Terminal material for connector, method for manufacturing same, and connector

Abstract

A coating film is formed on the surface of a substrate comprising copper or a copper alloy, and the coating film comprises: a nickel layer formed on the surface of the substrate and comprising nickel or a nickel alloy; a copper-tin alloy layer formed on the nickel layer and composed of an alloy of copper and tin; and a tin layer formed on the copper-tin alloy layer and comprising tin or a tin alloy, in which the average thickness of the nickel layer is 0.05 [mu] m to 3.00 [mu] m, the arithmetic mean curvature (Spc) of the peak points on the surface of the copper-tin alloy layer is 700 mm-1 to 2200 mm-1, and the average thickness of the tin layer is 0.05 [mu] m to 2.00 [mu] m. And the average thickness of the copper-tin alloy layer is 0.15 [mu] m or more and 1.55 [mu] m or less.

Description

TECHNICAL FIELD

[0001] The present application relates to a terminal material for a connector having a low friction coefficient on the surface of the terminal material, a manufacturing method thereof, and a connector.

[0002] This application is based on Japanese Patent Application No. 2024-8424 filed on January 24, 2024, and Japanese Patent Application No. 2024-154278 filed on September 6, 2024, in the Japan Patent Office, and this application claims priority to Japanese Patent Application No. 2024-8424 and Japanese Patent Application No. 2024-154278, the contents of which are incorporated by reference herein. BACKGROUND

[0003] Conventionally, a vehicle-mounted connector used in connection of an electric wiring of an automobile or the like is known. The vehicle-mounted connector (vehicle-mounted terminal) has a terminal pair designed to be electrically connected by a contact piece provided on a female terminal and a male terminal inserted into the female terminal to contact at a prescribed contact pressure.

[0004] As such a connector (terminal), a terminal material in which copper plating and tin plating are performed on a copper or copper alloy plate, and reflow soldering treatment is performed, thereby forming a copper-tin alloy layer and a tin layer on the copper or copper alloy plate, is known to have excellent wear resistance.

[0005] As the terminal material in which such a copper-tin alloy layer and a tin layer are formed, for example, in Patent Document 1, by controlling the roughness of the base material, the exposure state of the copper-tin alloy layer from the tin layer is controlled, and the insertion force is reduced, but in order to control the roughness of the base material, processing needs to be performed in advance.

[0006] Also, in Patent Document 2, the insertion force is reduced by making the tin layer composed of tin or a tin alloy on the copper-tin alloy layer very thin, but since the tin layer is small, there is a problem that the contact resistance increases after heating.

[0007] Also, in Patent Document 3, by replacing a part of the copper-tin alloy with nickel (Ni), the copper-tin alloy is provided in a steep concave-convex shape, and a tin layer of 0.2 μm or more and 0.6 μm or less is left, thereby reducing friction and preventing the contact resistance from becoming high at the time of heating, but since the copper-tin alloy layer is steep, there is a problem that it is easily shaved off at the time of sliding and has poor wear resistance.

[0008] Patent Document 1: Japanese Patent Application Publication No. 2007-100220

[0009] Patent Document 2: Japanese Patent Application Publication No. 2011-012320

[0010] Patent Document 3: Japanese Patent Application Publication No. 2014-240520

[0011] In the terminal material described in these patent documents, in order to reduce the coefficient of friction, the tin layer of the surface layer is thinned to increase the proportion of the hard copper-tin alloy layer. The tin layer, which is soft on the surface, easily causes sticking at the time of insertion, and there is a problem in that the insertion force becomes high, and therefore, in order to prevent this sticking, it is preferable for the copper-tin alloy layer to be exposed on the surface, but the contact resistance becomes high in a high-temperature environment, and the wear resistance against micro-slip wear is insufficient. SUMMARY

[0012] The present application was completed in view of this situation, and aims to control the shape of the surface of the copper-tin alloy layer, reduce the coefficient of friction, and improve the wear resistance and heat resistance.

[0013] The connector terminal material of the present application is provided with a coating film formed on the surface of a base material composed of copper or a copper alloy, and the coating film has a nickel layer formed on the surface of the base material and composed of nickel or a nickel alloy, a copper-tin alloy layer formed on the nickel layer and composed of an alloy of copper and tin, and a tin layer formed on the copper-tin alloy layer and composed of tin or a tin alloy, the average thickness of the nickel layer is 0.05 μm or more and 3.00 μm or less, the arithmetic mean curvature of the peak apex on the surface of the copper-tin alloy layer, Spc, is 700 mm or more and 2200 mm or less, and the average thickness of the tin layer is 0.05 μm or more and 2.00 μm or less, and the average thickness of the copper-tin alloy layer is 0.15 μm or more and 1.55 μm or less. -1 The average thickness of the tin layer is 0.05 μm or more and 2.00 μm or less, and the average thickness of the copper-tin alloy layer is 0.15 μm or more and 1.55 μm or less. -1 The average thickness of the tin layer is 0.05 μm or more and 2.00 μm or less, and the average thickness of the copper-tin alloy layer is 0.15 μm or more and 1.55 μm or less.

[0014] The smaller the arithmetic mean curvature of the peak apex, Spc, the more rounded the tip end is, and the larger the arithmetic mean curvature of the peak apex, Spc, the more pointed the tip end is. If the arithmetic mean curvature of the peak apex, Spc, is less than 700 mm -1 , the surface shape of the copper-tin alloy layer (and the interface shape with the tin layer) becomes gentle, the contact area with the counterpart terminal increases, and therefore the coefficient of friction becomes high. Also, the wear resistance decreases. On the other hand, if the arithmetic mean curvature of the peak apex, Spc, exceeds 2200 mm -1 , the surface shape of the copper-tin alloy layer becomes more pointed, and therefore the copper-tin alloy layer is easily shaved off at the time of sliding, the coefficient of friction becomes high. Also, the wear resistance decreases.

[0015] In this case, if the average thickness of the tin layer is less than 0.05 μm, the contact resistance in a high-temperature environment becomes high, and if it exceeds 2.00 μm, sticking wear easily occurs at the time of sliding, and the coefficient of friction becomes high.

[0016] Further, when the average thickness of the copper-tin alloy layer is less than 0.15 μm, the arithmetic mean curvature SPC of the peak apex becomes small, and thus the friction coefficient becomes high, and the wear resistance is reduced. When the average thickness of the copper-tin alloy layer exceeds 1.55 μm, the arithmetic mean curvature SPC of the peak apex becomes large, and thus the friction coefficient becomes high, and the wear resistance is reduced.

[0017] The nickel layer has an effect of preventing diffusion of copper from the base material in a high-temperature environment, but when the average thickness thereof is less than 0.05 μm, the effect of preventing diffusion of copper from the base material is poor, and the speed at which the copper-tin alloy is formed becomes fast, and the contact resistance becomes high. When the average thickness of the nickel layer exceeds 3.00 μm, a crack can be generated at the time of bending processing.

[0018] In the connector terminal material of the present application, the roundness of the copper-tin alloy particles on the surface of the copper-tin alloy layer is preferably 0.5 or more.

[0019] The closer the roundness is to 1, the closer it is to a perfect circle, and the function as a contact point is stable, and a good friction coefficient can be obtained. When the roundness is less than 0.5, the function as a contact point becomes uneven, the friction coefficient becomes slightly high, and the wear resistance is slightly reduced.

[0020] In the connector terminal material of the present application, the tin layer of the coating is removed to expose the copper-tin alloy layer, and a portion of the copper-tin alloy layer is exposed on the surface of the tin layer that is exposed, and the exposure area ratio of the copper-tin alloy layer on the surface of the tin layer is preferably 5% or more and 70% or less.

[0021] By exposing the copper-tin alloy layer that is harder than the tin layer to the surface, in combination with the lubricating effect of the soft tin layer, the friction coefficient can be reduced. When the exposure area ratio of the copper-tin alloy layer is less than 5%, the effect of reducing the friction coefficient is poor, and when the exposure area ratio exceeds 70%, the occupied area of the tin layer on the surface becomes small, and the contact resistance can become high in a high-temperature environment.

[0022] In the connector terminal material of the present application, it is preferable to have a connection portion connected to the opposite side and a substrate fixing portion fixed to a substrate, and the coating is formed at least in the connection portion.

[0023] In this case, a tin surface layer in which the surface is composed of tin or a tin alloy can be formed on the entire surface of the front and back surfaces and both side surfaces of the substrate fixing portion.

[0024] By forming the aforementioned coating at least in the connection portion, a terminal having excellent insertion properties is obtained.

[0025] Also, in the connector terminal material to be fixed to a substrate, a "post-plating method" in which plating is performed after punching a metal plate is preferably used, and a film is preferably formed at least on a connection portion to be connected to the other side, and a tin surface layer in which the surface is composed of tin or a tin alloy is preferably formed at least on the entire surface of a fixing portion to the substrate.

[0026] In the needle-shaped terminal, a tin surface layer in which the surface is composed of tin or a tin alloy is formed on the entire surface of the substrate fixing portion, whereby the solderability is excellent, and the film is formed on the connection portion to the other side, whereby the terminal is excellent in the insertion property.

[0027] The connector of the present application has one-side terminals and the other-side terminals which can be connected to each other, and at least either one of the one-side terminals and the other-side terminals can be composed of the connector terminal material, and the difference between the arithmetic average curvatures SPC of the peak apexes on the surfaces of the copper-tin alloy layers of the one-side terminals and the other-side terminals is in the range of 200 mm -1 or more and 1200 mm -1 or less.

[0028] By setting the difference between the arithmetic average curvatures SPC of the peak apexes to be in the range of 200 mm -1 or more and 1200 mm -1 or less, the real contact area becomes small, and thus the sliding trace becomes small, and the friction coefficient can be further reduced.

[0029] Also, when the difference between the roundnesses of the copper-tin alloy particles on the surfaces of the copper-tin alloy layers of the one-side terminals and the other-side terminals is in the range of 0.4 or less, the friction coefficient can be further reduced.

[0030] The manufacturing method of the connector terminal material of the present application includes: a plating layer forming step of sequentially laminating a nickel plating layer composed of nickel or nickel alloy, a copper plating layer composed of copper or copper alloy, and a tin plating layer composed of tin or tin alloy on the surface of a base material composed of copper or copper alloy, thereby forming a base material with plating layer; and a reflow soldering treatment step of performing reflow soldering treatment of heating the base material with plating layer, in the plating layer forming step, the thickness of the nickel plating layer is formed to be 0.05 μm or more and 3.00 μm or less, the thickness of the copper plating layer is formed to be 0.10 μm or more and 0.70 μm or less, and the thickness of the tin plating layer is formed to be 0.20 μm or more and 2.90 μm or less, the reflow soldering treatment step includes: a first heating treatment of heating the base material with plating layer to be less than the melting point of tin by passing the base material with plating layer through a first heating furnace set to a first furnace temperature of 150°C or more and 270°C or less in an atmosphere for a time of 3 seconds or more and 30 seconds or less; a second heating treatment of heating the base material with plating layer by passing the base material with plating layer through a second heating furnace set to a second furnace temperature of 232°C or more and 350°C or less higher than the first furnace temperature for a time of 3 seconds or more and 35 seconds or less after the first heating treatment; and a cooling treatment of immediately quenching the base material with plating layer after the tin plating layer is melted by the second heating treatment.

[0031] The reflow soldering treatment step is set to two-stage heating after cooling under prescribed temperature conditions, whereby the arithmetic mean curvature Spc of the peak apex on the surface of the copper-tin alloy layer can be controlled within a prescribed range. In this case, the copper-tin alloy is grown in the first heating treatment and is melted to form a copper-tin alloy layer of prescribed shape in the second heating treatment, so the temperature of the second heating treatment needs to be higher than that of the first heating treatment, and in the case where the first heating treatment and the second heating treatment are set to the same temperature or the temperature of the second heating treatment is lower than that of the first heating treatment, the copper-tin alloy layer cannot be set to a prescribed shape, and it is difficult to control the arithmetic mean curvature Spc of the peak apex on the surface thereof within a prescribed range. In addition, the plating layer is changed in the reflow soldering treatment step, but the base material with plating layer is referred to before the end of the reflow soldering treatment step.

[0032] If the heating of the reflow soldering treatment is insufficient, the average thickness of the copper-tin alloy layer is less than 0.15 μm, and if the heating of the reflow soldering treatment is excessive, the average thickness of the copper-tin alloy layer exceeds 1.55 μm.

[0033] In the first heating treatment in the reflow soldering process, the plated base material is heated to a temperature less than the melting point of tin without melting the tin plating layer. In the second heating treatment, immediately after the surface tin plating layer is melted and brightened, the process is shifted to the cooling treatment, and therefore the plated base material is always in a temperature rising state and does not remain at the peak temperature at which tin is melted in the second heating treatment.

[0034] Here, the shape of the copper-tin alloy layer is affected by the thicknesses of the tin plating layer and the copper plating layer in addition to the reflow soldering process conditions. The effects of the thicknesses of the tin plating layer and the copper plating layer are described below. In the case where the thickness of the copper plating layer is 0.10 μm or more and the thickness of the tin plating layer is less than 0.20 μm, the residual copper plating layer is observed, Spc becomes small, the friction coefficient becomes high, and the wear resistance is reduced. Also, since the tin layer is thin, the contact resistance becomes high. If the thickness of the copper plating layer is less than 0.10 μm, a part of the copper-tin alloy is replaced by nickel, and therefore the shape of the copper-tin alloy layer becomes steep, Spc becomes large, the friction coefficient becomes high, and the wear resistance is reduced.

[0035] Further, in the cooling treatment, it is preferable that the cooling time until the temperature of the plated base material reaches 50°C is set to 4 seconds or more and 60 seconds or less.

[0036] According to the present application, by controlling the surface of the copper-tin alloy layer to a prescribed shape, the friction coefficient can be reduced, and the wear resistance and the heat resistance can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a plan view of the connector terminal material according to the embodiment of the present application.

[0038] Figure 2 is a schematic cross-sectional view of the connector terminal material of Figure 1

[0039] Figure 3 is a flowchart showing the manufacturing method of the connector terminal material of Figure 1

[0040] Figure 4 is a schematic cross-sectional view of the plated base material before the reflow soldering process of the connector terminal material of Figure 2

[0041] Figure 5 is a Back Scattered Electron (BSE) image of the cross section of Test Material 7. DETAILED DESCRIPTION

[0042] Hereinafter, the embodiment of the present application is described with reference to the drawings.

[0043] ​​​[Structure of terminal material for connector]

[0044] As shown in Figure 1 , the terminal material for connector 1 of the present embodiment is a terminal chain body formed by punching a long plate material, and is formed by connecting a plurality of terminal portions 10 in a needle terminal shape.

[0045] Specifically, a plurality of terminal portions 10 are arranged side by side in a direction connecting the pair of elongated link members 11, 12. Each terminal portion 10 is formed continuously from a front end with a needle-shaped connecting portion 13, a shoulder portion 14 having a wide width, and a substrate fixing portion 15, and both ends (a front end of the connecting portion 13 and a base end of the substrate fixing portion 15) are connected to the link members 11, 12. The terminal portion 10 is used by being fixed to a substrate or the like in an electrically connected state by being pressed or welded into a through-hole or the like of the substrate, and is electrically connected by being inserted into another female terminal.

[0046] In addition, the shape of the terminal is an example, and is not limited to the Figure 1 shape shown in the drawing, as long as it has a connecting portion that electrically connects with a counterpart terminal.

[0047] Also, as schematically represented in the cross section in Figure 2 , the terminal material for connector 1 is formed with a film 22 on a base material 21 composed of copper or a copper alloy, and as the film 22, a nickel layer 23 composed of nickel or a nickel alloy, a copper-tin alloy layer 24 composed of an alloy of copper and tin, and a tin layer 25 composed of tin or a tin alloy are formed in this order.

[0048] In Figure 2 , a cross section in the thickness direction is shown, but the film 22 is formed on the entire surface of the front and back surfaces and the two side surfaces of the base material 21.

[0049] The base material 21 is composed of copper or a copper alloy, and its composition is not particularly limited, and for example, is composed of a plate material composed of oxygen-free copper (C10200) or a Cu-Mg-based copper alloy (C18665), brass, phosphor bronze, or the like.

[0050] The nickel layer 23 has a function of suppressing diffusion of copper from the base material 21 to the copper-tin alloy layer 24 and the tin layer 25 formed on the nickel layer 23. The average thickness (film thickness) of the nickel layer 23 is 0.05 μm or more and 3.00 μm or less. If the average thickness of the nickel layer 23 is less than 0.05 μm, the effect of preventing diffusion of copper from the base material 21 under a high-temperature environment is poor, the rate of becoming a copper-tin alloy becomes fast, and the contact resistance becomes high. On the other hand, if the average thickness of the nickel layer 23 exceeds 3.00 μm, a crack can occur at the time of bending processing. In addition, the nickel layer 23 is composed of nickel or a nickel alloy, and the composition thereof is not particularly limited. The average thickness of the nickel layer 23 is preferably 0.10 μm or more and 2.00 μm or less.

[0051] The copper-tin alloy layer 24 is a layer obtained by sequentially forming a copper plating layer and a tin plating layer on the nickel layer 23 and performing a reflow soldering process. The surface of the copper-tin alloy layer 24, that is, the interface with the tin layer 25 thereon is formed in a concave-convex shape, and a part thereof is exposed to the surface of the tin layer 25. The average thickness of the copper-tin alloy layer 24 is 0.15 μm or more and 1.55 μm or less. The average thickness of the copper-tin alloy layer 24 and the arithmetic mean curvature Spc of the peak apex on the surface of the copper-tin alloy layer 24 are affected by the reflow soldering process conditions described later and the thicknesses of the tin plating layer 33 and the copper plating layer 32 at the time of manufacturing.

[0052] Regarding the effect of the reflow soldering process conditions, first, in a case where the average thickness of the copper-tin alloy layer 24 is less than 0.15 μm due to insufficient heating of the reflow soldering process, the arithmetic mean curvature Spc of the peak apex on the surface of the copper-tin alloy layer 24 described later becomes small, the exposed area ratio on the surface of the tin layer 25 decreases, and the friction coefficient becomes high. Also, since the average thickness of the hard copper-tin alloy layer 24 is thin, the wear resistance decreases. On the other hand, in a case where the average thickness of the copper-tin alloy layer 24 exceeds 1.55 μm due to excessive heating of the reflow soldering process, the arithmetic mean curvature Spc of the peak apex on the surface of the copper-tin alloy layer 24 becomes large, the friction coefficient becomes high, and the wear resistance decreases. The lower limit of the average thickness of the copper-tin alloy layer 24 is preferably 0.31 μm.

[0053] Regarding the effect of the thicknesses of the tin plating layer 33 and the copper plating layer 32 at the time of manufacturing, first, in a case where the thickness of the copper plating layer is 0.10 μm or more and the thickness of the tin plating layer is less than 0.20 μm, the residual of the copper plating layer is observed, the Spc becomes small, the friction coefficient becomes high, and the wear resistance decreases. Also, since the tin layer is thin, the contact resistance becomes high. On the other hand, if the thickness of the copper plating layer is less than 0.10 μm, a part of the copper-tin alloy is replaced with nickel, and thus the shape of the copper-tin alloy layer becomes steep, the Spc becomes large, the friction coefficient becomes high, and the wear resistance decreases.

[0054] Further, the exposed area ratio of the copper-tin alloy layer 24 on the surface of the tin layer 25 is preferably 5% or more and 70% or less. By exposing the copper-tin alloy layer 24, which is harder than the tin layer 25, to the surface, in combination with the lubricating action of the soft tin layer 25, the friction coefficient can be reduced. When the exposed area ratio of the copper-tin alloy layer 24 is less than 5%, the effect of reducing the friction coefficient is poor, and the surface of the tin layer 25 increases by a corresponding amount, so that adhesive wear is likely to occur, and the friction coefficient can become high. Further, the wear resistance can also decrease. When the exposed area ratio exceeds 70%, the occupied area of the tin layer 25 on the surface becomes small, and the contact resistance can become high in a high-temperature environment. The exposed area ratio of the copper-tin alloy layer 24 is more preferably set to 10% or more and 50% or less.

[0055] Further, the arithmetic mean curvature SPC of the peak apex on the surface of the copper-tin alloy layer 24, which is measured by removing the tin layer 25, is 700 mm -1 or more and 2200 mm -1 or less. The arithmetic mean curvature SPC of the peak apex is a parameter measured in accordance with ISO 25178, and the smaller the value, the more rounded the front end, and the larger the value, the more pointed the front end. When the arithmetic mean curvature SPC of the peak apex is less than 700 mm -1 , the surface shape of the copper-tin alloy layer 24 (and the interface shape with the tin layer 25) becomes gentle. Further, the exposed area ratio decreases, and the occupied area of the tin layer 25 on the surface of the film 22 tends to increase. Therefore, the friction coefficient becomes high, and the wear resistance decreases.

[0056] On the other hand, when the arithmetic mean curvature SPC of the peak apex exceeds 2200 mm -1 , the surface shape of the copper-tin alloy layer 24 becomes more pointed, so that the copper-tin alloy layer 24 is easily shaved off during sliding, and the friction coefficient becomes high. Further, the wear resistance decreases. The arithmetic mean curvature SPC of the peak apex on the surface of the copper-tin alloy layer 24 is preferably 900 mm -1 or more and 1900 mm -1 or less.

[0057] Further, the roundness of the copper-tin alloy particles on the surface (interface with the tin layer 25) of the copper-tin alloy layer 24 is preferably 0.5 or more. The roundness is defined by 4π x (particle area) ÷ (perimeter) 2 . The closer the roundness of the copper-tin alloy particles to 1, the closer to a perfect circle, and when viewed from the surface, the particles are set to a state close to a circle, so that the contact is stable, and a low friction coefficient can be obtained.

[0058] If the roundness of the copper-tin alloy particles is less than 0.5, the contact between the copper-tin alloy layer 24 exposed on the surface of the tin layer 25 and the sliding counterpart terminal becomes uneven when the connector slides, and the friction coefficient is likely to increase. In addition, the wear resistance is slightly reduced. The roundness of the copper-tin alloy particles is more preferably 0.55 or more. In addition, the higher the roundness of the copper-tin alloy particles, the more the friction coefficient decreases and becomes better, but in fact it is difficult to control the shape of the copper-tin alloy layer 24 to a roundness exceeding 0.85.

[0059] The tin layer 25 is a layer composed of tin or a tin alloy, and its average thickness is formed to be greater than 0.05 μm and less than 2.00 μm. If the average thickness of the tin layer is less than 0.05 μm, the contact resistance in a high-temperature environment becomes high. If it exceeds 2.00 μm, adhesive wear is likely to occur, and the friction coefficient becomes high. In addition, the exposed area ratio of the copper-tin alloy layer 24 is also reduced. The average thickness of the tin layer 25 is preferably greater than 0.05 μm and less than 1.00 μm, and more preferably greater than 0.10 μm and less than 0.50 μm.

[0060] [Manufacturing method of connector terminal material]

[0061] Next, a method for manufacturing the connector terminal material 1 will be described.

[0062] like Figure 3 As shown, the manufacturing method of the connector terminal material 1 includes: a punching step, in which a slender plate is punched out by punching to form a terminal chain body that becomes the base material 21; a pretreatment step, in which the surface of the punched base material 21 is cleaned; a plating layer forming step, in which a nickel plating layer 31, a copper plating layer 32, and a tin plating layer 33 are sequentially formed on the surface of the base material 21; and a reflow treatment step, in which the base material 35 with the three plating layers 31 to 33 is heated and reflowed. The following describes the steps in order.

[0063] (Punching process)

[0064] While unwinding the elongated sheet wound into a coil, it is punched out by a punching press to form Figure 1 The terminal chain body of the substrate 21 is shown.

[0065] [Pretreatment process]

[0066] The punched base material 21 is subjected to a pre-treatment of cleaning the surface by degreasing, pickling, or the like.

[0067] (Plating Layer Forming Step)

[0068] -Nickel plating-

[0069] A nickel plating treatment for forming a nickel plating layer 31 composed of nickel or a nickel alloy is performed on the surface of the substrate 21 on which the pretreatment has been performed. The plating bath can use a general nickel plating bath, and for example, a sulfamic acid bath in which nickel sulfamate, nickel chloride, and boric acid are main components can be used. The temperature of the plating bath is 40°C or higher and 60°C or lower, and the current density is 1 A / dm 2 or lower and 10 A / dm 2 or lower. The thickness of the nickel plating layer 31 is 0.05 μm or more and 3.00 μm or less.

[0070] - Copper plating layer -

[0071] A copper plating treatment for forming a copper plating layer 32 composed of copper or a copper alloy is performed on the nickel plating layer 31. The copper plating can use a general copper plating bath, and for example, a copper sulfate bath in which copper sulfate and sulfuric acid are main components can be used. The temperature of the plating bath is 20°C or higher and 60°C or lower, and the current density is 1 A / dm 2 or lower and 10 A / dm 2 or lower.

[0072] The thickness of the copper plating layer 32 is 0.10 μm or more and 0.70 μm or less. In the case where the thickness of the copper plating layer is 0.10 μm or more and the thickness of the tin plating layer is less than 0.20 μm, the residual of the copper plating layer is observed after the reflow soldering treatment step, Spc becomes small, the friction coefficient becomes high, and the wear resistance can be reduced. If the thickness of the copper plating layer 32 exceeds 0.70 μm, the exposed area ratio of the copper-tin alloy layer 24 exposed from the surface of the tin layer 25 after the reflow soldering treatment step becomes large, and the contact resistance can become high. On the other hand, if the thickness of the copper plating layer 32 is less than 0.10 μm, a part of the copper-tin alloy is replaced with nickel, and thus the shape of the copper-tin alloy layer becomes steep, Spc becomes large, the friction coefficient becomes high, and the wear resistance can be reduced. The exposed area ratio of the copper-tin alloy layer 24 can also become small. The thickness of the copper plating layer 32 is preferably 0.20 μm or more and 0.50 μm or less. The lower limit of the thickness of the copper plating layer 32 is more preferably 0.30 μm.

[0073] - Tin plating layer -

[0074] A tin plating treatment for forming a tin plating layer 33 composed of tin or a tin alloy is performed on the copper plating layer 32. As the plating bath for forming the tin plating layer 33, a general tin plating bath can be used, and for example, a methanesulfonic acid bath in which methanesulfonic acid and tin methanesulfonate are main components can be used. The temperature of the plating bath is 20°C or higher and 40°C or lower, and the current density is 1 A / dm 2 or lower and 20 A / dm 2 or lower.

[0075] The thickness of the tin plating layer 33 is set to 0.20 μm or more and 2.90 μm or less. If the thickness of the tin plating layer 33 is less than 0.20 μm, the average thickness of the tin layer 25 after the reflow soldering process becomes thin, and thus the contact resistance in a high-temperature environment can become high. If the thickness of the tin plating layer 33 exceeds 2.90 μm, the tin layer 25 after the reflow soldering process becomes thick, the exposed area ratio of the copper-tin alloy layer 24 decreases, and galling is likely to occur, and thus the friction coefficient can become high. The thickness of the tin plating layer 33 is more preferably 0.20 μm or more and 1.30 μm or less, and further preferably 0.40 μm or more and 1.00 μm or less.

[0076] Thus, by sequentially forming the nickel plating layer 31, the copper plating layer 32, and the tin plating layer 33 on the surface of the base material 21, as shown in FIG. 1, a plated base material 35 in which three plating layers 31 to 33 are laminated is obtained. In this case, the base material 21 before plating is in a state in which it is punched and cut in a chain terminal shape, and the base material 21 is immersed in a plating bath to form the plating layers 31 to 33, and thus three plating layers 31 to 33 are formed not only on the front and back surfaces of the base material 21 but also on the two side surfaces (cut end surfaces at the time of cutting). However, the present application can also be used in a "partial plating" process in which a portion of a base material is immersed in a plating bath. Figure 4

[0077] (Reflow Soldering Process)

[0078] As described above, the plated base material 35 in which the plating layers 31 to 33 are formed is subjected to a reflow soldering process. In the reflow soldering process, in the case of an elongated plate material (strip material) that is wound around a roll, the above-described pretreatment and plating treatment are continuously performed while the plate material is caused to travel in the longitudinal direction, and the plate material is caused to pass through a reflow soldering furnace to be processed, but in the case of the plated base material 35 of the present embodiment, the plated base material 35 is supplied to a relatively small reflow soldering furnace to be processed after the above-described pretreatment and plating treatment are performed on a cut material that is cut to a predetermined length by punching as shown in FIG. 1. Figure 1

[0079] ​​Specifically, the first heating treatment is performed by first passing the plated base material 35 through a first heating furnace set to a first furnace temperature of 150°C or higher and 270°C or lower in an atmosphere, and heating to less than the melting point of tin within a time of 3 seconds or more and 30 seconds or less. The second heating treatment is performed by subsequently passing the plated base material 35 through a second heating furnace set to a second furnace temperature of 232°C or higher and 350°C or lower, which is higher than the first furnace temperature, and heating within a time of 3 seconds or more and 35 seconds or less. The cooling treatment is performed by immediately quenching the plated base material 35 after the tin plating layer is melted by the second heating treatment.

[0080] In the reflow soldering treatment process, the two-stage heating of heating to near the melting temperature of the tin plating layer 33 and then further reflow soldering the tin plating layer 33 to melt it causes the copper-tin alloy particles and tin particles formed by the copper plating layer 32 and the tin plating layer 33 to grow slowly, and enables control to a rounded shape. Thus, the arithmetic mean curvature Spc of the peak apex on the surface of the aforementioned copper-tin alloy layer 24 and the roundness can be controlled within a prescribed range.

[0081] In addition, the atmosphere of the first and second heating treatments of the reflow soldering treatment process can be in the atmosphere, and water vapor can be additionally introduced.

[0082] In this case, in the first heating treatment, the furnace temperature is sometimes, for example, a high temperature of 270°C, but the plated base material 35 does not rise to the melting temperature of tin, so the tin plating layer 33 does not melt at this stage. This first heating treatment is a preliminary stage for rapidly melting the tin plating layer 33 in the second heating treatment.

[0083] In the first heating treatment, if the first furnace temperature is less than 150°C or the time is less than 3 seconds, the heating is insufficient, the formation of the copper-tin alloy in the second heating treatment is insufficient, and it is difficult to form the copper-tin alloy layer 24 of the desired average thickness, and in addition, the arithmetic mean curvature Spc of the peak apex on the surface of the aforementioned copper-tin alloy layer is small, the roundness is small, and it is difficult to reliably control within a prescribed range. On the other hand, if the first furnace temperature exceeds 270°C, or the temperature of the plated base material 35 becomes the melting point of tin or higher and the tin plating layer 33 melts in the first heating treatment, the arithmetic mean curvature Spc of the peak apex on the surface of the copper-tin alloy layer 24 becomes large, so the wear resistance decreases. Also, the tin layer 25 becomes thin, and the contact resistance becomes high. When the time exceeds 30 seconds, it becomes excessive heating, the tin layer 25 becomes thin, and the contact resistance becomes high.

[0084] Further, in the second heat treatment, if the second furnace temperature is less than 232°C or the time is less than 3 seconds, the copper-tin alloy is not formed sufficiently, it is difficult to form the copper-tin alloy layer 24 of the desired average thickness, the Spc becomes small, and thus the friction coefficient becomes high, and the wear resistance can be reduced. On the other hand, if the second furnace temperature exceeds 350°C, the arithmetic average curvature Spc of the peak top on the surface of the copper-tin alloy layer 24 becomes large due to excessive heating, and thus the friction coefficient becomes high, and the wear resistance can be reduced. Further, the tin layer 25 becomes thin, and the contact resistance becomes high. Even in the case where both the first furnace temperature and the second furnace temperature exceed the prescribed temperature, the arithmetic average curvature Spc of the peak top on the surface of the copper-tin alloy layer 24 becomes large due to excessive heating, and thus the friction coefficient becomes high, and the wear resistance can be reduced. Further, the tin layer 25 becomes thin, and the contact resistance becomes high. If the time of the second heat treatment exceeds 35 seconds, the tin layer 25 becomes thin, and the contact resistance becomes high. However, in the case where the tin plating layer 33 is thick or in the case where the copper plating layer 32 is thin, even if the heating temperature becomes high or the heating time becomes long, the tin layer 25 becomes thick.

[0085] In the second heat treatment, the tin plating layer of the belt-plated substrate 35 is melted. With respect to the melting of the tin plating layer, if the tin of the belt-plated substrate 35 is melted, the surface changes from white to a lustrous silver color, and thus it can be confirmed.

[0086] In the second heat treatment, immediately after the tin plating layer of the most surface is melted and glossified, the cooling treatment is started, and thus in the second heat treatment, the belt-plated substrate 35 is always in a state of being heated, and is not kept at the peak temperature at which the tin is melted.

[0087] Further, with respect to the relationship between the furnace temperature and the time through the furnace in the reflow soldering process, the higher the furnace temperature, the shorter the time. For example, in the first heat treatment, if the furnace temperature is close to 150°C, the time is extended to about 30 seconds, and if the furnace temperature is close to 270°C, the time is shortened to about 3 seconds. In the second heat treatment as well, if the furnace temperature is close to 232°C, the time is extended to about 35 seconds, and if the furnace temperature is close to 350°C, the time is shortened to about 3 seconds.

[0088] In this case, the relationship between the furnace temperature and the time can be subdivided within a prescribed temperature range, for example, in the first heating treatment, the time is set to more than 19 seconds and 30 seconds or less when the furnace temperature is 150°C or higher and less than 200°C, 8 seconds or more and 19 seconds or less when the furnace temperature is 200°C or higher and less than 250°C, and 3 seconds or more and 8 seconds or less when the furnace temperature is 250°C or higher and 270°C or lower, and in the second heating treatment, the time is set to more than 23 seconds and 35 seconds or less when the furnace temperature is 232°C or higher and less than 280°C, 11 seconds or more and 23 seconds or less when the furnace temperature is 280°C or higher and less than 320°C, and 3 seconds or more and 11 seconds or less when the furnace temperature is 320°C or higher and 350°C or lower. This method of subdivision can be set by taking into account the ease of management and the like.

[0089] In addition, the first heating furnace and the second heating furnace are arranged without a gap, and the plated base material 35 is continuously passed from the first heating furnace to the second heating furnace.

[0090] Also, in the cooling treatment, the cooling time until the temperature of the plated base material 35 reaches 50°C is preferably set to 4 seconds or more and 60 seconds or less. It is physically difficult to cool the temperature of the plated base material 35 to 50°C with a cooling time of less than 4 seconds under atmospheric cooling. In addition, in the case where the temperature of the plated base material 35 is cooled to 50°C with a cooling time of more than 60 seconds, the formation of the copper-tin alloy is not sufficiently suppressed, and the alloy shape can not be circular and the circularity can be small.

[0091] The cooling treatment is started immediately after the tin plating layer of the plated base material 35 is melted in the second heating treatment, for example, within 2 seconds, preferably within 1 second after the melting. Strictly speaking, the plated base material 35 is cooled from the vicinity of the outlet of the second heating furnace. The cooling is preferably performed by blowing cold air or water against the plated base material 35 that has come out of the second heating furnace, or by passing the plated base material 35 through a water tank or the like.

[0092] By thus performing the reflow soldering treatment, the plated base material 21 becomes a state in which the nickel layer 23, the copper-tin alloy layer 24, and the tin layer 25 are sequentially formed as the plating layer 22 on the base material 21. As described above, the plating layer 31 to 33 is formed not only on the front and back surfaces of the base material 21 but also on the side surfaces, and thus the plating layer 22 composed of the nickel layer 23, the copper-tin alloy layer 24, and the tin layer 25 is formed on the side surfaces as well as on the front and back surfaces, and the entire surface of the base material 21 becomes covered with the plating layer 22.

[0093] In addition, by the reflow soldering process, the copper of the copper plating layer 32 reacts with the tin of the tin plating layer 33 to form the copper-tin alloy layer 24 and the tin layer 25, but there are cases where a portion of the copper of the copper plating layer 32 remains unreacted, and a thin copper layer exists between the nickel layer 23 and the copper-tin alloy layer 24.

[0094] In the case of a needle-shaped terminal of the terminal material 1 using this embodiment, as shown in FIG. 6, the connection portion 13 connected to the counter terminal is formed in an elongated needle shape, and thus not only the front and back surfaces of the terminal material 1 but also the side surface can come into contact with the counter terminal. Also, since the film 22 is formed on the entire surface, corrosion is less likely to occur. Figure 1

[0095] Furthermore, as a result of intensive research by the inventors, it was found that in the combination of terminals of the present development, by optimizing the shape of the copper-tin alloy layer of both terminals, further lower friction can be obtained when the terminals slide.

[0096] That is, in a set of terminals that are in a fitting state with each other, if the difference in the arithmetic mean curvature SPC of the peak apexes on the surface of the copper-tin alloy layer 24 is set to be within a range of 200 mm -1 or more and 1200 mm -1 or less, terminals with even lower friction can be obtained. In this case, it is further preferable to set the difference in the roundness of the copper-tin alloy particles on the surface of the copper-tin alloy layer 24 to be within a range of 0.4 or less.

[0097] In the case where the difference between the SPC of the female terminal material and the SPC of the male terminal material is 200 mm -1 or more and 1200 mm -1 or less, the difference in the unevenness of the copper-tin alloy layer 24 is moderate, and thus the contact points of the copper-tin alloy layer 24 become multiple points when sliding, the pressure on each contact point becomes small, the force is dispersed, and thus the coefficient of friction becomes low, and the amount of wear is reduced.

[0098] In addition, in the case of such a combination of terminals, the aforementioned film 22 only needs to be formed on at least one terminal, and with respect to the other terminal, for example, the arithmetic mean curvature SPC of the peak apexes on the surface of the copper-tin alloy layer 24, the roundness can be outside the numerical range described in the embodiment (the SPC is 700 mm -1 or more and 2200 mm -1 or less, the roundness is 0.5 or more).

[0099] Furthermore, the detailed structure is not limited to the structure of the embodiment, and various modifications can be added within the scope of the gist of the present application.

[0100] ​In the connector terminal material 1 of the embodiment, although the film 22 is formed on the entire surface of the base material 21, it is sufficient to form it at least on the connecting portion 13. In the connecting portion 13, even if the film 22 is not formed on the entire surface of the front and back surfaces and the two side surfaces, it is sufficient to form the film 22 at the location that contacts the other side component. Moreover, it is not necessary to form the film 22 on the entire surface (front and back surfaces and both side surfaces) of the substrate fixing portion 15. It is also possible to have a structure in which a tin surface layer composed of tin or a tin alloy is formed on the entire surface (front and back surfaces and both side surfaces). The tin surface layer when the film 22 is formed on the substrate fixing portion 15 becomes the tin layer 25.

[0101] Example

[0102] As a base material, a CDA (Copper Development Association) alloy symbol C18665 with a thickness of 0.40 mm was used. After being punched into the shape of the terminal chain body shown in the figure, electrolytic degreasing and pickling were performed as pretreatment. Nickel plating, copper plating, and tin plating were applied to the surface in this order. In addition, pickling treatment was implemented between the nickel plating and copper plating. If these electrolytic degreasing, pickling, and plating conditions are expressed in the order of the processes, as shown in Table 1, they are the same conditions as those in the following examples and comparative examples. In the table, RT represents room temperature.

[0103] [Table 1]

[0104]

[0105] In this manner, plated substrates having plating layers of various thicknesses were subjected to reflow treatment. The thickness of each plating layer, reflow conditions, etc. are shown in Table 2. The cooling time is the time until the temperature of the plated substrate reaches 50°C.

[0106] When measuring the thickness of each plating layer before and after the reflow process, the measuring unit is set to Figure 1 Part A. Part A is the central part of the connecting portion 13 of the terminal.

[0107] Regarding the thickness of the copper layer and the copper-tin alloy layer in the A portion where the three-layer plating layer is formed, the sample was cut and resin-embedded in such a manner that the cut surface became the observation portion, and then polished and CP (cross-section polishing) were performed. The cross-sectional reflected electron image was observed using a scanning electron microscope Reguls 8230 manufactured by Hitachi High-Tech Corporation, and the thickness at any 10 locations was measured, and the average value was calculated.

[0108] Further, the thicknesses of the tin layer and the nickel layer in the A part were measured by a fluorescent X-ray film thickness meter (FT150) manufactured by Hitachi High-Tech Science Corporation.

[0109] [Table 2]

[0110]

[0111] As to the terminal material after the reflow soldering treatment, the average thickness of each layer of the coating, the arithmetic average curvature of the peak top on the surface of the copper-tin alloy layer (Spc), the roundness of the copper-tin alloy particles on the surface of the copper-tin alloy layer, the exposed area ratio of the copper-tin alloy layer on the surface of the tin layer were measured, and the abrasion resistance (abrasion amount), the friction coefficient, and the contact resistance were evaluated.

[0112] (Average thickness of each layer)

[0113] In measuring the average thickness of each layer, the measurement part was set to the A part of the terminal. Figure 1 The A part is the central part of the connecting part of the terminal.

[0114] The thicknesses of the tin layer and the nickel layer were measured by a fluorescent X-ray film thickness meter (FT150) manufactured by Hitachi High-Tech Science Corporation.

[0115] As to the average thickness of the tin layer before and after the reflow soldering treatment, first, the thickness of the tin-containing layer (tin-containing layer: the entirety of the tin layer and the copper-tin alloy layer) of the test material after the reflow soldering treatment was measured, and then the tin layer was removed by, for example, immersing in an etching solution for tin plating coating film stripping composed of a component that etches tin but does not etch the copper-tin alloy, manufactured by LEYBOLD CO., LTD., for several minutes, and the average thickness of the tin layer was defined by subtracting the thickness of the tin-containing layer after etching from the thickness of the tin-containing layer before etching.

[0116] As to the average thickness of the copper-tin alloy layer, the test material was cut, and after resin embedding with the cut processing surface as the observation part, polishing processing and CP (CROSS SECTION POLISHER: cross section polishing) processing were performed, and a cross section reflection electron image was observed using a scanning electron microscope Reguls8230 manufactured by Hitachi High-Tech Corporation. Figure 2 In the distance a between the peak top of the nickel layer and the copper-tin alloy layer and the distance b between the valley part of the nickel layer and the copper-tin alloy layer in the schematic view of the cross section in FIG. 6, the thicknesses of 10 arbitrary places were measured, the height of the copper-tin alloy layer was calculated from (a+b) / 2 for each, and the average value thereof was obtained.

[0117] (arithmetic average curvature of peak apex on surface of copper-tin alloy layer)

[0118] Regarding Figure 1 The arithmetic average curvature of the peak apex of the protruding portion in A was measured after the tin layer was removed by immersion in the etching solution for stripping of tin plating film to expose the underlying copper-tin alloy layer, using a laser microscope (VK-X200) manufactured by KEYENCE CORPORATION, under conditions of an objective lens 150 times (measurement field 96 μm x 72 μm), and the S filter cutoff wavelength was set to 1 μm and the L filter cutoff wavelength was set to 0.1 mm. The average value of SPC after five points were measured was used.

[0119] (roundness of copper-tin alloy particles on surface of copper-tin alloy layer)

[0120] After the tin layer was removed by immersion in the etching solution for stripping of tin plating film to expose the underlying copper-tin alloy layer, the measurement portion was set to A, and a SEM (Scanning Electron Microscope) (JCM-7000 manufactured by JEOL Ltd.) was used to observe the secondary electron image of a 0.0008 mm 2 field at 4000 times magnification. The value indicating the degree of circularity, i.e., the roundness, was calculated from 4π x (alloy area) ÷ (perimeter) 2 . The edge portion of the copper-tin alloy particles was extracted from the above-obtained secondary electron image using the well-known image processing software image J (ver. 1.54f), and the alloy area and the perimeter were calculated. The roundness of at least 10 or more copper-tin alloy particles was obtained for one secondary electron image, and the average value was used.

[0121] (exposed area ratio of copper-tin alloy layer on surface of tin layer)

[0122] The measurement portion was set to A, and a SEM (Scanning Electron Microscope) (JSM-7001F manufactured by JEOL Ltd.) was used to observe the backscattered electron image of a 0.0028 mm 2 field at 2000 times magnification. The above-obtained backscattered electron image was binarized using the well-known image processing software image J (ver. 1.54f) so that the Cu-Sn alloy layer exposed on the surface became black and the Sn layer became white, and the exposed area ratio was calculated by finding the area of the Cu-Sn alloy layer. The binarization was performed by setting 112 in the gray scale range 255.

[0123] (wear amount)

[0124] Each of the test pieces was cut into a test piece of 60 mm in length parallel to the rolling direction, and used as a male terminal (male terminal test piece). The test piece as a female terminal was all the same, and was produced by cutting the test piece 31 of Table 3, which was not processed into a terminal shape, into 60 mm x 10 mm, and performing embossing processing with a curvature radius of 2.5 mm at the central portion of the test piece. A friction and wear tester (UMT-Tribolab) manufactured by Bruker AXS K.K. was used for the test. The convex surface of the female terminal test piece was brought into contact with the portion of the male terminal test piece, which was a sliding portion, i.e., the A portion of the male terminal test piece, which was set horizontally, and the male terminal test piece was reciprocally slid 500 times by 1 mm while applying a load of 1 N to the male terminal test piece. At the time of measurement, a white light interference microscope (NexView8300 manufactured by AMETEK Co., Ltd.) was used, and the sliding trace of the test piece of the male terminal was observed in the depth direction in a direction perpendicular to the sliding at a magnification of 20 times. Figure 1 The cross-sectional wear area of the position where the wear was deepest was derived, and the case where the area was less than 300 μm 2 was set as A, the case where 300 μm 2 or more and less than 1200 μm 2 was set as B, and the case where 1200 μm 2 or more was set as C.

[0125] (coefficient of friction)

[0126] Each of the test pieces was cut into a test piece of 60 mm in length parallel to the rolling direction, and used as a male terminal (male terminal test piece). The test piece as a female terminal was all the same, and was produced by cutting the test piece 31 of Table 3, which was not processed into a terminal shape, into 60 mm x 10 mm, and performing embossing processing with a curvature radius of 2.5 mm at the central portion of the test piece. The coefficient of friction of the test piece sample was measured. At the time of measurement, a friction and wear tester (UMT-Tribolab) manufactured by Bruker AXS K.K. was used, and the A portion of the male terminal test piece, which indicated the terminal Figure 1 of the male terminal test piece set horizontally was made to be the center of the sliding portion, the convex surface of the female terminal test piece was brought into contact with the position 5 mm below the A portion, and the male terminal test piece was slid until the position 5 mm above the A portion by 10 mm while applying a load of 5 N to the male terminal test piece. The coefficient of friction data was acquired every 0.013 mm of the sliding distance, and the average value of the coefficient of friction obtained at a distance of 0.1 mm to 10 mm was taken as the coefficient of friction value.

[0127] (contact resistance)

[0128] The test pieces were prepared in the same manner as the coefficient of friction, in which the curvature radius of the embossing process was 1.5 mm. After heating at 150°C for 250 hours, the contact resistance (mΩ) was measured for each. At the time of measurement, using a friction and wear tester (UMT-Tribolab) manufactured by Bruker AXS K.K., the convex surface of the parent test piece was brought into contact with a horizontally disposed male terminal test piece, and the contact resistance when a load of 5 N was applied to the male terminal test piece was measured by the 4-terminal method.

[0129] In addition, with respect to the material in which a crack was generated in the indentation process, evaluation of the coefficient of friction, the amount of wear, and the contact resistance was not performed.

[0130] The measurement results are shown in Table 3.

[0131] [Table 3]

[0132]

[0133] The coefficient of friction, the amount of wear, and the contact resistance of Test Materials 1 to 30 were all low and good. Among these test materials, the average thickness of the nickel layer was 0.05 μm or more and 3.00 μm or less, the average thickness of the tin layer was 0.05 μm or more and 2.00 μm or less, and the average thickness of the copper-tin alloy layer was 0.15 μm or more and 1.55 μm or less, and the arithmetic mean curvature Spc of the peak apex on the surface of the copper-tin alloy layer was in the range of 700 mm -1 or more and 2200 mm -1 or less.

[0134] Among these, the roundness of Test Materials 4 and 19 was not 0.5 or more compared to the others, and thus the amount of wear was slightly more. The exposure area ratio of the copper-tin alloy layer of Test Material 19 exceeded the prescribed range. It is presumed to be due to the long cooling time for reducing the temperature of the base material with the plated layer to 50°C in the reflow soldering process. In Test Materials 28 to 30, the average thickness of the tin layer was larger than that of the other test materials, and thus the exposure area ratio of the copper-tin alloy layer became small.

[0135] Figure 5 is a backscattered electron (BSE) image of the cross section of Test Material 3. It can be seen that the copper-tin alloy layer having a concave-convex shape is formed on the nickel layer, and the tin layer is formed thereon. Further, it is confirmed that the copper-tin alloy layer is composed of a Cu3Sn layer formed slightly dispersed on the nickel layer and a Cu6Sn5 layer formed so as to cover the upper portion of the Cu3Sn layer and the upper portion of the nickel layer where the Cu3Sn layer is not present.

[0136] For these samples, the average thickness of the tin layer of sample 31 was within the prescribed range, but the Spc was large and the amount of wear was large. It is presumed that this was due to the high first furnace temperature during the reflow soldering process. For samples 32 and 37, the copper-tin alloy layer was too thin, so the Spc and the roundness could not be measured, the coefficient of friction was high, and the amount of wear was large. This was due to the fact that either the first heating treatment or the second heating treatment during the reflow soldering process was not performed.

[0137] In samples 33 and 34, the copper-tin alloy layer was thin and the Spc was also small, so the coefficient of friction was high and the amount of wear was large. It is presumed that this was due to the fact that the first heating treatment during the reflow soldering process was not sufficient.

[0138] In sample 35, the first furnace temperature and the second furnace temperature during the reflow soldering process were too high, so the Spc was large and the amount of wear was large. Also, the tin layer was thin, so the contact resistance was high.

[0139] In sample 36, the first heating treatment during the reflow soldering process was too long, so the tin layer was thin and the contact resistance was high.

[0140] In samples 38 and 39, the Spc was small, so the coefficient of friction was high and the amount of wear was large. It is presumed that this was due to the fact that the second heating treatment during the reflow soldering process was not sufficient.

[0141] In sample 40, the second furnace temperature during the reflow soldering process was too high, so the Spc was large and the wear resistance was reduced. On the other hand, the tin layer was thin, so the contact resistance was high.

[0142] In sample 41, the second heating treatment during the reflow soldering process was too long, so the tin layer was thin and the contact resistance was high.

[0143] In sample 42, the tin plating layer was too thick, so the tin layer was thick and the coefficient of friction was high.

[0144] In samples 43 and 44, the copper plating layer remained after the reflow soldering process.

[0145] In sample 43, the copper plating layer satisfied the prescribed thickness, but the tin plating layer did not satisfy the prescribed thickness, so the exposure rate after the reflow soldering process was larger than the prescribed value, the Spc was small, and the amount of wear was large. Also, the tin layer was thin, so the contact resistance was high. In contrast, in sample 44, the thickness of the copper plating layer was thicker than the prescribed range, so the average thickness of the copper-tin alloy layer after the reflow soldering process was thicker than the prescribed range, the tin layer was thin, and the exposure rate was larger than the prescribed value. Also, the copper plating layer remained after the reflow soldering process, the shape of the copper-tin alloy layer became flat, so the Spc was slightly small and within the prescribed range. Therefore, the amount of wear was slightly large. Also, the tin layer was thin, so the contact resistance was high.

[0146] In the test piece 45, the thickness of the copper plating layer and the average thickness of the copper-tin alloy layer were thinner than the prescribed range, and thus a part of the copper-tin alloy was replaced with nickel, the shape of the copper-tin alloy became steep, Spc was greater than the prescribed range, and thus the friction coefficient became high and the wear amount was also large.

[0147] In the test piece 46, the nickel layer was too thick, and thus a crack was generated when indentation processing was performed, and evaluation of the friction coefficient, the wear amount, and the contact resistance was not performed.

[0148] In the test piece 47, the contact resistance was high because the nickel layer was too thin.

[0149] In the test piece 48, the copper-tin alloy layer did not become the prescribed shape because the temperatures of the first heating treatment and the second heating treatment at the time of reflow soldering treatment were the same, Spc was smaller than the prescribed range, and the wear amount was large.

[0150] In the test piece 49, the copper-tin alloy layer did not become the prescribed shape because the temperature of the second heating treatment at the time of reflow soldering treatment was lower than the temperature of the first heating treatment, Spc was smaller than the prescribed range, and the wear amount was large.

[0151] Next, the test pieces were combined arbitrarily, the difference between Spc and the roundness of the copper-tin alloy layer was found, and the friction coefficient was measured. In this case, one was set as the male terminal and the other was set as the female terminal, and the friction coefficient was measured in the same manner as described above.

[0152] The results thereof are shown in Table 4.

[0153] [Table 4]

[0154]

[0155] In the case of arbitrary combination, the friction coefficient was good, but in the case where the difference between Spc of the male terminal and the female terminal was 200 mm -1 or more and 1200 mm -1 or less, the friction coefficient was slightly high. In the test pieces 53 to 62 below, particularly good friction coefficients were exhibited. The difference between the roundnesses was 0.4 or less. It is presumed that because the shape of the copper-tin alloy layer had a moderate difference, the contact point of the copper-tin alloy layer became small at the time of sliding, the real contact area became small, and thus the sliding trace became small. In addition, the male terminal and the female terminal of the test piece 52 were within the range of the present application, but because the difference between Spc was less than 200 mm -1 , the friction coefficient was slightly high.

[0156] In the test pieces 55, 56, 59, and 60, the Spc of the single-side terminal exceeded 2200 mm -1 , but the Spc of the other-side terminal was appropriate, and thus a low friction coefficient was obtained.

[0157] On the other hand, the Sps of the male terminal and the female terminal of the test piece 51 each exceeded 2200 mm -1 and the friction coefficient was high. In the test pieces 63 and 64 in which the difference between the Sps of the female terminal and the male terminal exceeded 1200 mm -1 , the friction coefficient showed a slightly high value. It is presumed that, compared with the uneven shape of the copper-tin alloy layer of one terminal, the uneven shape of the copper-tin alloy layer of the other terminal was thin, and thus it was likely to be broken during sliding.

[0158] Industrial Applicability

[0159] According to the present application, a vehicle-mounted connector or the like used in connection of an electric wiring for a vehicle or the like can be utilized.

[0160] Explanation of Symbols

[0161] 1 Terminal material for connector

[0162] 10 Terminal portion

[0163] 11, 12 Connecting member

[0164] 13 Connecting portion

[0165] 14 Shoulder portion

[0166] 15 Substrate fixing portion

[0167] 21 Base material

[0168] 22 Coating film

[0169] 23 Nickel layer

[0170] 24 Copper-tin alloy layer

[0171] 25 Tin layer

[0172] 31 Nickel plating layer

[0173] 32 Copper plating layer

[0174] 33 Tin plating layer

[0175] 35 Base material with plating layer

Claims

1. A terminal material for a connector, characterized in that: A coating is formed on the surface of a substrate composed of copper or a copper alloy, and the coating comprises: a nickel layer formed on the surface of the substrate and composed of nickel or a nickel alloy; a copper-tin alloy layer formed on the nickel layer and composed of an alloy of copper and tin; and a tin layer formed on the copper-tin alloy layer and composed of tin or a tin alloy. The average thickness of the nickel layer is 0.05 μm or more and 3.00 μm or less, The arithmetic mean curvature Spc of the peak apex on the surface of the copper-tin alloy layer is 700 mm -1 Above and 2200mm -1 Hereinafter, the average thickness of the tin layer is 0.05 μm or more and 2.00 μm or less, and the average thickness of the copper-tin alloy layer is 0.15 μm or more and 1.55 μm or less.

2. The connector terminal material according to claim 1, wherein: The tin layer of the film is removed to expose the copper-tin alloy layer, and the circularity of the copper-tin alloy particles on the surface of the exposed copper-tin alloy layer is 0.5 or more.

3. The connector terminal material according to claim 1 or 2, characterized in that: A portion of the copper-tin alloy layer is exposed on the surface of the tin layer, and an exposed area ratio of the copper-tin alloy layer on the surface of the tin layer is 5% or more and 70% or less.

4. The connector terminal material according to claim 1 or 2, characterized in that: The device includes a connection portion connected to a mating side and a substrate fixing portion fixed to a substrate, and the film is formed at least on the connection portion.

5. The connector terminal material according to claim 4, characterized in that: A tin surface layer composed of tin or a tin alloy is formed on the entire front, back, and both side surfaces of the substrate fixing portion.

6. A connector, characterized in that: A connector having a terminal on one side and a terminal on the other side that can be connected to each other, wherein at least one of the terminal on one side and the terminal on the other side is composed of the terminal material for connector according to claim 1 or 2, and the difference in arithmetic mean curvature Spc of the peak vertices on the surface of the copper-tin alloy layer of the terminal on the one side and the terminal on the other side is within 200 mm. -1 Above and 1200mm -1 Within the following range.

7. The connector according to claim 6, wherein: A difference in roundness of copper-tin alloy particles on the surface of the copper-tin alloy layer of the one terminal and the other terminal is within a range of 0.4 or less.

8. A method for manufacturing a connector terminal material, characterized in that: include: a plating layer forming step of sequentially laminating a nickel plating layer made of nickel or a nickel alloy, a copper plating layer made of copper or a copper alloy, and a tin plating layer made of tin or a tin alloy on the surface of a base material made of copper or a copper alloy, thereby forming a base material with a plated layer; and a reflow treatment step of performing a reflow treatment of heating the base material with the plated layer. In the plating layer forming step, the nickel plating layer is formed to have a thickness of 0.05 μm or more and 3.00 μm or less, the copper plating layer is formed to have a thickness of 0.10 μm or more and 0.70 μm or less, and the tin plating layer is formed to have a thickness of 0.20 μm or more and 2.90 μm or less. The reflow soldering process includes: a first heating treatment, in which the substrate with the plated layer is passed through a first heating furnace set at a first furnace temperature of 150° C. to 270° C. in an atmospheric atmosphere for a period of 3 seconds to 30 seconds to heat the substrate with the plated layer to a temperature lower than the melting point of tin; a second heating treatment, after the first heating treatment, in which the substrate with the plated layer is passed through a second heating furnace set at a second furnace temperature of 232° C. to 350° C., which is higher than the first furnace temperature, for a period of 3 seconds to 35 seconds to heat the substrate; and a cooling treatment, in which the substrate with the plated layer is rapidly cooled immediately after the tin plating layer is melted by the second heating treatment.

9. The method for manufacturing a connector terminal material according to claim 8, wherein: In the cooling process, the cooling time until the temperature of the base material with the plated layer reaches 50° C. is set to 4 seconds to 60 seconds.

Images