then oxidized to increase the contact resistance. Further, in the configuration of Patent Document 3, since the silver-tin alloy plating film is hard, when the base material on which the silver-tin alloy plating layer is formed is bent, cracks may occur in the silver-tin alloy plating layer. Therefore, there is a problem in press working (post-processing) after plating. Further, when the nickel plating layer is used as a base, there is a problem that nickel oxide is generated between the nickel plating layer and the silver plating layer by heating and the nickel oxide causes the peeling of the plating layer.

The present invention has been made in view of the above circumstances, and provides a terminal material for a connector, a terminal for a connector, and a method for manufacturing the terminal material for a connector, which can improve wear resistance, heat resistance, and crack resistance. To aim.

The connector terminal material of the present invention includes a base material having at least a surface layer made of copper or a copper alloy, a silver layer containing silver as a main component coated on at least a part of the surface of the base material, and at least the silver layer. And a silver-platinum alloy layer partially formed of a silver-platinum alloy, the silver-platinum alloy layer being formed at least partially by an intermetallic compound of Ag ₃ Pt and forming a compound with Ag. The Pt concentration is 10% by mass or less, and the intermetallic compound film thickness of Ag ₃ Pt is 0.04 μm or more and 1.9 μm or less.

In the present invention, since at least a part of the silver-platinum alloy layer formed on the outermost surface of the base material is formed of the intermetallic compound of Ag ₃ Pt, the hardness of the silver-platinum alloy layer is increased and the wear resistance is improved. it can. Note that the intermetallic compound of Ag ₃ Pt has high heat resistance unlike silver that softens due to heat, and thus can suppress the decrease in hardness after heating. In addition, since the silver-platinum alloy layer is formed of an intermetallic compound of Ag ₃ Pt containing noble Pt that hardly forms an oxide like Ag of the silver-plated layer, oxidation of the silver-platinum alloy layer can be suppressed. Even in a high temperature environment, increase in contact resistance is suppressed, and heat resistance can be improved.

Furthermore, when the terminal material for a connector is used as a terminal for a connector, the surface of the contact portion of the terminal is formed of a silver-platinum alloy layer, whereby the occurrence of adhesive wear can be suppressed and the wear resistance can be improved. Further, a silver-platinum alloy layer is formed only on the outermost surface of the base material, and the film thickness of the intermetallic compound of Ag ₃ Pt is reduced to 0.04 μm or more and 1.9 μm or less to improve crack resistance, It suppresses cracking due to processing. If the film thickness of the intermetallic compound of Ag ₃ Pt is less than 0.04 μm, heat resistance and wear resistance cannot be improved, and if it exceeds 1.9 μm, the silver-platinum alloy layer is too thick and press working, etc. Causes cracking. Further, if the concentration of the Pt silver-platinum alloy layer that does not form a compound with Ag exceeds 10 mass %, the hardness decreases.

In a preferred embodiment of the connector terminal material of the present invention, a nickel layer made of nickel or a nickel alloy is provided between the base material and the silver layer, and the thickness of the nickel layer is 0.5 μm or more and 5 μm or more. The following is preferable.

In the above aspect, since the silver layer is formed on the nickel layer, peeling of the silver layer from the base material can be suppressed. If the thickness of the nickel layer is less than 0.5 μm, the Cu component diffuses from the base material made of copper or copper alloy into the silver plating layer in a high temperature environment, and the resistance value of the silver plating layer increases, The heat resistance may decrease. On the other hand, if the thickness of the nickel layer exceeds 5 μm, cracks may occur during press working or the like.

The connector terminal of the present invention is a connector terminal made of the above-mentioned connector terminal material, and the silver-platinum alloy layer is located on the surface of the contact portion.

The method for producing a terminal material for a connector of the present invention is the method for producing a terminal material for a connector as described above, wherein at least a part of the surface of a substrate having at least a surface layer made of copper and a copper alloy is silver-plated to have a thickness of 1 μm. After forming a silver plating layer having a thickness of 50 μm or less, at least a part of the silver plating layer is plated with platinum to form a platinum plating layer having a thickness of 0.01 μm or more and 0.5 μm or less, and the surface of the platinum plating layer. Hold at a temperature of 30° C. or higher and 80° C. or lower for 1 hour or longer.

In the present invention, after the silver plating layer is formed on the surface of the base material, the platinum plating layer is formed and a predetermined heat treatment is performed, so that the outermost surface of the base material has high wear resistance, heat resistance and crack resistance. A connector terminal material having a silver-platinum alloy layer can be manufactured. In this manufacturing process, when the thickness of the platinum plating film is less than 0.01 μm or when the thickness of the silver plating layer is less than 1 μm, the intermetallic compound of Ag ₃ Pt cannot be sufficiently generated. However, the silver-platinum alloy layer cannot be properly formed, and the heat resistance and wear resistance of the connector terminal material may be reduced. On the other hand, when the film thickness of the platinum plating layer exceeds 0.5 μm, the intermetallic compound of Ag ₃ Pt is generated in the above predetermined heat treatment, but a large amount of Pt component remains in the silver platinum alloy layer, and Ag ₃ Pt remains. Since a Pt unreacted layer in which Ag and Pt are not alloyed is formed on the intermetallic compound layer of Pt (the pure Pt concentration exceeds 10 mass %), the hardness of the silver-platinum alloy layer is reduced and the wear resistance is reduced. As the silver-platinum alloy layer becomes thicker, the crack resistance decreases, and cracking may occur due to press working or the like. Further, when the thickness of the silver plating layer is more than 50 μm, the silver layer becomes thick, so that cracking may occur in the silver layer due to press working or the like, and the crack resistance may decrease.

In the above predetermined heat treatment, when the surface temperature of the platinum plating layer is lower than 30°C, the intermetallic compound of Ag ₃ Pt cannot be sufficiently generated, and when it exceeds 80°C, the base material made of copper or copper alloy is used. This is not appropriate because the diffusion of the Cu component of 3 becomes easier to proceed. Further, if the heat treatment time is less than 1 hour, the intermetallic compound of Ag ₃ Pt cannot be sufficiently generated, and therefore the silver-platinum alloy layer cannot be properly formed. If the heat treatment time exceeds 24 hours, the diffusion amount of the Cu component from the base material increases, so it is desirable to finish the heat treatment within 24 hours.

According to the present invention, the wear resistance, heat resistance and crack resistance of the connector terminal material and the connector terminal can be improved.

It is sectional drawing which shows typically the terminal material for connectors which concerns on embodiment of this invention. It is a SIM (Scanning Ion Microscope) image of the cross section of the connector terminal material before heating in the example.

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

[Construction of connector terminal material]
The connector terminal material 1 of the present embodiment has a plate-shaped base material 2 having at least a surface layer made of copper or a copper alloy, and a whole upper surface of the base material 2, as shown in the cross-sectional view of FIG. A nickel layer 3 made of nickel or a nickel alloy, a silver layer 4 covering the entire upper surface of the nickel layer 3, and a silver platinum alloy layer 5 covering a part of the silver layer 4. The composition of the surface layer of the base material 2 is not particularly limited as long as it is made of copper or a copper alloy. Further, in the present embodiment, as shown in FIG. 1, the base material 2 is made of a plate material made of copper or a copper alloy, but is made of a plated material in which the surface of the base material is plated with copper or copper alloy. It may be configured. In this case, oxygen-free copper (C10200), Cu-Mg-based copper alloy (C18665), or the like can be applied as the base material.

The nickel layer 3 is coated by plating the base material 2 with nickel or a nickel alloy. The nickel layer 3 has a function of suppressing diffusion of copper from the base material 2 into the silver layer 4 and the silver-platinum alloy layer 5 coated on the nickel layer 3. The thickness of the nickel layer 3 is preferably 0.5 μm or more and 5 μm or less, and more preferably 0.5 μm or more and 2 μm or less. When the thickness of the nickel layer 3 is less than 0.5 μm, the Cu component diffuses from the base material 2 made of copper or copper alloy into the silver layer 4 in a high temperature environment, and the resistance value of the silver layer 4 increases, The heat resistance may decrease. On the other hand, if the thickness of the nickel layer 3 exceeds 5 μm, cracks may occur during bending. The composition of the nickel layer 3 is not particularly limited as long as it is made of nickel or a nickel alloy. The nickel layer 3 is not an essential component, and the silver layer 4 may be formed on the surface of the base material 2 plated with silver strike, for example.

The silver layer 4 and the silver-platinum alloy layer 5 are formed by performing silver strike plating on the nickel layer 3 and then performing silver plating and platinum plating on the upper surface of the nickel layer 3 and heat-treating them. Among these, the silver layer 4 is formed on the nickel layer 3, and the silver platinum alloy layer 5 is formed on the outermost surface of the connector terminal material 1 on the silver layer 4.

The silver layer 4 contains silver as a main component, and preferably contains, for example, pure silver in an amount of 95% by mass or more. The thickness of such a silver layer 4 is set to, for example, 0.5 μm or more and 50 μm or less.

At least a part of the silver-platinum alloy layer 5 is formed of an intermetallic compound of Ag ₃ Pt, and the concentration of Pt not forming a compound with Ag is 10 mass% or less. Such an intermetallic compound increases the hardness of the silver-platinum alloy layer 5 and improves wear resistance. Specifically, the Vickers hardness of the silver-platinum alloy layer 5 is set within the range of 110 HV to 150 HV. Further, in the present embodiment, since the silver-platinum alloy layer 5 is formed of the intermetallic compound of Ag ₃ Pt containing Pt which is more noble than Ag of the silver layer 4, oxidation of the silver-platinum alloy layer 5 is suppressed. Improves heat resistance. Since pure Pt is soft, the hardness of the plating film surface decreases as the concentration of Pt that does not form a compound with Ag in the silver-platinum alloy layer 5 increases. Further, the above concentration is preferably lower than 10% by mass, and more preferably 0% by mass. That is, the silver-platinum alloy layer 5 may be made of only the intermetallic compound of Ag ₃ Pt.

Further, the film thickness of the intermetallic compound of Ag ₃ Pt is set to 0.04 μm or more and 1.9 μm or less, and more preferably 0.08 μm or more and 1.1 μm or less. By thus reducing the film thickness of the intermetallic compound of Ag ₃ Pt, the crack resistance is improved, and cracking due to press working or the like is suppressed. If the film thickness of the intermetallic compound of Ag ₃ Pt is less than 0.04 μm, the heat resistance and wear resistance cannot be improved, and if it exceeds 1.9 μm, the silver-platinum alloy layer 5 is too thick and the press Cracks occur due to processing etc.
In the case where a silver platinum alloy layer 5 is formed of only the intermetallic compound of Ag 3 _Pt is the thickness of the silver platinum alloy layer 5 is the same as the thickness of the intermetallic compound Ag 3 _Pt, and Ag When the Pt unreacted layer in which the compound is not formed is formed, the film thickness of the silver platinum alloy 5 does not match the film thickness of the intermetallic compound of Ag ₃ Pt.

Next, a method for manufacturing the connector terminal material 1 will be described. The method for manufacturing the terminal material 1 for a connector includes a pretreatment step of washing a plate material at least a surface layer of which is a base material 2 made of copper or a copper alloy, a nickel layer forming step of forming a nickel layer 3 on the base material 2, A silver strike plating step of performing silver strike plating on the nickel layer 3, a silver plating layer forming step of performing silver plating on the silver strike plating layer to form a silver plating layer, and a platinum plating on the silver plating layer. A platinum plating layer forming step of forming a platinum plating layer by applying the heat treatment step and a heat treatment step of holding the surface temperature of the platinum plating layer at a temperature of 30° C. or higher and 80° C. or lower for 1 hour or longer are provided.

[Pretreatment process]
First, as the base material 2, a plate material having at least a surface layer made of copper or a copper alloy is prepared, and a pretreatment for cleaning the surface by performing degreasing, pickling, etc. on the plate material is performed.

[Nickel layer forming process]
At least a part of the surface of the base material 2 is plated with nickel or nickel alloy to form the nickel layer 3 on the base material 2. For example, using a nickel plating bath consisting of 300 g/L of nickel sulfamate, 30 g/L of nickel chloride, and 30 g/L of boric acid, nickel plating is performed under conditions of a bath temperature of 45° C. and a current density of 3 A/dm ^2. To be done. The nickel plating for forming the nickel 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. Further, when the silver layer 4 is directly formed on the surface of the base material 2, the nickel layer forming step need not be performed.

[Silver strike plating process]
After performing an activation treatment on the nickel layer 3 using a potassium hydroxide aqueous solution of 5 to 10 mass %, silver strike plating is performed on the nickel layer 3 to form a silver strike plating layer. This silver strike plating is performed in order to enhance the adhesion between the silver layer 4 formed on the nickel layer 3 and the nickel layer 3. The composition of the plating bath for performing this silver strike plating is not particularly limited, but is, for example, 1 g/L to 5 g/L of silver cyanide (AgCN) and 80 g/L to 120 g/L of potassium cyanide (KCN). Then, using a stainless steel plate (SUS316) as an anode for this silver plating bath, silver plating is applied for about 30 seconds under conditions of a bath temperature of 25° C. and a current density of 1 A/dm ² to form a silver strike plating layer. To be done.

[Silver plating layer forming process]
Silver plating is applied on the silver strike plating layer to form a silver plating layer. The silver plating layer may have a pure Ag concentration of 95% by mass or more. This means that if the pure Ag concentration of the silver plating layer is less than 95% by mass, a large amount of impurities will be contained, and when the silver plating layer is heat-treated to form the silver layer 4, the silver plating layer is alloyed, This is because there is a possibility of cracking when bent by press processing or the like. 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 an additive for smooth deposition of the silver plating layer. The additive may be a general additive as long as it does not contain antimony. Then, using a pure silver plate as an anode, the silver plating bath is subjected to silver plating 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. It

The thickness of the silver plating layer formed in the silver plating layer forming step is set to 0.5 μm or more and 50 μm or less. If the thickness of the silver plating layer is less than 0.5 μm, the intermetallic compound of Ag ₃ Pt cannot be sufficiently generated, so that the silver-platinum alloy layer 5 cannot be appropriately generated, and heat resistance and wear resistance are deteriorated. there's a possibility that. Further, since the silver plating layer is thin, the connection reliability required for the silver plating layer cannot be secured. On the other hand, when the silver plating layer has a thickness of more than 50 μm, the crack resistance of the silver layer 4 is lowered, and cracks may occur due to press working or the like.

[Platinum plating layer forming process]
Then, after the silver plating layer forming step, platinum plating is performed on the silver plating layer to form a platinum plating layer. The composition of the plating bath for forming this platinum plating layer is, for example, pH adjusted to 1, sulfuric acid 15 g/L to 25 g/L, diamminedinitroplatinum [Pt(NH ₃ ) ₂ (NO ₂ ) ₂ ] 5 g/L to 15 g/L, consisting of sulfamic acid (H ₂ NSO ₂ OH), and organic additives. Then, a platinum plate is used as an anode for this platinum plating bath, and the platinum plating layer is formed by applying a platinum plating at a bath temperature of 60° C. and a current density of 1 A/dm ² for about 30 seconds to 15 minutes. If platinum plating with a purity of more than 99% is applied, the plating bath for forming the platinum plating layer is not limited to the above plating bath, and its composition is not particularly limited.

The thickness of the platinum plating layer formed in this platinum plating layer forming step is set to 0.01 μm or more and 0.5 μm or less. When the film thickness of the platinum plating layer is less than 0.01 μm, the intermetallic compound of Ag ₃ Pt cannot be sufficiently generated, so that the silver-platinum alloy layer 5 cannot be properly formed, and the heat resistance of the connector terminal material 1 is not achieved. And the abrasion resistance may decrease. On the other hand, when the film thickness of the platinum plating film exceeds 0.5 μm, an intermetallic compound of Ag ₃ Pt is generated in the heat treatment step, but a large amount of Pt component remains in the silver-platinum alloy layer 5 (with Ag and Ag). Since the concentration of Pt in the silver-platinum alloy layer 5 that does not form the compound of above exceeds 10% by mass), a Pt unreacted layer in which Ag and Pt are not alloyed is formed on the outermost surface in the silver-platinum alloy layer 5. To be done. For this reason, the hardness of the silver-platinum alloy layer 5 is reduced and the wear resistance is reduced, and the thickening of the silver-platinum alloy layer 5 reduces the crack resistance, which may cause cracks by press working or the like. is there.

[Heat treatment process]
Then, a heat treatment is performed in which the surface temperature of the platinum plating layer of the base material 2 on which the silver plating layer and the platinum plating layer are formed is maintained at 30° C. or higher and 80° C. or lower for 1 hour or longer. In addition, in the heat treatment of the present embodiment, it was held for 24 hours or less. As a result, the Ag component of the silver plating layer diffuses into the platinum plating layer, and an intermetallic compound of Ag ₃ Pt is generated. At this time, since almost all of Pt in the platinum plating layer is bonded to Ag, the platinum plating layer and a part of the silver plating layer are formed by an intermetallic compound of Ag ₃ Pt and form a compound with Ag. The silver-platinum alloy layer 5 has a Pt concentration of 10% by mass or less, and the rest of the silver-plated layer becomes the silver layer 4.

In the heat treatment step, if the surface temperature of the platinum plating layer is lower than 30°C, the intermetallic compound of Ag ₃ Pt cannot be sufficiently generated, and if it exceeds 80°C, the base material 2 made of copper or copper alloy is This is not suitable because diffusion of the Cu component is more likely to proceed. Further, if the heat treatment time is less than 1 hour, the intermetallic compound of Ag ₃ Pt cannot be sufficiently generated, so that the silver-platinum alloy layer cannot be properly formed, and if it exceeds 24 hours, the Cu component from the base material 2 is not formed. Therefore, it is desirable to complete the heat treatment within 24 hours because the amount of diffusion of H.

In this way, the connector terminal material 1 in which the nickel layer 3, the silver layer 4, and the silver-platinum alloy layer 5 are formed on the surface of the base material 2 is formed. Then, the connector terminal material 1 is subjected to press working or the like to form the connector terminal in which the silver-platinum alloy layer 5 is located at the contact portion.

In the connector terminal material 1 of the present embodiment, since the silver-platinum alloy layer 5 formed on the outermost surface of the base material 2 is formed of an intermetallic compound of Ag ₃ Pt, the hardness of the silver-platinum alloy layer 5 is increased. The wear resistance can be improved. In addition, since the silver-platinum alloy layer 5 is formed of an intermetallic compound of Ag ₃ Pt containing noble Pt which hardly forms an oxide like Ag of the silver-plated layer, it suppresses the oxidation of the silver-platinum alloy layer 5. By doing so, the increase in contact resistance is suppressed even in a high temperature environment, and heat resistance can be improved. Further, when the connector terminal material 1 is used as a connector terminal, the surface of the contact portion of the connector terminal is formed of the silver-platinum alloy layer 5, so that the occurrence of adhesive wear can be suppressed and the wear resistance can be improved. Can be improved. Further, a silver-platinum alloy layer is formed only on the outermost surface of the base material, and the film thickness of the intermetallic compound of Ag ₃ Pt is reduced to 0.04 μm or more and 1.9 μm or less to improve crack resistance, It suppresses cracking due to processing. Furthermore, since the silver layer 4 is formed on the nickel layer 3, it is possible to prevent the silver layer 4 from peeling from the base material. That is, the heat resistance of the connector terminal material 1 and the connector terminal using the same can be improved. When the silver-platinum alloy layer 5 is formed on the entire surface of the silver layer 4 because the silver-platinum alloy layer 5 is formed only on a part of the silver layer 4, that is, the contact portion of the connector terminal. Compared with, the manufacturing cost of the connector terminal can be reduced.

In the method of manufacturing the connector terminal material 1 of the present embodiment, after the silver plating layer is formed on the surface of the base material 2, the platinum plating layer is formed and a predetermined heat treatment is performed, so that the outermost surface of the base material 2 is formed. It is possible to manufacture the connector terminal material 1 on which the silver-platinum alloy layer 5 having high wear resistance, heat resistance, and crack resistance is formed.

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. For example, in the above embodiment, the nickel layer 3 is provided between the base material 2 and the silver layer 4, but the present invention is not limited to this, and the nickel layer 3 may not be included. That is, the silver layer 4 may be directly formed on the base material 2, and in this case, the nickel layer forming step and the silver strike plating step may not be performed.

Further, in the above-described embodiment, the silver-platinum alloy layer 5 is formed on a part of the silver layer 4, but the present invention is not limited to this. For example, the silver-platinum alloy layer 5 is formed on the entire upper surface of the silver layer 4. It may be formed. Further, the coating film composed of the nickel layer 3, the silver layer 4, and the silver-platinum alloy layer 5 may be formed only on a part of the surface of the base material 2.

[First embodiment]
Each sample of Examples 1-6 and Comparative Examples 1-5 was manufactured by the following method. For Examples 1 to 6, a base material made of a copper alloy plate and having a thickness of 0.3 mm was prepared, and the base material was pretreated by degreasing, pickling, or the like to clean the surface. A part of the surface of the material was nickel-plated to form a nickel-plated layer having a film thickness shown in Table 1 on the substrate. Then, an activation treatment for cleaning the nickel plating surface was performed using a 5 mass% potassium hydroxide aqueous solution. After this activation treatment, the base material coated with the nickel plating layer was subjected to silver strike plating to form a silver strike plating layer.

Then, a silver plating layer having a film thickness of 3 μm was formed by applying silver plating for 3 minutes on the silver strike plating layer. Then, the plating time was adjusted so that the Pt plating thickness expected value in Table 1 was obtained, and platinum plating was performed to form a platinum plating layer. The substrate on which the silver plating layer and the platinum plating layer were formed was held at the surface temperature of the platinum plating layer of 40° C. for 2 hours. In this way, a silver-platinum alloy layer formed of an intermetallic compound of Ag ₃ Pt having a film thickness shown in Table 1 was formed to obtain samples of Examples 1 to 6.

The conditions of each plating were 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 3A/dm ²

<Silver strike plating conditions>
・Plating bath composition Silver cyanide 2 g/L,
Potassium cyanide 100g/L
・Anode stainless steel plate (SUS316)
・Bath temperature 25℃
・Current density 1 A/dm ²

<Silver plating conditions>
・Plating bath composition Silver cyanide 40g/L
Potassium cyanide 140g/L
Potassium carbonate 15g/L
Additive 4ml/L
・Anode pure silver plate・Bath temperature 25℃
・Current density 2A/dm ²

<Platinum plating conditions>
・Plating bath composition Platinum concentration 8g/L
Sulfuric acid 20 g/L
Diammine dinitroplatinum 10g/L
Sulfamic acid, pH 1
・Anode platinum plate・Bath temperature 60℃
・Current density 1 A/dm ²

Further, in Comparative Examples 1 and 3, the silver-platinum alloy layer formed of the intermetallic compound of Ag ₃ Pt having the film thickness shown in Table 1 was formed by the same method as in Examples 1 to 6 above. In Comparative Example 1, the predicted Pt plating thickness was set to 1 μm. Further, in the sample of Comparative Example 3, the expected Pt plating thickness was thinned to 0.005 μm, so that no intermetallic compound of Ag ₃ Pt was generated and the outermost layer was a silver layer. On the other hand, for the sample of Comparative Example 5, the Pt plating thickness expected value was set to 1 μm by the same method as in Comparative Example 1 above, but the Pt plating thickness expected value was as large as 1 μm, and the Pt component was large in the silver-platinum alloy layer. Since it is contained, the Pt component in the silver-platinum alloy layer was made into an intermetallic compound of Ag ₃ Pt by heating this sample at 150° C. for 240 hours.

In addition, the sample of Comparative Example 2 uses a Nisshin Bright N bath to which antimony made by Nikkosei Co., Ltd. was added after performing nickel plating and silver strike plating on the surface of the base material as in Examples 1 to 6. Then, bright silver plating was performed. The composition of the plating bath was the standard composition, the bath temperature was 25° C., the current density was 1 A/dm ² , the pure silver plate was used as the anode, the silver alloy layer (AgSb layer) was formed, and the sample of Comparative Example 2 was obtained. ..

Further, for the sample of Comparative Example 4, nickel plating and silver strike plating were performed on the surface of the base material in the same manner as in Examples 1 to 6 and then silver plating was performed in the same manner as in Examples 1 to 6 to obtain a film thickness of 3 μm. Of the silver layer was formed and no platinum plating was applied. That is, in the sample of Comparative Example 4, the outermost surface was formed of the silver layer.
And various evaluation was performed about these Examples 1-6 and Comparative Examples 1-5.

[Estimated Pt plating thickness]
In addition, the Pt plating thickness expected value is a method similar to the manufacturing methods of Examples 1 to 6 and Comparative Examples 1 and 3 described above after performing strike gold plating on a copper alloy plate to prevent displacement. The plating was performed for a predetermined time. The sample was analyzed with a fluorescent X-ray film thickness meter to obtain the film thickness of the platinum plating layer. From the obtained film thickness of the platinum plating layer and the plating time, the deposition rate of plating was calculated using the following formula (1), and the samples of Examples 1 to 6 and Comparative Examples 1 and 3 are shown in Table 1. Platinum plating was performed by adjusting the plating time so that the Pt plating thickness would be the expected value. The predicted Pt plating thickness in Table 1 corresponds to the thickness of the platinum plating layer in the present invention.
Formula (1)... Deposition rate (μm/min)=platinum plating layer thickness (μm)÷plating time (min)

[Presence or absence of Ag ₃ Pt]
Regarding the intermetallic compound of Ag ₃ Pt, XRD measurement was performed at 45 kV, 40 mA and a scanning range of 2θ:30 to 100° by using an X-ray diffractometer (Empyrean manufactured by Malvern Panoramic Co., Ltd.), and the obtained peak was obtained. From the results, it was confirmed whether Ag ₃ Pt was produced and whether platinum remained. Thus, for those Ag 3 _Pt is generated, in Table 1 indicated as "Yes", for those Ag 3 _Pt is not generated, indicated by "none" in Table 1.

[Concentration of Pt not forming a compound with Ag]
Regarding the concentration of Pt, XRD measurement was performed using an X-ray diffractometer (Empyrean manufactured by Malvern Panoramic Co., Ltd.) at 45 kV, 40 mA, and a scanning range of 2θ:30 to 100°, and Pt remained from the obtained peak. I confirmed whether or not. As a result, in the case where Pt does not remain, it is shown as "0.0" in Table 1, and in the case where Pt remains, its concentration was calculated by the method shown below and shown in Table 1. .. Specifically, a focused ion beam device: FIB (model number: SMI3050TB) manufactured by Seiko Instruments Inc. is used to perform cross-section processing, and Ag and Pt are alloyed from a cross-section SIM (Scanning Ion Microscopy) image with an inclination angle of 60°. The thickness of the unreacted Pt unreacted layer was measured at three arbitrary positions, the arithmetic mean thereof was calculated, and then converted to the actual length to obtain the Pt unreacted layer thickness. Then, the concentration of Pt in the silver-platinum alloy layer that did not form a compound with Ag was calculated using the following formula (2).
Formula (2) Pt concentration=Pt unreacted layer thickness/(platinum plated layer thickness+silver plated layer thickness)
The film thickness of the platinum plating layer and the film thickness of the silver plating layer in the above formula (2) are the thicknesses before the heat treatment (before the heat treatment reaction).

[Ag ₃ Pt thickness]
Regarding the sample in which the platinum peak was not observed by the X-ray diffraction apparatus, it was considered that the platinum plating was the silver-platinum alloy layer made of Ag ₃ Pt. Then, cross-section processing was performed using a focused ion beam device: FIB (model number: SMI3050TB) manufactured by Seiko Instruments Inc., and Ag ₃ Pt thickness was measured from the cross-section SIM image, and shown in Table 1. On the other hand, regarding the sample in which the peak of platinum was observed by the X-ray diffraction apparatus, the platinum plating remained on the Ag ₃ Pt layer. Then, a cross section is processed using the focused ion beam device, and the cross section is subjected to composition mapping using an Auger electron spectroscope AES (model number PHI700xi, PHI670) manufactured by ULVAC-PHI at an acceleration voltage of 10 kV and an irradiation current of 5 nA. Then, the layer in which the at% ratio of Ag and Pt was 3:1 was regarded as the Ag ₃ Pt layer, and the Ag ₃ Pt thickness was measured.

[Vickers hardness]
Using a micro Vickers hardness tester HM-200 (manufactured by Mitutoyo Corporation) for each sample before heating (initial) and each sample after heating at 150° C. for 96 hours, under a load of 0.005 N The Vickers hardness was measured 10 times each.

[Hardness reduction amount]
The hardness decrease amount was calculated by subtracting the value of Vickers hardness after heating at 150° C. for 96 hours from the value of Vickers hardness before (initial) heating. In Comparative Example 1, since the Vickers hardness increased by 49 Hv, it was shown as “−49” in Table 1.

[Bending test]
A test piece was cut out from each sample before heating into a strip having a width of 10 mm so that the area between the silver-platinum alloy layer and the silver layer was 1:1 so that the boundary between the silver-platinum alloy layer and the silver layer became a bent portion. Then, after performing 120° bending with a bending 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 base material was 0.3 mm as described above. 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 evaluated as bad “B”, and the case where no abnormality was observed was evaluated as good “A”.

[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 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. is used, and the convex surface of the female test piece is brought into contact with the horizontally mounted male terminal test piece, and the male terminal test piece is 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. Since the sample of Comparative Example 5 was obtained by heating the sample of Comparative Example 1 at 150° C. for 240 hours, only the initial contact resistance value was measured.

As is clear from Table 1 and Table 2, in Examples 1 to 6, the silver-platinum alloy layer was formed of an intermetallic compound of Ag ₃ Pt, and the concentration of Pt not forming a compound with Ag was 10 mass. %, the initial Vickers hardness is 125 HV or more, the decrease amount after heating for 96 hours is as small as 15 HV or less, and the Vickers hardness after heating for 96 hours is 120 HV or more, so the wear resistance is high. Was shown. Further, in Examples 1 to 6, since the film thickness of the intermetallic compound of Ag ₃ Pt was as thin as 0.04 μm or more and 1.9 μm or less, the result of the bending test was also good “A”, and therefore the crack resistance was high. It was shown to be high. Furthermore, in Examples 1 to 6, the contact resistance value was as small as 0.4 mΩ or less at the maximum both in the initial case and after heating at 150° C. for 240 hours, and it was shown that the heat resistance was high. Note that FIG. 2 is a SIM image of Example 1 before heating at 150° C. for 240 hours. As shown in FIG. 2, it can be seen that the silver-platinum alloy layer formed of the intermetallic compound of Ag ₃ Pt is formed on the silver layer (Ag).

On the other hand, in Comparative Example 1, the thickness of the platinum plating layer (Pt plating thickness expected value) is as large as 1 μm, so the concentration of Pt not forming the compound with Ag is as high as 13% by mass. (Exceeding 10% by mass), the initial Vickers hardness was as low as 106 HV. This is also clear from the fact that the Vickers hardness after heating at 150° C. for 96 hours is 155 HV. Further, since the sample of Comparative Example 5 was obtained by heating the sample of Comparative Example 1 at 150° C. for 240 hours, the initial Vickers hardness was as high as 188 HV, but the silver-platinum alloy layer was 3.9 μm. Since it was too thick, the bending test was evaluated as "B". Furthermore, in Comparative Example 3, the film thickness of the platinum plating layer (the predicted value of the Pt plating film) was too thin as 0.005 μm, so that no intermetallic compound of Ag ₃ Pt was formed between the platinum plating layer and the silver plating layer. , The outermost layer became a silver layer. Therefore, the decrease in Vickers hardness was as large as 37 HV. This also applies to Comparative Example 4 in which the outermost layer is a silver layer. Further, in the sample of Comparative Example 2, since the outermost surface layer was composed of the silver alloy layer (AgSb) to which antimony was added, the initial Vickers hardness was as high as 195 HV, but the silver alloy layer was too hard. Was evaluated as poor "B", and the contact resistance after heating for 240 hours exceeded 20 mΩ, resulting in low crack resistance and heat resistance.

[Second Embodiment]
Each sample of Examples 7 to 9 and Comparative Example 6 was manufactured by the following method. For Examples 7 to 9, a base material made of a copper alloy plate and having a thickness of 0.3 mm was prepared, and the base material was subjected to degreasing, pickling, and the like for pretreatment to clean the surface, and then silver. Strike plating was applied to form a silver strike plating layer.

Then, a silver plating layer having a film thickness of 3 μm was formed by applying silver plating for 3 minutes on the silver strike plating layer. Then, the plating time was adjusted so as to reach the Pt plating thickness expected value in Table 3, and platinum plating was performed to form a platinum plating layer. The substrate on which the silver plating layer and the platinum plating layer were formed was held at the surface temperature of the platinum plating layer of 40° C. for 2 hours. In this way, a silver-platinum alloy layer formed of an intermetallic compound of Ag ₃ Pt having a film thickness shown in Table 3 was formed to obtain samples of Examples 7 to 9. The conditions of each plating were the same as in the first embodiment.

Further, in Comparative Example 6, silver strike plating was performed on the surface of the base material in the same manner as in Examples 7 to 9 and then silver plating was performed in the same manner as in Examples 6 to 8 to form a silver layer having a thickness of 3 μm. However, no platinum plating was applied. That is, in the sample of Comparative Example 6, the outermost surface was formed of the silver layer.
And various evaluation was performed about these Examples 7-9 and the comparative example 6.

As is clear from Tables 3 and 4, in Examples 7 to 9, the silver-platinum alloy layer was formed of an intermetallic compound of Ag ₃ Pt, and platinum was not present (a compound with Ag was formed). The initial Vickers hardness is 127 HV or higher, the decrease amount after heating for 96 hours is as low as 9 HV or less, and the Vickers hardness after heating for 96 hours is 123 HV or higher because the Pt concentration is not more than 10% by mass. It was shown that the wear resistance was high. Moreover, in Examples 7 to 9, since the film thickness of the intermetallic compound of Ag ₃ Pt was as thin as 0.04 μm or more and 1.9 μm or less, the result of the bending test was also good “A”, and therefore the crack resistance was high. It was shown to be high. Further, in Examples 7 to 9, the contact resistance value was as small as 0.5 mΩ or less at the maximum both in the initial case and after heating at 150° C. for 240 hours, and it was shown that the heat resistance was high. That is, it was found that even when the silver-platinum alloy layer was formed directly on the substrate without the nickel layer, the wear resistance, heat resistance and crack resistance could be improved.
On the other hand, in Comparative Example 6, since the outermost layer was composed of the silver layer, the amount of decrease in Vickers hardness was as large as 33 HV, resulting in low wear resistance.

1 Connector Terminal Material 2 Base Material 3 Nickel Layer 4 Silver Layer 5 Silver Platinum Alloy Layer

Claims (4)

A base material having at least a surface layer made of copper or a copper alloy, a silver layer containing silver as a main component coated on at least a part of the surface of the base material, and a silver-platinum alloy coated on at least a part of the silver layer. And a silver-platinum alloy layer consisting of
At least a part of the silver-platinum alloy layer is formed of an intermetallic compound of Ag ₃ Pt, the concentration of Pt not forming a compound with Ag is 10% by mass or less, and the intermetallic compound of Ag ₃ Pt is A terminal material for a connector, wherein the compound film thickness is 0.04 μm or more and 1.9 μm or less. The nickel layer made of nickel or a nickel alloy is provided between the base material and the silver layer, and the thickness of the nickel layer is 0.5 μm or more and 5 μm or less. Connector terminal material. It is a connector terminal which consists of the connector terminal material of Claim 1 or 2, Comprising: The said silver platinum alloy layer is located in the surface of a contact part, The connector terminal characterized by the above-mentioned. It is a manufacturing method of the terminal material for connectors of Claim 1, Comprising: At least one part of the surface of the base material whose surface layer consists of copper and a copper alloy is silver-plated, and a silver plating layer with a film thickness of 1 micrometer or more and 50 micrometers or less. And then at least a part of the silver-plated layer is plated with platinum to form a platinum-plated layer having a film thickness of 0.01 μm or more and 0.5 μm or less, and the surface temperature of the platinum-plated layer is 30° C. or more and 80° C. A method for manufacturing a terminal material for a connector, which is characterized by holding at the following temperature for 1 hour or more.