JP2011140676A - Tinned copper alloy sheet material for fit type terminal and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tinned copper alloy sheet for fit type terminals that has a small coefficient of friction and a small change of contact resistance with the lapse of time. <P>SOLUTION: An optional Ni covering layer, a Cu-Sn alloy covering layer and a surface plating layer comprising an Sn covering layer are formed in this order on a copper or copper alloy sheet and graphite particles are dispersedly attached onto the Sn covering layer. The Ni covering layer has an average thickness of 0.1-1.0 μm, the Cu-Sn alloy covering layer has an average thickness of 0.1-1.0 μm and the Sn covering layer has an average thickness of 0.1-2.5 μm. The graphite particles cover the surface of the Sn covering layer in an area ratio of 3-30%, and among the graphite particles, graphite particles whose particle diameter is ≥2 μm have an average particle diameter of 3-30 μm and graphite particles whose particle diameter is ≥10 μm occupy ≥3% by number. Optional Ni plating, Cu plating and Sn plating are carried out on a copper or copper alloy sheet, graphite particles are attached to the surface and reflow treatment is carried out to manufacture the objective tinned copper alloy sheet material. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a tin-plated copper alloy sheet suitable for fitting type connection terminals with a low friction coefficient, and a method for producing the same.

Conventionally, as a fitting type terminal for in-vehicle use or the like that obtains electrical contact by fitting a male terminal and a female terminal, a copper alloy plate material with tin plating is punched and formed into a terminal, which is generally used. Yes.
In the terminal fitting operation, the male terminal is inserted in contact with the indent portion of the female terminal. In the terminal using tin-plated copper alloy plate material, tin plating is very soft, so that tin adheres to each other in the sliding part, and the shearing force becomes a frictional force, and the force required for insertion is large. Become.

In recent years, with the reduction in weight and size of in-vehicle components, these fitting type terminals are also in the trend of miniaturization and miniaturization. The mating type terminal is manually fitted by the operator, and the terminal using the tin-plated copper alloy plate has a high insertion force at the time of mating. There is a strong demand for a reduction in insertion force at the time of terminal fitting due to an increased physical load.
For this reason, there is an increasing demand for a tin-plated copper alloy sheet for a fitting-type terminal that can reduce the insertion force and ensure electrical characteristics even if the connection terminal is reduced in size and multipolarity.

In response to such a requirement, a mating type terminal is formed by forming a surface plating layer comprising a Ni plating layer (if necessary), a Cu-Sn alloy layer, and a Sn plating layer on the surface of the copper alloy sheet. There has been proposed a tin-plated copper alloy sheet material capable of reducing the insertion force and the temporal change of the contact resistance.
For example, in Patent Document 1, after Cu plating and Sn plating are performed on the surface of a copper alloy plate material, a reflow process is performed to form a Cu-Sn alloy layer from the Cu plating and Sn plating, and a Cu-Sn alloy coating layer And forming a surface plating layer comprising a Sn coating layer.

In Patent Documents 2 to 4, Ni plating, Cu plating, and Sn plating are performed on the surface of a copper alloy sheet, and then reflow treatment is performed to form a Cu-Sn alloy layer from Cu plating and Sn plating. Forming a surface plating layer comprising a layer, a Cu—Sn alloy coating layer, and a Sn coating layer, among which, Patent Documents 3 and 4 describe a Cu coating between a Ni coating layer and a Cu—Sn alloy coating layer. It is also described that a surface plating layer consisting of four layers is formed by leaving the layer.
However, to further reduce the insertion force of the mating type terminal in this technique, it is necessary to make the outermost Sn coating layer thin to reduce the adhesion between tins as much as possible. It becomes difficult to achieve both reduction.

  In Patent Documents 5 and 6, as in Patent Documents 1 to 4, after performing Cu plating and Sn plating on the surface of the copper alloy plate material, or after performing Ni plating, Cu plating and Sn plating, reflow treatment is performed. Then, a surface plating layer composed of a Cu-Sn alloy coating layer and a Sn coating layer or a surface plating layer composed of a Ni coating layer, a Cu-Sn alloy coating layer and a Sn coating layer is formed. Using a roughened copper alloy sheet, the Cu-Sn alloy coating layer is partially exposed (at the peak of the roughness curve) on the surface, or the thickness of the Sn coating layer is made extremely thin. A tin-plated copper alloy sheet material capable of reducing the insertion force of the fitting type terminal has been proposed. In Patent Documents 5 and 6, in the case of a surface plating layer comprising a Cu—Sn alloy coating layer and a Sn coating layer, a Ni coating layer and a Cu—Sn alloy coating are provided between the copper alloy plate material and the Cu—Sn alloy layer. In the case of a surface plating layer comprising a layer and a Sn coating layer, it is described that the Cu coating layer may be left between the Ni coating layer and the Cu—Sn alloy coating layer.

  On the other hand, a tin-plated copper alloy sheet that can reduce the insertion force of the mating type terminal and change the contact resistance with time by forming an Sn plating layer in which carbon particles are dispersed on the surface of the copper alloy sheet is proposed. (See Patent Document 7). However, in order to produce this plate material, a special Sn plating bath in which graphite particles are dispersed is necessary, and it is difficult to manage the bath to form a Sn plating layer in which graphite particles are uniformly dispersed in a predetermined amount. This leads to cost increase. In addition, the carbon particles are present in the Sn plating layer, and only a part of the carbon particles exposed on the surface is insufficient as an effect of reducing the insertion force.

  Also, tin or tin for multipolar terminals with a reduced friction coefficient by adjusting the brightener concentration in the tin plating bath and forming a Sn or Sn alloy plating layer containing C on the surface of the copper alloy sheet. An alloy-plated copper alloy sheet has been proposed (see Patent Document 8). However, even with this plate material, the effect of reducing the insertion force is insufficient, and there is a concern that a short circuit due to whiskers occurs because no reflow treatment is performed.

Japanese Patent Laid-Open No. 10-60666 JP 2004-68026 A JP 2002-226882 A JP-A-11-135226 JP 2007-258156 A JP 2006-77307 A JP 2006-97062 A Japanese Patent No. 2971035

  It is an object of the present invention to provide a tin-plated copper alloy sheet for a mating type terminal that has a smaller friction coefficient, can reduce insertion force, has high electrical reliability (less change in contact resistance with time), and is inexpensive. Objective.

  The copper or copper alloy sheet with tin plating for mating type terminals according to the present invention has a Cu-Sn alloy coating layer with an average thickness of 0.1 to 1.0 μm and an average thickness on the surface of the copper or copper alloy sheet. A surface plating layer made of 0.1 to 2.5 μm of Sn coating layer is formed in this order, and the Sn coating layer is reflow-treated, and the graphite particles are dispersed and adhered to the surface, and the graphite particles are The surface plating layer surface is covered at an area ratio of 30% or less, and among the graphite particles, the average particle diameter of graphite particles having a particle diameter of 2 μm or more is 3 to 30 μm, and the surface plating layer surface is covered at an area ratio of 3% or more. Among them, the ratio of the number of particles having a particle diameter of 10 μm or more is 3% or more. The region where the surface plating layer is formed may extend over one side or both sides of the plate material, or may occupy only part of one side or both sides.

In the copper or copper alloy plate with tin plating, a Cu coating layer having an average thickness of 0.5 μm or less is further formed between the surface of the copper or copper alloy plate material that is the plating base and the Cu—Sn alloy coating layer. May be.
Further, as a part of the surface plating layer, a Ni coating layer having an average thickness of 0.1 to 1.0 μm is formed between the surface of the copper or copper alloy plate material which is the plating base and the Cu—Sn alloy coating layer. It may be. In this case, a Cu coating layer having an average thickness of 0.5 μm or less may be further formed between the Ni coating layer and the Cu—Sn alloy coating layer.
Furthermore, the present invention includes a case where the Cu—Sn alloy coating layer is partially exposed on the surface of the surface plating layer (Sn coating layer) (see Patent Document 6).
In the present invention, the Ni coating layer, the Cu coating layer, and the Sn coating layer include Ni alloy, Cu alloy, and Sn alloy in addition to Ni, Cu, and Sn metal, respectively.

The tin-plated copper or copper alloy plate material for mating type terminals is formed by forming a Ni plating layer (if necessary), a Cu plating layer, and a Sn plating layer in this order on the surface of the copper or copper alloy plate material. It is manufactured by attaching graphite particles to the surface of the plating layer and then performing a reflow treatment. The Cu—Sn alloy coating layer is formed by mutual diffusion of Cu and Sn in the Cu plating layer and the Sn plating layer by reflow treatment. In this case, all of the initial Cu plating layer disappears. May remain (in this case, the Cu coating layer is formed).
In the present invention, the Ni plating layer, the Cu plating layer, and the Sn plating layer include Ni alloy, Cu alloy, and Sn alloy in addition to Ni, Cu, and Sn metal, respectively.
In the present invention, each layer constituting the surface plating layer after the reflow treatment is expressed as “coating layer”, and each layer constituting the surface plating layer before the reflow treatment is expressed as “plating layer”.

   According to the present invention, the friction coefficient of the tin-plated copper alloy plate can be greatly reduced, the insertion force of the fitting type terminal can be greatly reduced, and the graphite particles can be adhered to the Sn-coated surface. It can be realized by inexpensive means. Moreover, the electrical reliability of the tin-plated copper alloy sheet is not lowered by the graphite particles adhering to the surface of the Sn coating layer.

It is a stereomicroscope structure | tissue photograph of the surface of the copper alloy sheet | seat with a tin plating which made the reflow process after making a graphite particle adhere. It is the structure photograph which compares the surface of the tin-plated copper alloy sheet material (top) to which graphite particles were adhered after reflow treatment and the surface of the tin-plated copper alloy sheet material (bottom) to which graphite particles were adhered and reflow-treated is there. A stereomicrograph showing a comparison of the surface of a tin-plated copper alloy sheet (upper) with graphite particles adhered after reflow treatment and a tin-plated copper alloy sheet (lower) with graphite particles deposited and reflowed is there.

Hereinafter, the tin-plated copper alloy sheet according to the present invention and the manufacturing method thereof will be described more specifically. In addition, about copper or a copper alloy board | plate material (plating base material) and a surface plating layer (Ni coating layer, Cu-Sn alloy coating layer, Sn coating layer, Cu coating layer) itself, it is well-known technique (patent documents 1-1). 6).
(Copper or copper alloy sheet)
The copper or copper alloy plate material (plating base material) may have any composition and characteristics as long as it can be used after being molded into a terminal. For example, brass, phosphor bronze, Cu—Ni—Si alloy, Cu—Fe—P alloy, Cu—Ni—Sn—P alloy, or the like can be used. The plate thickness may be determined in accordance with the use of the terminal, the conductivity of the plate material, the mechanical properties, etc., but about 0.1 to 2.0 mm is generally appropriate.

(Cu-Sn alloy coating layer)
When the Cu-Sn alloy coating layer is formed as an intermediate layer between the copper or copper alloy plate material which is the plating base and the Sn coating layer among the surface plating layers, from the copper or copper alloy plate material to the Sn coating layer Prevent diffusion of Cu. When the average thickness of the Cu—Sn alloy coating layer is less than 0.1 μm, the diffusion preventing effect is insufficient, Cu diffuses to the surface layer of the Sn coating layer to form an oxide, and the contact resistance increases with discoloration. Reliability decreases. On the other hand, when the average thickness exceeds 1.0 μm, the formability to the terminal is deteriorated, for example, cracking occurs in bending. Therefore, the average thickness of the Cu—Sn alloy coating layer is 0.1 to 1.0 μm. Preferably it is 0.1-0.5 micrometer.

  Further, the Cu—Sn alloy coating layer prevents the diffusion of Ni into the Sn coating layer when the Ni coating layer, the Cu—Sn alloy coating layer, and the Sn coating layer are formed in this order. When the average thickness of the Cu—Sn alloy coating layer is less than 0.1 μm, the effect of preventing diffusion is insufficient, Ni diffuses to the surface layer of the Sn coating layer to form an oxide, and the contact resistance increases with discoloration. Reliability decreases. On the other hand, when the average thickness exceeds 1.0 μm, the formability to the terminal is deteriorated, for example, cracking occurs in bending. Preferably it is 0.1-0.5 micrometer.

In the Cu—Sn alloy coating layer, a part of the Cu ₃ Sn phase may be included, and the copper alloy plate material that is the plating substrate and the component elements in the Sn coating layer may be included. However, if the Cu content of the Cu—Sn alloy coating layer is less than 20 at%, the effect of preventing diffusion of Cu from the copper or copper alloy sheet or Ni from the Ni coating layer is insufficient, and the Cu content is 70 at%. If it exceeds, the Cu diffuses to the surface layer to form an oxide, the contact resistance increases, the electrical reliability decreases, and the bending workability decreases. Therefore, the Cu content of the Cu—Sn alloy coating layer is 20 to 70 at%. Preferably it is 45-65 at%.
This Cu—Sn alloy coating layer is generally formed by interdiffusion of Cu and Sn in the Cu plating layer and the Sn plating layer by a reflow process. However, it can also be formed by directly performing Cu—Sn alloy plating with the above composition.

(Sn coating layer)
Of the surface plating layer, the Sn coating layer is applied to ensure corrosion resistance and reliability as an electrical contact. If the average thickness of the Sn coating layer is less than 0.1 μm, the corrosion resistance and the reliability as an electrical contact are insufficient, and if it exceeds 2.5 μm, the cost increases and unevenness in appearance increases. Therefore, the average thickness of the Sn coating layer is 0.1 to 2.5 μm. Preferably it is 0.2-2.0 micrometers, More preferably, it is 0.5-1.5 micrometers. The Sn coating layer includes not only pure Sn but also an Sn alloy containing about 1 to 10% by mass of one or more elements selected from the group of Cu, Ag, Ni, Co, Bi, P, Zn and the like. This Sn coating layer is formed by surface plating even when the Cu-Sn alloy coating layer is formed when the Cu-Sn alloy coating layer is formed by mutual diffusion of Cu and Sn of the Cu plating layer and the Sn plating layer by reflow treatment. It is the layer that remains as the top layer of the layer. Even when the Cu—Sn alloy coating layer is formed by directly performing Cu—Sn alloy plating, the Sn plating layer is subjected to reflow treatment.

(Ni coating layer)
Of the surface plating layers, the Ni coating layer is formed as an intermediate layer between the copper or copper alloy plate material that is the plating base and the Cu-Sn alloy coating layer, and is applied to the Cu-Sn alloy coating layer and the Sn coating layer. It is applied to prevent the diffusion of Cu from the copper or copper alloy sheet. Regarding the difference in the diffusion prevention effect between the Cu—Sn alloy coating layer and the Ni coating layer, the Ni coating layer exhibits the diffusion prevention effect even when a higher temperature environment is assumed compared to the Cu—Sn alloy coating layer. When the average thickness of the Ni coating layer is less than 0.1 μm, the diffusion preventing effect is insufficient, Cu diffuses to the surface of the Sn coating layer to form an oxide, and the contact resistance increases with discoloration. The reliability of the machine is reduced. On the other hand, if it exceeds 1.0 μm, the formability to the terminal is deteriorated, for example, cracking occurs in bending. Therefore, when forming a Ni coating layer, the average thickness shall be 0.1-1.0 micrometer. Preferably it is 0.1-0.5 micrometer. The Ni coating layer contains not only pure Ni but also a Ni alloy containing about 1 to 10% by mass of one or more elements selected from the group of Cu, Ag, Sn, Co, P, B and the like.

(Cu coating layer)
When the Cu-Sn alloy is formed from Cu of the Cu plating layer and Sn of the Sn plating layer by the reflow process, the Cu coating layer is formed when the Cu plating layer does not completely disappear and a part remains. . The remaining Cu coating layer has an average thickness of 0.1 μm or more, so that it has a role of an anti-diffusion layer of alloy elements in the copper alloy plate material that is the plating base and Ni in the Ni coating layer. The average thickness is limited to 0.5 μm or less because there is a possibility that the corrosion resistance is reduced and the plating is peeled off due to diffusion. The Cu coating layer may contain not only pure Cu but also other elements such as Sn and Zn. In the case of Sn, it is desirable that it is 50 mass% or less, and about 5 mass% or less about another element. Further, a small amount of components contained in the copper alloy sheet may be mixed.

(Graphite particles)
Graphite particles adhering to and dispersing on the surface of the Sn coating layer have a very low shearing force and lubricity, so that the friction coefficient at the sliding part of the mating type terminal is reduced, thereby inserting the graphite particles. The power can be greatly reduced.
Graphite particles having a small diameter (particle diameter of less than 2 μm) are less effective for reducing the friction coefficient. For graphite particles having a particle size of 2 μm or more with a large lubricating effect, if the average particle size is less than 3 μm, there is a high probability that the particles will not be caught in the contact surface during sliding, and even if they are caught, the graphite particles are small. Therefore, even if cleavage occurs, the lubricating effect is small. On the other hand, when the average particle size exceeds 30 μm, large graphite is bitten and cleaved during sliding, so that a sufficient lubricating effect is obtained, but conversely, it is difficult to secure a contact area at the contact point between tins, Electrical reliability may be impaired.

The area ratio of the graphite particles covering the surface plating layer surface means the area ratio of the graphite particles occupying the surface plating layer surface. If this exceeds 30%, it becomes difficult to ensure the contact area at the contact point between the tins. Reliability may be compromised. On the other hand, if the area ratio of graphite particles having a large particle size of 2 μm or more among the graphite particles is less than 3%, the lubricating effect cannot be obtained at the sliding portion of the fitting type terminal.
Further, if the ratio of the number of particles having a particle size of 10 μm or more among the graphite particles having a particle size of 2 μm or more is less than 3%, the graphite particles necessary for reducing the insertion force do not bite into the sliding portion of the fitting type terminal, A sufficient lubricating effect cannot be obtained.

Therefore, in the present invention, the graphite particles cover the surface plating layer surface with an area ratio of 30% or less, and among the graphite particles, the average particle size of graphite particles having a particle size of 2 μm or more is 3 to 30 μm, and the surface plating layer surface Is covered with an area ratio of 3% or more (30% or less), of which the ratio of the number of particles having a particle diameter of 10 μm or more is 3% or more. Preferably, for graphite particles having a particle diameter of 2 μm or more, the average particle diameter is 5 to 25 μm, the area ratio is 5 to 28%, the ratio of the number of particles having a particle diameter of 10 μm or more is 5 to 40%, more preferably the average particle diameter Is 10 to 15 μm, the area ratio is 10 to 20%, and the ratio of the number of particles having a particle diameter of 10 μm or more is 20 to 35%. FIG. 1 shows a stereoscopic microscope photograph of the surface plating layer surface to which the graphite particles are attached.
Regarding the shape and properties of the graphite particles to be used, the shape is preferably a flake shape, a flake shape, a soil shape, or a lump shape, and preferably has a high purity and few impurities.

(Characteristic)
The copper or copper alloy plate material for mating type terminals according to the present invention has a dynamic friction coefficient of 0.30 or less, contact, as shown in the examples, by adhering graphite particles to the Sn coating layer surface in the above surface plating layer configuration. A resistance value of 2.0 mΩ or less and excellent bendability can be realized.

(Production method)
The copper or copper alloy plate material for fitting type terminals is formed with a Ni plating layer (if necessary), a Cu plating layer, and a Sn plating layer in this order on a copper or copper alloy plate which is a plating substrate. It can be produced by attaching flake graphite to the surface of the Sn plating layer and subsequently performing a reflow treatment. The reflow treatment is preferably a heat treatment in which heating is performed at a temperature of 230 ° C. to 600 ° C. for 3 to 30 seconds.
In addition, when the Ni plating layer, the Cu plating layer, and the Sn plating layer are respectively made of a Ni alloy, a Cu alloy, and a Sn alloy, it is possible to use the respective alloys described above regarding the Ni coating layer, the Cu coating layer, and the Sn coating layer. it can.

To attach graphite particles to the surface of a tin-plated copper or copper alloy sheet (before reflow treatment), after Sn plating, the graphite particles are blown onto the surface (one or both sides) of the sheet by air or the like. Spraying turbid alcohol, passing a plate material through a container filled with graphite particles, or dropping graphite particles on the surface while passing the plate material, then air blowing to remove excess graphite particles, etc. A method is possible.
Even if the graphite particles adhere non-uniformly (partially in an aggregated state) to the Sn plating layer surface, the Sn plating layer can be melted by reflowing the Sn plating layer. Are uniformly dispersed and adhere to the surface of the Sn coating layer. Graphite particles that are simply physically attached to the surface of the Sn coating layer are weakly bonded and easily detached by the degreasing process or wiping, whereas the adhesion to the surface of the Sn coating layer is strong by manufacturing in the above process. Thus, desorption due to a degreasing process or wiping can be minimized, and a low friction effect can be maintained. Therefore, it is desirable to adhere the graphite particles before the reflow treatment, rather than the graphite particles after the reflow treatment.

  A tin-plated copper or copper alloy plate material with graphite particles attached to the surface of the surface plating layer after the reflow treatment, and a tin-plated copper or copper alloy plate material with graphite particles attached to the surface of the surface plating layer and then reflow treatment; Are clearly distinguishable. When visually observed, the former (the upper part of FIG. 2) covers the surface of the surface plating layer with black graphite particles, and the mirror gloss is not seen, whereas the latter (the lower part of FIG. 2) has a certain mirror surface. The appearance is almost the same as a general reflow tin plating in the state that it has a gloss and has a thin graphite film on its surface. Further, from a stereoscopic micrograph, the former (the upper part in FIG. 3) is in a state where some of the graphite particles are aggregated, while the latter (the lower part in FIG. 3) is in a substantially uniformly dispersed state. Further, for example, when acetone ultrasonic degreasing and wiping are performed, the former has many graphite particles to be detached, but the latter is small and the difference is remarkable.

In the above manufacturing method, it is desirable that the Ni plating layer, the Cu plating layer, and the Sn plating layer formed on the copper or copper alloy plate as the plating base material are all formed by electroplating. Although there is a method of performing electroless plating, the reducing agent is taken into the plating film, and voids are generated after being left at a high temperature.
As a desirable condition for electroplating, a watt bath or a sulfamic acid bath is used as a plating bath for Ni plating. The plating conditions are a temperature of 45 ° C. to 60 ° C. and a current density of 3 to 20 A / dm ² . What is important in the Ni plating is the current density. If it is less than 3 A / dm ² , the throwing power is poor, and if it exceeds 20 A / dm ² , the Ni plating grains become rough.

As a plating bath for Cu plating, a cyan bath is usually used, but a sulfuric acid bath is desirable because there is a problem of liquid deterioration and wastewater treatment due to cyan mixing in the Sn plating solution. The plating conditions are a temperature of 30 ° C. to 40 ° C. and a current density of 2.5 to 10 A / dm ² . When the temperature exceeds 40 ° C., Cu plating grains are rough, and a Cu plating layer having a uniform thickness cannot be formed. On the other hand, when the temperature is less than 30 ° C., the Cu plating grains are not roughened, but the throwing power is deteriorated.
A sulfuric acid bath is used as a plating bath for Sn plating. The plating conditions are a temperature of 25 ° C. or less and a current density of ² to 10 A / dm ² .

As for the heating conditions for the reflow treatment, Sn does not melt at temperatures below 230 ° C., and when it exceeds 600 ° C., the copper or copper alloy plate as the plating base material is softened and distortion occurs. If the heating time is less than 3 seconds, the heat transfer is non-uniform and uneven appearance after reflow occurs, and if it exceeds 30 seconds, the oxidation of the Sn plating layer on the surface proceeds and the contact resistance increases. By performing this reflow treatment, Cu and Sn are mutually diffused from the Cu plating layer and the Sn plating layer to form a Cu—Sn alloy coating layer, the residual stress of plating is relaxed, and whiskers are not generated. Further, by performing the reflow treatment, the graphite particles can be adhered and dispersed on the surface at a uniform rate as described above. In any case, in order to uniformly grow the Cu—Sn alloy layer, it is desirable that the reflow process is performed at a temperature at which Sn melts and with a heat quantity as low as possible of 300 ° C. or less.
When the Cu plating layer is not completely disappeared by the reflow process and a part thereof remains, the average thickness of the remaining Cu plating layer is limited to 0.5 μm or less.

  Up to now, regarding the method for producing a surface plating layer according to the present invention, a Ni plating layer (if necessary), a Cu plating layer, and a Sn plating layer are formed in this order on a copper or copper alloy sheet, and a reflow treatment is performed. The method of forming a Cu-Sn alloy coating layer by interdiffusing Cu and Sn from the plating layer and the Sn plating layer has been described. On the Ni plating layer (if the Ni plating layer is not formed, copper or a copper alloy plate material) It can also be obtained by applying a Cu—Sn alloy plating layer on the surface and forming a Sn plating layer thereon. Also in this case, it is desirable to adhere the flake graphite to the surface of the Sn plating layer, and subsequently to perform a reflow treatment of the Sn plating layer.

  Ni plating (only a part), Cu plating, and Sn plating are applied at a predetermined thickness on a Cu-Ni-Si-based copper alloy plate having a thickness of 0.25 mm, a width of 50 mm, and a length of 100 mm. Copper alloy sheet materials (No. 1 to 26) were produced. The plating baths and plating conditions for Ni plating, Cu plating and Sn plating are shown in Tables 1 to 3, and the average thickness of each plating layer is shown in the column of initial surface plating layer in Tables 4 and 5.

In addition, the average thickness of each plating layer which comprises an initial stage surface plating layer (before reflow process) was measured in the following way.
[Measurement of thickness of Ni plating layer and Sn plating layer]
The average thickness was measured using a fluorescent X-ray film thickness meter (Seiko Electronics Co., Ltd .; model SFT156A).
[Cu plating layer thickness measurement]
The cross section of the plate material processed by the microtome method was observed with an SEM, and the average thickness was calculated by image analysis processing.

  Subsequently, scaly graphite particles were adhered to the surface of the tin-plated copper alloy sheet (No. 11 and 25 were not adhered), and a reflow treatment was performed, which was used as a test material. The average thickness of each coating layer constituting the surface plating layer after the reflow treatment is shown in the column of the surface plating layer after reflow in Tables 4 and 5, and the area ratio of the graphite particles adhering to the surface, graphite having a particle size of 2 μm or more Tables 4 and 5 show the average particle diameter of the particles, and the ratio of the number of particles having a particle diameter of 10 μm or more. The area ratio of graphite particles having a particle diameter of less than 2 μm was 1% or less. Tables 4 and 5 show only the area ratio of graphite particles having a particle diameter of 2 μm or more.

The average thickness of each coating layer (after reflow treatment) was measured in the following manner, and the Cu content in the Cu-Sn alloy coating layer was confirmed in the following manner. Further, the area ratio of the graphite particles, the average particle diameter of the graphite particles, and the ratio of the number of particles having a particle diameter of 10 μm or more were measured in the following manner.
[Sn coating layer thickness measurement]
First, the Sn plating thickness is measured using a fluorescent X-ray film thickness meter (Seiko Electronics Co., Ltd .; model SFT156A). Then, after dipping in a stripping solution containing p-nitrophenol and caustic soda as components for 10 minutes and stripping the Sn layer, the amount of Sn in the Cu-Sn alloy layer is again measured with a fluorescent X-ray film thickness meter. The Sn layer thickness was calculated by subtracting the Sn amount in the Cu—Sn alloy layer from the Sn plating thickness thus determined.

[Measurement of thickness of Cu-Sn alloy coating layer]
The thickness of the Cu—Sn alloy layer was measured using a fluorescent X-ray film thickness meter after immersing the test material in the above stripping solution and stripping the Sn layer.
[Cu coating layer thickness measurement]
The thickness of the Cu coating layer was calculated as an average thickness by SEM observation of the cross section of the plate material processed by the microtome method, and image analysis processing.
[Measurement of Ni coating layer thickness]
The thickness of the Ni coating layer was measured using a fluorescent X-ray film thickness meter.

[Measurement of Cu content (at%) in Cu-Sn alloy]
First, the outermost Sn layer is removed by immersing in a stripping solution containing p-nitrophenol and caustic soda as components for 10 minutes. Thereafter, the surface of the sample was subjected to argon etching to a depth of 300 mm in order to eliminate the influence of oxidation and contamination on the sample surface, and the Cu content in the Cu—Sn alloy layer was measured with ESCA-LAB210D (manufactured by VG). No. The Cu contents of 1 to 25 were all 55 at% (composition of Cu ₆ Sn ₅ ).

[Area ratio of graphite particles]
The surface of the test material to which the graphite particles are adhered is observed with a stereomicroscope to obtain a surface image (magnification × 500, area 500 μm × 670 μm). Based on the image, all the graphite particles having a particle size of 2 μm or more are obtained. Is calculated by image analysis software, and the sum of the areas is defined as the total area of graphite particles having a particle size of 2 μm or more in the image, and the value obtained by dividing this by the area of the entire image is calculated for the graphite particles having a particle size of 2 μm or more. The area ratio was used. An example of a stereoscopic microscope image is shown in FIG. On the other hand, the area ratio of the graphite particles having a particle diameter of less than 2 μm was obtained by obtaining a larger image (higher magnification) and using the same image analysis technique as described above. As a result, in this example, the area ratio of graphite particles having a particle diameter of less than 2 μm was extremely small, and both were calculated to be 1% or less. This result coincided with the result of visual judgment in advance using the 500 times image (determined to be 1% or less).

[Average particle size]
The particle diameter of graphite particles having a particle diameter of 2 μm or more was set to the equivalent circle diameter (the diameter of a circle having the same area as each particle). Based on the image, the particle size was obtained for all graphite particles having a particle size of 2 μm or more, and the average particle size was obtained by dividing the sum of the particle sizes by the number of all graphite particles having a particle size of 2 μm or more.
[Ratio of particle size of 10 μm or more]
Based on the image, the ratio of graphite particles having a particle size of 10 μm or more out of graphite particles having a particle size of 2 μm or more is divided by the total number of graphite particles having a particle size of 2 μm or more. Asked.

Subsequently, no. Using the test materials 1 to 26, the dynamic friction coefficient, the contact resistance value, and the bending workability were evaluated in the following manner. The results are also shown in Tables 4 and 5.
[Measuring method of dynamic friction coefficient]
A dynamic friction coefficient was used as an evaluation of the insertion force at the time of terminal fitting. Assuming the shape of the contact part of the mating type terminal, a female plate obtained by fixing a plate-shaped male test piece cut out from the test material to a horizontal base and processing the test material with an inner diameter of 1.5 mm thereon Place the test piece, bring the tin-plated surfaces into contact with each other, apply a load W (3.0 N) to the female test piece to hold the male test piece, and use a horizontal load measuring machine (Model-2152 manufactured by Aiko Engineering Co., Ltd.). The male test piece was pulled in the horizontal direction (sliding speed 80 mm / min), and the maximum frictional force F up to a sliding distance of 5 mm was measured. The friction coefficient F was determined by the following formula (1). The test material was applied to a male test piece, and the female test piece was a copper alloy material with tin plating to which graphite was not attached (Cu-Sn alloy coating layer having an average thickness of 0.5 μm as a surface plating layer and an average thickness of 0). Having a Sn coating layer of 5 μm).
Friction coefficient = F / W (1)

[Measurement of contact resistance after standing at high temperature]
As an evaluation of the reliability of the electrical contact during heating, the contact resistance value after leaving at high temperature was used. After the heat treatment of 160 ° C. × 120 hr was performed on the test material in the air, the contact resistance was measured by a four-terminal method under the conditions of an open circuit voltage of 20 mV, a current of 10 mA, a load of 3 N, and sliding.
[Bending workability]
The test piece was cut out so that the rolling direction was long, and was bent with a load of 9.8 × 103 N so as to be perpendicular to the rolling direction using a W bending test jig defined in JISH3110. Then, the cross section was cut out and observed by the microtome method. For the evaluation of bending workability, the level at which the crack generated in the bent part after the test does not propagate to the copper alloy sheet is evaluated as ◯, and the level at which the crack propagates to the copper alloy base material and the crack occurs in the copper alloy sheet is evaluated as x. evaluated.

As shown in Tables 4 and 5, No. 1 satisfying the provisions of the present invention regarding the structure of the surface plating layer after reflow and the distribution form of the graphite particles. As for 1, 5, 12-17, and 19, all, a dynamic friction coefficient falls large compared with a prior art example (No. 11, 25), the contact resistance value after high temperature leaving is low, and it is excellent in bending workability. In addition, No. with a large average thickness of Sn coating layer. Nos. 5 and 19 were slightly uneven in appearance.
On the other hand, No. which does not satisfy any of the provisions of the present invention regarding the distribution form of graphite particles. 6 to 10 and 21 to 24 have a small decrease in the dynamic friction coefficient or a high contact resistance value after being left at a high temperature. Moreover, No. which does not satisfy any of the provisions of the present invention relating to the configuration of the surface plating layer after reflow. Nos. 2 to 4, 18 and 20 have high contact resistance values after being left at high temperature or have poor bending workability.

Claims (11)

On the surface of the copper or copper alloy sheet, a surface plating layer comprising a Cu—Sn alloy coating layer having an average thickness of 0.1 to 1.0 μm and an Sn coating layer having an average thickness of 0.1 to 2.5 μm in this order. The Sn coating layer is reflow-treated, and the graphite particles are dispersed and adhered to the surface, the graphite particles cover the surface plating layer surface with an area ratio of 30% or less, and the graphite particles Of these, the average particle diameter of graphite particles having a particle diameter of 2 μm or more is 3 to 30 μm, the surface plating layer surface is covered with an area ratio of 3% or more, and the ratio of the number of particles having a particle diameter of 10 μm or more is 3% or more. A copper or copper alloy sheet with tin plating for fitting type terminals. 2. The fitting type terminal according to claim 1, wherein a Cu coating layer having an average thickness of 0.5 μm or less is further formed between the surface of the copper or copper alloy sheet and the Cu—Sn alloy coating layer. Copper or copper alloy sheet with tin plating. Of the graphite particles, the average particle size of graphite particles having a particle size of 2 μm or more is 10 to 15 μm, and the surface plating layer surface is covered with an area ratio of 10 to 20%, of which the ratio of the number of particles having a particle size of 10 μm or more is It is 20 to 40%, The copper or copper alloy board | plate material with a tin plating for fitting type terminals described in Claim 1 or 2. 4. The copper or copper alloy plate with tin plating for fitting type terminals according to claim 1, wherein a part of the Cu-Sn alloy coating layer is exposed on the surface of the surface plating layer. On the surface of the copper or copper alloy sheet, an Ni coating layer having an average thickness of 0.1 to 1.0 μm, a Cu—Sn alloy coating layer having an average thickness of 0.1 to 1.0 μm, and an average thickness of 0.1 A surface plating layer comprising a Sn coating layer of ~ 2.0 μm is formed in this order, and the Sn coating layer is reflow-treated, and the graphite particles are dispersed and adhered to the surface, and the graphite particles are adhered to the surface plating layer. Covering the surface with an area ratio of 30% or less, and covering the surface plating layer surface with an area ratio of 3% or more with an average particle diameter of 3 to 30 μm of graphite particles having a particle diameter of 2 μm or more among the graphite particles, A copper or copper alloy plate material with tin plating for fitting type terminals, wherein the ratio of the number of particles having a particle size of 10 μm or more is 3% or more. The tin coating for fitting type terminals according to claim 5, wherein a Cu coating layer having an average thickness of 0.5 μm or less is further formed between the Ni coating layer and the Cu—Sn alloy coating layer. Copper or copper alloy sheet. Of the graphite particles, the average particle size of graphite particles having a particle size of 2 μm or more is 10 to 15 μm, and the surface plating layer surface is covered with an area ratio of 10 to 20%, of which the ratio of the number of particles having a particle size of 10 μm or more is It is 20 to 40%, The copper or copper alloy board | plate material with a tin plating for fitting type terminals described in Claim 5 or 6. The Cu-Sn alloy coating layer is partially exposed on the surface of the surface plating layer, and the copper or copper alloy sheet with tin plating for fitting type terminals described in any one of claims 5 to 7. The said Sn coating layer is a reflow-processed after graphite particle adhesion, The copper or copper alloy board | plate material with a tin plating for fitting type terminals described in any one of Claims 1-8 characterized by the above-mentioned. The Cu plating layer and the Sn plating layer are formed in this order on the surface of the copper or copper alloy sheet, the graphite particles are adhered to the surface of the Sn plating layer, and then the reflow treatment of the Sn plating layer is performed. The manufacturing method of the copper or copper alloy board | plate material with a tin plating for fitting type terminals described in any one of 1-4. The Ni plating layer, the Cu plating layer, and the Sn plating layer are formed in this order on the surface of the copper or copper alloy sheet, the graphite particles are adhered to the surface of the Sn plating layer, and then the reflow treatment is performed. The manufacturing method of the copper or copper alloy board | plate material with a tin plating for fitting type terminals described in any one of 5-8.