WO2010119489A1 - Conductive member and manufacturing method thereof - Google Patents

Conductive member and manufacturing method thereof Download PDF

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Publication number
WO2010119489A1
WO2010119489A1 PCT/JP2009/003280 JP2009003280W WO2010119489A1 WO 2010119489 A1 WO2010119489 A1 WO 2010119489A1 JP 2009003280 W JP2009003280 W JP 2009003280W WO 2010119489 A1 WO2010119489 A1 WO 2010119489A1
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WO
WIPO (PCT)
Prior art keywords
layer
plating
conductive member
alloy
intermetallic compound
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PCT/JP2009/003280
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French (fr)
Japanese (ja)
Inventor
櫻井健
石川誠一
久保田賢治
玉川隆士
Original Assignee
三菱伸銅株式会社
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Priority claimed from JP2009115289A external-priority patent/JP5442316B2/en
Priority claimed from JP2009127085A external-priority patent/JP4372835B1/en
Application filed by 三菱伸銅株式会社 filed Critical 三菱伸銅株式会社
Priority to CN200980158742.4A priority Critical patent/CN102395713B/en
Publication of WO2010119489A1 publication Critical patent/WO2010119489A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R13/00—Details of coupling devices of the kinds covered by groups H01R12/70 or H01R24/00 - H01R33/00
    • H01R13/02—Contact members
    • H01R13/03—Contact members characterised by the material, e.g. plating, or coating materials
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/10—Electroplating with more than one layer of the same or of different metals
    • C25D5/12—Electroplating with more than one layer of the same or of different metals at least one layer being of nickel or chromium
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/48—After-treatment of electroplated surfaces
    • C25D5/50—After-treatment of electroplated surfaces by heat-treatment
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/60—Electroplating characterised by the structure or texture of the layers
    • C25D5/615—Microstructure of the layers, e.g. mixed structure
    • C25D5/617—Crystalline layers
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D7/00—Electroplating characterised by the article coated

Definitions

  • the present invention relates to a conductive member used for an electrical connection connector, a fuse, or the like, in which a plurality of plating layers are formed on the surface of a substrate made of Cu or Cu alloy, and a method for manufacturing the same.
  • This application includes Japanese Patent Application No. 2009-98043 filed in Japan on April 14, 2009, Japanese Patent Application No. 2009-115289 filed in Japan on May 12, 2009, and May 26, 2009. Claim priority based on Japanese Patent Application No. 2009-127085 filed in Japan, the contents of which are incorporated herein.
  • Sn-based metal plating is applied to the surface of a Cu-based substrate made of Cu or a Cu alloy for the purpose of improving electrical connection characteristics. Many of them have been used. Examples of such conductive members include those described in Patent Document 1 to Patent Document 4.
  • the conductive members described in Patent Document 1 to Patent Document 3 are subjected to a reflow treatment by heating after forming Ni, Cu, Sn on the surface of a substrate made of Cu or Cu alloy in order to form a three-layered plating layer. Thus, an Sn layer is formed on the outermost surface layer, and a Cu—Sn intermetallic compound layer (for example, Cu 6 Sn 5 ) is formed between the Ni layer and the Sn layer.
  • the technique described in Patent Document 4 is a technique in which a base plating layer is made of, for example, Ni—Fe, Fe, or the like, and Cu and Sn are sequentially plated thereon to perform a reflow process.
  • such a conductive member is continuously manufactured as a copper strip, but with a limited line length by using an inorganic acid and an insoluble anode on the surface of a wide thin plate such as this copper strip.
  • the relative flow rate between the copper strip and the plating solution in each plating bath is increased to increase the current density, thereby shortening the time required to obtain the desired properties of plating. This is very important.
  • the reflow treatment after plating is a major factor, which greatly affects the performance during use as a conductive member.
  • the characteristics of the surface layer formed after the reflow treatment and the intermediate alloy layer which is the lower layer greatly contribute to the connector insertion / removability.
  • Patent Document 5 a current density of 50 A / dm 2 or more and a temperature of 30 to 70 ° C. are used in an insoluble anode in a tin plating sulfuric acid bath for high current density used for the production of electroplated tin and thin tin-plated steel sheet.
  • a method of tin plating is disclosed.
  • Patent Document 6 a Ni or Ni alloy layer is formed on the surface of copper or a copper alloy, a Sn or Sn alloy layer is formed on the outermost surface, and the Ni or Ni alloy layer and the Sn or Sn alloy layer are formed.
  • At least one intermediate layer containing Cu and Sn as a main component or an intermediate layer containing Cu, Ni and Sn as a main component is formed between the at least one intermediate layer, and the Cu content is 50 wt. %, And the Ni content is 50% by weight or less, and the Cu content is 50% by weight, projected in the direction perpendicular to each layer formed on the surface of the copper or copper alloy.
  • a plated copper or copper alloy characterized in that the average crystal grain size of the layer having the following and Ni content of 50% by weight or less is 0.5 to 3.0 ⁇ m.
  • Ni or Ni alloy As a manufacturing method, Ni or Ni alloy, Cu plating is applied on the surface of copper or copper alloy, Sn or Sn alloy plating is applied to the outermost surface layer, then at least one reflow treatment is performed, and a heating temperature is set. Is 400 to 900 ° C., the time from the melting of the Sn or Sn alloy layer to the solidification is 0.05 to 60 seconds.
  • the connectors when used for connectors, as the circuit density increases, the connectors also become multipolar, and the insertion force at the time of assembling the automobile wiring is increasing. Therefore, a conductive member that can reduce the insertion / extraction force is required. ing. Furthermore, the use as a fuse is found about the electrically conductive member which plated the Sn type metal on the surface of such Cu type base material, and the favorable fusing characteristic as a fuse is calculated
  • the invention described in Patent Document 5 is a production method of tin-plated steel sheets such as tinplate, in a sulfuric acid bath using an insoluble anode, at a temperature of 30 to 70 ° C., and a current density of 50 A / dm 2 or more.
  • the steel strip is tin-plated at a relative speed of the steel strip and the electrolyte of 160 m / min or more.
  • Ni or Ni alloy Cu plating is applied on the surface of copper or a copper alloy, and Sn or Sn alloy plating is applied to the outermost surface layer. Is 400 to 900 ° C., and the time from when the Sn or Sn alloy layer melts to solidification is 0.05 to 60 seconds, the Cu content is 50% by weight or less and the Ni content is One intermediate layer having an average crystal grain size of 0.5 to 3.0 ⁇ m is formed by 50% by weight or less. This average crystal grain size is greatly related to the pluggability when the conductive member is used as a connector, but appropriate pluggability cannot be obtained only by controlling the average grain size.
  • the present invention has been made in view of such circumstances, and has a stable contact resistance, is difficult to peel off, can reduce and stabilize the insertion / extraction force when used as a connector, and is used as a fuse.
  • a Cu—Sn intermetallic compound layer is formed between a Ni-based underlayer formed on a Cu-based substrate and a Sn-based surface layer forming the surface, and Cu— Sn intermetallic compound layer further made from the the Cu 3 Sn layer disposed on the Ni-based base layer, the Cu 6 Sn 5 layer disposed on the said Cu 3 Sn layer, the Cu 3 Sn
  • the surface roughness of the surface of the Cu-Sn intermetallic compound layer combined with the Sn-based surface layer in combination with the Cu 6 Sn 5 layer is 0.05 to 0.25 ⁇ m in terms of arithmetic average roughness Ra, and
  • the maximum valley depth Rv of the roughness curve is 0.05 to 1.00 ⁇ m
  • the Cu 3 Sn layer covers the Ni-based underlayer, and the area coverage is 60 to 100%. It is characterized by that.
  • the conductive member, Cu-Sn intermetallic compound layer between the Ni-based base layer and the Sn-based surface layer is a two-layer structure of the Cu 3 Sn layer and the Cu 6 Sn 5 layer, the underlying Cu 3
  • the Cu 6 Sn 5 layer is present so that the Sn layer covers the Ni-based underlayer and covers it.
  • the Cu—Sn intermetallic compound layer formed by combining the Cu 3 Sn alloy layer and the Cu 6 Sn 5 layer has a film thickness that is not necessarily uniform and has irregularities, but is a surface in contact with the Sn-based surface layer.
  • the surface roughness is 0.05 to 0.25 ⁇ m in terms of arithmetic average roughness Ra, and 0.05 to 1.00 ⁇ m in terms of the maximum valley depth Rv of the roughness curve.
  • the arithmetic average roughness Ra represents the average size of the irregularities on the surface. If this Ra exceeds 0.25 ⁇ m, large irregularities are formed under the Sn-based surface layer.
  • the insertion / extraction force when used is not preferable. When the unevenness of the Cu—Sn intermetallic compound layer is reduced, the insertion / extraction force during use of the connector is reduced, but it is preferable that Ra is less than 0.05 ⁇ m because the unevenness of the Cu—Sn intermetallic compound layer is almost eliminated. This is not preferable because the Cu—Sn intermetallic compound layer becomes extremely brittle and peeling of the film easily occurs during bending.
  • Ra is averaged, even if there is a large valley, it is averaged and hardly appears in the numerical value. If there is such a large valley, Sn diffuses from the valley to the Ni-based underlayer at a high temperature, and there is a risk that defects will occur in the Ni-based underlayer.
  • the contact resistance is increased. Further, at this time, Kirkendall voids are likely to be generated due to diffusion of Cu from the defect portion of the Ni-based underlayer. Therefore, if Ra is in the above-mentioned range and the maximum valley depth Rv of the roughness curve is 1.00 ⁇ m or less, it is possible to prevent the Ni-based underlayer from being damaged.
  • the Rv be less than 0.05 ⁇ m because the Cu—Sn intermetallic compound layer becomes brittle as in the case of Ra.
  • the flexible Sn base is hardened and used in a multipolar connector or the like. It is possible to reduce the insertion / extraction force and to suppress variations thereof.
  • the reason why the area coverage of the Cu 3 Sn layer with respect to the Ni-based underlayer is 60% or more is that when the coverage is low, the Ni atoms in the Ni-based underlayer are Cu 6 Sn at high temperatures from the uncoated portion. This is because the Ni-based underlayer is deficient in five layers and the Cu of the base material diffuses from the deficient portion, resulting in increased contact resistance and generation of Kirkendall voids as in the above case. is there. In order to prevent this increase in contact resistance at high temperatures and the generation of Kirkendall voids and to achieve heat resistance higher than that of the prior art, it is necessary that the Ni-based underlayer is coated at least 60% or more. Further, it is desirable that the area coverage is 80% or more.
  • the Cu 3 Sn layer preferably has an average thickness of 0.01 to 0.5 ⁇ m.
  • This average thickness is an average value when the thickness of the Cu 3 Sn layer portion is measured at a plurality of locations.
  • the average thickness of the Sn-based surface layer is preferably 0.5 to 1.5 ⁇ m.
  • the Sn-based surface layer preferably has an average thickness of 0.5 to 1.5 ⁇ m as a layer forming the surface of the conductive member in order to maintain performance such as heat resistance and insertion / removability as a connector terminal.
  • a Sn—Ag coating layer having an average thickness of 0.05 to 0.5 ⁇ m may be formed on the Sn surface layer.
  • the Sn—Ag coating layer preferably contains 0.1 to 5.0% by weight of Ag.
  • the manufacturing method of the electrically-conductive member of this invention heats, after plating the surface of Cu base material, Ni or Ni alloy, Cu or Cu alloy, Sn or Sn alloy in this order, and forming each plating layer And reflow treatment to produce a conductive member in which a Ni-based underlayer, a Cu—Sn intermetallic compound layer, and a Sn-based surface layer are sequentially formed on the Cu-based substrate,
  • a plating layer made of Cu alloy is formed by electrolytic plating with a current density of 20 to 60 A / dm 2
  • a plating layer made of Sn or Sn alloy is formed by electrolytic plating with a current density of 10 to 30 A / dm 2
  • the average thickness of the plating layer made of Cu or Cu alloy is 0.3 to 0.5 ⁇ m, and the reflow treatment is performed after 1 to 15 minutes have passed since the formation of the plating layer.
  • Cu plating at a high current density increases the grain boundary density and helps to form a uniform alloy layer.
  • the reason why the current density of Cu plating is set to 20 to 60 A / dm 2 is that when the current density is less than 20 A / dm 2 , the reaction activity of the Cu plating crystal is poor, and therefore the effect of forming a smooth intermetallic compound when alloying is performed.
  • the current density exceeds 60 A / dm 2 the smoothness of the Cu plating layer is lowered, and thus a smooth Cu—Sn intermetallic compound layer cannot be formed.
  • the current density of Sn plating was set to 10 to 30 A / dm 2 because when the current density was less than 10 A / dm 2 , the Sn grain boundary density was low, and smooth Cu-Sn intermetallic This is because the effect of forming the compound layer is poor, and on the other hand, if the current density exceeds 30 A / dm 2 , the current efficiency is remarkably lowered, which is undesirable. Also, in order to reduce the unevenness of the Cu—Sn intermetallic compound layer, the thickness of the plating layer made of Cu or Cu alloy as the base is important, and the reflow treatment was performed by forming this slightly thicker. The unevenness of the subsequent Cu—Sn intermetallic compound layer can be reduced.
  • the plating layer made of Cu or Cu alloy is formed to be relatively thick and has a thickness of 0.3 ⁇ m or more, so that the surface roughness of the Cu—Sn intermetallic compound layer after reflow treatment is small and the surface roughness is reduced. An appropriate state can be obtained. Even if it exceeds 0.5 ⁇ m, the effect is saturated.
  • the reflow process may be performed within 15 minutes, preferably within 5 minutes.
  • Ni or Ni alloy, Cu or Cu alloy, Sn or Sn alloy is plated at a higher current density than in the prior art, and Cu and Sn are activated actively during reflow by performing reflow treatment immediately after plating. By reacting, a large amount of Ni-based underlayer is covered with the Cu 3 Sn layer, and a uniform Cu 6 Sn 5 layer is generated.
  • the cooling step by providing a primary cooling step with a low cooling rate, Cu atoms diffuse gently in the Sn grains and grow with a desired intermetallic compound structure.
  • the cooling rate in the primary cooling step exceeds 30 ° C./second, the intermetallic compound cannot grow into a smooth shape due to the effect of rapid cooling, and unevenness increases.
  • the cooling time is less than 2 seconds, the intermetallic compound cannot grow into a smooth shape.
  • the cooling time exceeds 10 seconds, the growth of the Cu 6 Sn 5 layer proceeds excessively and the coverage of the Cu 3 Sn layer decreases. Air cooling is appropriate for this primary cooling step. Then, after the primary cooling step, the secondary cooling step is rapidly cooled to complete the growth of the intermetallic compound layer with a desired structure. When the cooling rate in the secondary cooling step is less than 100 ° C./second, the intermetallic compound further proceeds, and a desired intermetallic compound shape cannot be obtained. Thus, by precisely controlling the electrodeposition conditions and the reflow conditions for plating, a stable Cu—Sn intermetallic compound layer having a two-layer structure with few irregularities can be obtained.
  • the average thickness of the plating layer made of Sn or Sn alloy is preferably 1.5 to 2.0 ⁇ m. This is for ensuring adequate thicknesses of the Cu—Sn intermetallic compound layer and the Sn-based surface layer.
  • the plating layer made of Ni or Ni alloy is preferably formed by electrolytic plating with a current density of 20 to 50 A / dm 2 .
  • the current density of Ni plating 20 A / dm 2 or more the crystal grains are made finer and effectively prevent Ni atoms from diffusing into Sn or intermetallic compounds during reflow or heating after product production.
  • the current density is 50 A / dm 2 or less, the generation of hydrogen on the plating surface during electrolysis is suppressed, and the plating quality is further improved. For this reason, it is desirable that the current density of Ni plating be 20 to 50 A / dm 2 .
  • the oxide film of the Sn-based surface layer after the reflow treatment is removed, and the surface roughness of the Sn-based surface layer is 0.005 to 0 in terms of arithmetic average roughness Ra.
  • a Sn—Ag coating layer may be formed thereon. Since an oxide film is easily formed on the Sn-based surface layer, when the Sn-Ag coating layer is provided on the outermost surface to improve heat resistance and connector insertion / extraction, the surface is smoothed after removing the oxide film. Thus, the unevenness of the Sn—Ag coating layer can be reduced, and the effect of improving heat resistance and insertion / extraction can be effectively exhibited.
  • a copper strip is continuously run while passing through a plurality of plating baths, and Ni or Ni alloy, Cu or Cu alloy, Sn or Sn alloy plating layer is formed on the surface thereof in this order. Then, in the method of manufacturing a conductive member in which a Ni-based underlayer, a Cu—Sn intermetallic compound layer, and a Sn-based surface layer are sequentially formed on the copper strip by heating and reflow treatment.
  • the inventors have found that a plating film having a desired property can be obtained more efficiently by appropriately selecting the current density, bath temperature, and Reynolds number in each plating bath, and in particular, by selecting the Reynolds number optimally.
  • the plating bath it is optimal to use a plating bath mainly composed of an inorganic acid that does not require special wastewater treatment equipment.
  • the Reynolds number is appropriate as an index that represents the turbulent flow value. From the experimental results, it has been found that the theoretical current efficiency value of the plating remains flat above the optimum value, and the appearance defect (plating burn) occurs below the optimum value. (See FIG. 6).
  • the Reynolds number is a dimensionless number determined by the three factors of plating solution viscosity, plating channel diameter, and relative flow velocity between the plating solution and the object to be plated. The optimum value is obtained by appropriately changing the three factors according to the situation. Can be obtained.
  • the Reynolds number is considered to be correlated with the interface (boundary layer) between the object to be plated and the plating solution, unlike the relative speed.
  • the plating efficiency is further increased by providing a means for removing bubbles and sludge generated in a large amount during tin plating.
  • the surface roughness of the intermediate layer can be controlled by examining the reflow conditions.
  • the intermediate layer is basically laminar, and it is important that the unevenness of the intermediate layer itself, that is, the surface roughness be in an optimum numerical range based on the average crystal grain size.
  • the electrolytic plating uses an insoluble anode in a plating bath mainly composed of an inorganic acid, and has an Reynolds number of 1 ⁇ 10 4 to 5 ⁇ 10 5. It is good to do.
  • the surface roughness of the Cu—Sn intermetallic compound layer under the Sn-based surface layer is formed within a predetermined range, so that the insertion / extraction force when used as a connector is reduced and the variation is suppressed.
  • the diffusion of Cu at high temperatures can be prevented, the surface state can be maintained well, the increase in contact resistance can be suppressed, and the peeling of the plating film and the generation of Kirkendall voids can be prevented.
  • the electrical characteristics of the Cu—Sn intermetallic compound layer are stabilized, and excellent fusing characteristics can be exhibited even when used as a fuse.
  • the copper strip plated in the multilayer which has a favorable characteristic at the time of use as an electrically-conductive member can be obtained continuously and efficiently.
  • FIG. 2 is a cross-sectional view showing an embodiment in which a Sn—Ag coating layer is formed on the outermost surface of the conductive member of FIG. 1. It is the temperature profile which made the relationship between the temperature of reflow conditions and time concerning the manufacturing method of this invention a graph. It is a schematic block diagram which shows the example of the manufacturing apparatus used for the manufacturing method of 2nd Embodiment of this invention. It is sectional drawing which shows the positional relationship of the electrode in a plating tank in FIG. 4, and a copper strip. It is a graph which shows the relationship between the Reynolds number during plating processing, and current efficiency.
  • the conductive member 10 As shown in FIG. 1, the conductive member 10 according to the first embodiment includes a Ni-based underlayer 3, a Cu—Sn intermetallic compound layer 4, and a Cu-based substrate 1 with a Fe-based underlayer 2 interposed therebetween.
  • the Sn-based surface layer 5 is formed in this order, and the Cu—Sn intermetallic compound layer 4 further includes a Cu 3 Sn layer 6 and a Cu 6 Sn 5 layer 7.
  • the Cu-based substrate 1 is, for example, a plate-like one made of Cu or a Cu alloy.
  • the material of the Cu alloy is not necessarily limited, but Cu—Zn alloy, Cu—Ni—Si alloy (Corson alloy), Cu—Cr—Zr alloy, Cu—Mg—P alloy, Cu—Fe -P-based alloys and Cu-Sn-P-based alloys are suitable.
  • MSP1, MZC1, MAX251C, MAX375, and MAX126 manufactured by Mitsubishi Shindoh Co., Ltd. are preferably used.
  • the Fe-based underlayer 2 is formed by electrolytic plating of Fe or Fe alloy, and is formed on the surface of the Cu-based substrate 1 with a thickness of 0.1 to 1.0 ⁇ m.
  • an Fe—Ni alloy is used as the Fe alloy.
  • the Ni-based underlayer 3 is formed by electrolytic plating of Ni or a Ni alloy, and is formed on the surface of the Fe-based underlayer 2 with a thickness of, for example, 0.05 to 0.3 ⁇ m. By setting the Ni-based underlayer 3 to a thickness in this range, diffusion at high temperatures is effectively prevented, peeling is less likely to occur, and bending workability is improved.
  • the Cu—Sn intermetallic compound layer 4 is an alloy layer formed by diffusing Cu plated on the Ni-based underlayer 3 and Sn on the surface by reflow treatment.
  • the Cu—Sn intermetallic compound layer 4 is formed to a thickness of 0.05 to 1.8 ⁇ m as a whole, preferably 0.1 ⁇ m or more, and further disposed on the Ni-based underlayer 3.
  • the Cu 3 Sn layer 6 and the Cu 6 Sn 5 layer 7 disposed on the Cu 3 Sn layer 6 are configured.
  • the Cu—Sn intermetallic compound layer 4 as a whole is uneven, and the surface roughness of the surface in contact with the Sn-based surface layer 5 is an arithmetic average roughness Ra of 0.05 to 0.25 ⁇ m.
  • the maximum valley depth Rv of the roughness curve is 0.05 to 1.00 ⁇ m.
  • the reason why the arithmetic average roughness Ra is 0.05 to 0.25 ⁇ m is that when Ra is used as the connector terminal portion 3, it is preferable that Ra is small because the insertion / extraction force is reduced, but Ra is less than 0.05 ⁇ m. Then, the unevenness of the Cu—Sn intermetallic compound layer 4 is almost eliminated and the Cu—Sn intermetallic compound layer 4 becomes extremely fragile, and the film is easily peeled off during bending.
  • the unevenness of the Cu—Sn intermetallic compound layer 4 becomes resistance at the time of insertion / extraction when used as a connector, so that the effect of reducing the insertion / extraction force is poor.
  • the maximum valley depth Rv of the roughness curve when Rv exceeds 1.00 ⁇ m, Sn diffuses from the valley portion to the Ni-based underlayer at a high temperature, and the Ni-based underlayer may be damaged. Due to the defect, Cu of the base material diffuses, the Cu 6 Sn 5 layer reaches the surface, and Cu oxide is formed on the surface, thereby increasing the contact resistance.
  • the Cu 3 Sn layer 6 disposed in the lower layer of the Cu—Sn intermetallic compound layer 4 covers the Ni-based underlayer 3 and has an area coverage of 60 to 100%. If the area coverage is less than 60%, diffusion of Ni atoms in the Ni-based underlayer 3 from the uncoated portion to the Cu 6 Sn 5 layer 7 at a high temperature is promoted, and the Ni-based underlayer 3 There is a risk of loss. More preferably, 80% or more is covered. This area coverage can be confirmed from a scanning ion image (SIM image) of the surface obtained by processing the cross section of the film with a focused ion beam (FIB) and observing with a scanning ion microscope (SIM). it can.
  • SIM image scanning ion image
  • the area coverage is 60% or more with respect to the Ni-based underlayer 3
  • the area coverage is less than 100%, the portion where the Cu 3 Sn layer 6 does not locally exist on the surface of the Ni-based underlayer 3 Even in this case, the Cu 6 Sn 5 layer 7 of the Cu—Sn intermetallic compound layer 4 covers the Ni-based underlayer 3.
  • the Cu 3 Sn layer 6 constituting the lower layer of the Cu—Sn intermetallic compound layer 4 has an average thickness of 0.01 to 0.5 ⁇ m. Since this Cu 3 Sn layer 6 is a layer covering the Ni-based underlayer 3, the average thickness within this range is preferable in order to suppress diffusion of the Ni-based underlayer 3. If the thickness is too thick, the Cu 3 Sn layer 6 changes to a Sn-rich Cu 6 Sn 5 layer 7 at a high temperature, and the Sn-based surface layer 5 is reduced correspondingly, and the contact resistance may be increased. A range up to about 5 ⁇ m is preferred. This average thickness is a portion where the Cu 3 Sn layer 6 exists and is an average value when the thickness is measured at a plurality of locations.
  • the Cu—Sn intermetallic compound layer 4 is an alloy formed by diffusion of Cu plated on the Ni-based underlayer 3 and Sn on the surface, and depending on conditions such as reflow treatment, In some cases, the entire Cu plating layer is diffused to form the Cu—Sn intermetallic compound layer 4, but the Cu plating layer may remain. When this Cu plating layer remains, the Cu plating layer has a thickness of 0.01 to 0.1 ⁇ m, for example. Further, since Ni in the Ni-based underlayer 3 is slightly diffused into the Cu—Sn intermetallic compound layer 4, Ni is slightly mixed in the Cu 6 Sn 5 layer 7.
  • the Sn-based surface layer 5 is formed by performing reflow treatment after electrolytic plating of Sn or Sn alloy. In order to maintain performance such as heat resistance and insertion / removability as a connector terminal, for example, 0.05 to It is formed to a thickness of 1.5 ⁇ m. Further, an Sn—Ag coating layer may be further formed on the Sn-based surface layer 5 to further improve heat resistance and pluggability as a connector.
  • FIG. 2 shows a conductive member 11 in which a Sn—Ag coating layer 8 is formed on the outermost surface of the same conductive member as in FIG.
  • the Sn—Ag coating layer 8 is formed to have a thin thickness of 0.05 to 0.5 ⁇ m, for example, and contains 0.1 to 5.0% by weight of Ag.
  • the Fe-based underlayer 2, Ni-based underlayer 3, Cu—Sn intermetallic compound layer 4, and Sn-based surface layer 5 are formed after the Fe, Ni, Cu, and Sn plating layers are attached by electrolytic plating.
  • the Sn—Ag coating layer 8 is formed by electrolysis on the Sn-based surface layer 5 after the reflow treatment.
  • a method for manufacturing such a conductive member will be described.
  • a Cu-based substrate a Cu or Cu alloy plate material is prepared, and after cleaning the surface by degreasing, pickling, etc., Fe plating, Ni plating, Cu plating, and Sn plating are sequentially performed in this order. .
  • pickling or rinsing is performed between the plating processes.
  • a sulfuric acid bath mainly composed of ferrous sulfate (FeSO 4 ) and ammonium chloride (NH 4 Cl) is used as a plating bath.
  • a plating bath mainly composed of nickel sulfate (NiSO 4 ), ferrous sulfate (FeSO 4 ), and boric acid (H 3 BO 3 ) is used.
  • the plating temperature is 45 to 55 ° C., and the current density is 5 to 25 A / dm 2 .
  • Ni plating conditions include a plating bath, a watt bath mainly composed of nickel sulfate (NiSO 4 ), boric acid (H 3 BO 3 ), nickel sulfamate (Ni (NH 2 SO 3 ) 2 ) and boric acid.
  • a sulfamic acid bath or the like mainly composed of (H 3 BO 3 ) is used.
  • nickel chloride (NiCl 2 ) or the like is added as a salt that easily causes an oxidation reaction.
  • the plating temperature is 45 to 55 ° C., and the current density is 20 to 50 A / dm 2 .
  • a copper sulfate bath mainly composed of copper sulfate (CuSO 4 ) and sulfuric acid (H 2 SO 4 ) is used as a plating bath, and chlorine ions (Cl ⁇ ) are added for leveling. .
  • the plating temperature is 35 to 55 ° C., and the current density is 20 to 60 A / dm 2 .
  • a sulfuric acid bath containing sulfuric acid (H 2 SO 4 ) and stannous sulfate (SnSO 4 ) as main components is used for the plating bath, the plating temperature is 15 to 35 ° C., and the current density is 10 to 30 A / dm 2 .
  • All the plating processes are performed at a higher current density than a general plating technique.
  • the plating solution agitation technology is important.
  • a fresh plating solution can be supplied quickly, and a uniform plating layer can be formed in a short time with a high current density.
  • the flow rate of the plating solution is desirably 0.5 m / second or more on the surface of the treatment plate.
  • an insoluble anode such as a Ti plate coated with iridium oxide (IrO 2 ) having a high anode limit current density is used as the anode. It is desirable.
  • IrO 2 iridium oxide
  • an Fe-based underlayer is formed on the Cu-based substrate.
  • a Ni-based underlayer, a Cu plating layer, and a Sn plating layer are formed in this order.
  • the average thickness of the Cu plating layer is 0.3 to 0.5 ⁇ m
  • the average thickness of the Sn plating layer is 1.5 to 2.0 ⁇ m.
  • the Sn-based surface layer has a heat resistance as a connector terminal as described above. From the viewpoint of insertion / extraction, it is formed to a thickness of 0.5 to 1.5 ⁇ m, and in order to ensure the thickness of this Sn-based surface layer, the Sn plating layer as a base is 1.5 to 2. 0 ⁇ m is required. In order to obtain a Cu—Sn intermetallic compound layer with small irregularities under this Sn plating layer, the Cu plating layer should have a thickness of 0.3 to 0.5 ⁇ m, which is slightly larger than a normal one. preferable.
  • the Sn plating layer is composed of columnar crystals grown in the thickness direction, and when Cu and Sn react in the next reflow process to form an alloy layer, Cu is a grain boundary of Sn columnar crystals. It is considered that an alloy is formed from the grain boundary so as to penetrate into the grain boundary. However, when the Cu plating layer is thick and the amount of Cu is large, along the grain boundary of the columnar crystal along the thickness direction of the Sn plating layer It is considered that the Cu—Sn alloy formed in this way grows while spreading in the plane direction from the grain boundary, so that the convex portion becomes smooth and becomes a Cu—Sn intermetallic compound layer with few irregularities.
  • the reflow process is performed by heating.
  • the reflow process is preferably performed under the temperature profile shown in FIG.
  • the reflow process is a heating process in which the treated material after plating is heated to a peak temperature of 240 to 300 ° C. for 2.9 to 11 seconds at a temperature rising rate of 20 to 75 ° C./second in a heating furnace having a CO reducing atmosphere.
  • a secondary cooling step is a heating process in which the treated material after plating is heated to a peak temperature of 240 to 300 ° C. for 2.9 to 11 seconds at a temperature rising rate of 20 to 75 ° C./second in a heating furnace having a CO reducing atmosphere.
  • the primary cooling step is performed by air cooling
  • the secondary cooling step is performed by water cooling using 10 to 90 ° C. water.
  • the conductive member subjected to the reflow treatment as described above is pickled and electropolished to remove the oxide film of the Sn-based surface layer, and Sn After the surface of the system surface layer is smoothed, a Sn—Ag coating layer containing 0.1 to 5.0% by weight of Ag is formed thereon. Since the Sn-based surface layer is easily oxidized, the surface roughness of the Sn—Ag coating layer is reduced by removing the oxide film and smoothing the surface at that time. The degree of smoothness is preferably about 0.005 to 0.3 ⁇ m in terms of arithmetic average roughness Ra. Then, an Sn—Ag coating layer is formed on the smooth surface by electrolysis with a thickness of 0.05 to 0.5 ⁇ m.
  • FIG. 4 schematically shows an example of a manufacturing apparatus for carrying out the manufacturing method of the second embodiment.
  • the conductive member manufacturing apparatus 31 includes a degreasing / cleaning tank 32, a Ni plating tank 33, a Cu plating tank 34, a Sn plating tank 35, and cleaning tanks 36 to 38 disposed after the plating tanks 33 to 35.
  • the copper strip 51 is plated while being continuously conveyed in the order of the degreasing / cleaning tank 32, the Ni plating tank 33, the Cu plating tank 34, and the Sn plating tank 35.
  • the degreasing / cleaning tank 32 further includes a degreasing tank 32a, a cleaning tank 32b, a pickling tank 32c, and a cleaning tank 32d.
  • a pair of electrode plates 39 are disposed in each of the plating tanks 33 to 35 so as to face both surfaces of a continuously running copper strip material (Cu-based substrate) 51.
  • the copper strip 51 and the plating solution are relative to each other so that the Reynolds number in the flow field of the plating solution formed between each electrode plate 39 and the copper strip 51 is 1 ⁇ 10 4 to 5 ⁇ 10 5.
  • the plating solution is circulated between a circulation tank 40 (only the circulation tank of the Sn plating tank 35 is shown in FIG. 4).
  • the Sn plating tank 35 is provided with a bubble removing means 41.
  • Sludge removal means 42 is also provided. This sludge removal means 42 connects a sludge settling tank to the circulation tank 40, extracts the plating solution from the circulation tank 40 to the sludge settling tank in a fixed amount, and adds a settling agent. The sludge is allowed to settle while returning the upper liquid to the circulation tank 40 again. The settled sludge is subjected to a centrifuge, sent to a refining company, and reused as Sn.
  • a dryer 43 that dries the copper strip material 51 that has passed through the cleaning tank 38 is provided at a downstream position of the Sn plating tank 35.
  • a reflow furnace 44 is provided at a downstream position of the dryer 43.
  • the reflow furnace 44 is provided with an air cooling zone 45 for primary cooling and a water cooling zone 46 for secondary cooling, which will be described later.
  • Reference numeral 47 denotes a dryer that dries the copper strip material 51 that has passed through the water cooling zone 46.
  • Ni plating conditions include a plating bath, a watt bath mainly composed of nickel sulfate (NiSO 4 ), boric acid (H 3 BO 3 ), nickel sulfamate (Ni (NH 2 SO 3 ) 2 ) and boric acid.
  • a sulfamic acid bath or the like mainly composed of (H 3 BO 3 ) is used.
  • NiCl 2 nickel chloride
  • the plating temperature is 45 to 55 ° C.
  • the current density is 20 to 50 A / dm 2
  • the Reynolds number is 1 ⁇ 10 4 to 5 ⁇ 10 5 .
  • a copper sulfate bath mainly composed of copper sulfate (CuSO 4 ) and sulfuric acid (H 2 SO 4 ) is used as a plating bath, and chlorine ions (Cl ⁇ ) are added for leveling. .
  • the plating temperature is 35 to 55 ° C.
  • the current density is 20 to 60 A / dm 2
  • the Reynolds number is 1 ⁇ 10 4 to 5 ⁇ 10 5 .
  • a sulfuric acid bath containing sulfuric acid (H 2 SO 4 ) and stannous sulfate (SnSO 4 ) as main components is used for the plating bath
  • the plating temperature is 15 to 35 ° C.
  • the current density is 10 to 30 A / dm 2 and Reynolds number of 1 ⁇ 10 4 to 5 ⁇ 10 5 .
  • the sulfuric acid bath is provided with a sludge removing device and a foam removing device.
  • Ni plating layer, Cu plating layer, and Sn plating layer are formed in order on a copper strip.
  • the Cu plating layer has an average thickness of 0.3 to 0.5 ⁇ m
  • the Ni plating layer has an average thickness of 0.1 to 2.0 ⁇ m
  • the Sn plating layer has an average thickness of 1.5 to 0.5 ⁇ m. 2.0 ⁇ m.
  • These Cu plating layer and Sn plating layer are converted into a Cu-Sn intermetallic compound layer and a Sn-based surface layer by a reflow process described later.
  • the Sn-based surface layer has heat resistance and insertion / removal as a connector terminal as described above.
  • the Sn plating layer as a base is required to be 1.5 to 2.0 ⁇ m become.
  • the Cu plating layer is usually 0.3 to 0.5 ⁇ m as in the case of the first embodiment.
  • the thickness is preferably slightly larger than the above.
  • This reflow treatment is a heating process in which a treated material after plating is heated to a peak temperature of 240 to 300 ° C. at a temperature rising rate of 20 to 75 ° C./second in a heating furnace having a CO reducing atmosphere, and the peak temperature is reached. Then, a primary cooling step of cooling for 2 to 10 seconds at a cooling rate of 30 ° C./second or less, and a secondary cooling step of cooling for 0.5 to 5 seconds at a cooling rate of 100 to 250 ° C./second after the primary cooling. Process.
  • the primary cooling step is performed by air cooling
  • the secondary cooling step is performed by water cooling using 10 to 90 ° C. water.
  • the reflow process may be performed immediately after the plating process.
  • the reflow process may be performed within 15 minutes, more preferably within 5 minutes.
  • a short standing time after plating does not cause a problem, but in a normal processing line, it is about one minute after construction.
  • the conductive member 50 includes a Ni-based underlayer 3, a Cu—Sn intermetallic compound layer 4, and a Sn-based surface layer 5 formed in this order on the surface of a copper strip 51, and Cu
  • the —Sn intermetallic compound layer 4 is further composed of a Cu 3 Sn layer 6 and a Cu 6 Sn 5 layer 7.
  • the Ni-based underlayer 3 is formed to a thickness of 0.05 ⁇ m or more, for example, and functions as a barrier layer that prevents Cu diffusion at high temperatures.
  • the Cu—Sn intermetallic compound layer 4 as a whole is formed to a thickness of 0.05 to 1.8 ⁇ m, preferably 0.1 ⁇ m or more, and is further disposed on the Ni-based underlayer 3.
  • the Cu—Sn intermetallic compound layer 4 as a whole is uneven, and the surface roughness of the surface in contact with the Sn-based surface layer 5 is an arithmetic average roughness Ra of 0.05 to 0.25 ⁇ m.
  • the maximum valley depth Rv of the roughness curve is 0.05 to 1.00 ⁇ m.
  • the Cu 3 Sn layer 6 disposed in the lower layer of the Cu—Sn intermetallic compound layer 4 covers the Ni-based underlayer 3 and has a function of suppressing its diffusion, and has an area relative to the Ni-based underlayer 3.
  • the coverage is 60 to 100%, and the average thickness is 0.01 to 0.5 ⁇ m.
  • the Cu—Sn intermetallic compound layer 4 is an alloy formed by diffusion of Cu plated on the Ni-based underlayer 3 and Sn on the surface, and depending on conditions such as reflow treatment, In some cases, the entire Cu plating layer is diffused to form the Cu—Sn intermetallic compound layer 4, but the Cu plating layer may remain. Further, since Ni in the Ni-based underlayer 3 is slightly diffused into the Cu—Sn intermetallic compound layer 4, Ni is slightly mixed in the Cu 6 Sn 5 layer 7.
  • the outermost Sn-based surface layer 5 is formed to have a thickness of, for example, 0.5 to 1.5 ⁇ m in order to optimize surface contact resistance, solderability, corrosion resistance, and insertion / extraction force when used as a connector. .
  • the Ni-based underlayer 3 is formed on the surface of the Cu-based substrate (copper strip) 1.
  • the Ni-based underlayer is interposed via the Fe-based underlayer. May be formed.
  • the Fe density is 5 to 25 A / dm 2 as shown in Table 1 or Table 2, and the Reynolds number in the flow field of the plating solution formed between the electrode plate and the copper strip is used. Is 1 ⁇ 10 4 to 5 ⁇ 10 5 electrolytic plating.
  • a water washing step for washing the plating solution from the surface of the treatment material was inserted between these four types of plating steps.
  • an insoluble anode of a Ti plate coated with iridium oxide was sprayed on the Cu alloy plate at a high speed.
  • a reflow treatment was performed on the treated material. This reflow process was performed 1 minute after the last Sn plating process, and the heating process, the primary cooling process, and the secondary cooling process were performed under various conditions. The above test conditions are summarized in Table 9.
  • the cross section of the treated material in this example is the result of energy dispersive X-ray spectroscopic analysis (TEM-EDS analysis) using a transmission electron microscope.
  • TEM-EDS analysis energy dispersive X-ray spectroscopic analysis
  • Cu 6 Sn 5 layers, and Sn-based surface layer, and the minimum thickness of the Cu—Sn intermetallic compound layer was 0.05 ⁇ m or more.
  • the Cu 6 at the interface Sn 5 layer and the Ni-based base layer has discontinuous Cu 3 Sn layer, Ni of Cu 3 Sn layer observed from a scanning ion microscope of a cross section by focused ion beam (FIB-SIM image)
  • the surface coverage with respect to the system underlayer was 60% or more.
  • the Sn-based surface layer was removed, and the surface roughness of the underlying Cu—Sn intermetallic compound layer was measured.
  • pure Sn such as L80 manufactured by Reybold Co., Ltd. is etched and immersed in an etching solution for removing the plating film made of a component that does not corrode the Cu—Sn alloy for 5 minutes.
  • the surface layer is removed, and the underlying Cu—Sn intermetallic compound layer is exposed.
  • the surface roughness was determined by using a scanning confocal infrared laser microscope LEXT OLS-3000-IR manufactured by Olympus Co., Ltd.
  • the contact resistance after 175 ° C. ⁇ 1000 hours, the presence or absence of peeling, and the wear resistance were measured. Further, the coefficient of dynamic friction and the rate of change in resistance value after 175 ° C. ⁇ 1000 hours were also measured.
  • the contact resistance was measured under the condition of sliding with a load of 0.49 N (50 gf) using an electrical contact simulator manufactured by Yamazaki Seiki Co., Ltd. after the sample was left at 175 ° C. for 1000 hours.
  • 90 ° bending (curvature radius R: 0.7 mm) was performed with a load of 9.8 kN, then held in the atmosphere at 160 ° C.
  • the abrasion resistance was determined by a reciprocating wear test specified in JIS H 8503, with a test load of 9.8 N and abrasive paper no. 400, the number of times until the substrate (Cu-based substrate) was exposed was measured, a sample in which plating remained even after 50 times of testing, and a sample in which the substrate was exposed within 50 times were evaluated as x. .
  • the dynamic friction coefficient a plate-shaped male test piece and a hemispherical female test piece having an inner diameter of 1.5 mm are prepared for each sample so as to simulate the contact portion of the male terminal and female terminal of the fitting type connector.
  • the frictional force between the two test pieces was measured to obtain the dynamic friction coefficient.
  • the male test piece 22 is fixed on the horizontal base 21, the hemispherical convex surface of the female test piece 23 is placed on the male test piece 23, and the plated surfaces are brought into contact with each other.
  • the load P of 9N (500 gf) is applied and the male test piece 22 is pressed. With the load P applied, the frictional force F when the male test piece 22 was pulled 10 mm in the horizontal direction indicated by the arrow at a sliding speed of 80 mm / min was measured by the load cell 25.
  • the resistance value change rate is such that each sample is formed to a size of 10 mm (L) ⁇ 1 m (W), its electric resistance value (R) is measured, and the change rate ⁇ R of the resistance value after heating at 175 ° C. ⁇ 1000 hours. / R (%) was measured.
  • the conductive member of this example has a low contact resistance at high temperatures, no occurrence of peeling or Kirkendall voids, and a small coefficient of dynamic friction. Therefore, the insertion / extraction force when using the connector is also small. It can be judged that it is good.
  • the rate of change in resistance value ( ⁇ R / R) is also small and stable, and it can be determined that it is excellent in fusing characteristics when used as a fuse.
  • Sample 5 and Sample 18 were also measured over time during heating at 175 ° C. for 1000 hours. The result is shown in FIG. As shown in FIG. 9, the sample 5 according to the present invention has a slight increase in contact resistance even when exposed to a high temperature for a long time, whereas the sample 18 according to the prior art has a contact resistance after 1000 hours. Increased to 10 m ⁇ or more.
  • the sample 5 of the present invention has a five-layer structure in which the Sn-based surface layer remains due to the heat resistance of the Fe-based underlayer, whereas in the sample 18 of the prior art, the Fe-based underlayer is thin and has a barrier. Since the function as a layer is not sufficient, it is considered that the contact resistance increased due to the Cu oxide covering the surface. In this case, the thickness of the Fe-based underlayer was 0.5 ⁇ m for sample 5 and 0.05 ⁇ m for sample 18.
  • peeling occurs when the standing time after plating becomes longer. This is because Cu crystal grains precipitated at a high current density are enlarged due to a long standing time, and Cu and Sn react spontaneously to form Cu 6 Sn 5, and smooth Cu 6 Sn during reflowing. This is thought to be because the alloying between 5 and Cu 3 Sn is hindered.
  • the Cu—Sn intermetallic compound layer contains It shall also include those in which a slight amount of Ni is mixed.
  • an Fe-based underlayer is interposed between the Ni-based underlayer and the Cu-based substrate, and the presence of this Fe-based underlayer further enhances the Cu diffusion preventing function, and allows bending. Although generation of cracks during processing can be reduced, it is not always essential, and a Ni-based underlayer may be directly formed on a Cu-based substrate.
  • the cross section of the treated material of this example is a Ni-based underlayer, a Cu 3 Sn layer, and Cu 6 on a copper strip. It has a four-layer structure of Sn 5 layers and Sn-based surface layers.
  • the Cu 6 at the interface Sn 5 layer and the Ni-based base layer has discontinuous Cu 3 Sn layer, Ni of Cu 3 Sn layer observed from a scanning ion microscope of a cross section by focused ion beam (FIB-SIM image)
  • the surface coverage with respect to the system underlayer was 60% or more.
  • the Sn-based surface layer is removed by the same method as in the first embodiment, and the surface roughness of the Cu—Sn intermetallic compound layer below is removed using a scanning confocal infrared laser microscope manufactured by Olympus Corporation. The measurement was performed in the same manner as in the first example using LEXT OLS-3000-IR. The above measurement results are summarized in Table 15.
  • the conductive member of this example has a low contact resistance at high temperatures, no peeling or Kirkendall voids, and a small coefficient of dynamic friction. It can be judged that it is good.
  • Comparative Example 30 the generation of sludge was noticeable in Sn plating.
  • the present invention can be applied to a conductive member in which a plurality of plating layers are formed on the surface of a substrate made of Cu or a Cu alloy, and a method for manufacturing the conductive member.

Abstract

The conductive member has a stable contact resistance, resists peeling, displays a low insertion/removal force and is stable when used as a connector, and has an excellent fusing characteristic when used as a fuse. A Cu-Sn intermetallic compound layer (4) is formed between a Ni-based underlayer (3) formed on a Cu-based base material (1), and a Sn-based surface layer (5) that forms the surface. In addition, the Cu-Sn intermetallic compound layer (4) comprises a Cu3Sn layer (6) disposed on the Ni-based underlayer (3) and a Cu6Sn5 layer (7) that is disposed on the Cu3Sn layer (6). The surface roughness of the contact face between the Sn-based surface layer (5) and the Cu-Sn intermetallic compound layer (4) combining the Cu3Sn layer (6) and Cu6Sn5 layer (7) has an arithmetic mean roughness Ra of 0.05-0.25 μm, and the maximum valley depth Rv of the roughness curve is 0.05-1.00 μm. Furthermore, the Cu3Sn layer covers the Ni-based underlayer with a surface coverage of 60-100%.

Description

導電部材及びその製造方法Conductive member and manufacturing method thereof
　本発明は、電気接続用コネクタ、ヒューズ等に用いられ、Ｃｕ又はＣｕ合金からなる基材の表面に複数のめっき層を形成した導電部材及びその製造方法に関する。
　本出願は、２００９年４月１４日に日本に出願された特願２００９－９８０４３号、２００９年５月１２日に日本に出願された特願２００９－１１５２８９号、及び２００９年５月２６日に日本に出願された特願２００９－１２７０８５号に基づき優先権を主張し、その内容をここに援用する。 The present invention relates to a conductive member used for an electrical connection connector, a fuse, or the like, in which a plurality of plating layers are formed on the surface of a substrate made of Cu or Cu alloy, and a method for manufacturing the same.
This application includes Japanese Patent Application No. 2009-98043 filed in Japan on April 14, 2009, Japanese Patent Application No. 2009-115289 filed in Japan on May 12, 2009, and May 26, 2009. Claim priority based on Japanese Patent Application No. 2009-127085 filed in Japan, the contents of which are incorporated herein.
　自動車の電気接続用コネクタやプリント基板の接続端子等に用いられる導電部材として、電気接続特性の向上等のために、Ｃｕ又はＣｕ合金からなるＣｕ系基材の表面にＳｎ系金属のめっきを施したものが多く使用されている。
　そのような導電部材として、例えば特許文献１から特許文献４記載のものがある。特許文献１から特許文献３記載の導電部材は、Ｃｕ又はＣｕ合金からなる基材の表面にＮｉ、Ｃｕ、Ｓｎを順にめっきして３層のめっき層を形成した後に、加熱してリフロー処理することにより、最表面層にＳｎ層が形成され、Ｎｉ層とＳｎ層との間にＣｕ－Ｓｎ金属間化合物層（例えばＣｕ６Ｓｎ５）が形成された構成とされている。また、特許文献４記載のものは、下地めっき層を例えばＮｉ－ＦｅやＦｅ等から構成し、その上にＣｕ、Ｓｎを順にめっきして、リフロー処理する技術とされている。 As a conductive member used for automobile electrical connectors and printed circuit board connection terminals, Sn-based metal plating is applied to the surface of a Cu-based substrate made of Cu or a Cu alloy for the purpose of improving electrical connection characteristics. Many of them have been used.
Examples of such conductive members include those described in Patent Document 1 to Patent Document 4. The conductive members described in Patent Document 1 to Patent Document 3 are subjected to a reflow treatment by heating after forming Ni, Cu, Sn on the surface of a substrate made of Cu or Cu alloy in order to form a three-layered plating layer. Thus, an Sn layer is formed on the outermost surface layer, and a Cu—Sn intermetallic compound layer (for example, Cu 6 Sn 5 ) is formed between the Ni layer and the Sn layer. The technique described in Patent Document 4 is a technique in which a base plating layer is made of, for example, Ni—Fe, Fe, or the like, and Cu and Sn are sequentially plated thereon to perform a reflow process.
　また、このような導電部材は、銅条材として連続的に製造されるが、この銅条材の様な幅広の薄板表面に無機酸及び不溶性アノードを用いて、限られたライン長さにて連続的に効率良く多層にめっきする方策としては、各めっき浴内での銅条材とめっき液との相対流速を上げ電流密度を高くし、所望する性状のめっきを得るに要する時間を短くすることが重要である。
　また、めっき後のリフロー処理も大きな要因であり、導電部材として使用時の性能に大きな影響を及ぼす。特に、コネクタとして使用する場合は、リフロー処理後に形成される表面層およびその下層となる中間合金層の特性がコネクタの挿抜性に大きく寄与することがわかっている。 In addition, such a conductive member is continuously manufactured as a copper strip, but with a limited line length by using an inorganic acid and an insoluble anode on the surface of a wide thin plate such as this copper strip. As a measure for continuously and efficiently plating multiple layers, the relative flow rate between the copper strip and the plating solution in each plating bath is increased to increase the current density, thereby shortening the time required to obtain the desired properties of plating. This is very important.
In addition, the reflow treatment after plating is a major factor, which greatly affects the performance during use as a conductive member. In particular, when used as a connector, it has been found that the characteristics of the surface layer formed after the reflow treatment and the intermediate alloy layer which is the lower layer greatly contribute to the connector insertion / removability.
　特許文献５には、電気めっきブリキ及び薄錫めっき鋼板の製造に用いる高電流密度用錫めっき硫酸浴内にて、不溶性アノードを用いて、電流密度５０Ａ／ｄｍ２以上、温度３０～７０℃での錫めっきの方法が開示されている。
　特許文献６には、銅または銅合金の表面上に、ＮｉまたはＮｉ合金層が形成され、最表面上にＳｎまたはＳｎ合金層が形成され、前記ＮｉまたはＮｉ合金層と前記ＳｎまたはＳｎ合金層の間にＣｕとＳｎを主成分とする中間層またはＣｕとＮｉとＳｎを主成分とする中間層が一層以上形成され、これら中間層のうち少なくとも１つの中間層が、Ｃｕ含有量が５０重量％以下であり且つＮｉ含有量が５０重量％以下である層を含み、銅または銅合金の表面上に形成された各々の層に対して垂直方向に投影した、前記Ｃｕ含有量が５０重量％以下であり且つＮｉ含有量が５０重量％以下である層の平均結晶粒径が０．５～３．０μｍであることを特徴とするめっきを施した銅または銅合金が開示されている。また、製造方法としては、銅または銅合金の表面上に、ＮｉまたはＮｉ合金、Ｃｕめっき、最表面層にＳｎまたはＳｎ合金めっきを施した後、少なくとも１回以上のリフロー処理を行い、加熱温度が４００～９００℃で、ＳｎまたはＳｎ合金層が溶融してから凝固するまでの時間が０．０５～６０秒であることが記載されている。 In Patent Document 5, a current density of 50 A / dm 2 or more and a temperature of 30 to 70 ° C. are used in an insoluble anode in a tin plating sulfuric acid bath for high current density used for the production of electroplated tin and thin tin-plated steel sheet. A method of tin plating is disclosed.
In Patent Document 6, a Ni or Ni alloy layer is formed on the surface of copper or a copper alloy, a Sn or Sn alloy layer is formed on the outermost surface, and the Ni or Ni alloy layer and the Sn or Sn alloy layer are formed. At least one intermediate layer containing Cu and Sn as a main component or an intermediate layer containing Cu, Ni and Sn as a main component is formed between the at least one intermediate layer, and the Cu content is 50 wt. %, And the Ni content is 50% by weight or less, and the Cu content is 50% by weight, projected in the direction perpendicular to each layer formed on the surface of the copper or copper alloy. There is disclosed a plated copper or copper alloy characterized in that the average crystal grain size of the layer having the following and Ni content of 50% by weight or less is 0.5 to 3.0 μm. Further, as a manufacturing method, Ni or Ni alloy, Cu plating is applied on the surface of copper or copper alloy, Sn or Sn alloy plating is applied to the outermost surface layer, then at least one reflow treatment is performed, and a heating temperature is set. Is 400 to 900 ° C., the time from the melting of the Sn or Sn alloy layer to the solidification is 0.05 to 60 seconds.
特許第３８８０８７７号公報Japanese Patent No. 3880877 特許第４０９０４８８号公報Japanese Patent No. 4090488 特開２００４－６８０２６号公報JP 2004-68026 A 特開２００３－１７１７９０号公報JP 2003-171790 A 特開平６－３４６２７２号公報JP-A-6-346272 特開２００３－２９３１８７号公報JP 2003-293187 A
　ところで、このようなコネクタや端子が自動車のエンジン廻りのような高温環境下で使用される場合、特許文献１から特許文献３記載の導電部材では、その高温に長時間さらされることにより、ＳｎとＣｕとが互いに熱拡散して表面状態が経時変化し易く、接触抵抗が上昇する傾向がある。また、Ｃｕ系基材の表面にＣｕの拡散によってカーケンダルボイドが発生して、剥離が生じるおそれもあり、これらの解決が望まれている。
　一方、特許文献４記載のものは、Ｆｅ－ＮｉやＦｅの下地めっき層とＣｕとの密着性が悪く、剥離し易いという問題がある。
　また、コネクタに用いる場合には、回路の高密度化に伴いコネクタも多極化し、自動車配線の組み立て時の挿入力が大きくなってきているため、挿抜力を小さくすることができる導電部材が求められている。
　さらに、このようなＣｕ系基材の表面にＳｎ系金属のめっきを施した導電部材について、ヒューズとしての用途も見出されており、ヒューズとして良好な溶断特性も求められている。 By the way, when such a connector or terminal is used in a high temperature environment such as around an automobile engine, the conductive members described in Patent Document 1 to Patent Document 3 are exposed to the high temperature for a long time. Cu and each other are thermally diffused and the surface state tends to change with time, and the contact resistance tends to increase. Further, Kirkendall voids are generated on the surface of the Cu-based substrate due to the diffusion of Cu, and peeling may occur. These solutions are desired.
On the other hand, the one described in Patent Document 4 has a problem that the adhesion between the base plating layer of Fe—Ni or Fe and Cu is poor, and it is easy to peel off.
In addition, when used for connectors, as the circuit density increases, the connectors also become multipolar, and the insertion force at the time of assembling the automobile wiring is increasing. Therefore, a conductive member that can reduce the insertion / extraction force is required. ing.
Furthermore, the use as a fuse is found about the electrically conductive member which plated the Sn type metal on the surface of such Cu type base material, and the favorable fusing characteristic as a fuse is calculated | required.
　また、製造方法に関しては、特許文献５に記載の発明はブリキ等の錫めっき鋼板の製造方法であり、不溶性アノードを使用した硫酸浴にて、温度３０～７０℃、電流密度５０Ａ／ｄｍ２以上、鋼ストリップと電解液との相対速度を１６０ｍ／ｍｉｎ以上にて鋼ストリップに錫めっきを行っている。
　この様な錫めっきの条件を、導電部材として厳しいめっき性状、特に、コネクタとしての使用時の挿抜性、耐熱性等が要求される銅条材薄板の多層め２っきに適用するには次の理由から無理がある。
（１）主にめっき浴内の相対速度の大きさに起因して、めっきの最中に陰極表面から大量の水素ガスが発生し、めっきの電着性が妨げられて、電流効率が大きく低下し、外観不良（めっき焼け）が発生する。
（２）多層めっきとして、錫のみでなく下地となるＮｉ、Ｃｕ、Ｆｅ等の他金属めっきとの相関が考慮されていない。 As for the production method, the invention described in Patent Document 5 is a production method of tin-plated steel sheets such as tinplate, in a sulfuric acid bath using an insoluble anode, at a temperature of 30 to 70 ° C., and a current density of 50 A / dm 2 or more. The steel strip is tin-plated at a relative speed of the steel strip and the electrolyte of 160 m / min or more.
In order to apply such tin plating conditions to the second layer of copper strips that require strict plating properties as a conductive member, especially insertion / extraction and heat resistance when used as a connector, There is no reason for this.
(1) A large amount of hydrogen gas is generated from the cathode surface during plating, mainly due to the relative velocity in the plating bath, and the electrodeposition of the plating is hindered, resulting in a significant decrease in current efficiency. In addition, poor appearance (plating burn) occurs.
(2) As the multilayer plating, not only the tin but also the correlation with other metal plating such as Ni, Cu, Fe as a base is not considered.
　特許文献６記載の発明は、銅または銅合金の表面上に、ＮｉまたはＮｉ合金、Ｃｕめっき、最表面層にＳｎまたはＳｎ合金めっきを施した後、少なくとも１回以上のリフロー処理を、加熱温度が４００～９００℃で、ＳｎまたはＳｎ合金層が溶融してから凝固するまでの時間が０．０５～６０秒にて行うことにより、Ｃｕ含有量が５０重量％以下であり且つＮｉ含有量が５０重量％以下であり、平均結晶粒径が０．５～３．０μｍである１つの中間層を形成している。
　この平均結晶粒径は、導電部材をコネクタとして使用する場合の挿抜性に大きく関与するものであるが、平均粒径の制御だけでは適切な挿抜性を得ることはできない。 In the invention described in Patent Document 6, Ni or Ni alloy, Cu plating is applied on the surface of copper or a copper alloy, and Sn or Sn alloy plating is applied to the outermost surface layer. Is 400 to 900 ° C., and the time from when the Sn or Sn alloy layer melts to solidification is 0.05 to 60 seconds, the Cu content is 50% by weight or less and the Ni content is One intermediate layer having an average crystal grain size of 0.5 to 3.0 μm is formed by 50% by weight or less.
This average crystal grain size is greatly related to the pluggability when the conductive member is used as a connector, but appropriate pluggability cannot be obtained only by controlling the average grain size.
　本発明はこのような事情に鑑みてなされたもので、安定した接触抵抗を有するとともに、剥離し難く、また、コネクタとして用いる場合に挿抜力を小さくかつ安定させることができ、しかもヒューズとして用いた場合にも良好な溶断特性を有する導電部材及びその製造方法を提供する The present invention has been made in view of such circumstances, and has a stable contact resistance, is difficult to peel off, can reduce and stabilize the insertion / extraction force when used as a connector, and is used as a fuse. A conductive member having good fusing characteristics even in some cases and a method for manufacturing the same
　本発明の導電部材は、Ｃｕ系基材の上に形成したＮｉ系下地層と、表面を形成するＳｎ系表面層との間に、Ｃｕ－Ｓｎ金属間化合物層が形成されるとともに、Ｃｕ－Ｓｎ金属間化合物層は、さらに、前記Ｎｉ系下地層の上に配置されるＣｕ３Ｓｎ層と、該Ｃｕ３Ｓｎ層の上に配置されるＣｕ６Ｓｎ５層とからなり、前記Ｃｕ３Ｓｎ層及びＣｕ６Ｓｎ５層を合わせた前記Ｃｕ－Ｓｎ金属間化合物層の前記Ｓｎ系表面層と接する面の表面粗さが、算術平均粗さＲａで０．０５～０．２５μｍであり、かつ、粗さ曲線の最大谷深さＲｖで０．０５～１．００μｍであり、また、前記Ｃｕ３Ｓｎ層は前記Ｎｉ系下地層を覆っており、その面積被覆率が６０～１００％であることを特徴とする。 In the conductive member of the present invention, a Cu—Sn intermetallic compound layer is formed between a Ni-based underlayer formed on a Cu-based substrate and a Sn-based surface layer forming the surface, and Cu— Sn intermetallic compound layer further made from the the Cu 3 Sn layer disposed on the Ni-based base layer, the Cu 6 Sn 5 layer disposed on the said Cu 3 Sn layer, the Cu 3 Sn The surface roughness of the surface of the Cu-Sn intermetallic compound layer combined with the Sn-based surface layer in combination with the Cu 6 Sn 5 layer is 0.05 to 0.25 μm in terms of arithmetic average roughness Ra, and The maximum valley depth Rv of the roughness curve is 0.05 to 1.00 μm, and the Cu 3 Sn layer covers the Ni-based underlayer, and the area coverage is 60 to 100%. It is characterized by that.
　この導電部材は、Ｎｉ系下地層とＳｎ系表面層との間のＣｕ－Ｓｎ金属間化合物層が、Ｃｕ３Ｓｎ層とＣｕ６Ｓｎ５層との二層構造とされ、その下層のＣｕ３Ｓｎ層がＮｉ系下地層を覆い、その上から被さるようにＣｕ６Ｓｎ５層が存在している。このＣｕ３Ｓｎ合金層とＣｕ６Ｓｎ５層とを合わせたＣｕ－Ｓｎ金属間化合物層は、その膜厚が必ずしも一様ではなく、凹凸を有しているが、Ｓｎ系表面層と接する面の表面粗さが、算術平均粗さＲａで０．０５～０．２５μｍ、粗さ曲線の最大谷深さＲｖで０．０５～１．００μｍとされる。
　ここで算術平均粗さＲａは表面の凹凸の平均的な大きさを表しており、このＲａが０．２５μｍを超えると、Ｓｎ系表面層の下に大きな凹凸が形成されることから、コネクタとして用いたときの挿抜力が増大して好ましくない。このＣｕ－Ｓｎ金属間化合物層の凹凸が少なくなると、コネクタ使用時の挿抜力が低減して好ましいが、Ｒａを０．０５μｍ未満とするのは、Ｃｕ－Ｓｎ金属間化合物層の凹凸がほとんどなくなってＣｕ－Ｓｎ金属間化合物層が著しく脆くなり、曲げ加工時に皮膜の剥離が発生し易くなるため好ましくない。 The conductive member, Cu-Sn intermetallic compound layer between the Ni-based base layer and the Sn-based surface layer is a two-layer structure of the Cu 3 Sn layer and the Cu 6 Sn 5 layer, the underlying Cu 3 The Cu 6 Sn 5 layer is present so that the Sn layer covers the Ni-based underlayer and covers it. The Cu—Sn intermetallic compound layer formed by combining the Cu 3 Sn alloy layer and the Cu 6 Sn 5 layer has a film thickness that is not necessarily uniform and has irregularities, but is a surface in contact with the Sn-based surface layer. The surface roughness is 0.05 to 0.25 μm in terms of arithmetic average roughness Ra, and 0.05 to 1.00 μm in terms of the maximum valley depth Rv of the roughness curve.
Here, the arithmetic average roughness Ra represents the average size of the irregularities on the surface. If this Ra exceeds 0.25 μm, large irregularities are formed under the Sn-based surface layer. The insertion / extraction force when used is not preferable. When the unevenness of the Cu—Sn intermetallic compound layer is reduced, the insertion / extraction force during use of the connector is reduced, but it is preferable that Ra is less than 0.05 μm because the unevenness of the Cu—Sn intermetallic compound layer is almost eliminated. This is not preferable because the Cu—Sn intermetallic compound layer becomes extremely brittle and peeling of the film easily occurs during bending.
　この場合、このＲａは平均化されるため、大きな谷がある場合にも平均化され数値には現れにくい。この大きな谷があると、高温時にその谷部からＳｎがＮｉ系下地層へと拡散し、Ｎｉ系下地層に欠損が発生するおそれがあり、その欠損により、基材のＣｕが拡散してＣｕ６Ｓｎ５層が表面まで達し、表面にＣｕ酸化物が形成されることにより、接触抵抗が増大することになる。また、このとき、Ｎｉ系下地層の欠損部からのＣｕの拡散により、カーケンダルボイドが発生し易い。
　そこで、Ｒａが前述の範囲の下、粗さ曲線の最大谷深さＲｖが１．００μｍ以下であれば、Ｎｉ系下地層の欠損を防止することができる。また、このＲｖを０．０５μｍ未満とするのは、Ｒａの場合と同様、Ｃｕ－Ｓｎ金属間化合物層が脆くなるため好ましくない。
　そして、このように所定の表面粗さのＣｕ－Ｓｎ金属間化合物層がＳｎ系表面層の下層に配置されることにより、柔軟なＳｎの下地を硬くして、多極コネクタなどで使用したときの挿抜力の低減及びそのバラツキの抑制を図ることができる。 In this case, since Ra is averaged, even if there is a large valley, it is averaged and hardly appears in the numerical value. If there is such a large valley, Sn diffuses from the valley to the Ni-based underlayer at a high temperature, and there is a risk that defects will occur in the Ni-based underlayer. When the 6 Sn 5 layer reaches the surface and Cu oxide is formed on the surface, the contact resistance is increased. Further, at this time, Kirkendall voids are likely to be generated due to diffusion of Cu from the defect portion of the Ni-based underlayer.
Therefore, if Ra is in the above-mentioned range and the maximum valley depth Rv of the roughness curve is 1.00 μm or less, it is possible to prevent the Ni-based underlayer from being damaged. Also, it is not preferable that the Rv be less than 0.05 μm because the Cu—Sn intermetallic compound layer becomes brittle as in the case of Ra.
When the Cu—Sn intermetallic compound layer having a predetermined surface roughness is disposed under the Sn-based surface layer as described above, the flexible Sn base is hardened and used in a multipolar connector or the like. It is possible to reduce the insertion / extraction force and to suppress variations thereof.
　また、Ｓｎ系表面層の下のＣｕ－Ｓｎ金属間化合物層がこのような表面粗さに形成されＮｉ系下地層の欠損が生じにくい状態であると、Ｃｕ系基材からＣｕがＣｕ－Ｓｎ金属間化合物層に侵入することが抑制され、その結果、Ｃｕ－Ｓｎ金属間化合物層の電気的特性が変化することがなく、ヒューズとして用いた場合にも安定した溶断特性を発揮することができる。 In addition, when the Cu—Sn intermetallic compound layer under the Sn-based surface layer is formed in such a surface roughness and the Ni-based underlayer is not easily damaged, Cu is removed from the Cu-based substrate. Intrusion into the intermetallic compound layer is suppressed, and as a result, the electrical characteristics of the Cu—Sn intermetallic compound layer are not changed, and stable fusing characteristics can be exhibited even when used as a fuse. .
　また、Ｎｉ系下地層に対するＣｕ３Ｓｎ層の面積被覆率が６０％以上としたのは、その被覆率が低いと、被覆されていない部分から高温時にＮｉ系下地層のＮｉ原子がＣｕ６Ｓｎ５層に拡散して、Ｎｉ系下地層に欠損が発生し、その欠損部分から基材のＣｕが拡散することにより上記の場合と同様に接触抵抗の増大やカーケンダルボイドの発生を招くからである。この高温時の接触抵抗の増大やカーケンダルボイドの発生を防止して、従来技術以上の耐熱性を実現するためには、Ｎｉ系下地層が少なくとも６０％以上被覆されていることが必要であり、さらに８０％以上の面積被覆率とすることが望ましい。 The reason why the area coverage of the Cu 3 Sn layer with respect to the Ni-based underlayer is 60% or more is that when the coverage is low, the Ni atoms in the Ni-based underlayer are Cu 6 Sn at high temperatures from the uncoated portion. This is because the Ni-based underlayer is deficient in five layers and the Cu of the base material diffuses from the deficient portion, resulting in increased contact resistance and generation of Kirkendall voids as in the above case. is there. In order to prevent this increase in contact resistance at high temperatures and the generation of Kirkendall voids and to achieve heat resistance higher than that of the prior art, it is necessary that the Ni-based underlayer is coated at least 60% or more. Further, it is desirable that the area coverage is 80% or more.
　本発明の導電部材において、前記Ｃｕ３Ｓｎ層の平均厚さは０．０１～０．５μｍであることが好ましい。
　Ｃｕ３Ｓｎ層の平均厚みがこの範囲であると、Ｎｉ系下地層の拡散をより有効に抑えるとともに、高温時の接触抵抗の増大を抑えることができる。
　この平均厚さは、Ｃｕ３Ｓｎ層の部分で、その厚さを複数個所測定したときの平均値である。 In the conductive member of the present invention, the Cu 3 Sn layer preferably has an average thickness of 0.01 to 0.5 μm.
When the average thickness of the Cu 3 Sn layer is within this range, it is possible to more effectively suppress diffusion of the Ni-based underlayer and to suppress increase in contact resistance at high temperatures.
This average thickness is an average value when the thickness of the Cu 3 Sn layer portion is measured at a plurality of locations.
　本発明の導電部材において、前記Ｓｎ系表面層の平均厚さは０．５～１．５μｍであることが好ましい。
　Ｓｎ系表面層は、導電部材の表面を形成する層として、耐熱性、コネクタ端子としての挿抜性などの性能維持のために、０．５～１．５μｍの平均厚さを有することが好ましい。 In the conductive member of the present invention, the average thickness of the Sn-based surface layer is preferably 0.5 to 1.5 μm.
The Sn-based surface layer preferably has an average thickness of 0.5 to 1.5 μm as a layer forming the surface of the conductive member in order to maintain performance such as heat resistance and insertion / removability as a connector terminal.
　また、本発明の導電部材において、前記Ｓｎ表面層の上に、平均厚さが０．０５～０．５μｍのＳｎ－Ａｇ被覆層が形成されているとよい。
　その場合、前記Ｓｎ－Ａｇ被覆層が、０．１～５．０重量％のＡｇを含有するものとするのが好ましい。
　最表面にＳｎ－Ａｇ被覆層を形成することにより、導電部材としての耐熱性及びコネクタ使用時の挿抜性をより向上させることができる。 In the conductive member of the present invention, a Sn—Ag coating layer having an average thickness of 0.05 to 0.5 μm may be formed on the Sn surface layer.
In this case, the Sn—Ag coating layer preferably contains 0.1 to 5.0% by weight of Ag.
By forming the Sn—Ag coating layer on the outermost surface, it is possible to further improve the heat resistance as the conductive member and the insertion / extraction properties when using the connector.
　そして、本発明の導電部材の製造方法は、Ｃｕ系基材の表面に、Ｎｉ又はＮｉ合金、Ｃｕ又はＣｕ合金、Ｓｎ又はＳｎ合金をこの順にめっきしてそれぞれのめっき層を形成した後、加熱してリフロー処理することにより、前記Ｃｕ系基材の上に、Ｎｉ系下地層、Ｃｕ－Ｓｎ金属間化合物層、Ｓｎ系表面層を順に形成した導電部材を製造する方法であって、前記Ｃｕ又はＣｕ合金によるめっき層を電流密度が２０～６０Ａ／ｄｍ２の電解めっきにより形成し、前記Ｓｎ又はＳｎ合金によるめっき層を電流密度が１０～３０Ａ／ｄｍ２の電解めっきにより形成するとともに、前記Ｃｕ又はＣｕ合金によるめっき層の平均厚さが０．３～０．５μｍであり、前記リフロー処理は、前記めっき層を形成してから１～１５分経過した後に、めっき層を２０～７５℃／秒の昇温速度で２４０～３００℃のピーク温度まで加熱する加熱工程と、前記ピーク温度に達した後、３０℃／秒以下の冷却速度で２～１０秒間冷却する一次冷却工程と、一次冷却後に１００～２５０℃／秒の冷却速度で冷却する二次冷却工程とを有することを特徴とする。 And the manufacturing method of the electrically-conductive member of this invention heats, after plating the surface of Cu base material, Ni or Ni alloy, Cu or Cu alloy, Sn or Sn alloy in this order, and forming each plating layer And reflow treatment to produce a conductive member in which a Ni-based underlayer, a Cu—Sn intermetallic compound layer, and a Sn-based surface layer are sequentially formed on the Cu-based substrate, Alternatively, a plating layer made of Cu alloy is formed by electrolytic plating with a current density of 20 to 60 A / dm 2 , and a plating layer made of Sn or Sn alloy is formed by electrolytic plating with a current density of 10 to 30 A / dm 2 , and The average thickness of the plating layer made of Cu or Cu alloy is 0.3 to 0.5 μm, and the reflow treatment is performed after 1 to 15 minutes have passed since the formation of the plating layer. A heating process for heating to a peak temperature of 240 to 300 ° C. at a temperature rising rate of 0 to 75 ° C./second, and primary cooling for cooling for 2 to 10 seconds at a cooling rate of 30 ° C./second or less after reaching the peak temperature. And a secondary cooling step of cooling at a cooling rate of 100 to 250 ° C./second after the primary cooling.
　高電流密度でのＣｕめっきは粒界密度を増加させ、均一な合金層形成を助ける。Ｃｕめっきの電流密度を２０～６０Ａ／ｄｍ２としたのは、電流密度が２０Ａ／ｄｍ２未満ではＣｕめっき結晶の反応活性が乏しいため、合金化する際に平滑な金属間化合物を形成する効果が乏しく、一方、電流密度が６０Ａ／ｄｍ２を超えると、Ｃｕめっき層の平滑性が低くなるため、平滑なＣｕ－Ｓｎ金属間化合物層を形成することができないからである。
　また、Ｓｎめっきの電流密度を１０～３０Ａ／ｄｍ２としたのは、電流密度が１０Ａ／ｄｍ２未満ではＳｎの粒界密度が低くなって、合金化する際に平滑なＣｕ－Ｓｎ金属間化合物層を形成する効果が乏しく、一方、電流密度が３０Ａ／ｄｍ２を超えると、電流効率が著しく低下するため望ましくないからである。
　また、Ｃｕ－Ｓｎ金属間化合物層の凹凸を小さくするには、その下地となるＣｕ又はＣｕ合金によるめっき層の厚さが重要であり、これを若干厚く形成しておくことにより、リフロー処理した後のＣｕ－Ｓｎ金属間化合物層の凹凸を小さくすることができる。したがって、Ｃｕ又はＣｕ合金によるめっき層は比較的厚く形成され、０．３μｍ以上の厚さを有することで、リフロー処理後のＣｕ－Ｓｎ金属間化合物層の表面の凹凸が少なく、表面粗さを適切な状態とすることができる。０．５μｍを超えても、その効果は飽和する。 Cu plating at a high current density increases the grain boundary density and helps to form a uniform alloy layer. The reason why the current density of Cu plating is set to 20 to 60 A / dm 2 is that when the current density is less than 20 A / dm 2 , the reaction activity of the Cu plating crystal is poor, and therefore the effect of forming a smooth intermetallic compound when alloying is performed. On the other hand, when the current density exceeds 60 A / dm 2 , the smoothness of the Cu plating layer is lowered, and thus a smooth Cu—Sn intermetallic compound layer cannot be formed.
In addition, the current density of Sn plating was set to 10 to 30 A / dm 2 because when the current density was less than 10 A / dm 2 , the Sn grain boundary density was low, and smooth Cu-Sn intermetallic This is because the effect of forming the compound layer is poor, and on the other hand, if the current density exceeds 30 A / dm 2 , the current efficiency is remarkably lowered, which is undesirable.
Also, in order to reduce the unevenness of the Cu—Sn intermetallic compound layer, the thickness of the plating layer made of Cu or Cu alloy as the base is important, and the reflow treatment was performed by forming this slightly thicker. The unevenness of the subsequent Cu—Sn intermetallic compound layer can be reduced. Therefore, the plating layer made of Cu or Cu alloy is formed to be relatively thick and has a thickness of 0.3 μm or more, so that the surface roughness of the Cu—Sn intermetallic compound layer after reflow treatment is small and the surface roughness is reduced. An appropriate state can be obtained. Even if it exceeds 0.5 μm, the effect is saturated.
　また、高電流密度で電析したＣｕとＳｎは安定性が低く、室温においても合金化や結晶粒肥大化が発生し、リフロー処理で所望の金属間化合物構造をつくることが困難になる。このため、めっき処理後、速やかにリフロー処理を行うことが望ましい。具体的には１５分以内、望ましくは５分以内にリフロー処理を行うと良い。
　従来技術よりも高電流密度でＮｉ又はＮｉ合金、Ｃｕ又はＣｕ合金、Ｓｎ又はＳｎ合金のめっき処理を行い、なおかつ、めっき後、速やかにリフロー処理を行うことにより、リフロー時にＣｕとＳｎが活発に反応し、Ｃｕ３Ｓｎ層によりＮｉ系下地層を多く被覆し、均一なＣｕ６Ｓｎ５層が生成される。 Further, Cu and Sn electrodeposited at a high current density are low in stability, and alloying and grain enlargement occur even at room temperature, making it difficult to form a desired intermetallic compound structure by reflow treatment. For this reason, it is desirable to perform the reflow process immediately after the plating process. Specifically, the reflow process may be performed within 15 minutes, preferably within 5 minutes.
Ni or Ni alloy, Cu or Cu alloy, Sn or Sn alloy is plated at a higher current density than in the prior art, and Cu and Sn are activated actively during reflow by performing reflow treatment immediately after plating. By reacting, a large amount of Ni-based underlayer is covered with the Cu 3 Sn layer, and a uniform Cu 6 Sn 5 layer is generated.
　また、このリフロー処理においては、加熱工程における昇温速度が２０℃／秒未満であると、Ｓｎめっきが溶融するまでの間にＣｕ原子がＳｎの粒界中を優先的に拡散し粒界近傍で金属間化合物が異常成長するため、被覆率の高いＣｕ３Ｓｎ層が形成され難い。一方、昇温速度が７５℃／秒を超えると、金属間化合物の成長が不十分かつＣｕめっきが過剰に残存し、その後の冷却において所望の金属間化合物層を得ることができない。
　また、加熱工程でのピーク温度が２４０℃未満であると、Ｓｎが均一に溶融せず、ピーク温度が３００℃を超えると、金属間化合物が急激に成長しＣｕ－Ｓｎ金属間化合物層の凹凸が大きくなるので好ましくない。
　さらに、冷却工程においては、冷却速度の小さい一次冷却工程を設けることにより、Ｃｕ原子がＳｎ粒内に穏やかに拡散し、所望の金属間化合物構造で成長する。この一次冷却工程の冷却速度が３０℃／秒を超えると、急激に冷却される影響で金属間化合物は滑らかな形状に成長することができず、凹凸が大きくなる。冷却時間が２秒未満であっても同様に金属間化合物は滑らかな形状に成長することができない。冷却時間が１０秒を超えると、Ｃｕ６Ｓｎ５層の成長が過度に進み、Ｃｕ３Ｓｎ層の被覆率が低下する。この一次冷却工程は空冷が適切である。
　そして、この一次冷却工程の後、二次冷却工程によって急冷して金属間化合物層の成長を所望の構造で完了させる。この二次冷却工程の冷却速度が１００℃／秒未満であると、金属間化合物がより進行し、所望の金属間化合物形状を得ることができない。
　このようにめっきの電析条件とリフロー条件を緻密に制御することによって、二層構造で凹凸が少なく安定したＣｕ－Ｓｎ金属間化合物層を得ることができる。 Further, in this reflow treatment, if the rate of temperature increase in the heating process is less than 20 ° C./second, Cu atoms preferentially diffuse in the Sn grain boundary until Sn plating melts, and in the vicinity of the grain boundary. Since the intermetallic compound grows abnormally, it is difficult to form a Cu 3 Sn layer having a high coverage. On the other hand, if the rate of temperature rise exceeds 75 ° C./second, the growth of the intermetallic compound is insufficient and the Cu plating remains excessively, and a desired intermetallic compound layer cannot be obtained in the subsequent cooling.
In addition, when the peak temperature in the heating process is less than 240 ° C., Sn does not melt uniformly, and when the peak temperature exceeds 300 ° C., the intermetallic compound grows rapidly and the unevenness of the Cu—Sn intermetallic compound layer Is unfavorable because of the increase.
Further, in the cooling step, by providing a primary cooling step with a low cooling rate, Cu atoms diffuse gently in the Sn grains and grow with a desired intermetallic compound structure. When the cooling rate in the primary cooling step exceeds 30 ° C./second, the intermetallic compound cannot grow into a smooth shape due to the effect of rapid cooling, and unevenness increases. Similarly, even when the cooling time is less than 2 seconds, the intermetallic compound cannot grow into a smooth shape. When the cooling time exceeds 10 seconds, the growth of the Cu 6 Sn 5 layer proceeds excessively and the coverage of the Cu 3 Sn layer decreases. Air cooling is appropriate for this primary cooling step.
Then, after the primary cooling step, the secondary cooling step is rapidly cooled to complete the growth of the intermetallic compound layer with a desired structure. When the cooling rate in the secondary cooling step is less than 100 ° C./second, the intermetallic compound further proceeds, and a desired intermetallic compound shape cannot be obtained.
Thus, by precisely controlling the electrodeposition conditions and the reflow conditions for plating, a stable Cu—Sn intermetallic compound layer having a two-layer structure with few irregularities can be obtained.
　また、本発明の導電部材の製造方法において、前記Ｓｎ又はＳｎ合金によるめっき層の平均厚さが１．５～２．０μｍであるとよい。Ｃｕ－Ｓｎ金属間化合物層及びＳｎ系表面層の厚さを適切に確保するためである。 In the method for producing a conductive member of the present invention, the average thickness of the plating layer made of Sn or Sn alloy is preferably 1.5 to 2.0 μm. This is for ensuring adequate thicknesses of the Cu—Sn intermetallic compound layer and the Sn-based surface layer.
　また、本発明の導電部材の製造方法において、前記Ｎｉ又はＮｉ合金によるめっき層は電流密度が２０～５０Ａ／ｄｍ２の電解めっきにより形成するとよい。
　Ｎｉめっきの電流密度を２０Ａ／ｄｍ２以上とすることにより、結晶粒を微細化して、リフローや製品化された後の加熱時にＮｉ原子のＳｎや金属間化合物への拡散を有効に防止することができ、一方、電流密度を５０Ａ／ｄｍ２以下とすることにより、電解時のめっき表面での水素発生を抑えてめっき品質がより向上する。このため、Ｎｉめっきの電流密度を２０～５０Ａ／ｄｍ２とするのが望ましい。 In the method for producing a conductive member of the present invention, the plating layer made of Ni or Ni alloy is preferably formed by electrolytic plating with a current density of 20 to 50 A / dm 2 .
By making the current density of Ni plating 20 A / dm 2 or more, the crystal grains are made finer and effectively prevent Ni atoms from diffusing into Sn or intermetallic compounds during reflow or heating after product production. On the other hand, when the current density is 50 A / dm 2 or less, the generation of hydrogen on the plating surface during electrolysis is suppressed, and the plating quality is further improved. For this reason, it is desirable that the current density of Ni plating be 20 to 50 A / dm 2 .
　また、本発明の導電部材の製造方法において、前記リフロー処理後の前記Ｓｎ系表面層の酸化膜を除去し、該Ｓｎ系表面層の表面粗さを算術平均粗さＲａで０．００５～０．３μｍとした後、その上にＳｎ－Ａｇ被覆層を形成するとよい。
　Ｓｎ系表面層には酸化膜が形成され易いので、最表面にＳｎ－Ａｇ被覆層を設けて耐熱性、コネクタとしての挿抜性を向上させる場合、その酸化膜を除去後、表面を平滑にすることでＳｎ－Ａｇ被覆層の凹凸を減少させ、耐熱性、挿抜性の向上効果を有効に発揮させることができる。 In the method for producing a conductive member of the present invention, the oxide film of the Sn-based surface layer after the reflow treatment is removed, and the surface roughness of the Sn-based surface layer is 0.005 to 0 in terms of arithmetic average roughness Ra. After setting the thickness to 3 μm, a Sn—Ag coating layer may be formed thereon.
Since an oxide film is easily formed on the Sn-based surface layer, when the Sn-Ag coating layer is provided on the outermost surface to improve heat resistance and connector insertion / extraction, the surface is smoothed after removing the oxide film. Thus, the unevenness of the Sn—Ag coating layer can be reduced, and the effect of improving heat resistance and insertion / extraction can be effectively exhibited.
　このような導電部材として銅条材を連続的に走行させながら複数のめっき浴に挿通して、その表面に、Ｎｉ又はＮｉ合金、Ｃｕ又はＣｕ合金、Ｓｎ又はＳｎ合金のめっき層をこの順に形成して、その後、加熱してリフロー処理することにより、前記銅条材の上に、Ｎｉ系下地層、Ｃｕ－Ｓｎ金属間化合物層、Ｓｎ系表面層を順に形成する導電部材の製造する方法において、各めっき浴内の電流密度、浴温度、レイノルズ数を適切に選択すること、特に、レイノルズ数を最適に選択することにより、より効率良く所望の性状のめっき膜が得られることを見出した。めっき浴としては、特殊な排水処理設備が不要な無機酸を主成分とするめっき浴を使用することが最適である。 As such a conductive member, a copper strip is continuously run while passing through a plurality of plating baths, and Ni or Ni alloy, Cu or Cu alloy, Sn or Sn alloy plating layer is formed on the surface thereof in this order. Then, in the method of manufacturing a conductive member in which a Ni-based underlayer, a Cu—Sn intermetallic compound layer, and a Sn-based surface layer are sequentially formed on the copper strip by heating and reflow treatment. The inventors have found that a plating film having a desired property can be obtained more efficiently by appropriately selecting the current density, bath temperature, and Reynolds number in each plating bath, and in particular, by selecting the Reynolds number optimally. As the plating bath, it is optimal to use a plating bath mainly composed of an inorganic acid that does not require special wastewater treatment equipment.
　即ち、良好なめっき膜を得るためには、めっき時に発生する水素ガスを連続的かつ効率的に排除することが必要であり、めっき液の流れ場を最適な乱流値にすると強力な攪拌効果が得られ、水素ガスを連続的かつ効率的に排除出来ることを見出した。乱流値を表す指数としてはレイノルズ数が適切であり、実験結果より、最適値以上ではめっきの理論電流効率値は横ばいとなり、最適値以下では外観不良（めっき焼け）が発生することが判明した（図６参照）。
　レイノルズ数は、めっき液粘度、めっき流路径、めっき液と被めっき物との間の相対流速の３要素で決定される無次元数であり、状況に応じ３要素を適宜変更することにより最適値を得ることが出来る。
　また、レイノルズ数は相対速度と異なり、被めっき物とめっき液との界面（境界層）とも相関性があると考えられる。 In other words, in order to obtain a good plating film, it is necessary to eliminate hydrogen gas generated during plating continuously and efficiently. If the flow field of the plating solution is set to an optimum turbulent flow value, a strong stirring effect is obtained. It was found that hydrogen gas can be eliminated continuously and efficiently. The Reynolds number is appropriate as an index that represents the turbulent flow value. From the experimental results, it has been found that the theoretical current efficiency value of the plating remains flat above the optimum value, and the appearance defect (plating burn) occurs below the optimum value. (See FIG. 6).
The Reynolds number is a dimensionless number determined by the three factors of plating solution viscosity, plating channel diameter, and relative flow velocity between the plating solution and the object to be plated. The optimum value is obtained by appropriately changing the three factors according to the situation. Can be obtained.
In addition, the Reynolds number is considered to be correlated with the interface (boundary layer) between the object to be plated and the plating solution, unlike the relative speed.
　また、錫めっき時に多量に発生する泡及びスラッジを除去する手段を併設することにより、めっき効率が更に高まることが判った。
　更に、リフロー条件を検討することにより、中間層の表面粗さがコントロール出来ることを見出した。中間層は基本的に層状であり平均結晶粒径より、中間層自体の凸凹、即ち、表面粗さを最適な数値範囲とすることが重要である。 Further, it has been found that the plating efficiency is further increased by providing a means for removing bubbles and sludge generated in a large amount during tin plating.
Furthermore, it has been found that the surface roughness of the intermediate layer can be controlled by examining the reflow conditions. The intermediate layer is basically laminar, and it is important that the unevenness of the intermediate layer itself, that is, the surface roughness be in an optimum numerical range based on the average crystal grain size.
　このような観点から、本発明の製造方法において、前記電解めっきは、無機酸を主成分とするめっき浴中にて不溶性アノードを使用し、レイノルズ数１×１０４～５×１０５なる電解めっきとするとよい。 From such a point of view, in the production method of the present invention, the electrolytic plating uses an insoluble anode in a plating bath mainly composed of an inorganic acid, and has an Reynolds number of 1 × 10 4 to 5 × 10 5. It is good to do.
　また、本発明の製造方法において、前記用Ｓｎ又はＳｎ合金によるめっき層の形成時に泡及びスラッジを除去する手段を併設して、めっき液の泡及びスラッジを除去するとよく、めっき効率が更に高まることが判った。 Further, in the production method of the present invention, it is preferable to provide a means for removing bubbles and sludge at the time of forming the plating layer with the Sn or Sn alloy, and to remove the bubbles and sludge of the plating solution, thereby further increasing the plating efficiency. I understood.
　本発明によれば、Ｓｎ系表面層の下のＣｕ－Ｓｎ金属間化合物層の表面粗さを所定範囲に形成したことにより、コネクタとして用いたときの挿抜力を低減してそのバラツキを抑制するとともに、高温時のＣｕの拡散を防止し、表面状態を良好に維持して接触抵抗の増大を抑制することができ、めっき皮膜の剥離やカーケンダルボイドの発生を防止することができる。また、Ｃｕ系基材からのＣｕの拡散が抑制されるので、Ｃｕ－Ｓｎ金属間化合物層の電気的特性が安定し、ヒューズとして用いた場合にも優れた溶断特性を発揮することができる。また、その製造方法によれば、導電部材としての使用時に良好な特性を有する多層にめっきされた銅条材を連続的に効率良く得ることが出来る。 According to the present invention, the surface roughness of the Cu—Sn intermetallic compound layer under the Sn-based surface layer is formed within a predetermined range, so that the insertion / extraction force when used as a connector is reduced and the variation is suppressed. At the same time, the diffusion of Cu at high temperatures can be prevented, the surface state can be maintained well, the increase in contact resistance can be suppressed, and the peeling of the plating film and the generation of Kirkendall voids can be prevented. Further, since the diffusion of Cu from the Cu-based substrate is suppressed, the electrical characteristics of the Cu—Sn intermetallic compound layer are stabilized, and excellent fusing characteristics can be exhibited even when used as a fuse. Moreover, according to the manufacturing method, the copper strip plated in the multilayer which has a favorable characteristic at the time of use as an electrically-conductive member can be obtained continuously and efficiently.
本発明に係る導電部材の第１実施形態の表層部分をモデル化して示した断面図である。It is sectional drawing which modeled and showed the surface layer part of 1st Embodiment of the electrically-conductive member which concerns on this invention. 図１の導電部材の最表面にＳｎ－Ａｇ被覆層を形成した実施形態を示す断面図である。FIG. 2 is a cross-sectional view showing an embodiment in which a Sn—Ag coating layer is formed on the outermost surface of the conductive member of FIG. 1. 本発明の製造方法に係るリフロー条件の温度と時間の関係をグラフにした温度プロファイルである。It is the temperature profile which made the relationship between the temperature of reflow conditions and time concerning the manufacturing method of this invention a graph. 本発明の第２実施形態の製造方法に使用される製造装置の例を示す概略構成図である。It is a schematic block diagram which shows the example of the manufacturing apparatus used for the manufacturing method of 2nd Embodiment of this invention. 図４におけるめっき槽中の電極と銅条材との位置関係を示す断面図である。It is sectional drawing which shows the positional relationship of the electrode in a plating tank in FIG. 4, and a copper strip. めっき処理中のレイノルズ数と電流効率との関係を示すグラフである。It is a graph which shows the relationship between the Reynolds number during plating processing, and current efficiency. 本発明の第２実施形態の製造方法により製造された導電部材の表層部分をモデル化して示した断面図である。It is sectional drawing which modeled and showed the surface layer part of the electrically-conductive member manufactured by the manufacturing method of 2nd Embodiment of this invention. 導電部材の動摩擦係数を測定するための装置を概念的に示す正面図である。It is a front view which shows notionally the apparatus for measuring the dynamic friction coefficient of an electrically-conductive member. 本実施例及び比較例の各導電部材における接触抵抗の経時変化を示すグラフである。It is a graph which shows the time-dependent change of the contact resistance in each electrically-conductive member of a present Example and a comparative example.
　以下、本発明の実施形態を説明する。
（第１実施形態）
　第１実施形態の導電部材１０は、図１に示すように、Ｃｕ系基材１の表面に、Ｆｅ系下地層２を介して、Ｎｉ系下地層３、Ｃｕ－Ｓｎ金属間化合物層４、Ｓｎ系表面層５がこの順に形成されるとともに、Ｃｕ－Ｓｎ金属間化合物層４はさらに、Ｃｕ３Ｓｎ層６とＣｕ６Ｓｎ５層７とから構成されている。
　Ｃｕ系基材１は、Ｃｕ又はＣｕ合金から構成された例えば板状のものである。Ｃｕ合金としては、その材質は必ずしも限定されないが、Ｃｕ－Ｚｎ系合金、Ｃｕ－Ｎｉ－Ｓｉ系（コルソン系）合金、Ｃｕ－Ｃｒ－Ｚｒ系合金、Ｃｕ－Ｍｇ－Ｐ系合金、Ｃｕ－Ｆｅ－Ｐ系合金、Ｃｕ－Ｓｎ－Ｐ系合金が好適であり、例えば、三菱伸銅株式会社製ＭＳＰ１,ＭＺＣ１,ＭＡＸ２５１Ｃ,ＭＡＸ３７５,ＭＡＸ１２６が好適に用いられる。
　Ｆｅ系下地層２は、Ｆｅ又はＦｅ合金を電解めっきして形成されたものであり、Ｃｕ系基材１の表面に０，１～１．０μｍの厚さに形成される。Ｆｅ合金としては、例えばＦｅ－Ｎｉ合金が用いられる。
　Ｎｉ系下地層３は、Ｎｉ又はＮｉ合金を電解めっきして形成されたものであり、Ｆｅ系下地層２の表面に、例えば０．０５～０．３μｍの厚さに形成される。このＮｉ系下地層３をこの範囲の厚さとすることにより、高温時の拡散を有効に防止して、剥離を生じにくくし、また、曲げ加工性がよくなる。 Embodiments of the present invention will be described below.
(First embodiment)
As shown in FIG. 1, the conductive member 10 according to the first embodiment includes a Ni-based underlayer 3, a Cu—Sn intermetallic compound layer 4, and a Cu-based substrate 1 with a Fe-based underlayer 2 interposed therebetween. The Sn-based surface layer 5 is formed in this order, and the Cu—Sn intermetallic compound layer 4 further includes a Cu 3 Sn layer 6 and a Cu 6 Sn 5 layer 7.
The Cu-based substrate 1 is, for example, a plate-like one made of Cu or a Cu alloy. The material of the Cu alloy is not necessarily limited, but Cu—Zn alloy, Cu—Ni—Si alloy (Corson alloy), Cu—Cr—Zr alloy, Cu—Mg—P alloy, Cu—Fe -P-based alloys and Cu-Sn-P-based alloys are suitable. For example, MSP1, MZC1, MAX251C, MAX375, and MAX126 manufactured by Mitsubishi Shindoh Co., Ltd. are preferably used.
The Fe-based underlayer 2 is formed by electrolytic plating of Fe or Fe alloy, and is formed on the surface of the Cu-based substrate 1 with a thickness of 0.1 to 1.0 μm. For example, an Fe—Ni alloy is used as the Fe alloy.
The Ni-based underlayer 3 is formed by electrolytic plating of Ni or a Ni alloy, and is formed on the surface of the Fe-based underlayer 2 with a thickness of, for example, 0.05 to 0.3 μm. By setting the Ni-based underlayer 3 to a thickness in this range, diffusion at high temperatures is effectively prevented, peeling is less likely to occur, and bending workability is improved.
　Ｃｕ－Ｓｎ金属間化合物層４は、後述するようにＮｉ系下地層３の上にめっきしたＣｕと表面のＳｎとがリフロー処理によって拡散して形成された合金層である。このＣｕ－Ｓｎ金属間化合物層４は、全体としては、０．０５～１．８μｍの厚さ、好ましくは０．１μｍ以上の厚さに形成され、さらに、Ｎｉ系下地層３の上に配置されるＣｕ３Ｓｎ層６と、該Ｃｕ３Ｓｎ層６の上に配置されるＣｕ６Ｓｎ５層７とから構成されている。この場合、Ｃｕ－Ｓｎ金属間化合物層４全体としては凹凸が形成されており、Ｓｎ系表面層５に接する面の表面粗さが、算術平均粗さＲａで０．０５～０．２５μｍであり、かつ、粗さ曲線の最大谷深さＲｖで０．０５～１．００μｍとされている。
　算術平均粗さＲａが０．０５～０．２５μｍとしたのは、コネクタ端子部３として用いる場合には、Ｒａが小さい方が挿抜力が低減して好ましいが、Ｒａが０．０５μｍ未満であると、Ｃｕ－Ｓｎ金属間化合物層４の凹凸がほとんどなくなってＣｕ－Ｓｎ金属間化合物層４が著しく脆くなり、曲げ加工時に皮膜の剥離が発生し易くなる。Ｒａが０．２５μｍを超えるほどに凹凸が大きくなると、コネクタとして用いたときの挿抜時にＣｕ－Ｓｎ金属間化合物層４の凹凸が抵抗となるため、挿抜力を低減する効果が乏しい。
　一方、粗さ曲線の最大谷深さＲｖに関しては、Ｒｖが１．００μｍを超えると、高温時にその谷部からＳｎがＮｉ系下地層へと拡散し、Ｎｉ系下地層に欠損が発生するおそれがあり、その欠損により、基材のＣｕが拡散してＣｕ６Ｓｎ５層が表面まで達し、表面にＣｕ酸化物が形成されることにより、接触抵抗が増大することになる。また、このとき、Ｎｉ系下地層の欠損部からのＣｕの拡散により、カーケンダルボイドが発生し易い。このＲｖを０．０５μｍ未満とするのは、Ｒａの場合と同様、Ｃｕ－Ｓｎ金属間化合物層が脆くなるため好ましくない。
　また、このようにＣｕ－Ｓｎ金属間化合物層の凹凸が小さく、Ｎｉ系下地層の欠損によるＣｕの拡散が生じにくい状態であると、Ｃｕ－Ｓｎ金属間化合物層の電気的特性が変化することがなく、ヒューズとして用いた場合にも安定した溶断特性を発揮することができる。 As will be described later, the Cu—Sn intermetallic compound layer 4 is an alloy layer formed by diffusing Cu plated on the Ni-based underlayer 3 and Sn on the surface by reflow treatment. The Cu—Sn intermetallic compound layer 4 is formed to a thickness of 0.05 to 1.8 μm as a whole, preferably 0.1 μm or more, and further disposed on the Ni-based underlayer 3. The Cu 3 Sn layer 6 and the Cu 6 Sn 5 layer 7 disposed on the Cu 3 Sn layer 6 are configured. In this case, the Cu—Sn intermetallic compound layer 4 as a whole is uneven, and the surface roughness of the surface in contact with the Sn-based surface layer 5 is an arithmetic average roughness Ra of 0.05 to 0.25 μm. The maximum valley depth Rv of the roughness curve is 0.05 to 1.00 μm.
The reason why the arithmetic average roughness Ra is 0.05 to 0.25 μm is that when Ra is used as the connector terminal portion 3, it is preferable that Ra is small because the insertion / extraction force is reduced, but Ra is less than 0.05 μm. Then, the unevenness of the Cu—Sn intermetallic compound layer 4 is almost eliminated and the Cu—Sn intermetallic compound layer 4 becomes extremely fragile, and the film is easily peeled off during bending. If the unevenness becomes so large that Ra exceeds 0.25 μm, the unevenness of the Cu—Sn intermetallic compound layer 4 becomes resistance at the time of insertion / extraction when used as a connector, so that the effect of reducing the insertion / extraction force is poor.
On the other hand, regarding the maximum valley depth Rv of the roughness curve, when Rv exceeds 1.00 μm, Sn diffuses from the valley portion to the Ni-based underlayer at a high temperature, and the Ni-based underlayer may be damaged. Due to the defect, Cu of the base material diffuses, the Cu 6 Sn 5 layer reaches the surface, and Cu oxide is formed on the surface, thereby increasing the contact resistance. Further, at this time, Kirkendall voids are likely to be generated due to diffusion of Cu from the defect portion of the Ni-based underlayer. It is not preferable that Rv be less than 0.05 μm because the Cu—Sn intermetallic compound layer becomes brittle as in the case of Ra.
Further, when the unevenness of the Cu—Sn intermetallic compound layer is small and Cu diffusion due to defects in the Ni-based underlayer is difficult to occur, the electrical characteristics of the Cu—Sn intermetallic compound layer change. Therefore, stable fusing characteristics can be exhibited even when used as a fuse.
　また、このＣｕ－Ｓｎ金属間化合物層４のうちの下層に配置されるＣｕ３Ｓｎ層６は、Ｎｉ系下地層３を覆っており、その面積被覆率が６０～１００％とされている。この面積被覆率が６０％未満となって低いと、被覆されていない部分から高温時にＮｉ系下地層３のＮｉ原子のＣｕ６Ｓｎ５層７への拡散が促進して、Ｎｉ系下地層３に欠損が発生するおそれがある。より望ましくは８０％以上が被覆されているとよい。
　この面積被覆率は、皮膜を集束イオンビーム（ＦＩＢ；Focused Ion Beam）により断面加工し、走査イオン顕微鏡（ＳＩＭ；Scanning Ion Microscope）で観察した表面の走査イオン像（ＳＩＭ像）から確認することができる。
　このＮｉ系下地層３に対する面積被覆率が６０％以上ということは、面積被覆率が１００％満たない場合に、Ｎｉ系下地層３の表面には局部的にＣｕ３Ｓｎ層６が存在しない部分が生じることになるが、その場合でも、Ｃｕ－Ｓｎ金属間化合物層４のＣｕ６Ｓｎ５層７がＮｉ系下地層３を覆っていることになる。 The Cu 3 Sn layer 6 disposed in the lower layer of the Cu—Sn intermetallic compound layer 4 covers the Ni-based underlayer 3 and has an area coverage of 60 to 100%. If the area coverage is less than 60%, diffusion of Ni atoms in the Ni-based underlayer 3 from the uncoated portion to the Cu 6 Sn 5 layer 7 at a high temperature is promoted, and the Ni-based underlayer 3 There is a risk of loss. More preferably, 80% or more is covered.
This area coverage can be confirmed from a scanning ion image (SIM image) of the surface obtained by processing the cross section of the film with a focused ion beam (FIB) and observing with a scanning ion microscope (SIM). it can.
When the area coverage is 60% or more with respect to the Ni-based underlayer 3, when the area coverage is less than 100%, the portion where the Cu 3 Sn layer 6 does not locally exist on the surface of the Ni-based underlayer 3 Even in this case, the Cu 6 Sn 5 layer 7 of the Cu—Sn intermetallic compound layer 4 covers the Ni-based underlayer 3.
　また、Ｃｕ－Ｓｎ金属間化合物層４の下層を構成しているＣｕ３Ｓｎ層６においては、その平均厚さは０．０１～０．５μｍとされる。このＣｕ３Ｓｎ層６は、Ｎｉ系下地層３を覆っている層であるので、Ｎｉ系下地層３の拡散を抑えるために、この範囲の平均厚さとするとよい。厚くなり過ぎると、高温時にＣｕ３Ｓｎ層６がＳｎリッチのＣｕ６Ｓｎ５層７に変化し、その分、Ｓｎ系表面層５を減少させ、接触抵抗が高くなるおそれがあるので、０．５μｍ程度までの範囲が好ましい。この平均厚さは、Ｃｕ３Ｓｎ層６が存在する部分で、その厚さを複数個所測定したときの平均値である。
　なお、このＣｕ－Ｓｎ金属間化合物層４は、Ｎｉ系下地層３の上にめっきしたＣｕと表面のＳｎとが拡散することにより合金化したものであるから、リフロー処理等の条件によっては下地となったＣｕめっき層の全部が拡散してＣｕ－Ｓｎ金属間化合物層４となる場合もあるが、そのＣｕめっき層が残る場合もある。このＣｕめっき層が残る場合は、そのＣｕめっき層は例えば０．０１～０．１μｍの厚さとされる。
　また、Ｎｉ系下地層３のＮｉがＣｕ－Ｓｎ金属間化合物層４にわずかながら拡散するため、Ｃｕ６Ｓｎ５層７内にはわずかにＮｉが混入している。 The Cu 3 Sn layer 6 constituting the lower layer of the Cu—Sn intermetallic compound layer 4 has an average thickness of 0.01 to 0.5 μm. Since this Cu 3 Sn layer 6 is a layer covering the Ni-based underlayer 3, the average thickness within this range is preferable in order to suppress diffusion of the Ni-based underlayer 3. If the thickness is too thick, the Cu 3 Sn layer 6 changes to a Sn-rich Cu 6 Sn 5 layer 7 at a high temperature, and the Sn-based surface layer 5 is reduced correspondingly, and the contact resistance may be increased. A range up to about 5 μm is preferred. This average thickness is a portion where the Cu 3 Sn layer 6 exists and is an average value when the thickness is measured at a plurality of locations.
The Cu—Sn intermetallic compound layer 4 is an alloy formed by diffusion of Cu plated on the Ni-based underlayer 3 and Sn on the surface, and depending on conditions such as reflow treatment, In some cases, the entire Cu plating layer is diffused to form the Cu—Sn intermetallic compound layer 4, but the Cu plating layer may remain. When this Cu plating layer remains, the Cu plating layer has a thickness of 0.01 to 0.1 μm, for example.
Further, since Ni in the Ni-based underlayer 3 is slightly diffused into the Cu—Sn intermetallic compound layer 4, Ni is slightly mixed in the Cu 6 Sn 5 layer 7.
　Ｓｎ系表面層５は、Ｓｎ又はＳｎ合金を電解めっきした後にリフロー処理することによって形成されたものであり、耐熱性、コネクタ端子としての挿抜性などの性能維持のために、例えば０．０５～１．５μｍの厚さに形成される。
　また、このＳｎ系表面層５の上にさらにＳｎ－Ａｇ被覆層を薄く形成してもよく、耐熱性、コネクタとしての挿抜性をより向上させることができる。図２は、図１と同様の導電部材の最表面にＳｎ－Ａｇ被覆層８を形成した導電部材１１を示している。
　このＳｎ－Ａｇ被覆層８は、例えば０．０５～０．５μｍの薄肉に形成され、Ａｇが０．１～５．０重量％含有される。また、前述のＦｅ系下地層２、Ｎｉ系下地層３、Ｃｕ－Ｓｎ金属間化合物層４、Ｓｎ系表面層５は、Ｆｅ、Ｎｉ、Ｃｕ、Ｓｎの各めっき層を電解めっきによって付着した後にリフロー処理することによって形成されるものであるが、このＳｎ－Ａｇ被覆層８は、リフロー処理した後のＳｎ系表面層５の上に、電解にて成膜される。
　このＳｎ－Ａｇ被覆層８をＳｎ系表面層５の上の最表面に０．０５～０．５μｍの薄肉で形成することにより、さらに耐熱性が向上し、高温での接触抵抗がより小さくなる。また、コネクタ使用時の挿抜性もより向上する。 The Sn-based surface layer 5 is formed by performing reflow treatment after electrolytic plating of Sn or Sn alloy. In order to maintain performance such as heat resistance and insertion / removability as a connector terminal, for example, 0.05 to It is formed to a thickness of 1.5 μm.
Further, an Sn—Ag coating layer may be further formed on the Sn-based surface layer 5 to further improve heat resistance and pluggability as a connector. FIG. 2 shows a conductive member 11 in which a Sn—Ag coating layer 8 is formed on the outermost surface of the same conductive member as in FIG.
The Sn—Ag coating layer 8 is formed to have a thin thickness of 0.05 to 0.5 μm, for example, and contains 0.1 to 5.0% by weight of Ag. The Fe-based underlayer 2, Ni-based underlayer 3, Cu—Sn intermetallic compound layer 4, and Sn-based surface layer 5 are formed after the Fe, Ni, Cu, and Sn plating layers are attached by electrolytic plating. The Sn—Ag coating layer 8 is formed by electrolysis on the Sn-based surface layer 5 after the reflow treatment.
By forming the Sn—Ag coating layer 8 on the outermost surface of the Sn-based surface layer 5 with a thin thickness of 0.05 to 0.5 μm, the heat resistance is further improved and the contact resistance at high temperature is further reduced. . Moreover, the insertion / extraction property when using the connector is further improved.
　次に、このような導電部材を製造する方法について説明する。
　まず、Ｃｕ系基材として、Ｃｕ又はＣｕ合金の板材を用意し、これを脱脂、酸洗等によって表面を清浄にした後、Ｆｅめっき、Ｎｉめっき、Ｃｕめっき、Ｓｎめっきをこの順序で順次行う。また、各めっき処理の間には、酸洗又は水洗処理を行う。
　Ｆｅめっきの条件としては、めっき浴に、硫酸第一鉄（ＦｅＳＯ４）、塩化アンモニウム（ＮＨ4Ｃｌ）を主成分とした硫酸浴が用いられる。Ｆｅ－Ｎｉめっきとする場合は、硫酸ニッケル（ＮｉＳＯ４）、硫酸第一鉄（ＦｅＳＯ４）、ホウ酸（Ｈ３ＢＯ３）を主成分としためっき浴が用いられる。めっき温度は４５～５５℃、電流密度は、５～２５Ａ／ｄｍ２とされる。 Next, a method for manufacturing such a conductive member will be described.
First, as a Cu-based substrate, a Cu or Cu alloy plate material is prepared, and after cleaning the surface by degreasing, pickling, etc., Fe plating, Ni plating, Cu plating, and Sn plating are sequentially performed in this order. . In addition, pickling or rinsing is performed between the plating processes.
As conditions for Fe plating, a sulfuric acid bath mainly composed of ferrous sulfate (FeSO 4 ) and ammonium chloride (NH 4 Cl) is used as a plating bath. When Fe—Ni plating is used, a plating bath mainly composed of nickel sulfate (NiSO 4 ), ferrous sulfate (FeSO 4 ), and boric acid (H 3 BO 3 ) is used. The plating temperature is 45 to 55 ° C., and the current density is 5 to 25 A / dm 2 .
　Ｎｉめっきの条件としては、めっき浴に、硫酸ニッケル（ＮｉＳＯ４）、ホウ酸（Ｈ３ＢＯ３）を主成分としたワット浴、スルファミン酸ニッケル（Ｎｉ(ＮＨ２ＳＯ３)２）とホウ酸（Ｈ３ＢＯ３）を主成分としたスルファミン酸浴等が用いられる。酸化反応を起こし易くする塩類として塩化ニッケル（ＮｉＣｌ２）などが加えられる場合もある。また、めっき温度は４５～５５℃、電流密度は２０～５０Ａ／ｄｍ２とされる。
　Ｃｕめっきの条件としては、めっき浴に硫酸銅（ＣｕＳＯ４）及び硫酸（Ｈ２ＳＯ４）を主成分とした硫酸銅浴が用いられ、レベリングのために塩素イオン（Ｃｌ－）が添加される。めっき温度は３５～５５℃、電流密度は２０～６０Ａ／ｄｍ２とされる。
　Ｓｎめっきの条件としては、めっき浴に硫酸（Ｈ２ＳＯ４）と硫酸第一錫（ＳｎＳＯ４）を主成分とした硫酸浴が用いられ、めっき温度は１５～３５℃、電流密度は１０～３０Ａ／ｄｍ２とされる。 Ni plating conditions include a plating bath, a watt bath mainly composed of nickel sulfate (NiSO 4 ), boric acid (H 3 BO 3 ), nickel sulfamate (Ni (NH 2 SO 3 ) 2 ) and boric acid. A sulfamic acid bath or the like mainly composed of (H 3 BO 3 ) is used. In some cases, nickel chloride (NiCl 2 ) or the like is added as a salt that easily causes an oxidation reaction. The plating temperature is 45 to 55 ° C., and the current density is 20 to 50 A / dm 2 .
As the conditions for Cu plating, a copper sulfate bath mainly composed of copper sulfate (CuSO 4 ) and sulfuric acid (H 2 SO 4 ) is used as a plating bath, and chlorine ions (Cl − ) are added for leveling. . The plating temperature is 35 to 55 ° C., and the current density is 20 to 60 A / dm 2 .
As the conditions for Sn plating, a sulfuric acid bath containing sulfuric acid (H 2 SO 4 ) and stannous sulfate (SnSO 4 ) as main components is used for the plating bath, the plating temperature is 15 to 35 ° C., and the current density is 10 to 30 A / dm 2 .
　いずれのめっき処理も、一般的なめっき技術よりも高い電流密度で行われる。その場合に、めっき液の攪拌技術が重要となるが、めっき液を処理板に向けて高速で噴きつける方法やめっき液を処理板と平行に流す方法などとすることにより、処理板の表面に新鮮なめっき液を速やかに供給し、高電流密度によって均質なめっき層を短時間で形成することができる。そのめっき液の流速としては、処理板の表面において０．５ｍ／秒以上とすることが望ましい。また、この従来技術よりも一桁高い電流密度でのめっき処理を可能とするために、陽極には、アノード限界電流密度の高い酸化イリジウム（ＩｒＯ２）を被覆したＴｉ板等の不溶性陽極を用いることが望ましい。
　これらの各めっき条件をまとめると、以下の表１～表５に示す通りとなる。表１にはＦｅめっきの場合の条件を示し、表２にはＦｅ－Ｎｉめっきの場合の条件を示している。 All the plating processes are performed at a higher current density than a general plating technique. In this case, the plating solution agitation technology is important. However, by using a method of spraying the plating solution at a high speed toward the processing plate or a method of flowing the plating solution in parallel with the processing plate, A fresh plating solution can be supplied quickly, and a uniform plating layer can be formed in a short time with a high current density. The flow rate of the plating solution is desirably 0.5 m / second or more on the surface of the treatment plate. In addition, in order to enable the plating process at a current density that is an order of magnitude higher than that of the prior art, an insoluble anode such as a Ti plate coated with iridium oxide (IrO 2 ) having a high anode limit current density is used as the anode. It is desirable.
These plating conditions are summarized as shown in Tables 1 to 5 below. Table 1 shows the conditions for Fe plating, and Table 2 shows the conditions for Fe—Ni plating.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
　そして、表１又は表２のいずれかの条件のめっき処理と、表３～表５の条件のめっき処理との四種類のめっき処理を施すことにより、Ｃｕ系基材の上にＦｅ系下地層、Ｎｉ系下地層、Ｃｕめっき層、Ｓｎめっき層が順に形成される。この状態で、Ｃｕめっき層の平均厚さは０．３～０．５μｍとされ、Ｓｎめっき層の平均厚さは１．５～２．０μｍとされる。
　これらＣｕめっき層とＳｎめっき層とが後述のリフロー処理によってＣｕ－Ｓｎ金属間化合物層とＳｎ系表面層となるのであり、その場合、Ｓｎ系表面層は前述したようにコネクタ端子としての耐熱性、挿抜性の観点から０．５～１．５μｍの厚さに形成され、このＳｎ系表面層の厚さを確保するためには、下地となるＳｎめっき層としては、１．５～２．０μｍ必要になる。そして、このＳｎめっき層の下で、凹凸の小さいＣｕ－Ｓｎ金属間化合物層を得るには、Ｃｕめっき層としては、０．３～０．５μｍと通常のものより若干大きい厚さとするのが好ましい。
　これは、Ｓｎめっき層は、厚さ方向に成長した柱状結晶からなっており、次のリフロー処理においてＣｕとＳｎとが反応して合金層を形成する際に、ＣｕがＳｎ柱状結晶の粒界に侵入するようにして、その粒界から合金を形成していくと考えられるが、Ｃｕめっき層が厚くＣｕの量が多いと、Ｓｎめっき層の厚さ方向に沿う柱状結晶の粒界に沿って形成されたＣｕ－Ｓｎ合金が粒界から面方向に広がりながら成長するため、その凸部がなだらかになり、凹凸の少ないＣｕ－Ｓｎ金属間化合物層となるものと考えられる。
　この場合、Ｓｎめっき層形成時の電流密度が高いと、柱状結晶の粒界が増えるため、これら粒界に分散して合金が成長して、Ｃｕ－Ｓｎ金属間化合物層の凹凸を小さくする効果がある。 Then, by performing four types of plating treatments, that is, the plating treatment under the conditions in either Table 1 or Table 2 and the plating treatments in the conditions in Tables 3 to 5, an Fe-based underlayer is formed on the Cu-based substrate. A Ni-based underlayer, a Cu plating layer, and a Sn plating layer are formed in this order. In this state, the average thickness of the Cu plating layer is 0.3 to 0.5 μm, and the average thickness of the Sn plating layer is 1.5 to 2.0 μm.
These Cu plating layer and Sn plating layer become a Cu-Sn intermetallic compound layer and an Sn-based surface layer by a reflow process described later. In this case, the Sn-based surface layer has a heat resistance as a connector terminal as described above. From the viewpoint of insertion / extraction, it is formed to a thickness of 0.5 to 1.5 μm, and in order to ensure the thickness of this Sn-based surface layer, the Sn plating layer as a base is 1.5 to 2. 0 μm is required. In order to obtain a Cu—Sn intermetallic compound layer with small irregularities under this Sn plating layer, the Cu plating layer should have a thickness of 0.3 to 0.5 μm, which is slightly larger than a normal one. preferable.
This is because the Sn plating layer is composed of columnar crystals grown in the thickness direction, and when Cu and Sn react in the next reflow process to form an alloy layer, Cu is a grain boundary of Sn columnar crystals. It is considered that an alloy is formed from the grain boundary so as to penetrate into the grain boundary. However, when the Cu plating layer is thick and the amount of Cu is large, along the grain boundary of the columnar crystal along the thickness direction of the Sn plating layer It is considered that the Cu—Sn alloy formed in this way grows while spreading in the plane direction from the grain boundary, so that the convex portion becomes smooth and becomes a Cu—Sn intermetallic compound layer with few irregularities.
In this case, if the current density at the time of forming the Sn plating layer is high, the grain boundaries of the columnar crystals increase, so that the alloy grows by dispersing at these grain boundaries, and the unevenness of the Cu—Sn intermetallic compound layer is reduced. There is.
　次に、加熱してリフロー処理を行う。そのリフロー処理としては、図３に示す温度プロファイルとする条件が望ましい。
　すなわち、リフロー処理はＣＯ還元性雰囲気にした加熱炉内でめっき後の処理材を２０～７５℃／秒の昇温速度で２４０～３００℃のピーク温度まで２．９～１１秒間加熱する加熱工程と、そのピーク温度に達した後、３０℃／秒以下の冷却速度で２～１０秒間冷却する一次冷却工程と、一次冷却後に１００～２５０℃／秒の冷却速度で０．５～５秒間冷却する二次冷却工程とを有する処理とする。一次冷却工程は空冷により、二次冷却工程は１０～９０℃の水を用いた水冷により行われる。
　このリフロー処理を還元性雰囲気で行うことによりＳｎめっき表面に溶融温度の高いすず酸化物皮膜が生成するのを防ぎ、より低い温度かつより短い時間でリフロー処理を行うことが可能となり、所望の金属間化合物構造を作製することが容易となる。また、冷却工程を二段階とし、冷却速度の小さい一次冷却工程を設けることにより、Ｃｕ原子がＳｎ粒内に穏やかに拡散し、所望の金属間化合物構造で成長する。つまり、前述したＳｎ柱状結晶の粒界からのＣｕの拡散を緩やかにして、その凸部をなだらかにする。そして、その後に急冷を行うことにより金属間化合物層の成長を止め、所望の構造で固定化することができ、適切な状態の表面粗さ（Ｒａ、Ｒｖ）のＣｕ－Ｓｎ金属間化合物層を得ることができる。
　ところで、高電流密度で電析したＣｕとＳｎは安定性が低く室温においても合金化や結晶粒肥大化が発生し、リフロー処理で所望の金属間化合物構造を作ることが困難になる。このため、めっき処理後速やかにリフロー処理を行うことが望ましい。具体的には１５分以内、望ましくは５分以内にリフローを行う必要がある。めっき後の放置時間が短いことは問題とならないが、通常の処理ラインでは構成上１分後程度となる。 Next, the reflow process is performed by heating. The reflow process is preferably performed under the temperature profile shown in FIG.
In other words, the reflow process is a heating process in which the treated material after plating is heated to a peak temperature of 240 to 300 ° C. for 2.9 to 11 seconds at a temperature rising rate of 20 to 75 ° C./second in a heating furnace having a CO reducing atmosphere. And a primary cooling step of cooling for 2 to 10 seconds at a cooling rate of 30 ° C./second or less after reaching the peak temperature, and cooling for 0.5 to 5 seconds at a cooling rate of 100 to 250 ° C./second after the primary cooling. And a secondary cooling step. The primary cooling step is performed by air cooling, and the secondary cooling step is performed by water cooling using 10 to 90 ° C. water.
By performing this reflow treatment in a reducing atmosphere, it is possible to prevent the formation of a tin oxide film having a high melting temperature on the Sn plating surface, and it is possible to perform the reflow treatment at a lower temperature and in a shorter time. It becomes easy to produce an intermetallic compound structure. Further, by providing a cooling process in two stages and providing a primary cooling process with a low cooling rate, Cu atoms diffuse gently in the Sn grains and grow with a desired intermetallic compound structure. In other words, the diffusion of Cu from the grain boundaries of the Sn columnar crystals described above is moderated, and the convex portions are smoothed. Then, by rapidly cooling, the growth of the intermetallic compound layer can be stopped and fixed with a desired structure, and a Cu—Sn intermetallic compound layer with an appropriate surface roughness (Ra, Rv) can be formed. Obtainable.
By the way, Cu and Sn electrodeposited at a high current density are low in stability, and alloying and crystal grain enlargement occur at room temperature, making it difficult to produce a desired intermetallic compound structure by reflow treatment. For this reason, it is desirable to perform the reflow process immediately after the plating process. Specifically, it is necessary to perform reflow within 15 minutes, preferably within 5 minutes. A short standing time after plating does not cause a problem, but in a normal processing line, it is about one minute after construction.
　以上のように、Ｃｕ系基材１の表面に表１又は表２と、表３～表５との組み合わせのめっき条件により四層のめっきを施した後、図３に示す温度プロファイル条件でリフロー処理することにより、図１に示すように、Ｃｕ系基材１の表面がＦｅ系下地層２によって覆われ、その上にＮｉ系下地層３を介してＣｕ３Ｓｎ層６、その上にさらにＣｕ６Ｓｎ５層７がそれぞれ形成され、このＣｕ－Ｓｎ金属間化合物層４の上にＳｎ系表面層５が形成される。
　また、最表面にＳｎ－Ａｇ被覆層を形成する場合は、以上のようにしてリフロー処理された導電部材を酸洗処理及び電解研磨することにより、Ｓｎ系表面層の酸化膜を除去し、Ｓｎ系表面層の表面を平滑にした後、その上に、Ａｇが０．１～５．０重量％含有したＳｎ－Ａｇ被覆層を成膜する。Ｓｎ系表面層は酸化し易いので、酸化膜を除去し、その際に表面を平滑にすることにより、Ｓｎ－Ａｇ被覆層の表面の凹凸を少なくするのである。平滑の程度としては、算術平均粗さＲａで０．００５～０．３μｍ程度がよい。そして、その平滑面の上に、電解にてＳｎ－Ａｇ被覆層を０．０５～０．５μｍの厚さで形成する。 As described above, after four-layer plating is performed on the surface of the Cu-based substrate 1 according to the plating conditions in combination of Table 1 or Table 2 and Tables 3 to 5, reflow is performed under the temperature profile conditions shown in FIG. by processing as shown in FIG. 1, the surface of the Cu Keimotozai 1 is covered by the Fe-based base layer 2, Cu 3 Sn layer 6 through the Ni-based base layer 3 thereon, further thereon A Cu 6 Sn 5 layer 7 is formed, and an Sn-based surface layer 5 is formed on the Cu—Sn intermetallic compound layer 4.
Further, when the Sn—Ag coating layer is formed on the outermost surface, the conductive member subjected to the reflow treatment as described above is pickled and electropolished to remove the oxide film of the Sn-based surface layer, and Sn After the surface of the system surface layer is smoothed, a Sn—Ag coating layer containing 0.1 to 5.0% by weight of Ag is formed thereon. Since the Sn-based surface layer is easily oxidized, the surface roughness of the Sn—Ag coating layer is reduced by removing the oxide film and smoothing the surface at that time. The degree of smoothness is preferably about 0.005 to 0.3 μm in terms of arithmetic average roughness Ra. Then, an Sn—Ag coating layer is formed on the smooth surface by electrolysis with a thickness of 0.05 to 0.5 μm.
（第２実施形態）
　次に第２実施形態について説明する。
　図４は、第２実施形態の製造方法を実施するための製造装置の例を模式化して示している。この導電部材製造装置３１は、脱脂・洗浄槽３２、Ｎｉめっき槽３３、Ｃｕめっき槽３４、Ｓｎめっき槽３５、各めっき槽３３～３５の後に配置される洗浄槽３６～３８が連続して配置され、銅条材５１を脱脂・洗浄槽３２、Ｎｉめっき槽３３、Ｃｕめっき槽３４、Ｓｎめっき槽３５の順に連続的に搬送しながらめっきするようになっている。脱脂・洗浄槽３２は、さらに脱脂槽３２ａ、洗浄槽３２ｂ、酸洗槽３２ｃ、洗浄槽３２ｄによって構成されている。
　また、各めっき槽３３～３５には、図５に示すように、連続的に走行する銅条材（Ｃｕ系基材）５１の両面と対向するように一対の電極板３９が配置されており、各電極板３９と銅条材５１との間に形成されるめっき液の流れ場におけるレイノルズ数が１×１０４～５×１０５となるように、銅条材５１とめっき液とを相対移動する。めっき液は循環タンク（図４にはＳｎめっき槽３５の循環タンクのみ示している）４０との間で循環させられるようになっている。 (Second Embodiment)
Next, a second embodiment will be described.
FIG. 4 schematically shows an example of a manufacturing apparatus for carrying out the manufacturing method of the second embodiment. The conductive member manufacturing apparatus 31 includes a degreasing / cleaning tank 32, a Ni plating tank 33, a Cu plating tank 34, a Sn plating tank 35, and cleaning tanks 36 to 38 disposed after the plating tanks 33 to 35. The copper strip 51 is plated while being continuously conveyed in the order of the degreasing / cleaning tank 32, the Ni plating tank 33, the Cu plating tank 34, and the Sn plating tank 35. The degreasing / cleaning tank 32 further includes a degreasing tank 32a, a cleaning tank 32b, a pickling tank 32c, and a cleaning tank 32d.
Further, as shown in FIG. 5, a pair of electrode plates 39 are disposed in each of the plating tanks 33 to 35 so as to face both surfaces of a continuously running copper strip material (Cu-based substrate) 51. The copper strip 51 and the plating solution are relative to each other so that the Reynolds number in the flow field of the plating solution formed between each electrode plate 39 and the copper strip 51 is 1 × 10 4 to 5 × 10 5. Moving. The plating solution is circulated between a circulation tank 40 (only the circulation tank of the Sn plating tank 35 is shown in FIG. 4).
　また、Ｓｎめっき液で使用される光沢剤は泡が発生し易く、このため、Ｓｎめっき槽３５には泡除去手段４１が併設されている。また、スラッジ除去手段４２も併設されており、このスラッジ除去手段４２は、循環タンク４０にスラッジ沈降槽を接続し、循環タンク４０から定量ずつスラッジ沈降槽にめっき液を抜き取り、沈降剤を添加しつつスラッジを沈降させ、その上済み液を再び循環タンク４０に戻すようにしている。沈降したスラッジは、遠心分離機にかけられ、精錬会社に送られてＳｎとして再利用される。
　また、Ｓｎめっき槽３５の下流位置には、洗浄槽３８を経由した銅条材５１を乾燥する乾燥機４３が設けられる。また、その乾燥機４３の下流位置には、リフロー炉４４が設けられ、このリフロー炉４４に、後述する一次冷却のための空冷ゾーン４５、二次冷却のための水冷ゾーン４６が備えられる。符号４７は、水冷ゾーン４６を経由した銅条材５１を乾燥する乾燥機である。 Further, the brightener used in the Sn plating solution is liable to generate bubbles. For this reason, the Sn plating tank 35 is provided with a bubble removing means 41. Sludge removal means 42 is also provided. This sludge removal means 42 connects a sludge settling tank to the circulation tank 40, extracts the plating solution from the circulation tank 40 to the sludge settling tank in a fixed amount, and adds a settling agent. The sludge is allowed to settle while returning the upper liquid to the circulation tank 40 again. The settled sludge is subjected to a centrifuge, sent to a refining company, and reused as Sn.
In addition, a dryer 43 that dries the copper strip material 51 that has passed through the cleaning tank 38 is provided at a downstream position of the Sn plating tank 35. A reflow furnace 44 is provided at a downstream position of the dryer 43. The reflow furnace 44 is provided with an air cooling zone 45 for primary cooling and a water cooling zone 46 for secondary cooling, which will be described later. Reference numeral 47 denotes a dryer that dries the copper strip material 51 that has passed through the water cooling zone 46.
　次に、このような製造装置３１によって導電部材を製造する方法について説明する。
　まず、銅条材５１を脱脂、酸洗等によって表面を清浄にした後、Ｎｉめっき、Ｃｕめっき、Ｓｎめっきをこの順序で順次行う。また、各めっき処理の間には、酸洗又は水洗処理を行う。
　Ｎｉめっきの条件としては、めっき浴に、硫酸ニッケル（ＮｉＳＯ４）、ホウ酸（Ｈ３ＢＯ３）を主成分としたワット浴、スルファミン酸ニッケル（Ｎｉ(ＮＨ２ＳＯ３)２）とホウ酸（Ｈ３ＢＯ３）を主成分としたスルファミン酸浴等が用いられる。酸化反応を起こし易くする塩類として塩化ニッケル（ＮｉＣｌ２）などが加えられる場合もある。また、めっき温度は４５～５５℃、電流密度は２０～５０Ａ／ｄｍ２、レイノルズ数１×１０４～５×１０５とされる。
　Ｃｕめっきの条件としては、めっき浴に硫酸銅（ＣｕＳＯ４）及び硫酸（Ｈ２ＳＯ４）を主成分とした硫酸銅浴が用いられ、レベリングのために塩素イオン（Ｃｌ－）が添加される。めっき温度は３５～５５℃、電流密度は２０～６０Ａ／ｄｍ２、レイノルズ数１×１０４～５×１０５とされる。
　Ｓｎめっきの条件としては、めっき浴に硫酸（Ｈ２ＳＯ４）と硫酸第一錫（ＳｎＳＯ４）を主成分とした硫酸浴が用いられ、めっき温度は１５～３５℃、電流密度は１０～３０Ａ／ｄｍ２、レイノルズ数１×１０４～５×１０５とされる。また、硫酸浴には、スラッジ除去装置及び泡除去装置が備えられる。 Next, a method for manufacturing a conductive member using such a manufacturing apparatus 31 will be described.
First, after the surface of the copper strip 51 is cleaned by degreasing, pickling, etc., Ni plating, Cu plating, and Sn plating are sequentially performed in this order. In addition, pickling or rinsing is performed between the plating processes.
Ni plating conditions include a plating bath, a watt bath mainly composed of nickel sulfate (NiSO 4 ), boric acid (H 3 BO 3 ), nickel sulfamate (Ni (NH 2 SO 3 ) 2 ) and boric acid. A sulfamic acid bath or the like mainly composed of (H 3 BO 3 ) is used. In some cases, nickel chloride (NiCl 2 ) or the like is added as a salt that easily causes an oxidation reaction. The plating temperature is 45 to 55 ° C., the current density is 20 to 50 A / dm 2 , and the Reynolds number is 1 × 10 4 to 5 × 10 5 .
As the conditions for Cu plating, a copper sulfate bath mainly composed of copper sulfate (CuSO 4 ) and sulfuric acid (H 2 SO 4 ) is used as a plating bath, and chlorine ions (Cl − ) are added for leveling. . The plating temperature is 35 to 55 ° C., the current density is 20 to 60 A / dm 2 , and the Reynolds number is 1 × 10 4 to 5 × 10 5 .
As the conditions for Sn plating, a sulfuric acid bath containing sulfuric acid (H 2 SO 4 ) and stannous sulfate (SnSO 4 ) as main components is used for the plating bath, the plating temperature is 15 to 35 ° C., and the current density is 10 to 30 A / dm 2 and Reynolds number of 1 × 10 4 to 5 × 10 5 . The sulfuric acid bath is provided with a sludge removing device and a foam removing device.
　このレイノルズ数Ｒｅは、めっき液と銅条材との相対速度Ｕ（ｍ／ｓ）とめっき槽内のめっき液の流れ場の相当直径Ｄｅ（ｍ）と、めっき液の動粘性係数ν（ｍ２／ｓ）との関係から、Ｒｅ＝ＵＤｅ／νによって求められる。めっき液の流れ場の相当直径Ｄｅは、図５に示す電極板３９の幅ａ、電極板３９と銅条材５１との間の間隔ｂとの関係から、Ｄｅ＝２ａｂ／（ａ＋ｂ）により求められる。
　このレイノルズ数Ｒｅは、図６に示すように、大きい値に設定することにより電流効率は向上する。しかし、レイノルズ数が５×１０５を超えると、理論電流効率値に限りなく近くなるが、Ｓｎめっきの場合は、めっき液中のスラッジが増大するため、好ましくない。一方、１×１０４未満では攪拌効果が弱く、めっき焼けが発生し易くなる。
　このため、いずれのめっき処理も、めっき液の流れ場をレイノルズ数１×１０４～５×１０５にて乱流として、発生した水素ガスを連続的かつ効率的に排除し、処理板の表面に新鮮な金属イオンを速やかに供給し、高電流密度によって均質なめっき層を短時間で形成することができる。
　これらの各めっき条件をまとめると、以下の表６～表８に示す通りとなる The Reynolds number Re includes the relative velocity U (m / s) between the plating solution and the copper strip, the equivalent diameter De (m) of the flow field of the plating solution in the plating tank, and the kinematic viscosity coefficient ν (m 2 / s), Re = UDe / ν. The equivalent diameter De of the flow field of the plating solution is obtained by De = 2ab / (a + b) from the relationship between the width a of the electrode plate 39 and the distance b between the electrode plate 39 and the copper strip 51 shown in FIG. It is done.
As shown in FIG. 6, the current efficiency is improved by setting the Reynolds number Re to a large value. However, when the Reynolds number exceeds 5 × 10 5 , the theoretical current efficiency value is as close as possible. However, in the case of Sn plating, since sludge in the plating solution increases, it is not preferable. On the other hand, if it is less than 1 × 10 4 , the stirring effect is weak and plating burn is likely to occur.
For this reason, in any plating process, the flow field of the plating solution is turbulent with a Reynolds number of 1 × 10 4 to 5 × 10 5 , and the generated hydrogen gas is continuously and efficiently removed, and the surface of the processing plate Thus, a fresh metal ion can be rapidly supplied, and a uniform plating layer can be formed in a short time with a high current density.
These plating conditions are summarized as shown in Table 6 to Table 8 below.
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000008
　そして、このめっき処理により、銅条材の上にＮｉめっき層、Ｃｕめっき層、Ｓｎめっき層が順に形成される。この状態で、Ｃｕめっき層の平均厚さは０．３～０．５μｍとされ、Ｎｉめっき層の平均厚さは０．１～２．０μｍ、Ｓｎめっき層の平均厚さは１．５～２．０μｍとされる。
　これらＣｕめっき層とＳｎめっき層とが、後述のリフロー処理によってＣｕ－Ｓｎ金属間化合物層とＳｎ系表面層となり、その場合、Ｓｎ系表面層は前述したようにコネクタ端子としての耐熱性、挿抜性の観点から０．５～１．５μｍの厚さに形成され、このＳｎ系表面層の厚さを確保するためには、下地となるＳｎめっき層としては、１．５～２．０μｍ必要になる。そして、このＳｎめっき層の下で、凹凸の小さいＣｕ－Ｓｎ金属間化合物層を得るには、Ｃｕめっき層としては、第１実施形態の場合と同様、０．３～０．５μｍと通常のものより若干大きい厚さとするのが好ましい。 And by this plating process, Ni plating layer, Cu plating layer, and Sn plating layer are formed in order on a copper strip. In this state, the Cu plating layer has an average thickness of 0.3 to 0.5 μm, the Ni plating layer has an average thickness of 0.1 to 2.0 μm, and the Sn plating layer has an average thickness of 1.5 to 0.5 μm. 2.0 μm.
These Cu plating layer and Sn plating layer are converted into a Cu-Sn intermetallic compound layer and a Sn-based surface layer by a reflow process described later. In this case, the Sn-based surface layer has heat resistance and insertion / removal as a connector terminal as described above. From the viewpoint of safety, it is formed to a thickness of 0.5 to 1.5 μm, and in order to ensure the thickness of this Sn-based surface layer, the Sn plating layer as a base is required to be 1.5 to 2.0 μm become. Then, in order to obtain a Cu—Sn intermetallic compound layer with small irregularities under this Sn plating layer, the Cu plating layer is usually 0.3 to 0.5 μm as in the case of the first embodiment. The thickness is preferably slightly larger than the above.
　次に、加熱してリフロー処理を行う。
　このリフロー処理はＣＯ還元性雰囲気にした加熱炉内でめっき後の処理材を２０～７５℃／秒の昇温速度で２４０～３００℃のピーク温度まで加熱する加熱工程と、そのピーク温度に達した後、３０℃／秒以下の冷却速度で２～１０秒間冷却する一次冷却工程と、一次冷却後に１００～２５０℃／秒の冷却速度で０．５～５秒間冷却する二次冷却工程とを有する処理とする。一次冷却工程は空冷により、二次冷却工程は１０～９０℃の水を用いた水冷により行われる。
　また、第１実施形態でも説明したように、めっき処理後速やかにリフロー処理を行うことが望ましい。具体的には１５分以内、より好ましくは５分以内にリフロー処理を行うとよい。めっき後の放置時間が短いことは問題とならないが、通常の処理ラインでは構成上１分後程度となる。 Next, the reflow process is performed by heating.
This reflow treatment is a heating process in which a treated material after plating is heated to a peak temperature of 240 to 300 ° C. at a temperature rising rate of 20 to 75 ° C./second in a heating furnace having a CO reducing atmosphere, and the peak temperature is reached. Then, a primary cooling step of cooling for 2 to 10 seconds at a cooling rate of 30 ° C./second or less, and a secondary cooling step of cooling for 0.5 to 5 seconds at a cooling rate of 100 to 250 ° C./second after the primary cooling. Process. The primary cooling step is performed by air cooling, and the secondary cooling step is performed by water cooling using 10 to 90 ° C. water.
Further, as described in the first embodiment, it is desirable to perform the reflow process immediately after the plating process. Specifically, the reflow process may be performed within 15 minutes, more preferably within 5 minutes. A short standing time after plating does not cause a problem, but in a normal processing line, it is about one minute after construction.
　以上のような方法により、従前の多段式連続めっき装置より効率的に短時間にて、銅条材の上に形成したＮｉ系下地層と、表面を形成するＳｎ系表面層との間に、Ｃｕ－Ｓｎ金属間化合物層を有する３層めっきの導電部材が完成される。
　この導電部材５０は、図７に示すように、銅条材５１の表面に、Ｎｉ系下地層３、Ｃｕ－Ｓｎ金属間化合物層４、Ｓｎ系表面層５がこの順に形成されるとともに、Ｃｕ－Ｓｎ金属間化合物層４はさらに、Ｃｕ３Ｓｎ層６とＣｕ６Ｓｎ５層７とから構成されている。
　Ｎｉ系下地層３は、例えば０．０５μｍ以上の厚さに形成されるものであり、高温時にＣｕの拡散を防止するバリア層として機能する。 By the method as described above, between the Ni-based underlayer formed on the copper strip material and the Sn-based surface layer forming the surface in a short time more efficiently than the conventional multistage continuous plating apparatus, A three-layer plating conductive member having a Cu—Sn intermetallic compound layer is completed.
As shown in FIG. 7, the conductive member 50 includes a Ni-based underlayer 3, a Cu—Sn intermetallic compound layer 4, and a Sn-based surface layer 5 formed in this order on the surface of a copper strip 51, and Cu The —Sn intermetallic compound layer 4 is further composed of a Cu 3 Sn layer 6 and a Cu 6 Sn 5 layer 7.
The Ni-based underlayer 3 is formed to a thickness of 0.05 μm or more, for example, and functions as a barrier layer that prevents Cu diffusion at high temperatures.
　Ｃｕ－Ｓｎ金属間化合物層４は、全体としては、０．０５～１．８μｍの厚さ、好ましくは０．１μｍ以上の厚さに形成され、さらに、Ｎｉ系下地層３の上に配置されるＣｕ３Ｓｎ層６と、該Ｃｕ３Ｓｎ層６の上に配置されるＣｕ６Ｓｎ５層７とから構成されている。この場合、Ｃｕ－Ｓｎ金属間化合物層４全体としては凹凸が形成されており、Ｓｎ系表面層５に接する面の表面粗さが、算術平均粗さＲａで０．０５～０．２５μｍであり、かつ、粗さ曲線の最大谷深さＲｖで０．０５～１．００μｍとされている。 The Cu—Sn intermetallic compound layer 4 as a whole is formed to a thickness of 0.05 to 1.8 μm, preferably 0.1 μm or more, and is further disposed on the Ni-based underlayer 3. Cu 3 Sn layer 6 and a Cu 6 Sn 5 layer 7 disposed on the Cu 3 Sn layer 6. In this case, the Cu—Sn intermetallic compound layer 4 as a whole is uneven, and the surface roughness of the surface in contact with the Sn-based surface layer 5 is an arithmetic average roughness Ra of 0.05 to 0.25 μm. The maximum valley depth Rv of the roughness curve is 0.05 to 1.00 μm.
　また、このＣｕ－Ｓｎ金属間化合物層４のうちの下層に配置されるＣｕ３Ｓｎ層６は、Ｎｉ系下地層３を覆って、その拡散を抑える機能があり、Ｎｉ系下地層３に対する面積被覆率が６０～１００％とされ、その平均厚さは０．０１～０．５μｍとされる。 Further, the Cu 3 Sn layer 6 disposed in the lower layer of the Cu—Sn intermetallic compound layer 4 covers the Ni-based underlayer 3 and has a function of suppressing its diffusion, and has an area relative to the Ni-based underlayer 3. The coverage is 60 to 100%, and the average thickness is 0.01 to 0.5 μm.
　なお、このＣｕ－Ｓｎ金属間化合物層４は、Ｎｉ系下地層３の上にめっきしたＣｕと表面のＳｎとが拡散することにより合金化したものであるから、リフロー処理等の条件によっては下地となったＣｕめっき層の全部が拡散してＣｕ－Ｓｎ金属間化合物層４となる場合もあるが、そのＣｕめっき層が残る場合もある。
　また、Ｎｉ系下地層３のＮｉがＣｕ－Ｓｎ金属間化合物層４にわずかながら拡散するため、Ｃｕ６Ｓｎ５層７内にはわずかにＮｉが混入している。 The Cu—Sn intermetallic compound layer 4 is an alloy formed by diffusion of Cu plated on the Ni-based underlayer 3 and Sn on the surface, and depending on conditions such as reflow treatment, In some cases, the entire Cu plating layer is diffused to form the Cu—Sn intermetallic compound layer 4, but the Cu plating layer may remain.
Further, since Ni in the Ni-based underlayer 3 is slightly diffused into the Cu—Sn intermetallic compound layer 4, Ni is slightly mixed in the Cu 6 Sn 5 layer 7.
　最表面のＳｎ系表面層５は、表面の接触抵抗、はんだ付け性、耐食性、コネクタとしての使用時の挿抜力の適切化のため、例えば０．５～１．５μｍの厚さに形成される。
　なお、この第２実施形態ではＣｕ系基材（銅条材）１の表面にＮｉ系下地層３を形成したが、第１実施形態と同様に、Ｆｅ系下地層を介してＮｉ系下地層を形成してもよい。その場合も、このＦｅめっきの条件として、電流密度が表１又は表２に示す５～２５Ａ／ｄｍ２で、電極板と銅条材との間に形成されるめっき液の流れ場におけるレイノルズ数が１×１０４～５×１０５の電解めっきとされる。 The outermost Sn-based surface layer 5 is formed to have a thickness of, for example, 0.5 to 1.5 μm in order to optimize surface contact resistance, solderability, corrosion resistance, and insertion / extraction force when used as a connector. .
In the second embodiment, the Ni-based underlayer 3 is formed on the surface of the Cu-based substrate (copper strip) 1. However, as in the first embodiment, the Ni-based underlayer is interposed via the Fe-based underlayer. May be formed. In this case as well, the Fe density is 5 to 25 A / dm 2 as shown in Table 1 or Table 2, and the Reynolds number in the flow field of the plating solution formed between the electrode plate and the copper strip is used. Is 1 × 10 4 to 5 × 10 5 electrolytic plating.
　次に本発明の実施例を説明する。
（第１実施例）
　Ｃｕ合金板（Ｃｕ系基材）として、厚さ０．２５ｍｍの三菱伸銅株式会社製ＭＡＸ２５１Ｃ材を用い、これにＦｅ、Ｎｉ、Ｃｕ、Ｓｎの各めっき処理を順次行った。この場合、表９に示すように、各めっき処理の電流密度を変えて複数の試料を作成した。実施例については表１、表３～表５の各めっき条件の中から選定した。実施例におけるＦｅめっき層及びＮｉめっき層の目標厚さについては、Ｆｅめっき層を０．５μｍ、Ｎｉめっき層を０．３μｍとした。また、これら四種類の各めっき工程間には、処理材表面からめっき液を洗い流すための水洗工程を入れた。
　本実施例におけるめっき処理では、Ｃｕ合金板にめっき液を高速で噴きつけ、なおかつ酸化イリジウムを被覆したＴｉ板の不溶性陽極を用いた。
　上記の四種類のめっき処理を行った後、その処理材に対してリフロー処理を行った。このリフロー処理は、最後のＳｎめっき処理をしてから１分後に行い、加熱工程、一次冷却工程、二次冷却工程について種々の条件で行った。
　以上の試験条件を表９にまとめた。 Next, examples of the present invention will be described.
(First embodiment)
As a Cu alloy plate (Cu-based substrate), a MAX251C material manufactured by Mitsubishi Shindoh Co., Ltd. having a thickness of 0.25 mm was used, and each of the plating treatments of Fe, Ni, Cu, and Sn was sequentially performed. In this case, as shown in Table 9, a plurality of samples were prepared by changing the current density of each plating treatment. Examples were selected from the plating conditions shown in Tables 1 and 3 to 5. Regarding the target thicknesses of the Fe plating layer and the Ni plating layer in the examples, the Fe plating layer was 0.5 μm and the Ni plating layer was 0.3 μm. Further, a water washing step for washing the plating solution from the surface of the treatment material was inserted between these four types of plating steps.
In the plating treatment in this example, an insoluble anode of a Ti plate coated with iridium oxide was sprayed on the Cu alloy plate at a high speed.
After performing the above four types of plating treatments, a reflow treatment was performed on the treated material. This reflow process was performed 1 minute after the last Sn plating process, and the heating process, the primary cooling process, and the secondary cooling process were performed under various conditions.
The above test conditions are summarized in Table 9.
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000009
　本実施例の処理材断面は、透過電子顕微鏡を用いたエネルギー分散型Ｘ線分光分析（ＴＥＭ－ＥＤＳ分析）の結果、Ｃｕ系基材、Ｆｅ系下地層、Ｎｉ系下地層、Ｃｕ３Ｓｎ層、Ｃｕ６Ｓｎ５層、Ｓｎ系表面層の５層構造となっており、なおかつＣｕ－Ｓｎ金属間化合物層の最小厚さが０．０５μm以上であった。またＣｕ６Ｓｎ５層とＮｉ系下地層の界面には不連続なＣｕ３Ｓｎ層があり、集束イオンビームによる断面の走査イオン顕微鏡（ＦＩＢ－ＳＩＭ像）から観察されるＣｕ３Ｓｎ層のＮｉ系下地層に対する表面被覆率は６０％以上であった。 The cross section of the treated material in this example is the result of energy dispersive X-ray spectroscopic analysis (TEM-EDS analysis) using a transmission electron microscope. As a result, a Cu-based substrate, an Fe-based underlayer, a Ni-based underlayer, and a Cu 3 Sn layer. , Cu 6 Sn 5 layers, and Sn-based surface layer, and the minimum thickness of the Cu—Sn intermetallic compound layer was 0.05 μm or more. The Cu 6 at the interface Sn 5 layer and the Ni-based base layer has discontinuous Cu 3 Sn layer, Ni of Cu 3 Sn layer observed from a scanning ion microscope of a cross section by focused ion beam (FIB-SIM image) The surface coverage with respect to the system underlayer was 60% or more.
　また、Ｓｎ系表面層を除去して、その下のＣｕ－Ｓｎ金属間化合物層の表面粗さを測定した。
　このＳｎ系表面層を除去する場合、例えばレイボルド株式会社製のＬ８０等の純ＳｎをエッチングしＣｕ－Ｓｎ合金を腐食しない成分からなるめっき被膜剥離用のエッチング液に５分間浸漬することによりＳｎ系表面層が除去され、その下層のＣｕ－Ｓｎ金属間化合物層が露出される。
　表面粗さは、露出させたＣｕ－Ｓｎ金属間化合物層の表面に、オリンパス株式会社製の走査型共焦点赤外レーザ顕微鏡ＬＥＸＴ　ＯＬＳ－３０００－ＩＲを用い、対物レンズ１００倍の条件でレーザ光を照射して、その反射光から距離を測定し、そのレーザ光をＣｕ－Ｓｎ金属間化合物層の表面に沿って直線的にスキャンしながら距離を連続的に測定することにより求めた。
　以上の測定結果を表１０にまとめた。 Further, the Sn-based surface layer was removed, and the surface roughness of the underlying Cu—Sn intermetallic compound layer was measured.
When removing this Sn-based surface layer, for example, pure Sn such as L80 manufactured by Reybold Co., Ltd. is etched and immersed in an etching solution for removing the plating film made of a component that does not corrode the Cu—Sn alloy for 5 minutes. The surface layer is removed, and the underlying Cu—Sn intermetallic compound layer is exposed.
The surface roughness was determined by using a scanning confocal infrared laser microscope LEXT OLS-3000-IR manufactured by Olympus Co., Ltd. on the surface of the exposed Cu—Sn intermetallic compound layer, and laser light under conditions of an objective lens of 100 times. The distance was measured from the reflected light, and the distance was continuously measured while linearly scanning the laser light along the surface of the Cu—Sn intermetallic compound layer.
The above measurement results are summarized in Table 10.
Figure JPOXMLDOC01-appb-T000010
Figure JPOXMLDOC01-appb-T000010
　次に、表９及び表１０に示される試料について、１７５℃×１０００時間経過後の接触抵抗、剥離の有無、耐摩耗性を測定した。また、動摩擦係数及び１７５℃×１０００時間経過後の抵抗値変化率についても測定した。
　接触抵抗は、試料を１７５℃×１０００時間放置した後、山崎精機株式会社製電気接点シミュレーターを用い荷重０．４９Ｎ（５０ｇｆ）摺動有りの条件で測定した。
　剥離試験は、９．８ｋＮの荷重にて９０°曲げ（曲率半径Ｒ：０．７ｍｍ）を行った後、大気中で１６０℃×２５０時間保持し、曲げ戻して、曲げ部の剥離状況の確認を行った。
　耐摩耗性は、ＪＩＳ　Ｈ　８５０３に規定される往復運動摩耗試験によって、試験荷重が９．８Ｎ、研磨紙Ｎｏ．４００とし、素地（Ｃｕ系基材）が露出するまでの回数を測定し、５０回試験を行ってもめっきが残存していた試料を○、５０回以内に素地が露出した試料を×とした。
　動摩擦係数については、嵌合型のコネクタのオス端子とメス端子の接点部を模擬するように、各試料によって板状のオス試験片と内径１．５ｍｍの半球状としたメス試験片とを作成し、アイコーエンジニアリング株式会社製の横型荷重測定器（Ｍｏｄｅｌ－２１５２ＮＲＥ）を用い、両試験片間の摩擦力を測定して動摩擦係数を求めた。図８により説明すると、水平な台２１上にオス試験片２２を固定し、その上にメス試験片２３の半球凸面を置いてめっき面どうしを接触させ、メス試験片２３に錘２４によって４．９Ｎ（５００ｇｆ）の荷重Ｐをかけてオス試験片２２を押さえた状態とする。この荷重Ｐをかけた状態で、オス試験片２２を摺動速度８０ｍｍ／分で矢印で示す水平方向に１０ｍｍ引っ張ったときの摩擦力Ｆをロードセル２５によって測定した。その摩擦力Ｆの平均値Ｆａｖと荷重Ｐより動摩擦係数（＝Ｆａｖ／Ｐ）を求めた。
　抵抗値変化率は、各試料を１０ｍｍ（Ｌ）×１ｍ（Ｗ)の大きさに形成し、その電気抵抗値（Ｒ）を測定し、１７５℃×１０００時間加熱後の抵抗値の変化率ΔＲ／Ｒ（％）を測定した。
　これらの結果を表１１に示す。 Next, for the samples shown in Table 9 and Table 10, the contact resistance after 175 ° C. × 1000 hours, the presence or absence of peeling, and the wear resistance were measured. Further, the coefficient of dynamic friction and the rate of change in resistance value after 175 ° C. × 1000 hours were also measured.
The contact resistance was measured under the condition of sliding with a load of 0.49 N (50 gf) using an electrical contact simulator manufactured by Yamazaki Seiki Co., Ltd. after the sample was left at 175 ° C. for 1000 hours.
In the peel test, 90 ° bending (curvature radius R: 0.7 mm) was performed with a load of 9.8 kN, then held in the atmosphere at 160 ° C. for 250 hours, bent back, and the peeled state of the bent portion was confirmed. Went.
The abrasion resistance was determined by a reciprocating wear test specified in JIS H 8503, with a test load of 9.8 N and abrasive paper no. 400, the number of times until the substrate (Cu-based substrate) was exposed was measured, a sample in which plating remained even after 50 times of testing, and a sample in which the substrate was exposed within 50 times were evaluated as x. .
As for the dynamic friction coefficient, a plate-shaped male test piece and a hemispherical female test piece having an inner diameter of 1.5 mm are prepared for each sample so as to simulate the contact portion of the male terminal and female terminal of the fitting type connector. Then, using a horizontal load measuring device (Model-2152NRE) manufactured by Aiko Engineering Co., Ltd., the frictional force between the two test pieces was measured to obtain the dynamic friction coefficient. Referring to FIG. 8, the male test piece 22 is fixed on the horizontal base 21, the hemispherical convex surface of the female test piece 23 is placed on the male test piece 23, and the plated surfaces are brought into contact with each other. The load P of 9N (500 gf) is applied and the male test piece 22 is pressed. With the load P applied, the frictional force F when the male test piece 22 was pulled 10 mm in the horizontal direction indicated by the arrow at a sliding speed of 80 mm / min was measured by the load cell 25. A dynamic friction coefficient (= Fav / P) was obtained from the average value Fav of the friction force F and the load P.
The resistance value change rate is such that each sample is formed to a size of 10 mm (L) × 1 m (W), its electric resistance value (R) is measured, and the change rate ΔR of the resistance value after heating at 175 ° C. × 1000 hours. / R (%) was measured.
These results are shown in Table 11.
Figure JPOXMLDOC01-appb-T000011
Figure JPOXMLDOC01-appb-T000011
　この表１１から明らかなように、本実施例の導電部材においては、高温時の接触抵抗が小さく、剥離やカーケンダルボイドの発生がなく、動摩擦係数も小さいことから、コネクタ使用時の挿抜力も小さく良好であると判断できる。また、本実施例の場合は抵抗値の変化率（ΔＲ／Ｒ）も小さく安定しており、ヒューズとして用いた場合にも溶断特性にも優れると判断できる。 As is apparent from Table 11, the conductive member of this example has a low contact resistance at high temperatures, no occurrence of peeling or Kirkendall voids, and a small coefficient of dynamic friction. Therefore, the insertion / extraction force when using the connector is also small. It can be judged that it is good. In the case of this example, the rate of change in resistance value (ΔR / R) is also small and stable, and it can be determined that it is excellent in fusing characteristics when used as a fuse.
　また、接触抵抗に関しては、試料５と試料１８について、１７５℃×１０００時間の加熱中の経時変化も測定した。その結果を図９に示す。
　この図９に示すように、本発明の試料５では高温時に長時間さらされても接触抵抗の上昇はわずかであるのに対して、従来技術の試料１８の場合は、１０００時間経過で接触抵抗が１０ｍΩ以上にまで上昇した。本発明の試料５では、Ｆｅ系下地層の耐熱性により、Ｓｎ系表面層が残存した５層構造となっているのに対して、従来技術の試料１８では、Ｆｅ系下地層が薄くてバリア層としての機能が十分でないため、Ｃｕ酸化物が表面を覆ってしまったことにより、接触抵抗の上昇となったと考えられる。この場合、Ｆｅ系下地層の厚さは、試料５で０．５μｍ、試料１８で０．０５μｍであった。 Regarding the contact resistance, Sample 5 and Sample 18 were also measured over time during heating at 175 ° C. for 1000 hours. The result is shown in FIG.
As shown in FIG. 9, the sample 5 according to the present invention has a slight increase in contact resistance even when exposed to a high temperature for a long time, whereas the sample 18 according to the prior art has a contact resistance after 1000 hours. Increased to 10 mΩ or more. The sample 5 of the present invention has a five-layer structure in which the Sn-based surface layer remains due to the heat resistance of the Fe-based underlayer, whereas in the sample 18 of the prior art, the Fe-based underlayer is thin and has a barrier. Since the function as a layer is not sufficient, it is considered that the contact resistance increased due to the Cu oxide covering the surface. In this case, the thickness of the Fe-based underlayer was 0.5 μm for sample 5 and 0.05 μm for sample 18.
　次に、めっき処理後リフロー処理するまでの間の放置時間によるめっき剥離性について実験した。剥離試験は前述と同じように、９．８ｋＮの荷重にて９０°曲げ（曲率半径Ｒ：０．７ｍｍ）を行った後、大気中で１６０℃、２５０時間保持し、曲げ戻して、曲げ部の剥離状況の確認を行った。その結果を表１２に示す。 Next, an experiment was conducted on plating peelability depending on the standing time after the plating treatment until the reflow treatment. As described above, the peel test was performed by bending 90 ° with a load of 9.8 kN (curvature radius R: 0.7 mm), holding in the atmosphere at 160 ° C. for 250 hours, bending back, The peeling state of was confirmed. The results are shown in Table 12.
Figure JPOXMLDOC01-appb-T000012
Figure JPOXMLDOC01-appb-T000012
　この表１２からわかるように、めっき後の放置時間が長くなると剥離が発生する。これは、放置時間が長いことにより、高電流密度で析出したＣｕ結晶粒が肥大化すると共に自然にＣｕとＳｎが反応することによりＣｕ６Ｓｎ５を生成し、リフロー時の平滑なＣｕ６Ｓｎ５とＣｕ３Ｓｎとの合金化を妨げるからと考えられる。 As can be seen from Table 12, peeling occurs when the standing time after plating becomes longer. This is because Cu crystal grains precipitated at a high current density are enlarged due to a long standing time, and Cu and Sn react spontaneously to form Cu 6 Sn 5, and smooth Cu 6 Sn during reflowing. This is thought to be because the alloying between 5 and Cu 3 Sn is hindered.
　また、最表面にＳｎ－Ａｇ被覆層を形成した場合の高温時の耐熱性、コネクタ使用時の挿抜性について実験した。試料としては、実施例の３，５，７の条件で製作されたものを選んで、その表面を酸洗、電解研磨して平滑にし、その平滑面の上に、電解にてＳｎ－Ａｇ被覆層を約０．２μｍの厚さで成膜した。平滑面にした状態で、Ｓｎ系表面層の表面粗さを前述の走査型共焦点赤外レーザ顕微鏡ＬＥＸＴ　ＯＬＳ－３０００－ＩＲで測定したところ、算術平均粗さＲａで０．００５～０．３μｍの範囲であった。
　これらの試料について、前述と同様にして接触抵抗と動摩擦係数について測定したところ、表１３に示す通りであった。 In addition, an experiment was conducted on the heat resistance at a high temperature when the Sn—Ag coating layer was formed on the outermost surface, and the insertion / removal property when using the connector. As a sample, the one manufactured under the conditions of 3, 5 and 7 in the example is selected, and the surface is pickled and electropolished to be smooth, and the smooth surface is coated with Sn-Ag by electrolysis. The layer was deposited to a thickness of about 0.2 μm. When the surface roughness of the Sn-based surface layer was measured with the above-mentioned scanning confocal infrared laser microscope LEXT OLS-3000-IR in a smooth surface, the arithmetic average roughness Ra was 0.005 to 0.3 μm. Range.
When these samples were measured for contact resistance and dynamic friction coefficient in the same manner as described above, they were as shown in Table 13.
Figure JPOXMLDOC01-appb-T000013
Figure JPOXMLDOC01-appb-T000013
　この表１３から明らかなように、最表面にＳｎ－Ａｇ被覆層を形成することにより、Ｓｎ系表面層が最表面の場合の表８の同一試料番号のものと比較して、接触抵抗及び動摩擦係数とも優れるものとなった。 As is apparent from Table 13, by forming the Sn—Ag coating layer on the outermost surface, contact resistance and dynamic friction are compared with those of the same sample number in Table 8 when the Sn-based surface layer is the outermost surface. The coefficient was also excellent.
　なお、前述のＴＥＭ－ＥＤＳ分析により、Ｃｕ６Ｓｎ５層内に０．７６～５．３２重量％のＮｉの混入が認められており、本発明においては、Ｃｕ－Ｓｎ金属間化合物層内にわずかな量のＮｉが混入しているものも含むものとする。
　また、実施形態ではＮｉ系下地層とＣｕ系基材との間にＦｅ系下地層を介在させるようにしており、このＦｅ系下地層の存在により、Ｃｕの拡散防止機能がさらに高められ、曲げ加工時のクラック発生も少なくすることができるのであるが、必ずしも必須というものではなく、Ｃｕ系基材の上にＮｉ系下地層を直接形成するようにしてもよい。 According to the TEM-EDS analysis described above, 0.76 to 5.32 wt% of Ni was found in the Cu 6 Sn 5 layer. In the present invention, the Cu—Sn intermetallic compound layer contains It shall also include those in which a slight amount of Ni is mixed.
Further, in the embodiment, an Fe-based underlayer is interposed between the Ni-based underlayer and the Cu-based substrate, and the presence of this Fe-based underlayer further enhances the Cu diffusion preventing function, and allows bending. Although generation of cracks during processing can be reduced, it is not always essential, and a Ni-based underlayer may be directly formed on a Cu-based substrate.
（第２実施例）
　銅条材（Ｃｕ系基材）として、厚さ０．２５ｍｍの三菱伸銅株式会社製ＴＣ材を用い、これにＮｉ、Ｃｕ、Ｓｎの各めっき処理を順次行った。この場合、表１４に示すように、各めっき処理の電流密度、レイノルズ数、リフロー条件を変えて複数の試料を作成した。 (Second embodiment)
A 0.25 mm thick TC material manufactured by Mitsubishi Shindoh Co., Ltd. was used as the copper strip (Cu-based substrate), and Ni, Cu, and Sn plating treatments were sequentially performed thereon. In this case, as shown in Table 14, a plurality of samples were prepared by changing the current density, Reynolds number, and reflow conditions of each plating treatment.
Figure JPOXMLDOC01-appb-T000014
Figure JPOXMLDOC01-appb-T000014
　本実施例の処理材断面は、透過電子顕微鏡を用いたエネルギー分散型Ｘ線分光分析（ＴＥＭ－ＥＤＳ分析）の結果、銅条材の上に、Ｎｉ系下地層、Ｃｕ３Ｓｎ層、Ｃｕ６Ｓｎ５層、Ｓｎ系表面層の４層構造となっていた。またＣｕ６Ｓｎ５層とＮｉ系下地層の界面には不連続なＣｕ３Ｓｎ層があり、集束イオンビームによる断面の走査イオン顕微鏡（ＦＩＢ－ＳＩＭ像）から観察されるＣｕ３Ｓｎ層のＮｉ系下地層に対する表面被覆率は６０％以上であった。 As a result of energy dispersive X-ray spectroscopic analysis (TEM-EDS analysis) using a transmission electron microscope, the cross section of the treated material of this example is a Ni-based underlayer, a Cu 3 Sn layer, and Cu 6 on a copper strip. It has a four-layer structure of Sn 5 layers and Sn-based surface layers. The Cu 6 at the interface Sn 5 layer and the Ni-based base layer has discontinuous Cu 3 Sn layer, Ni of Cu 3 Sn layer observed from a scanning ion microscope of a cross section by focused ion beam (FIB-SIM image) The surface coverage with respect to the system underlayer was 60% or more.
　また、第１実施例の場合と同様の方法でＳｎ系表面層を除去して、その下のＣｕ－Ｓｎ金属間化合物層の表面粗さをオリンパス株式会社製の走査型共焦点赤外レーザ顕微鏡ＬＥＸＴ　ＯＬＳ－３０００－ＩＲを用いて第１実施例と同様の方法で測定した。
　以上の測定結果を表１５にまとめた。 Further, the Sn-based surface layer is removed by the same method as in the first embodiment, and the surface roughness of the Cu—Sn intermetallic compound layer below is removed using a scanning confocal infrared laser microscope manufactured by Olympus Corporation. The measurement was performed in the same manner as in the first example using LEXT OLS-3000-IR.
The above measurement results are summarized in Table 15.
Figure JPOXMLDOC01-appb-T000015
Figure JPOXMLDOC01-appb-T000015
　次に、表１４及び表１５に示される試料について、１７５℃×１０００時間経過後の接触抵抗、剥離の有無、耐摩耗性を測定した。また、動摩擦係数及び１７５℃×１０００時間経過後の抵抗値変化率についても測定した。これら接触抵抗、剥離試験、耐摩耗性、動摩擦係数の各試験方法は第１実施例で述べた方法と同じである。
　これらの結果を表１６に示す。 Next, with respect to the samples shown in Tables 14 and 15, the contact resistance after 175 ° C. × 1000 hours, the presence or absence of peeling, and the wear resistance were measured. Further, the coefficient of dynamic friction and the rate of change in resistance value after 175 ° C. × 1000 hours were also measured. These test methods for contact resistance, peel test, wear resistance, and dynamic friction coefficient are the same as those described in the first embodiment.
These results are shown in Table 16.
Figure JPOXMLDOC01-appb-T000016
Figure JPOXMLDOC01-appb-T000016
　この表１６から明らかなように、本実施例の導電部材においては、高温時の接触抵抗が小さく、剥離やカーケンダルボイドの発生がなく、動摩擦係数も小さいことから、コネクタ使用時の挿抜力も小さく良好であると判断できる。なお、比較例７は表面にめっき焼けが生じていた。また、比較例3０ではＳｎめっきにおいてスラッジの発生が目立った。 As can be seen from Table 16, the conductive member of this example has a low contact resistance at high temperatures, no peeling or Kirkendall voids, and a small coefficient of dynamic friction. It can be judged that it is good. In Comparative Example 7, plating burn occurred on the surface. In Comparative Example 30, the generation of sludge was noticeable in Sn plating.
　本発明は、Ｃｕ又はＣｕ合金からなる基材の表面に複数のめっき層を形成した導電部材及びその製造方法に適用することができる。 The present invention can be applied to a conductive member in which a plurality of plating layers are formed on the surface of a substrate made of Cu or a Cu alloy, and a method for manufacturing the conductive member.
　１　Ｃｕ系基材
　２　Ｆｅ系下地層
　３　Ｎｉ系下地層
　４　Ｃｕ－Ｓｎ金属間化合物層
　５　Ｓｎ系表面層
　６　Ｃｕ３Ｓｎ層
　７　Ｃｕ６Ｓｎ５層
　８　Ｓｎ－Ａｇ被覆層
　１０　導電部材
　１１　導電部材
　３１　導電部材製造装置
　３２　脱脂・洗浄槽
　３３　Ｎｉめっき槽
　３４　Ｃｕめっき槽
　３５　Ｓｎめっき槽
　３６～３８　洗浄槽
　３９　電極板
　４０　循環タンク
　４１　泡除去手段
　４２　スラッジ除去手段
　４４　リフロー炉
　４５　空冷ゾーン
　４６　水冷ゾーン
　５０　導電部材
　５１　銅条材
  DESCRIPTION OF SYMBOLS 1 Cu-type base material 2 Fe-type base layer 3 Ni-type base layer 4 Cu-Sn intermetallic compound layer 5 Sn-type surface layer 6 Cu 3 Sn layer 7 Cu 6 Sn 5 layer 8 Sn-Ag coating layer 10 Conductive member 11 Conductive Member 31 Conductive member manufacturing device 32 Degreasing / cleaning tank 33 Ni plating tank 34 Cu plating tank 35 Sn plating tank 36-38 Cleaning tank 39 Electrode plate 40 Circulating tank 41 Foam removing means 42 Sludge removing means 44 Reflow furnace 45 Air cooling zone 46 Water cooling Zone 50 Conductive member 51 Copper strip

Claims (12)

  1. Ｃｕ系基材の上に形成したＮｉ系下地層と、表面を形成するＳｎ系表面層との間に、Ｃｕ－Ｓｎ金属間化合物層が形成されるとともに、Ｃｕ－Ｓｎ金属間化合物層は、さらに、前記Ｎｉ系下地層の上に配置されるＣｕ３Ｓｎ層と、該Ｃｕ３Ｓｎ層の上に配置されるＣｕ６Ｓｎ５層とからなり、前記Ｃｕ３Ｓｎ層及びＣｕ６Ｓｎ５層を合わせた前記Ｃｕ－Ｓｎ金属間化合物層の前記Ｓｎ系表面層と接する面の表面粗さが、算術平均粗さＲａで０．０５～０．２５μｍであり、かつ、粗さ曲線の最大谷深さＲｖで０．０５～１．００μｍであり、また、前記Ｃｕ３Ｓｎ層は前記Ｎｉ系下地層を覆っており、その面積被覆率が６０～１００％であることを特徴とする導電部材。 A Cu-Sn intermetallic compound layer is formed between the Ni-based underlayer formed on the Cu-based substrate and the Sn-based surface layer forming the surface. further, a Cu 3 Sn layer disposed on the Ni-based base layer composed of a Cu 6 Sn 5 layer disposed on the said Cu 3 Sn layer, the Cu 3 Sn layer and Cu 6 Sn 5 layer The surface roughness of the Cu—Sn intermetallic compound layer in contact with the Sn-based surface layer is 0.05 to 0.25 μm in terms of arithmetic average roughness Ra, and the maximum valley of the roughness curve Conductive member having a depth Rv of 0.05 to 1.00 μm, the Cu 3 Sn layer covering the Ni-based underlayer, and an area coverage of 60 to 100% .
  2. 　前記Ｃｕ３Ｓｎ層の平均厚さは０．０１～０．５μｍであることを特徴とする請求項１に記載の導電部材。 The conductive member according to claim 1, wherein an average thickness of the Cu 3 Sn layer is 0.01 to 0.5 µm.
  3. 　前記Ｓｎ系表面層の平均厚さは０．５～１．５μｍであることを特徴とする請求項１又は２に記載の導電部材。 3. The conductive member according to claim 1, wherein the average thickness of the Sn-based surface layer is 0.5 to 1.5 μm.
  4. 　前記Ｓｎ系表面層の上に、平均厚さが０．０５～０．５μｍのＳｎ－Ａｇ被覆層が形成されていることを特徴とする請求項１又は２に記載の導電部材。 3. The conductive member according to claim 1, wherein a Sn—Ag coating layer having an average thickness of 0.05 to 0.5 μm is formed on the Sn-based surface layer.
  5. 　前記Ｓｎ－Ａｇ被覆層が、０．１～５．０重量％のＡｇを含有することを特徴とする請求項４記載の導電部材。 The conductive member according to claim 4, wherein the Sn-Ag coating layer contains 0.1 to 5.0 wt% of Ag.
  6. 　Ｃｕ系基材の表面に、Ｎｉ又はＮｉ合金、Ｃｕ又はＣｕ合金、Ｓｎ又はＳｎ合金をこの順にめっきしてそれぞれのめっき層を形成した後、加熱してリフロー処理することにより、前記Ｃｕ系基材の上に、Ｎｉ系下地層、Ｃｕ－Ｓｎ金属間化合物層、Ｓｎ系表面層を順に形成した導電部材を製造する方法であって、前記Ｃｕ又はＣｕ合金によるめっき層を電流密度が２０～６０Ａ／ｄｍ２の電解めっきにより形成し、前記Ｓｎ又はＳｎ合金によるめっき層を電流密度が１０～３０Ａ／ｄｍ２の電解めっきにより形成するとともに、前記Ｃｕ又はＣｕ合金によるめっき層の平均厚さが０．３～０．５μｍであり、前記リフロー処理は、前記めっき層を形成してから１～１５分経過した後に、めっき層を２０～７５℃／秒の昇温速度で２４０～３００℃のピーク温度まで加熱する加熱工程と、前記ピーク温度に達した後、３０℃／秒以下の冷却速度で２～１０秒間冷却する一次冷却工程と、一次冷却後に１００～２５０℃／秒の冷却速度で冷却する二次冷却工程とを有することを特徴とする導電部材の製造方法。 The surface of the Cu-based substrate is plated with Ni or Ni alloy, Cu or Cu alloy, Sn or Sn alloy in this order to form each plating layer, and then heated and reflowed, whereby the Cu-based substrate is obtained. A method for producing a conductive member in which a Ni-based underlayer, a Cu—Sn intermetallic compound layer, and a Sn-based surface layer are formed in this order on a material, wherein the plating layer made of Cu or Cu alloy has a current density of 20 to The plating layer is formed by electrolytic plating at 60 A / dm 2, the plating layer by Sn or Sn alloy is formed by electrolytic plating at a current density of 10 to 30 A / dm 2 , and the average thickness of the plating layer by Cu or Cu alloy is In the reflow process, after 1 to 15 minutes have elapsed from the formation of the plating layer, the plating layer is subjected to 240 to 30 at a temperature rising rate of 20 to 75 ° C./second. A heating step of heating to a peak temperature of 0 ° C., a primary cooling step of cooling for 2 to 10 seconds at a cooling rate of 30 ° C./second or less after reaching the peak temperature, and a temperature of 100 to 250 ° C./second after the primary cooling. And a secondary cooling step of cooling at a cooling rate.
  7. 　前記Ｓｎ又はＳｎ合金によるめっき層の平均厚さが１．５～２．０μｍであることを特徴とする請求項６記載の導電部材の製造方法。 The method for producing a conductive member according to claim 6, wherein an average thickness of the plating layer made of Sn or Sn alloy is 1.5 to 2.0 µm.
  8. 　前記Ｎｉ又はＮｉ合金によるめっき層は電流密度が２０～５０Ａ／ｄｍ２の電解めっきにより形成することを特徴とする請求項６記載の導電部材の製造方法。 The method for manufacturing a conductive member according to claim 6, wherein the plating layer made of Ni or Ni alloy is formed by electrolytic plating with a current density of 20 to 50 A / dm 2 .
  9. 　前記リフロー処理後の前記Ｓｎ系表面層の酸化膜を除去し、該Ｓｎ系表面層の表面粗さを算術平均粗さＲａで０．００５～０．３μｍとした後、その上にＳｎ－Ａｇ被覆層を形成することを特徴とする請求項６記載の導電部材の製造方法。 After removing the oxide film of the Sn-based surface layer after the reflow treatment, the surface roughness of the Sn-based surface layer is set to 0.005 to 0.3 μm in arithmetic mean roughness Ra, and then Sn—Ag is formed thereon. The method for producing a conductive member according to claim 6, wherein a coating layer is formed.
  10. 　前記電解めっきは、無機酸を主成分とするめっき浴中にて不溶性アノードを使用し、レイノルズ数１×１０４～５×１０５なる電解めっきとすることを特徴とする請求項６記載の導電部材の製造方法。 The conductive film according to claim 6, wherein the electrolytic plating uses an insoluble anode in a plating bath containing an inorganic acid as a main component, and is an electrolytic plating having a Reynolds number of 1 × 10 4 to 5 × 10 5. Manufacturing method of member.
  11. 　前記Ｓｎ又はＳｎ合金によるめっき層の形成時に、スラッジ除去手段及び泡除去手段を使用することを特徴とする請求項６記載の導電部材の製造方法 The method for producing a conductive member according to claim 6, wherein sludge removing means and bubble removing means are used when the plating layer is formed of the Sn or Sn alloy.
  12. 　請求項６から１１のいずれか一項に記載の製造方法により製造された導電部材。 A conductive member manufactured by the manufacturing method according to any one of claims 6 to 11.
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