JP2016044358A - Conductive material for connection part excellent in minute slide abrasion resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive material for a connection part suitable for miniaturization of fitting type terminals, having small reduction of contact pressure even when used at a temperature over 160°C for long time, and exhibiting more excellent minute slide abrasion resistance than conventional conductive materials having high conductivity.SOLUTION: There is provided a conductive material for a connection part excellent in minute slide abrasion resistance, where a Cu-Sn alloy coated layer having Cu content of 20 to 70 at% and average thickness of 0.2 to 3.0 μm and a Sn coated layer having average thickness of 0.05 to 5.0 μm are formed on a base material surface after a reflow treatment, arithmetic average roughness Ra in one direction of a material surface is 0.15 μm or more, arithmetic average roughness Ra in all directions is 3.0 μm or less, a part of the Cu-Sn alloy coated layer exposes on a surface of the Sn coated layer with exposure area ratio of 3 to 75%, average crystal particle diameter of the surface of the Cu-Sn alloy coated layer is less than 2 μm, a copper alloy sheet stripe used as a base material has conductivity of over 50%IACS and stress relaxation rate after holding at 200°C for 1000 hours is 25% or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a conductive material for connecting parts such as terminals mainly used in the automotive field and general consumer field, and more particularly to a conductive material for a Sn-plated connecting part that can reduce fine sliding wear.

As a material for a fitting terminal for a multipolar connector used in an electronic control unit (ECU: Electronic Control Unit) for an automobile engine, Cu-Ni-Si, Cu-Ni-Sn-P, Cu- Various copper alloys such as Fe-P and Cu-Zn are used.
Among these, Cu-Ni-Si-based alloys have a tensile strength of 600 MPa or more, a medium conductivity (35-50% IACS), and 150 ° C. × 1000 in an 80% bending stress load state of 0.2% proof stress. The stress relaxation rate after time retention has a characteristic of about 15 to 20%, and is excellent in strength and stress relaxation resistance.

The fitting terminal is provided with a Sn coating layer (reflow Sn plating or the like) having a thickness of about 1 μm on the surface in order to ensure corrosion resistance and reduce contact resistance at the contact portion. In the fitting terminal in which the Sn coating layer is formed, when the male terminal is inserted into the female terminal, the soft Sn coating layer (Hv: about 10 to 30) is plastically deformed, and Sn—Sn generated between the male and female terminals. The adhesion part is sheared. Due to the deformation resistance and shear resistance generated at this time, the insertion force of the terminal is increased in the fitting terminal in which the Sn coating layer is formed.
Since the ECU is connected by a connector that accommodates a large number of fitting terminals, the insertion force at the time of connection increases as the number of stations increases. Therefore, a reduction in the insertion force of the fitting terminal is required from the viewpoint of reducing the burden on the operator and ensuring the integrity of the connection.

  After terminal fitting, the fine sliding wear phenomenon becomes a problem. The fine sliding wear phenomenon refers to sliding between the male terminal and the female terminal due to the vibration of the engine of the automobile, the vibration during traveling, and the expansion and contraction caused by the fluctuation of the ambient temperature. This is a phenomenon in which the Sn plating is worn. When the wear powder of Sn generated by the fine sliding wear phenomenon is oxidized and deposited in a large amount in the vicinity of the contact portion, and bites between the sliding contact portions, the contact resistance between the contact portions increases. This fine sliding wear phenomenon is more likely to occur as the contact pressure between the male terminal and the female terminal is smaller, and is particularly likely to occur in a fitting terminal having a small insertion force (small contact pressure).

In the case of a terminal incorporated in equipment such as an ECU used in a high temperature environment such as an engine room of an automobile, in order to ensure reliability as a terminal, it remains above a certain value even after being held at a temperature of about 150 ° C. for a long time. The initial contact pressure of the terminal is determined so that the contact pressure can be maintained.
When a fitting terminal is manufactured using a Cu—Ni—Si alloy having a low stress relaxation rate, the initial contact pressure can be set low, and the insertion force of the terminal can be greatly reduced. On the other hand, as described above, since the contact pressure is small, there is a problem that fine sliding wear easily occurs.

  On the other hand, in Patent Document 1, a Ni layer having a thickness of 0.1 to 1.0 μm, a Cu—Sn alloy layer having a thickness of 0.1 to 1.0 μm, and a thickness of 2 μm are formed on the surface of the copper alloy base material. A conductive material for connecting parts in which a surface plating layer composed of the following Sn layer is formed in this order is described. According to the description in Patent Document 1, the dynamic friction coefficient decreases when the thickness of the Sn layer is 0.5 μm or less, and the insertion force can be kept low when used as a multipolar fitting terminal.

In Patent Document 2, the surface of the copper alloy base material with increased surface roughness is obtained by performing Ni plating as necessary, followed by Cu plating and Sn plating in this order, and then performing a reflow treatment. In addition, conductive materials for connecting parts are described. This conductive material for connecting parts has a surface of a copper alloy base material, a Ni coating layer having a thickness of 3 μm or less (when Ni plating is performed), and a Cu—Sn alloy coating layer having a thickness of 0.2 to 3 μm. And a surface coating layer made of a Sn coating layer having a thickness of 0.2 to 5 μm. This conductive material for connecting parts has a small coefficient of dynamic friction because a part of the hard Cu-Sn alloy coating layer is exposed between the Sn coating layers, and when used as a fitting terminal, reduces the contact pressure of the terminal. Therefore, the insertion force can be reduced. Patent Document 2 describes an invention example in which a copper alloy base material is a Cu—Zn alloy and a Cu—Fe—P alloy.
Patent Document 3 describes a conductive material for connecting parts having a coating layer configuration similar to that of Patent Document 2, and an invention example in which a copper alloy base material is a Cu-Ni-Si alloy in the conductive material for connecting parts. Yes.

JP 2004-68026 A JP 2006-183068 A JP 2007-258156 A

  Along with the recent miniaturization of terminals, the contact area of the fitting portion is also reduced, and the temperature rise of the terminals due to this has become a problem. For this reason, a copper alloy material for a terminal having a stress relaxation rate of about 20% even after being held at a temperature exceeding 160 ° C., for example, at 180 ° C. for 1000 hours is demanded. At the same time, in order to suppress the temperature rise of the terminal fitting portion, a copper alloy having higher conductivity than the Cu—Ni—Si based alloy is required. In addition, the stress relaxation rate after hold | maintaining 180 degreeC x 1000 hours of a general Cu-Ni-Si type alloy exceeds 25%, and electrical conductivity is about 50% at the maximum.

  On the other hand, since the conductive material for connecting parts described in Patent Documents 2 and 3 can reduce the coefficient of dynamic friction at the time of inserting a terminal as compared with the conductive material for connecting parts described in Patent Document 1, it has a low insertion force. It is not necessary to reduce the contact pressure of the terminal for the purpose of making it easier. Therefore, compared with the conventional copper alloy material with Sn plating, fine sliding wear is less likely to occur, and the amount of Sn wear powder generated is small. As a result, increase in contact resistance is suppressed. For this reason, this conductive material for connecting parts is actually used more frequently in the field of automobiles and the like. At the same time, however, there is a need for further improvements in higher conductivity and fine sliding wear resistance that are suitable for terminal miniaturization.

  The present invention is suitable for miniaturization of a fitting type terminal, and there is little decrease in contact pressure even when used for a long time at a temperature exceeding 160 ° C. Compared with the conventional conductive material for connecting parts described in Patent Document 2. It is an object of the present invention to provide a conductive material for connecting parts that exhibits excellent fine sliding wear resistance.

  In the conductive material for connecting parts according to the present invention, a Cu-Sn alloy coating layer having a Cu content of 20 to 70 at% and a Sn coating layer are formed in this order on the surface of a base material made of a copper alloy sheet. The material surface is reflow-treated, the arithmetic average roughness Ra in at least one direction is 0.15 μm or more, the arithmetic average roughness Ra in all directions is 3.0 μm or less, and the surface of the Sn coating layer is In the conductive material for connecting parts, in which a part of the Cu-Sn alloy coating layer is exposed and formed, and the exposed surface area ratio of the material of the Cu-Sn alloy coating layer is 3 to 75%, the conductivity of the copper alloy sheet The rate is over 50% IACS, the stress relaxation rate after holding at 200 ° C. for 1000 hours is 25% or less, and the average thickness of the Cu—Sn alloy coating layer is 0.2 to 3.0 μm. The average grain size of the surface of the layer is Less than [mu] m, the average thickness of the Sn coating layer is characterized in that it is a 0.05～5.0Myuemu.

In the conductive material for connecting parts, the copper alloy strip as a base material includes, for example, one or two of Cr: 0.15 to 0.70 mass% and Zr: 0.01 to 0.20 mass%. The balance consists of Cu and inevitable impurities.
The copper alloy preferably further contains Ti: 0.01 to 0.30% by mass.
The copper alloy preferably further contains Si: 0.01 to 0.20 mass%.
If necessary, the copper alloy further contains Zn: 0.001 to 1.0 mass%, Sn: 0.001 to 0.5 mass%, Mg: 0.001 to 0.15 mass%, Ag: 0. 0.005-0.50 mass%, Fe: 0.005-0.50 mass%, Ni: 0.005-0.50 mass%, Co: 0.005-0.50 mass%, Al: 0.005 One or more of ˜0.10 mass% and Mn: 0.005 to 0.10 mass% may be added in total and 1.0 mass% or less in total.

Similar to the conductive material for connecting parts described in Patent Document 2, the conductive material for connecting parts can take the following preferred embodiments.
As for the said material surface, the average material surface exposure space | interval of the said Cu-Sn alloy coating layer in at least one direction is 0.01-0.5 mm.
The thickness of the Cu—Sn alloy coating layer exposed on the surface of the Sn coating layer is 0.2 μm or more.
The surface of the base material has an arithmetic average roughness Ra in at least one direction of 0.3 μm or more and an arithmetic average roughness Ra in all directions of 4.0 μm or less.
The surface of the base material has an average interval Sm of irregularities in at least one direction of 0.01 to 0.5 mm.

Moreover, the surface coating layer of the conductive material for connecting parts can take the following preferred embodiments.
A Cu coating layer is further provided between the surface of the base material and the Cu-Sn alloy coating layer.
A base layer made of any one of a Ni coating layer, a Co coating layer, and an Fe coating layer is further formed between the surface of the base material and the Cu-Sn alloy coating layer, and the average thickness of the base layer Is 0.1 to 3.0 μm.
Between the surface of the base material and the Cu—Sn alloy coating layer, any two of the Ni coating layer, the Co coating layer, and the Fe coating layer are formed, and the total of the two base layers is formed. The average thickness is 0.1 to 3.0 μm.
When the foundation layer is formed, a Cu coating layer is further provided between the foundation layer and the Cu—Sn alloy coating layer.
An Sn plating layer having an average thickness of 0.02 to 0.2 μm is further formed on the surface of the reflowed material.
The Sn coating layer, Cu coating layer, Ni coating layer, Co coating layer, and Fe coating layer are Sn, Cu, Ni, Co, Fe metal, Sn alloy, Cu alloy, Ni alloy, Co alloy, Fe alloy, respectively. including. Moreover, the said Sn plating layer contains Sn alloy other than Sn metal.

  The conductive material for connecting parts according to the present invention is a fitting type by using a copper alloy base material having a conductivity exceeding 50% IACS and having a stress relaxation rate of 25% or less after holding at 200 ° C. for 1000 hours. It is suitable for miniaturization of terminals, and there is little decrease in contact pressure even after holding at a high temperature exceeding 160 ° C. for a long time. Further, since the decrease in contact pressure is small, the fine sliding wear resistance is improved as compared with, for example, a Cu—Ni—Si alloy. In addition, by making the average crystal grain size of the surface of the Cu—Sn alloy coating layer less than 2 μm, it exhibits excellent micro-sliding wear resistance compared to the conventional conductive material for connecting parts described in Patent Document 2. . When the Sn plating layer is formed on the material surface after the reflow treatment, the solderability can be improved as compared with the conventional conductive material for connecting parts described in Patent Document 2.

Example No. 6 is a SEM (scanning electron microscope) structural photograph of the surface of the Cu-Sn alloy coating layer of No. 6; It is a conceptual diagram of a fine sliding wear measuring jig. It is a conceptual diagram of a friction coefficient measuring jig.

[Copper alloy base material]
(1) Characteristics of copper alloy Cu-Ni-Si alloys widely used for mating type terminals relieve stress when held for 1000 hours with a bending stress of 80% of 0.2% proof stress. The rate is 12-20% when the holding temperature is 150 ° C. However, the stress relaxation rate increases as the holding temperature increases, and is 15 to 25% at 160 ° C, 25 to 30% at 180 ° C, and 30 to 40% at 200 ° C. In the case of a female terminal having a severe demand for the stress relaxation rate, as described above, the stress relaxation rate after holding for 1000 hours at the assumed use temperature is often required to be 25% or less as the design standard. For this reason, when the assumed use temperature exceeds 160 degreeC, for example, it is difficult to use a Cu-Ni-Si type alloy as a raw material of a female terminal.
Further, the conductivity of the Cu—Ni—Si based alloy is 50% IACS or less, which cannot be said to be suitable for further miniaturization of the fitting type terminal.

In the present invention, the copper alloy strip used as the base material of the conductive material for connecting parts has a stress relaxation rate of 25% or less after being held at 200 ° C. for 1000 hours, so even in a high temperature environment where the atmosphere exceeds 160 ° C. Can be used for a long time. In addition, it is estimated that the value of a stress relaxation rate does not change substantially before and after a reflow process. The copper alloy sheet according to the present invention has a conductivity exceeding 50% IACS, and is suitable for further miniaturization of the fitting type terminal. The electrical conductivity of the copper alloy sheet according to the present invention is preferably 60% IACS or more, more preferably 70% IACS or more.
As such copper alloy strips, the following Cu—Cr, Cu—Cr—Ti, Cu—Zr and Cu—Cr—Zr alloys are preferred. Since these alloys are excellent in stress relaxation resistance even at temperatures exceeding 160 ° C., the initial contact pressure can be set small, thereby reducing the insertion force during terminal insertion. On the other hand, even if the contact pressure is reduced, the decrease in contact pressure is small even after a long period of time at high temperatures, and at the same time, by adopting the structure of the surface coating layer according to the present invention, excellent resistance to conductive materials for connecting parts. Sliding wear characteristics can be imparted.

(2) Composition of copper alloy The copper alloy according to the present invention contains one or two of Cr: 0.15 to 0.70 mass% and Zr: 0.01 to 0.20 mass%, with the balance being Cu. And inevitable impurities. This copper alloy preferably further contains Ti: 0.01 to 0.30 mass% or / and Si: 0.01 to 0.20 mass%.

  Cr forms a compound such as Cr—Si, Cr—Ti, Cr—Si—Ti alone or together with Si and Ti, and improves the strength of the copper alloy by precipitation hardening. By this precipitation, the solid solution amount of Cr, Si and Ti in the Cu matrix is decreased, and the conductivity of the copper alloy is increased. If the Cr content is less than 0.15% by mass, the strength is not increased sufficiently by precipitation, and the stress relaxation resistance is not improved. On the other hand, if the Cr content exceeds 0.7% by mass, the precipitates become coarse, and the stress relaxation resistance and bending workability deteriorate. Therefore, the Cr content is in the range of 0.15 to 0.7 mass%. The lower limit of the Cr content is preferably 0.20% by mass, more preferably 0.25% by mass, and the upper limit is preferably 0.6% by mass, more preferably 0.50% by mass.

  Zr forms an intermetallic compound with Cu and Si, and improves the strength and stress relaxation resistance of the copper alloy by precipitation hardening. By this precipitation, the solid solution amount of Si and Ti in the Cu matrix is reduced, and the conductivity of the copper alloy is increased. Zr has an effect of refining crystal grains. If the content of Zr is less than 0.01% by mass, the above effect cannot be obtained sufficiently. Moreover, when it exceeds 0.20 mass%, a coarse compound will be formed and a stress relaxation resistance characteristic and bending workability will fall. Therefore, the Zr content is in the range of 0.01 to 0.20 mass%. The lower limit of the Zr content is preferably 0.015 mass%, more preferably 0.02 mass%, and the upper limit is preferably 0.18 mass%, more preferably 0.15 mass%.

  Ti has a function of improving the strength, heat resistance and stress relaxation characteristics of the copper alloy by dissolving in the Cu base material. Ti forms precipitates with Cr and Si, and improves the strength of the copper alloy by precipitation hardening. By this precipitation, the solid solution amount of Cr, Si and Ti in the Cu matrix is decreased, and the conductivity of the copper alloy is increased. When the Ti content is less than 0.01% by mass, the heat resistance of the copper alloy is low, and it becomes difficult to obtain high strength by softening in the annealing process. Further, the stress relaxation resistance of the copper alloy cannot be improved. On the other hand, when the Ti content exceeds 0.30 mass%, the solid solution amount of Ti in the Cu matrix increases, leading to a decrease in conductivity. Accordingly, the Ti content is in the range of 0.01 to 0.30 mass%. The lower limit of the Ti content is preferably 0.02% by mass, more preferably 0.03% by mass, and the upper limit is preferably 0.25% by mass, more preferably 0.20% by mass.

  Si forms compounds such as Cr—Si, Zr—Si, Ti—Si, and Cr—Si—Ti together with Cr, Zr, and Ti, and increases the strength of the copper alloy by precipitation hardening. By this precipitation, the amount of solid solution of Cr, Zr, Si and Ti in the Cu matrix is decreased and the conductivity is increased. When the Si content is less than 0.01% by mass, the strength is not sufficiently improved by precipitates such as Cr—Si, Zr—Si, Ti—Si or Cr—Si—Ti. On the other hand, when the Si content exceeds 0.20 mass%, the solid solution amount of Si in the Cu matrix increases and the conductivity decreases. In addition, the precipitate is coarsened, and bending workability and stress relaxation resistance are deteriorated. Therefore, the Si content is in the range of 0.01 to 0.20 mass%. The lower limit of the Si content is preferably 0.015 mass%, more preferably 0.02 mass%, and the upper limit is preferably 0.15 mass%, more preferably 0.10 mass%.

The copper alloy further contains Zn: 0.001 to 1.0 mass%, Sn: 0.001 to 0.5 mass%, Mg: 0.001 to 0.15 mass%, and Ag: as necessary. 0.005-0.50 mass%, Fe: 0.005-0.50 mass%, Ni: 0.005-0.50 mass%, Co: 0.005-0.50 mass%, Al: 0. One or more of 005 to 0.10% by mass and Mn: 0.005 to 0.10% by mass contain 1.0% by mass or less in total. All of these elements improve the strength of the copper alloy. However, if the total content of these elements exceeds 1.0% by mass, the conductivity of the copper alloy deteriorates.
These elements have the following effects in addition to the strength improvement effect.

Zn is an element effective for improving the heat-resistant peelability of Sn plating or solder used for joining electronic components. If the Zn content is less than 0.001% by mass, the effect is not obtained. If the Zn content exceeds 1.0% by mass, the conductivity of the copper alloy decreases. Accordingly, the Zn content is in the range of 0.001 to 1.0 mass%. The lower limit of the Zn content is preferably 0.01% by mass, more preferably 0.1% by mass, and the upper limit is preferably 0.8% by mass, more preferably 0.6% by mass.
Sn and Mg are effective in improving the stress relaxation characteristics. Moreover, Mg has a desulfurization action and improves hot workability. However, if the content of each element of Sn and Mg is less than 0.001% by mass, the effect is small. On the other hand, if the content of each element of Sn exceeds 0.5% by mass or the content of Mg exceeds 0.15% by mass, the electrical conductivity of the copper alloy decreases. Accordingly, the Sn content is in the range of 0.001 to 0.5 mass%, and the Mg content is in the range of 0.001 to 0.15%. The lower limit of the Sn content is preferably 0.005 mass%, more preferably 0.01 mass%, and the upper limit is preferably 0.40 mass%, more preferably 0.30 mass%. The lower limit of the Mg content is preferably 0.005 mass%, more preferably 0.01 mass%, and the upper limit is preferably 0.10 mass%, more preferably 0.05 mass%.

Ag has the effect of improving the heat resistance and stress relaxation characteristics of the copper alloy by dissolving in the Cu base material. If the Ag content is less than 0.005% by mass, the effect is small, and if it exceeds 0.5% by mass, the effect is saturated. Therefore, the Ag content is 0.005 to 0.50% by mass. The lower limit of the Ag content is preferably 0.01% by mass, more preferably 0.015% by mass, and the upper limit is preferably 0.30% by mass, more preferably 0.20% by mass.
Fe, Ni, and Co have the effect of precipitating a compound with Si and improving the conductivity of the copper alloy. However, as the content increases, the amount of solid solution increases and the conductivity deteriorates. The contents of Fe, Ni and Co are 0.005 to 0.50 mass%, respectively. The lower limit of these elements is preferably 0.01% by mass, more preferably 0.03% by mass, and the upper limit is preferably 0.40% by mass, more preferably 0.30% by mass.
Al and Mn have a desulfurization action and improve hot workability. However, when the content of Al or Mn is less than 0.005% by mass, the effect is small. On the other hand, when the content of Al or Mn exceeds 0.1% by mass, the conductivity of the copper alloy is lowered. The lower limit of these elements is preferably 0.01% by mass, more preferably 0.02% by mass, and the upper limit is preferably 0.08% by mass, more preferably 0.06% by mass.
The compositions of the Cu—Cr, Cu—Cr—Ti, Cu—Zr, and Cu—Cr—Zr alloys described above are known.

Inevitable impurities of the copper alloy include As, Sb, B, Pb, V, Mo, Hf, Ta, Bi, In, H, and O.
As, Sb, B, Pb, V, Mo, Hf, Ta, Bi, and In, when their total content exceeds 0.5% by mass, they segregate at grain boundaries or form crystallized substances. Thus, stress relaxation resistance and bending workability are deteriorated. Therefore, the content of these elements in the copper alloy is preferably 0.5% by mass or less in total. More preferably, it is 0.1% by mass or less in total.

In the melting and casting process, H is taken into the molten metal from the melting raw material and the atmosphere. When the content of H in the molten metal increases, it is discharged as H ₂ gas during solidification, blowholes are formed inside the ingot, and it is concentrated at the crystal grain boundary of the ingot to increase the strength of the crystal grain boundary of the ingot. Reduce. When such an ingot is heated to a predetermined temperature and hot-rolled, internal cracks occur during heating or hot-rolling, and hot workability deteriorates. Even if hot cracking does not occur, the plate surface is swollen during the subsequent heat treatment process, which reduces the product yield. For this reason, it is preferable that the content of H in the copper alloy is 0.0002% by mass or less. The H content is more preferably 0.00015% by mass or less, and further preferably 0.0001% by mass or less.

  Since the copper alloy according to the present invention contains one or more of Cr and Zr having a high affinity with O, and preferably further contains Ti, it is easily oxidized in the melt casting process. The oxide caught in the ingot causes problems such as cracks during hot rolling of the ingot, surface defects during cold rolling, and deterioration of bending workability of the thin plate. For this reason, it is preferable that content of O in a copper alloy shall be 0.0030 mass% or less. The O content is more preferably 0.0020% by mass or less, and still more preferably 0.001% by mass or less.

(3) Manufacturing method of copper alloy strips Cu-Cr, Cu-Zr and Cu-Cr-Zr alloy strips are usually homogenized, hot-rolled, and cold-melted into cast ingots. Manufactured by rolling and precipitating heat treatment. Even in the case of the copper alloy strip according to the present invention, it is not necessary to greatly change the manufacturing process itself.
In melting and casting of copper alloys, drying of raw materials, inert gas seal of melting furnace (nitrogen, argon, etc.), inert gas between melting furnace and mold so that H and O are not taken into the molten metal It is desirable to implement measures such as sealing.
The homogenization treatment is performed at 800 to 1000 ° C. for 0.5 hour or longer. Hot rolling after the homogenization treatment is performed at a processing rate of 60% or more, and then quenched from a temperature of 700 ° C. or more. When quenched in a temperature range lower than 700 ° C., coarse precipitates are easily generated, and the stress relaxation resistance and bending workability are lowered.

  Subsequently, the hot-rolled material is cold-rolled to a desired thickness and then subjected to precipitation heat treatment. Cold rolling may be further performed after the precipitation heat treatment, and strain relief annealing may be further performed after the cold rolling. Further, instead of the hot rolling-cold rolling-precipitation heat treatment step, a hot rolling-cold rolling-solution treatment-cold rolling-precipitation heat treatment step may be employed. Solution treatment is for re-dissolving Cr-containing precipitates formed during quenching after hot rolling, and is carried out at 750 to 850 ° C. for 30 seconds or more. It is desirable to select a condition in which the crystal grain size after the solution treatment is larger than the crystal grain size after the hot rolling is completed. Precipitation heat treatment is for precipitating compounds such as Cr alone, Cu-Zr, Cr-Si, Cr-Si-Ti, etc., and is carried out at 400 to 550 ° C. for 2 hours or more. It is desirable to select a temperature at which the elongation is as high as possible and the elongation is 10% or more.

[Surface coating layer]
(1) Cu content in the Cu—Sn alloy coating layer The Cu content in the Cu—Sn alloy coating layer is set to 20 to 70 at% as in the conductive material for connecting parts described in Patent Document 2. The Cu—Sn alloy coating layer having a Cu content of 20 to 70 at% is made of an intermetallic compound mainly composed of a Cu ₆ Sn ₅ phase. In the present invention, the Cu ₆ Sn ₅ phase partially protrudes from the surface of the Sn coating layer. Therefore, when the electrical contact portion slides, the contact pressure is received by the hard Cu ₆ Sn ₅ phase and the Sn coating layers contact each other. The area can be further reduced, thereby reducing wear and oxidation of the Sn coating layer. On the other hand, since the Cu ₃ Sn phase has a higher Cu content than the Cu ₆ Sn ₅ phase, when this is partially exposed on the surface of the Sn coating layer, the Cu 3 The amount of oxide and the like are increased, the contact resistance is easily increased, and it is difficult to maintain the reliability of electrical connection. Further, since the Cu ₃ Sn phase is more fragile than the Cu ₆ Sn ₅ phase, there is a problem that molding processability is inferior. Therefore, the constituent component of the Cu—Sn alloy coating layer is defined as a Cu—Sn alloy having a Cu content of 20 to 70 at%. This Cu—Sn alloy coating layer may contain a part of the Cu ₃ Sn phase, and may contain a base material, component elements during Sn plating, and the like. However, if the Cu content of the Cu—Sn alloy coating layer is less than 20 at%, the amount of adhesion increases and the fine sliding wear resistance decreases. On the other hand, if the Cu content exceeds 70 at%, it becomes difficult to maintain the reliability of electrical connection due to aging or corrosion, and the moldability and the like are also deteriorated. Therefore, the Cu content in the Cu—Sn alloy coating layer is 20 to 70 at%. The lower limit of the Cu content in the Cu—Sn alloy coating layer is preferably 45 at%, and the upper limit is preferably 65 at%.

(2) Average thickness of Cu—Sn alloy coating layer The average thickness of the Cu—Sn alloy coating layer is 0.2 to 3.0 μm, similar to the conductive material for connecting parts described in Patent Document 2. To do. In the present invention, the average thickness of the Cu—Sn alloy coating layer, the surface density (unit: g / mm ² ) of Sn contained in the Cu—Sn alloy coating layer, the density of Sn (unit: g / mm ³⁾ ) Is defined as the value divided by. The method for measuring the average thickness of the Cu—Sn alloy coating layer described in the following examples is based on this definition. When the average thickness of the Cu—Sn alloy coating layer is less than 0.2 μm, when the Cu—Sn alloy coating layer is partially exposed on the surface of the material as in the present invention, it is caused by thermal diffusion such as high temperature oxidation. The amount of Cu oxide on the material surface increases. When the amount of Cu oxide on the material surface increases, the contact resistance tends to increase, and it becomes difficult to maintain the reliability of electrical connection. On the other hand, if it exceeds 3.0 μm, it is economically disadvantageous, the productivity is poor, and the hard layer is formed thick, so that the molding processability is also deteriorated. Therefore, the average thickness of the Cu—Sn alloy coating layer is specified to be 0.2 to 3.0 μm. The lower limit of the average thickness of the Cu—Sn alloy coating layer is preferably 0.3 μm, and the upper limit is preferably 1.0 μm.

(3) Average thickness of Sn coating layer The average thickness of Sn coating layer shall be 0.05-5.0 micrometers. This range is slightly wider in the thickness direction than the average thickness (0.2 to 5.0 μm) of the Sn coating layer in the conductive material for connecting parts described in Patent Document 2. When the average thickness of the Sn coating layer is less than 0.2 μm, as described in Patent Document 2, the amount of Cu oxide on the material surface due to thermal diffusion such as high-temperature oxidation is increased, and the contact resistance is easily increased. Corrosion resistance also deteriorates. On the other hand, the coefficient of friction decreases, and a significant reduction in insertion force can be realized. However, when the average thickness of the Sn coating layer is further reduced to less than 0.05 μm, the lubrication effect due to the soft Sn is not exhibited, and the friction coefficient increases. When the average thickness of the Sn coating layer exceeds 5.0 μm, the adhesion of Sn not only increases the friction coefficient, but is also economically disadvantageous and the productivity is also deteriorated. Therefore, the average thickness of the Sn coating layer is specified to be 0.05 to 5.0 μm. Among these, 0.2 μm or more is preferable for applications where low contact resistance and high corrosion resistance are important, and less than 0.2 μm is preferable for applications where low friction coefficient is particularly important. The lower limit of the average thickness of the Sn coating layer is preferably 0.07 μm, more preferably 0.10 μm, and the upper limit is preferably 3.0 μm, more preferably 1.5 μm.
When the Sn coating layer is made of an Sn alloy, examples of the constituent components other than Sn of the Sn alloy include Pb, Bi, Zn, Ag, and Cu. Pb is preferably less than 50% by mass, and other elements are preferably less than 10% by mass.

(4) Arithmetic average roughness Ra of material surface
Similar to the conductive material for connecting parts described in Patent Document 2, the arithmetic average roughness Ra in at least one direction of the material surface is 0.15 μm or more, and the arithmetic average roughness Ra in all directions is 3.0 μm or less. When the arithmetic average roughness Ra is less than 0.15 μm in all directions, the Cu-Sn alloy coating layer has a low material surface protrusion height as a whole, and Cu ₆ Sn has a hard contact pressure when the electrical contact portion slides. _The proportion received by the _five phases becomes small, and it becomes difficult to reduce the amount of wear of the Sn coating layer due to fine sliding in particular. On the other hand, when the arithmetic average roughness Ra exceeds 3.0 μm in any direction, the amount of Cu oxide on the surface of the material due to thermal diffusion such as high-temperature oxidation increases, making it easy to increase the contact resistance and the reliability of electrical connection. It becomes difficult to maintain the sex. Accordingly, the surface roughness of the base material is defined such that the arithmetic average roughness Ra in at least one direction is 0.15 μm or more and the arithmetic average roughness Ra in all directions is 3.0 μm or less. Preferably, the arithmetic average roughness Ra in at least one direction is 0.2 μm or more, and the arithmetic average roughness Ra in all directions is 2.0 μm or less.

(5) Material surface exposed area ratio of Cu—Sn alloy coating layer The material surface exposed area ratio of the Cu—Sn alloy coating layer is set to 3 to 75% as in the conductive material for connecting parts described in Patent Document 2. . In addition, the material surface exposed area ratio of the Cu—Sn alloy coating layer is calculated as a value obtained by multiplying 100 by the surface area of the Cu—Sn alloy coating layer exposed per unit surface area of the material. When the material surface exposed area ratio of the Cu—Sn alloy coating layer is less than 3%, the amount of adhesion between the Sn coating layers increases, the fine sliding wear resistance decreases, and the wear amount of the Sn coating layer increases. On the other hand, if it exceeds 75%, the amount of Cu oxide on the surface of the material due to aging or corrosion increases, the contact resistance tends to increase, and it becomes difficult to maintain the reliability of electrical connection. Therefore, the material surface exposed area ratio of the Cu—Sn alloy coating layer is specified to be 3 to 75%. Preferably, the lower limit is 10% and the upper limit is 50%.

(6) Average crystal grain size of Cu—Sn alloy coating layer surface The average crystal grain size of the Cu—Sn alloy coating layer surface is less than 2 μm. When the average crystal grain size on the surface of the Cu-Sn alloy coating layer is reduced, the hardness of the surface of the Cu-Sn alloy coating layer and the apparent hardness of the Sn coating layer existing on the Cu-Sn alloy coating layer are increased. The dynamic friction coefficient is further reduced. Further, since the hardness of the surface of the Cu—Sn alloy coating layer is increased, it becomes difficult for the Cu—Sn alloy layer to be deformed or broken when the terminal is slid, and the fine sliding wear resistance is improved.
Further, when the average crystal grain size on the surface of the Cu-Sn alloy coating layer is reduced, the microscopic irregularities on the surface of the Cu-Sn alloy coating layer are reduced, and the exposed Cu-Sn alloy coating layer and the counterpart terminal The contact area increases. As a result, the adhesion force between the Cu-Sn alloy coating layer and the Cu-Sn alloy coating layer or Sn coating layer of the mating terminal increases, the static friction coefficient of the terminal increases, and vibration, thermal expansion / contraction between terminals Even if this works, the terminals are not easily displaced from each other, and the resistance to fine sliding wear is improved.
Therefore, the average crystal grain size on the surface of the Cu—Sn alloy coating layer is less than 2 μm, preferably 1.5 μm or less, and more preferably 1.0 μm or less. In addition, as shown in the Example mentioned later, in the conductive material for connection components obtained on the reflow processing conditions considered preferable in Patent Document 2, the average crystal grain size on the surface of the Cu—Sn alloy coating layer exceeds 2 μm. .

(7) Average material surface exposure interval of Cu—Sn alloy coating layer The average material surface exposure interval in at least one direction of the Cu—Sn alloy coating layer is the same as the conductive material for connecting parts described in Patent Document 2. It is preferable to set it as 0.01-0.5 mm. In addition, the average material surface exposure space | interval of a Cu-Sn alloy coating layer is the average width (length along the said straight line) of the Cu-Sn alloy coating layer which crosses the straight line drawn on the material surface, and the average of Sn coating layer. It is defined as a value obtained by adding the width of. When the average material surface exposure interval of the Cu—Sn alloy coating layer is less than 0.01 mm, the amount of Cu oxide on the material surface due to thermal diffusion such as high-temperature oxidation increases, and it is easy to increase the contact resistance, and the reliability of electrical connection It becomes difficult to maintain the sex. On the other hand, when it exceeds 0.5 mm, it may be difficult to obtain a low coefficient of friction particularly when used for a small terminal. In general, when the terminal is reduced in size, the contact area of an electrical contact portion (insertion / extraction portion) such as an indent or a rib is reduced, so that the contact probability of only the Sn coating layers increases during insertion / extraction. This increases the amount of adhesion and makes it difficult to obtain a low coefficient of friction. Therefore, it is preferable that the average material surface exposure interval of the Cu—Sn alloy coating layer be 0.01 to 0.5 mm in at least one direction. More preferably, the average material surface exposure interval of the Cu—Sn alloy coating layer is set to 0.01 to 0.5 mm in all directions. Thereby, the contact probability only of Sn coating layers in the case of insertion / extraction falls. Preferably, the lower limit is 0.05 mm and the upper limit is 0.3 mm.

(8) Thickness of Cu—Sn alloy coating layer exposed on the surface In the conductive material for connection parts according to the present invention, the thickness of the Cu—Sn alloy coating layer exposed on the surface is the connection described in Patent Document 2. Like the conductive material for parts, it is preferably 0.2 μm or more. When a part of the Cu—Sn alloy coating layer is exposed on the surface of the Sn coating layer as in the present invention, the thickness of the Cu—Sn alloy coating layer exposed on the surface of the Sn coating layer depends on the manufacturing conditions. This is because there may be a case where the alloy coating layer becomes extremely thin as compared with the average thickness of the alloy coating layer.
Note that the thickness of the Cu—Sn alloy coating layer exposed on the surface of the Sn coating layer is defined as a value measured by cross-sectional observation (different from the average thickness measurement method of the Cu—Sn alloy coating layer). When the thickness of the Cu—Sn alloy coating layer exposed on the surface of the Sn coating layer is less than 0.2 μm, the fine sliding wear phenomenon tends to occur early. In addition, the amount of Cu oxide on the material surface due to thermal diffusion such as high-temperature oxidation increases, and the corrosion resistance also decreases. Therefore, it is easy to increase the contact resistance and it is difficult to maintain the reliability of electrical connection. Therefore, the thickness of the Cu—Sn alloy coating layer exposed on the surface of the Sn coating layer is preferably 0.2 μm or more. More preferably, it is 0.3 μm or more.

(9) Sn plating layer formed after reflow treatment The average thickness of the Sn plating layer formed on the surface of the conductive material for connection parts after the reflow treatment is 0.02 to 0.2 μm. Since the conductive material for connecting parts on which the Sn plating layer is formed has improved solder wettability, it is suitable for manufacturing a terminal having a soldered joint. The Sn plating may be any of bright Sn plating, matte Sn plating, or semi-gloss Sn plating that provides an intermediate gloss level. When the average thickness of the Sn plating layer is less than 0.02 μm, the effect of improving the solder wettability is small, and when it exceeds 0.2 μm, the coefficient of friction increases and the resistance to fine sliding wear decreases. The average thickness of the Sn plating layer is preferably 0.03 μm or more, more preferably 0.05 μm or more.
The Sn plating layer is preferably formed with a uniform thickness over the entire surface after the reflow treatment, but the Cu-Sn alloy coating layer and the Sn coating layer exposed on the surface after the reflow treatment are attached with Sn plating. There is a difference in ease (the latter is easier to attach than the former). For this reason, a portion of the exposed Cu—Sn alloy coating layer may include a portion where the Sn plating is not deposited.

(10) Other surface coating layer configurations (a) As with the conductive material for connecting parts described in Patent Document 2, a Cu coating layer may be provided between the base material and the Cu—Sn alloy coating layer. This Cu coating layer is a layer in which the Cu plating layer remains after the reflow treatment. It is widely known that the Cu coating layer is useful for suppressing the diffusion of Zn and other base material constituent elements to the material surface, and improves the solderability. If the Cu coating layer becomes too thick, the moldability and the like deteriorate and the economic efficiency also deteriorates. Therefore, the thickness of the Cu coating layer is preferably 3.0 μm or less.
A small amount of component elements contained in the base material may be mixed in the Cu coating layer. Moreover, when a Cu coating layer consists of Cu alloys, Sn, Zn, etc. are mentioned as structural components other than Cu of Cu alloy. In the case of Sn, it is preferably less than 50% by mass, and for other elements, it is preferably less than 5% by mass.

(B) Similar to the conductive material for connecting parts described in Patent Document 2, between the base material and the Cu—Sn alloy coating layer (when there is no Cu coating layer), or between the base material and the Cu coating layer, A Ni coating layer may be formed as the base layer. The Ni coating layer suppresses the diffusion of Cu and matrix constituent elements to the surface of the material, suppresses the increase in contact resistance even after use at high temperature for a long time, and suppresses the growth of the Cu—Sn alloy coating layer to provide the Sn coating. It is known that layer consumption is prevented and sulfurous acid corrosion resistance is improved. Further, the diffusion of the Ni coating layer itself onto the material surface is suppressed by the Cu—Sn alloy coating layer or the Cu coating layer. For this reason, the connecting component material on which the Ni coating layer is formed is particularly suitable for connecting components that require heat resistance. However, when the average thickness of the Ni coating layer is less than 0.1 μm, the above effect cannot be sufficiently exhibited due to an increase in pit defects in the Ni coating layer. For this reason, it is preferable that the average thickness of Ni coating layer is 0.1 micrometer or more. On the other hand, if the Ni coating layer becomes too thick, the moldability and the like deteriorate and the economic efficiency also deteriorates. Therefore, the average thickness of the Ni coating layer is preferably 3.0 μm or less. The average thickness of the Ni coating layer is preferably 0.2 μm at the lower limit and 2.0 μm at the upper limit.
The Ni coating layer may contain a small amount of component elements contained in the base material. Moreover, when Ni coating layer consists of Ni alloy, Cu, P, Co etc. are mentioned as structural components other than Ni of Ni alloy. Cu is preferably 40% by mass or less, and P and Co are preferably 10% by mass or less.

(C) Instead of the Ni coating layer, a Co coating layer or an Fe coating layer can be used as the underlayer. The Co coating layer is made of Co or a Co alloy, and the Fe coating layer is made of Fe or an Fe alloy.
Similar to the Ni coating layer, the Co coating layer or the Fe coating layer suppresses the diffusion of the matrix constituent elements to the material surface. For this reason, the growth of the Cu—Sn alloy layer is suppressed to prevent the Sn layer from being consumed, and the increase in contact resistance after use at a high temperature for a long time is suppressed, and also good solder wettability is obtained. However, when the average thickness of the Co coating layer or the Fe coating layer is less than 0.1 μm, the above effect is sufficiently achieved by increasing the number of pit defects in the Co coating layer or the Fe coating layer, as in the case of the Ni coating layer. Cannot be used. In addition, when the average thickness of the Co coating layer or the Fe coating layer exceeds 3.0 μm, the above effects are saturated and cracking occurs during bending as in the Ni coating layer. The productivity is lowered and the productivity and economy are also deteriorated. Therefore, when the Co coating layer or the Fe coating layer is used as an underlayer instead of the Ni coating layer, the average thickness of the Co coating layer or the Fe coating layer is 0.1 to 3.0 μm. The average thickness of the Co coating layer or Fe coating layer is preferably 0.2 μm at the lower limit and 2.0 μm at the upper limit.

(D) Any two of the Ni coating layer, the Co coating layer, and the Fe coating layer can be used as the base layer. In this case, it is preferable to form the Co coating layer or the Fe coating layer between the base material surface and the Ni coating layer, or between the Ni coating layer and the Cu—Sn alloy layer. The total average thickness of the two underlayers (any two of the Ni coating layer, Co coating layer, and Fe coating layer) is as follows: the Ni coating layer only, the Co coating layer only, or the Fe coating layer only For the same reason as above, the thickness is set to 0.1 to 3.0 μm. The total average thickness is preferably such that the lower limit is 0.2 μm and the upper limit is 2.0 μm.

[Method of manufacturing conductive material for connecting parts]
The conductive material for connecting parts of the present invention, after roughening the surface of the copper alloy base material, forms a Sn plating layer directly on the surface of the base material or via a Ni plating layer or a Cu plating layer, Subsequently, it is manufactured by reflow processing. The steps of this manufacturing method are the same as the manufacturing method of the conductive material for connecting parts described in Patent Document 2.
As a method for roughening the surface of the base material, a physical method such as ion etching, a chemical method such as etching or electrolytic polishing, rolling (using a work roll roughened by polishing or shot blasting), polishing, etc. There are mechanical methods such as shot blasting. Among these, rolling and polishing are preferred as methods that are excellent in productivity, economy, and reproducibility of the base material surface form.
When the Ni plating layer, the Cu plating layer, and the Sn plating layer are made of a Ni alloy, a Cu alloy, and a Sn alloy, respectively, the alloys described above with respect to the Ni coating layer, the Cu coating layer, and the Sn coating layer can be used.

The average thickness of the Ni plating layer is 0.1 to 3 μm, the average thickness of the Cu plating layer is 0.1 to 1.5 μm, and the average thickness of the Sn plating layer is 0.4 to 8.0 μm. Is preferred. When the Ni plating layer is not formed, the Cu plating layer may not be formed at all.
By the reflow process, Cu of the Cu plating layer or the copper alloy base material and Sn of the Sn plating layer are mutually diffused to form a Cu-Sn alloy coating layer. There may be both cases of partial residue.

  The surface roughness of the base material after the roughening treatment is the same as the conductive material for connecting parts described in Patent Document 2, with an arithmetic average roughness Ra of at least one direction being 0.3 μm or more, and an arithmetic average roughness in all directions. The thickness Ra is preferably 4.0 μm or less. When the arithmetic average roughness Ra is less than 0.3 μm in all directions, it is difficult to manufacture the conductive material for connecting parts of the present invention. Specifically, the arithmetic average roughness Ra in at least one direction of the material surface after the reflow treatment is set to 0.15 μm or more, and the exposed area ratio of the material surface of the Cu—Sn alloy coating layer is set to 3 to 75%. It becomes difficult to set the average thickness of the Sn coating layer to 0.05 to 5.0 μm. On the other hand, when the arithmetic average roughness Ra exceeds 4.0 μm in any direction, it becomes difficult to smooth the surface of the Sn coating layer due to the flow action of molten Sn or Sn alloy. Accordingly, the surface roughness of the base material is such that at least the arithmetic average roughness Ra in one direction is 0.3 μm or more and the arithmetic average roughness Ra in all directions is 4.0 μm or less. Due to the surface roughness, a part of the Cu—Sn alloy coating layer grown by the reflow process is exposed on the material surface with the flow action of the molten Sn or Sn alloy (smoothing of the Sn coating layer). As for the surface roughness of the base material, the arithmetic average roughness Ra in at least one direction is preferably 0.4 μm or more, and the arithmetic average roughness Ra in all directions is 3.0 μm or less.

  Moreover, like the conductive material for connection parts described in Patent Document 2, the average interval Sm between the irregularities calculated in the one direction on the surface of the base material is preferably 0.01 to 0.5 mm. The Cu—Sn diffusion layer formed between the Cu plating layer or the copper alloy base material and the molten Sn plating layer by the reflow treatment usually grows reflecting the surface form of the base material. For this reason, the material surface exposure space | interval of the Cu-Sn alloy coating layer formed by a reflow process roughly reflects the average space | interval Sm of the unevenness | corrugation on a base material surface. Therefore, it is preferable that the average interval Sm between the irregularities calculated in the one direction on the surface of the base material is 0.01 to 0.5 mm. More preferably, the lower limit is 0.05 mm and the upper limit is 0.3 mm. This makes it possible to control the exposed form of the Cu—Sn alloy coating layer exposed on the material surface.

  Patent Document 2 describes that it is preferable to perform the reflow treatment at a temperature of 600 ° C. or less for 3 to 30 seconds, and particularly that it is preferable to carry out with a heat quantity as low as 300 ° C. or less. The example is mainly performed under the condition of 280 ° C. × 10 seconds. Further, paragraph 0035 of Patent Document 2 describes that the crystal grain size of the Cu—Sn alloy coating layer obtained under this reflow treatment condition is several to several tens of μm.

  On the other hand, according to the knowledge of the present inventor, in order to further reduce the crystal grain size of the Cu—Sn alloy coating layer to less than 2 μm, it is necessary to increase the temperature rising rate during the reflow treatment. In order to increase the rate of temperature increase, the amount of heat given to the material during the reflow process may be increased, that is, the atmosphere temperature of the reflow processing furnace may be set higher during the temperature increase. The heating rate is preferably 15 ° C./second or more, more preferably 20 ° C./second or more. In Patent Document 2, since the crystal grain size of the Cu—Sn alloy coating layer is described as several μm to several tens of μm, the temperature increase rate of the reflow process is about 8 to 12 ° C./second or less. I guess it is not.

The reflow treatment temperature as the solid temperature is preferably 400 ° C. or higher, more preferably 450 ° C. or higher. On the other hand, the reflow treatment temperature is preferably 650 ° C. or lower and more preferably 600 ° C. or lower so that the Cu content of the Cu—Sn alloy coating layer does not become too high. Moreover, it is desirable that the time for which the reflow treatment temperature is maintained (reflow treatment time) is about 5 to 30 seconds, and that the shorter the reflow treatment temperature, the shorter. After the reflow treatment, it is immersed in water according to a conventional method and rapidly cooled.
By performing the reflow process under the above conditions, a Cu—Sn alloy coating layer having a small crystal grain size is formed. Further, a Cu—Sn alloy coating layer having a Cu content of 20 to 70 at% is formed, the Cu—Sn alloy coating layer having a thickness of 0.2 μm or more is exposed on the surface, and the Sn plating layer is excessively consumed. Is suppressed.

  After the reflow treatment, an Sn plating layer having an average thickness of 0.02 to 0.2 μm is formed on the surface of the conductive material for connecting parts as necessary. The Sn plating may be any of bright Sn plating, matte Sn plating, or semi-gloss Sn plating that provides an intermediate gloss level.

  The copper alloy sheets A to D having a thickness of 0.25 mm having the composition, mechanical properties, and conductivity shown in Table 1 are subjected to surface roughening treatment by a mechanical method (rolling or polishing) (Nos. 1 to 11). ), Or without surface roughening (No. 12 to 14), copper alloy base materials having various surface roughnesses were finished. The copper alloy base materials A to D are subjected to Ni plating (No. 6, 7 and 14 are not performed), and further subjected to various thicknesses of Cu plating and Sn plating, and then the atmospheric temperature of the reflow processing furnace is set. A test material was obtained by adjusting and performing reflow treatment under various conditions (temperature × time) shown in Table 2. The rate of temperature increase to the reflow processing temperature is No. 1-10, 15 ° C./second or more. In 11-14, it was about 10 ° C./second.

In addition, the mechanical property and electrical conductivity of copper alloy board AD were measured in the following ways.
The 0.2% yield strength was measured using ASTM E08 specimens (parallel to the rolling direction (LD) and vertical (TD) directions) taken from each copper alloy plate.
The stress relaxation rate was measured by the cantilever method. A strip-shaped test piece having a width of 10 mm and a length of 90 mm, whose length direction is parallel to the rolling direction of the plate (LD) and perpendicular direction (TD), was sampled, and one end thereof was rigidly tested. Secure to the base. A deflection d (= 10 mm) is given to the test piece at a distance 1 from the fixed end, and the fixed end is set to 80% of the 0.2% yield strength of the material in the respective direction (LD or TD). Apply the corresponding surface stress. The distance l was calculated according to “Stress Relaxation Test Method by Bending Copper and Copper Alloy Sheet Strips” of the Japan Copper and Brass Association Technical Standard (JCBA-T309: 2004). The test piece to which deflection was applied was held in an oven heated to 200 ° C. for 1000 hours and then taken out. The permanent strain δ when the deflection amount d (= 10 mm) was removed was measured, and the stress relaxation rate RS = (δ / d ) × 100. The condition of holding at 200 ° C. for 1000 hours corresponds to the condition of holding at 160 ° C. for about 130,000 hours when calculated by the Larson Miller equation.
The electrical conductivity was measured using a test piece taken from the Cu—Zn alloy plate in the rolling parallel direction.

About the obtained test material, the average thickness of each coating layer, the Cu content of the Cu—Sn alloy coating layer, the material surface exposed area ratio of the Cu—Sn alloy coating layer, and the Cu—Sn alloy coating exposed on the material surface The layer thickness, the average material surface exposure interval of the Cu—Sn alloy coating layer, the average crystal grain size of the Cu—Sn alloy coating layer surface, and the material surface roughness were measured as follows. The results are shown in Table 2. In addition, No. In the test materials 1 to 14, the Cu plating layer disappears by the reflow treatment, and there is no Cu coating layer.
The following measurement method followed the method described in Patent Document 2 except for the measurement method of the average crystal grain size on the surface of the Cu—Sn alloy coating layer.

(Measuring method of average thickness of Ni coating layer)
The average thickness of the Ni coating layer after the reflow treatment was measured using a fluorescent X-ray film thickness meter (Seiko Instruments Inc .; SFT3200). The measurement conditions were Sn / Ni / base metal two-layer calibration curve for the calibration curve and the collimator diameter was φ0.5 mm.
(Cu content measurement method of Cu-Sn alloy coating layer)
First, the test material was immersed in an aqueous solution containing p-nitrophenol and caustic soda as components for 10 minutes to remove the Sn coating layer. Thereafter, the Cu content of the Cu—Sn alloy coating layer was determined by quantitative analysis using EDX (energy dispersive X-ray spectrometer).

(Method for measuring average thickness of Cu—Sn alloy coating layer)
First, the test material was immersed in an aqueous solution containing p-nitrophenol and caustic soda as components for 10 minutes to remove the Sn coating layer. Thereafter, the film thickness of the Sn component contained in the Cu—Sn alloy coating layer was measured using a fluorescent X-ray film thickness meter (Seiko Instruments Inc .; SFT3200). The measurement conditions were a single layer calibration curve of Sn / base material or a two-layer calibration curve of Sn / Ni / base material for the calibration curve, and the collimator diameter was φ0.5 mm. The obtained value was defined as the average thickness of the Cu—Sn alloy coating layer.

(Measuring method of average thickness of Sn coating layer)
First, the sum of the film thickness of the Sn coating layer of the test material and the film thickness of the Sn component contained in the Cu—Sn alloy coating layer was measured using a fluorescent X-ray film thickness meter (Seiko Instruments Inc .; SFT3200). . Then, it immersed in the aqueous solution which uses p-nitrophenol and caustic soda as a component for 10 minutes, and removed Sn coating layer. Again, the film thickness of the Sn component contained in the Cu—Sn alloy coating layer was measured using a fluorescent X-ray film thickness meter. The measurement conditions were a single layer calibration curve of Sn / base material or a two-layer calibration curve of Sn / Ni / base material for the calibration curve, and the collimator diameter was φ0.5 mm. By subtracting the film thickness of the Sn component contained in the Cu-Sn alloy coating layer from the sum of the film thickness of the obtained Sn coating layer and the film thickness of the Sn component contained in the Cu-Sn alloy coating layer, Sn The average thickness of the coating layer was calculated.

(Surface roughness measurement method)
It measured based on JISB0601-1994 using the contact-type surface roughness meter (Tokyo Seimitsu; Surfcom 1400). The surface roughness measurement conditions were a cutoff value of 0.8 mm, a reference length of 0.8 mm, an evaluation length of 4.0 mm, a measurement speed of 0.3 mm / s, and a stylus tip radius of 5 μmR. The measurement direction of the surface roughness was a direction perpendicular to the rolling or polishing direction performed during the surface roughening treatment (the direction in which the surface roughness is maximized).

(Measuring method of exposed surface area ratio of Cu—Sn alloy coating layer)
The surface of the test material was observed at a magnification of 200 times using an SEM (scanning electron microscope) equipped with EDX (energy dispersive X-ray spectrometer). The material surface exposed area ratio of the Cu—Sn alloy coating layer was measured by image analysis from the density of the obtained composition image (excluding contrast such as dirt and scratches).
(Measuring method of average material surface exposure interval of Cu-Sn alloy coating layer)
The surface of the test material was observed at a magnification of 200 times using an SEM (scanning electron microscope) equipped with EDX (energy dispersive X-ray spectrometer). From the obtained composition image, an average of values obtained by adding the average width (length along the straight line) of the Cu—Sn alloy coating layer crossing the straight line drawn on the material surface and the average width of the Sn coating layer is obtained. Thus, the average material surface exposure interval of the Cu—Sn alloy coating layer was measured. The measurement direction (the direction of the drawn straight line) was a direction perpendicular to the rolling or polishing direction performed during the surface roughening treatment.

(Method for measuring thickness of Cu—Sn alloy coating layer exposed on material surface)
The cross section of the test material processed by the microtome method is observed at a magnification of 10,000 using a scanning electron microscope (SEM), and the thickness of the Cu—Sn alloy coating layer exposed on the material surface by image analysis processing The minimum value of was measured.
(Measuring method of average grain size of Cu—Sn alloy coating layer surface)
The test material was immersed in an aqueous solution containing p-nitrophenol and caustic soda as components for 10 minutes to remove the Sn coating layer. Thereafter, the surface of the test material was observed with a SEM at a magnification of 3000 times, and the average value of the diameter (equivalent circle diameter) when each particle was made into a circle was obtained by image analysis, and this was the average crystal on the surface of the Cu—Sn alloy coating layer. The particle size was taken. The test material No. A surface texture photograph of No. 6 is shown in FIG.

Further, the obtained test material was subjected to a fine sliding wear test as described below, and the amount of wear after the fine sliding was measured. The results are also shown in Table 2.
(Fine sliding wear test)
The shape of the indented portion of the electrical contact in the fitting-type connecting part was simulated and evaluated using a sliding tester (Yamazaki Seiki Laboratory Co., Ltd .; CRS-B1050CHO) as shown in FIG. First, a male test piece 1 of a plate material cut out from each test material is fixed to a horizontal base 2, and a female test piece 3 of a hemispherical work material (outer diameter is φ1.8 mm) cut out from each test material thereon. The coating layers were brought into contact with each other. The male test piece 1 and the female test piece 3 used the same test material. A 3.0 N load (weight 4) was applied to the female test piece 3 to hold the male test piece 1 and the stepping motor 5 was used to slide the male test piece 1 in the horizontal direction (sliding distance was 50 μm, sliding The dynamic frequency was 1 Hz). The arrow indicates the sliding direction.
The male test piece 1 that had been slid 100 times was processed by the microtome method, and the cross section of the wear scar was observed with a SEM (scanning electron microscope) at a magnification of 10,000 times. The maximum depth of the observed wear scar was defined as the amount of wear after fine sliding.

As shown in Table 2, no. 1 to 10 are the average thickness of each coating layer, the Cu content of the Cu-Sn alloy coating layer, the material surface roughness, the material surface exposed area ratio of the Cu-Sn alloy coating layer, and the Cu- exposed on the material surface. The provisions of the present invention are satisfied with respect to the thickness of the Sn alloy coating layer and the average material surface exposure interval of the Cu—Sn alloy coating layer. Among these, the reflow treatment temperature was low and the heating rate was small. No. 11 has an average crystal grain size of 3.2 μm on the surface of the Cu—Sn alloy coating layer and does not satisfy the provisions of the present invention. On the other hand, the reflow treatment temperature was high and the heating rate was large. In Nos. 1 to 10, the average crystal grain size of the surface of the Cu—Sn alloy coating layer satisfies the definition of the present invention. No. In all of Nos. 1 to 10, the amount of fine sliding wear was No. 1. No. 11 having a similar covering layer structure with the same base material. 3 and no. 11 and No. 11 are compared. No. 3 has a fine sliding wear amount of No. 3. The wear amount of 7 is reduced to 64%.
In addition, No. No. 11 in which the material surface exposed area ratio of the Cu—Sn alloy coating layer is zero (the Cu—Sn alloy coating layer is not exposed on the outermost surface). Compared with 12-14, the amount of wear after fine sliding is small.

  The copper alloy plate of alloy symbol B shown in Table 1 is subjected to a surface roughening treatment by a mechanical method (rolling or polishing) (No. 15 to 22), or no surface roughening treatment is performed (No. 23 to No. 23). 25) Finished copper alloy base materials having various surface roughnesses. The copper alloy base material was subjected to base plating (one or two of Ni, Co, and Fe) (No. 21 and 25 were not performed), and further subjected to Cu plating and Sn plating of various thicknesses. Subsequently, the test material was obtained by adjusting the atmospheric temperature of a reflow processing furnace and performing a reflow process on various conditions (temperature x time) shown in Table 3. The rate of temperature increase to the reflow processing temperature is No. 15-21, 15 ° C./second or more, In 22-25, it was about 10 degreeC / second.

  About the obtained test material, the same measurement and test as Example 1 were performed. In addition, the average thickness of the Co coating layer and the Fe coating layer and the friction coefficient were measured for the obtained test materials in the following manner. The results are shown in Table 3. In addition, No. In the test materials of 11 to 25, the Cu plating layer disappeared.

(Measurement of average thickness of Co layer)
The average thickness of the Co layer of the test material was calculated using a fluorescent X-ray film thickness meter (Seiko Instruments Inc .; SFT3200). The measurement conditions were Sn / Co / matrix two-layer calibration curve for the calibration curve, and the collimator diameter was 0.5 mm.
(Measurement of average thickness of Fe layer)
The average thickness of the Fe layer of the test material was calculated using a fluorescent X-ray film thickness meter (Seiko Instruments Inc .; SFT3200). The measurement conditions were Sn / Fe / matrix two-layer calibration curve for the calibration curve, and the collimator diameter was 0.5 mm.

(Measurement of friction coefficient)
The shape of the indented portion of the electrical contact in the fitting type connecting part was simulated and measured using an apparatus as shown in FIG. First, no. A plate-shaped male test piece 6 cut out from each of the test materials 15 to 25 was fixed to a horizontal base 7, and No. 1 was placed thereon. A female test piece 8 of a hemispherical processed material (outer diameter was φ1.8 mm) cut out from 23 test materials (the Cu—Sn alloy layer was not exposed on the surface) was placed in contact with the surfaces. Subsequently, a load of 3.0 N (weight 9) is applied to the female test piece 8, the male test piece 6 is pressed, and the male test piece 6 is attached using a horizontal load measuring device (Aiko Engineering Co., Ltd .; Model-2152). The sample was pulled in the horizontal direction (sliding speed was 80 mm / min), and the maximum frictional force F (unit: N) up to a sliding distance of 5 mm was measured. The coefficient of friction was determined by the following formula (1). In addition, 10 is a load cell, the arrow is a sliding direction, and the sliding direction was a direction perpendicular to the rolling direction.
Friction coefficient = F / 3.0 (1)

As shown in Table 3, no. 15 to 21 are the average thickness of each coating layer, the Cu content of the Cu—Sn alloy coating layer, the material surface roughness, the material surface exposed area ratio of the Cu—Sn alloy coating layer, and the Cu— exposed on the material surface. The provisions of the present invention are satisfied with respect to the thickness of the Sn alloy coating layer and the average material surface exposure interval of the Cu—Sn alloy coating layer. Among these, the reflow treatment temperature was low and the heating rate was small. No. 22 has an average crystal grain size of 2.6 μm on the surface of the Cu—Sn alloy coating layer and does not satisfy the definition of the present invention. On the other hand, the reflow treatment temperature was high and the heating rate was large. As for 15-21, the average crystal grain diameter of the surface of a Cu-Sn alloy coating layer satisfies the rule of the present invention. No. In all of Nos. 15 to 21, the amount of fine sliding wear was No. Less than 22. In addition, No. No. 22 is also the case where the material surface exposed area ratio of the Cu—Sn alloy coating layer is zero (Cu—Sn alloy coating layer is not exposed on the outermost surface). Compared with 23 to 25, the amount of wear after fine sliding is small.
Moreover, the average thickness of the Sn coating layer was less than 0.2 μm. 16 and 21 have a very low coefficient of friction.

  Invention Example No. 2 produced in Example 2. 15 was subjected to electro-gloss Sn plating at various thicknesses after the reflow treatment. 26-29 test materials were obtained. The average thickness of the Sn plating layer was measured as follows, and the results are shown in Table 4. In addition to the fine sliding wear test and the friction coefficient measurement test similar to those in Example 2, the test material thus obtained was subjected to a solder wettability evaluation test. The results are shown in Table 4.

(Measuring method of average thickness of Sn plating layer)
No. For the test materials of 26 to 29, the average thickness of the entire Sn coating layer (including the Sn plating layer by electro-gloss Sn plating) was determined by the measurement method described in Example 1. From the average thickness of the entire Sn coating layer, no. The average thickness of the Sn plating layer was calculated by subtracting the average thickness of 15 Sn coating layers (not including the Sn plating layer by electro-gloss Sn plating).

(Solder wetting test)
Each test material No. After the inactive flux was dip-applied for 1 second to the test pieces cut out from 15, 26 to 29, the zero cross time and the maximum wetting stress were measured by the meniscograph method. The solder composition was Sn-3.0Ag-0.5Cu, the test piece was immersed in a solder at 255 ° C., and the immersion conditions were an immersion speed of 25 mm / sec, an immersion depth of 12 mm, and an immersion time of 5.0 sec. . For solder wettability, zero cross time ≤ 2.0 sec, maximum wetting stress ≥ 5 mN as standards, ○ satisfying all the standards, △ satisfying only one of them, △, evaluating not satisfying any of the standards as × did.

  As shown in Table 4, no. Nos. 26 to 29 have an Sn plating layer on the outermost surface. Compared to 15, the solder wettability is good. Among these, No. In Nos. 26 to 28, the average thickness of the Sn plating layer on the outermost surface satisfies the provisions of the present invention, has both a low friction coefficient and solder wettability, and has a small amount of fine sliding wear. In addition, No. No. 29 has good solder wettability, but the coefficient of friction increased.

1,6 Male test piece 2,7 units 3,8 Female test piece 4,9 Weight 5 Stepping motor 10 Load cell

Connecting parts for the conductive material according to the present invention, the surface of the base material made of a copper alloy plate strip, Cu content and 20～70At% of the Cu-Sn alloy coating layer, Sn coating layer are formed in this order, the material The surface is reflow-treated, the Sn coating layer is reflow Sn plating, and the material surface has an arithmetic average roughness Ra of at least 0.15 μm in at least one direction, and an arithmetic average roughness Ra in all directions. 3.0 μm or less, part of the Cu—Sn alloy coating layer is exposed on the surface of the Sn coating layer, and the material surface exposed area ratio of the Cu—Sn alloy coating layer is 3 to 75%. In a certain conductive material for connecting parts, the conductivity of the copper alloy sheet exceeds 50% IACS, and the stress relaxation rate after being held at 200 ° C. for 1000 hours is 25% or less, and the Cu—Sn alloy coating layer Average thickness The average crystal grain size of the surface of the coating layer is less than 2 μm, and the average thickness of the Sn coating layer is 0.05 to 5.0 μm.

Claims (12)

A Cu—Sn alloy coating layer having a Cu content of 20 to 70 at% and an Sn coating layer are formed in this order on the surface of a base material made of a copper alloy sheet, and the material surface is subjected to a reflow treatment. The arithmetic average roughness Ra in the direction is 0.15 μm or more, the arithmetic average roughness Ra in all directions is 3.0 μm or less, and a part of the Cu—Sn alloy coating layer is exposed on the surface of the Sn coating layer In the conductive material for connecting parts, in which the Cu—Sn alloy coating layer has a material surface exposed area ratio of 3 to 75%, the copper alloy sheet has a conductivity exceeding 50% IACS and 200 ° C. The stress relaxation rate after holding for 1000 hours is 25% or less, the average thickness of the Cu—Sn alloy coating layer is 0.2 to 3.0 μm, and the average crystal grain size of the surface of the coating layer is less than 2 μm And average of Sn coating layer Connecting parts for the conductive material excellent in 耐微 sliding wear, wherein the thickness is 0.05～5.0Myuemu. The said copper alloy strip contains 1 type or 2 types of Cr: 0.15-0.70 mass% and Zr: 0.01-0.20 mass%, and the remainder consists of Cu and an unavoidable impurity. 2. The conductive material for connecting parts according to claim 1, which is excellent in resistance to fine sliding wear. The conductive material for connecting parts according to claim 2, wherein the copper alloy strip further contains Ti: 0.01 to 0.30 mass%. 4. The conductive material for connecting parts according to claim 2, wherein the copper alloy strip further contains Si: 0.01 to 0.20 mass%. The copper alloy strip is further Zn: 0.001-1.0 mass%, Sn: 0.001-0.5 mass%, Mg: 0.001-0.15 mass%, Ag: 0.005- 0.50 mass%, Fe: 0.005-0.50 mass%, Ni: 0.005-0.50 mass%, Co: 0.005-0.50 mass%, Al: 0.005-0. 10% by mass, Mn: one or more of 0.005 to 0.10% by mass, 1.0% by mass or less in total, Conductive material for connecting parts with excellent dynamic wear. The material surface has an average material surface exposure interval of at least 0.01 to 0.5 mm in at least one direction, and is excellent in fine sliding wear resistance according to any one of claims 1 to 5. Conductive material for connecting parts. The thickness of the Cu-Sn alloy coating layer exposed on the surface of the Sn coating layer is 0.2 µm or more, and is excellent in micro-sliding wear resistance according to any one of claims 1 to 6. Conductive material for connecting parts. The conductive material for connecting parts according to any one of claims 1 to 7, further comprising a Cu coating layer between a surface of the base material and the Cu-Sn alloy coating layer. A base layer made of any one of a Ni coating layer, a Co coating layer, and an Fe coating layer is further formed between the surface of the base material and the Cu—Sn alloy coating layer, and the average thickness of the base layer The conductive material for connecting parts according to any one of claims 1 to 7, wherein the conductive material is 0.1 to 3.0 µm. Between the surface of the base material and the Cu-Sn alloy coating layer, a base layer made of any two of Ni coating layer, Co coating layer, and Fe coating layer is formed, and the average of the total of the base layer The conductive material for connection parts having excellent resistance to micro-sliding wear according to any one of claims 1 to 7, wherein the thickness is 0.1 to 3.0 µm. The conductive material for connecting parts according to claim 9 or 10, further comprising a Cu coating layer between the underlayer and the Cu-Sn alloy coating layer. The fine sliding wear resistance according to any one of claims 1 to 11, wherein an Sn plating layer having an average thickness of 0.02 to 0.2 µm is further formed on the surface of the reflowed material. Conductive material for connecting parts with excellent properties.