JP5442316B2 - Manufacturing method of conductive member - Google Patents

Description

  The present invention relates to a method for producing a conductive member obtained by plating a copper strip made of copper or a copper alloy.

Conventionally, as lead frames, terminals, and connectors used in semiconductor devices such as IC and LSI and various electronic / electrical components, the surface of a copper strip made of copper or a copper alloy (hereinafter referred to as copper strip) is made of Ni, Sn. A copper strip with plating on which a plating layer made of Cu or the like is formed is widely used.
Copper strips in each plating bath can be used as a means of continuously and efficiently plating multiple layers with a limited line length using inorganic acids and insoluble anodes on the surface of wide thin plates such as copper strips. It is important to increase the relative flow rate between the plating solution and the plating solution to increase the current density and to shorten the time required to obtain the desired properties of plating.
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.

In Patent Document 1, an insoluble anode is used in a tin plating sulfuric acid bath for high current density used in the production of electroplated tin and thin tin-plated steel sheet, at a current density of 50 A / dm ² and at a temperature of 30 to 70 ° C. A method of tin plating is disclosed.
In Patent Document 2, 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 a layer having a Ni content of 50% by weight or less is 0.5 to 3.0 μm. In addition, as a manufacturing method, Ni or Ni alloy, Cu plating on the surface of copper or copper alloy, Sn or Sn alloy plating on the outermost surface layer, at least one reflow treatment is performed, and the heating temperature 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.

JP-A-6-346272 JP 2003-293187 A

The invention described in Patent Document 1 is a method for producing a tin-plated steel sheet such as tinplate, in a sulfuric acid bath using an insoluble anode, at a temperature of 30 to 70 ° C., a current density of 50 A / dm ² or more, a steel strip and an electrolyte. The steel strip is tin-plated at a relative speed of 160 m / min or more.
In order to apply such tin plating conditions to multilayer plating of copper strip thin plates that require strict plating properties as a conductive member, especially insertion / extraction properties and heat resistance when used as connectors, for the following reasons It is impossible.
(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.

In the invention described in Patent Document 2, Ni or Ni alloy, Cu plating is applied on the surface of copper or 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. .

  This invention is made | formed in view of such a situation, By providing the method of obtaining the copper strip material by which the plating was carried out to the multilayer which has a favorable characteristic at the time of use as an electrically-conductive member efficiently. is there.

  The inventors inserted a plurality of plating baths while continuously running the copper strip, and formed Ni or Ni alloy, Cu or Cu alloy, Sn or Sn alloy plating layers on the surface thereof in this order. Then, in the method of manufacturing a conductive member for sequentially forming a Ni-based underlayer, a Cu-Sn intermetallic compound layer, and a Sn-based surface layer on the copper strip by heating and reflowing, It has been found that a plating film having a desired property can be efficiently obtained by appropriately selecting the current density, bath temperature, and Reynolds number in each plating bath, particularly 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.

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. 3).
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.

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.

From such a point of view, the manufacturing method of the present invention passes through a plurality of plating baths while continuously running a copper strip, and Ni, Ni alloy, Cu or Cu alloy, Sn or Sn alloy is formed on the surface thereof. In this order, the plating layer is formed in this order, and then heated and reflowed to form a Ni-based underlayer, a Cu-Sn intermetallic compound layer, and a Sn-based surface layer in this order on the copper strip. A method for producing a member, wherein the plating layer made of Ni or Ni alloy uses an insoluble anode in a plating bath mainly composed of an inorganic acid, has a bath temperature of 45 to 55 ° C., and a Reynolds number of 1 × 10 ^4. ~ 5 × 10 ⁵ , formed by electrolytic plating with a current density of 20 to 50 A / dm ² , and using the insoluble anode in the plating bath mainly composed of inorganic acid, the plating layer made of Cu or Cu alloy, Bath temperature 35-55 ° C Reynolds Number ^{1 × 10 4 ~5 × 10 5} , formed at a current density of 20~60A / dm ² becomes electrolytic plating, a plating layer by the Sn or Sn alloy, an inorganic acid in the plating bath mainly An insoluble anode is used, and it is formed by electrolytic plating with a bath temperature of 15 to 35 ° C., a Reynolds number of 1 × 10 ^{4 to} 5 × 10 ⁵ , and a current density of 10 to 30 A / dm ² .

  Further, the production method of the present invention may be provided with a means for removing bubbles and sludge at the time of forming the plating layer by the Sn or Sn alloy, and the bubbles and sludge of the plating solution may be removed, thereby further increasing the plating efficiency. I understood.

  In the production method of the present invention, the reflow treatment may be performed after 1 to 30 minutes have elapsed since the plating layer was formed.

  Furthermore, in the manufacturing method of the present invention, the reflow treatment is performed by heating the plating layer to a peak temperature of 240 to 300 ° C. at a temperature rising rate of 10 to 90 ° C./second, and after reaching the peak temperature, 30 It is good to have a primary cooling process which cools for 1 to 30 seconds with a cooling rate below ° C / second, and a secondary cooling process which cools at a cooling rate of 50-250 ° C / second after primary cooling.

  ADVANTAGE OF THE INVENTION According to this invention, the copper strip plated by the multilayer which has a favorable characteristic at the time of use as an electrically-conductive member can be obtained efficiently continuously.

It is a schematic block diagram which shows the example of the manufacturing apparatus used for the manufacturing method of one Embodiment of this invention. It is sectional drawing which shows the positional relationship of the electrode and copper strip in the plating tank in FIG. It is a graph which shows the relationship between the Reynolds number during plating processing, and current efficiency. It is the temperature profile which made the relationship between the temperature of the reflow conditions and time concerning the manufacturing method of one Embodiment of this invention a graph. It is sectional drawing which modeled and showed the surface layer part of the electrically-conductive member manufactured by the manufacturing method of one Embodiment of this invention. It is a front view which shows notionally the apparatus for measuring the dynamic friction coefficient of an electrically-conductive member.

Embodiments of the present invention will be described below.
FIG. 1 schematically shows an example of a production apparatus for carrying out the production method of the present invention. In this conductive member manufacturing apparatus 11, a degreasing / cleaning tank 12, a Ni plating tank 13, a Cu plating tank 14, a Sn plating tank 15, and cleaning tanks 16 to 18 arranged after the plating tanks 13 to 15 are continuously arranged. The copper strip 1 is plated while being continuously conveyed in the order of the degreasing / cleaning tank 12, the Ni plating tank 13, the Cu plating tank 14, and the Sn plating tank 15. The degreasing / cleaning tank 12 further includes a degreasing tank 12a, a cleaning tank 12b, a pickling tank 12c, and a cleaning tank 12d.
Moreover, in each plating tank 13-15, as shown in FIG. 2, a pair of electrode plate 19 is arrange | positioned so as to oppose both surfaces of the copper strip 1 which runs continuously, The copper strip 1 and the plating solution are relatively moved so that the Reynolds number in the flow field of the plating solution formed between the copper strip 1 is 1 × 10 ^{4 to} 5 × 10 ⁵ . The plating solution is circulated between a circulation tank (only the circulation tank of the Sn plating tank 15 is shown in FIG. 1) 20.

Further, the brightener used in the Sn plating solution is liable to generate bubbles. For this reason, the Sn plating tank 15 is provided with a bubble removing means 21. Sludge removal means 22 is also provided. This sludge removal means 22 connects a sludge settling tank to the circulation tank 20, extracts a plating solution from the circulation tank 20 into 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 20 again. The settled sludge is subjected to a centrifuge, sent to a refining company, and reused as Sn.
Further, a drier 23 for drying the copper strip material 1 that has passed through the cleaning tank 18 is provided at a downstream position of the Sn plating tank 15. A reflow furnace 24 is provided at a downstream position of the dryer 23. The reflow furnace 24 includes an air cooling zone 25 for primary cooling and a water cooling zone 26 for secondary cooling, which will be described later. Reference numeral 27 denotes a dryer for drying the copper strip 1 that has passed through the water cooling zone 26.

Next, a method for manufacturing a conductive member using such a manufacturing apparatus 11 will be described.
First, after the surface of the copper strip 1 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.
As the conditions for Ni plating, the plating bath is 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 containing copper sulfate (CuSO ₄ ) and sulfuric acid (H ₂ SO ₄ ) as main components is used in the 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 mainly composed of sulfuric acid (H ₂ SO ₄ ) and stannous sulfate (SnSO ₄ ) is used as a plating bath, the plating temperature is 15 to 35 ° C., and the current density is 10 to 10. 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.

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 19 and the distance b between the electrode plate 19 and the copper strip 1 shown in FIG. It is done.
As shown in FIG. 3, 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 Tables 1 to 3 below.

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 average thickness of the Cu plating layer is 0.3 to 0.5 μm, the average thickness of the Ni plating layer is 0.1 to 2.0 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 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 the base requires 1.5 to 2.0 μm. become. And 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 The Cu—Sn alloy formed in this manner grows while spreading in the plane direction from the grain boundary, so that it is considered 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 being dispersed at these grain boundaries, thereby reducing the unevenness of the Cu—Sn intermetallic compound layer. There is.

Next, the reflow process is performed by heating. The reflow process is preferably performed under the temperature profile shown in FIG.
That is, the reflow treatment is a heating step in which the treated material after plating is heated to a peak temperature of 240 to 300 ° C. at a temperature rising rate of 10 to 90 ° C./second in a heating furnace having a CO reducing atmosphere, After reaching, a primary cooling step of cooling for 1 to 30 seconds at a cooling rate of 30 ° C./sec or less and a secondary cooling step of cooling at a cooling rate of 50 to 250 ° C./sec after the primary cooling are performed. 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 surface of the Sn plating, and 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 performing rapid cooling after that, 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 obtained. Can be obtained.
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, the reflow process may be performed within 30 minutes, desirably 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.

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. 5, the conductive member 10 has 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 the copper strip 1. The -Sn intermetallic compound layer 4 further includes 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.

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 has irregularities, 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.

When used as the connector terminal portion 3, it is preferable that Ra is small because the insertion / extraction force is reduced. However, when Ra is less than 0.05 μm, the Cu—Sn intermetallic compound layer 4 is almost free from unevenness and Cu— The Sn intermetallic compound layer 4 becomes extremely fragile, and peeling of the film is likely to occur 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 during insertion / extraction when used as a connector, and thus 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. Setting Rv to less than 0.05 μm is not preferable because the Cu—Sn intermetallic compound layer becomes brittle as in the case of Ra.
Moreover, 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.

The Cu ₃ Sn layer 6 disposed in the lower layer of the Cu—Sn intermetallic compound layer 4 has a function of covering the Ni-based underlayer 3 and 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.
This area coverage can be confirmed from a surface scanning ion image (SIM image) obtained by observing a 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 such a case, the Cu ₆ Sn ₅ layer 7 of the Cu—Sn intermetallic compound layer 4 covers the Ni-based underlayer 3. The average thickness is a portion where the Cu ₃ Sn layer 6 is present and is an average value when the thickness is measured at a plurality of locations.

In addition, since this Cu-Sn intermetallic compound layer 4 is alloyed by diffusion of Cu plated on the Ni-based underlayer 3 and surface Sn, 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 diffuses slightly 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 μm in order to optimize surface contact resistance, solderability, corrosion resistance, and insertion / extraction force when used as a connector. .

Next, examples of the present invention will be described.
As the copper strip material, a TC material manufactured by Mitsubishi Shindoh Co., Ltd. having a thickness of 0.25 mm was used, and Ni, Cu, and Sn plating treatments were sequentially performed thereon. In this case, as shown in Table 4, a plurality of samples were prepared by changing the current density, Reynolds number, and reflow conditions of each plating treatment.

As a result of energy dispersive X-ray spectroscopic analysis (TEM-EDS analysis) using a transmission electron microscope, the cross section of the treatment 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.

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 the Sn-based surface layer is immersed for 5 minutes in an etching solution for removing the plating film made of a component that does not corrode the Cu-Sn alloy. The surface layer is removed, and the underlying Cu—Sn intermetallic compound layer is exposed.
The surface roughness of the exposed Cu-Sn intermetallic compound layer was measured by using a scanning confocal infrared laser microscope LEXT OLS-3000-IR manufactured by Olympus Co., Ltd. and laser light under conditions of 100 times the objective lens. 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 5.

Next, with respect to the samples shown in Tables 4 and 5, 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 (copper strip) was exposed was measured, and a sample in which plating remained even after 50 tests was evaluated as ◯, and a sample in which the substrate was exposed within 50 times was 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. 6, a male test piece 32 is fixed on a horizontal base 31, a hemispherical convex surface of a female test piece 33 is placed on the male test piece 33, and the plating surfaces are brought into contact with each other. The load P of 9N (500 gf) is applied and the male test piece 32 is pressed. With the load P applied, the frictional force F when the male test piece 32 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 35. A dynamic friction coefficient (= Fav / P) was obtained from the average value Fav of the friction force F and the load P.
These results are shown in Table 6.

  As is apparent from Table 6, 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. Therefore, the insertion / extraction force when using the connector is also small. It can be judged that it is good. In Comparative Example 7, plating burn occurred on the surface. In Comparative Example 10, the generation of sludge was noticeable in Sn plating.

DESCRIPTION OF SYMBOLS 1 Copper strip 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 10 Conductive member 11 Conductive member manufacturing apparatus 12 Degreasing / cleaning tank 13 Ni plating tank 14 Cu plating tank 15 Sn plating tank 16-18 Cleaning tank 19 Electrode plate 20 Circulating tank 21 Foam removing means 22 Sludge removing means 24 Reflow furnace 25 Air cooling zone 26 Water cooling zone

Claims (5)

The 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 layers are formed in this order on the surface, and then heated. 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 copper strip,
The plating layer made of Ni or Ni alloy is an insoluble anode in a plating bath mainly composed of an inorganic acid, the bath temperature is 45 to 55 ° C., the Reynolds number is 1 × 10 ^{4 to} 5 × 10 ⁵ , and the current density is 20. Formed by electrolytic plating of ~ 50 A / dm ² ,
The plating layer made of Cu or Cu alloy is an insoluble anode in a plating bath mainly composed of an inorganic acid, the bath temperature is 35 to 55 ° C., the Reynolds number is 1 × 10 ^{4 to} 5 × 10 ⁵ , and the current density is 20. was formed by ~60A / dm ² consisting of electrolytic plating,
The plating layer made of Sn or Sn alloy is an insoluble anode in a plating bath mainly composed of an inorganic acid, the bath temperature is 15 to 35 ° C., the Reynolds number is 1 × 10 ^{4 to} 5 × 10 ⁵ , and the current density is 10 method for manufacturing a conductive member, and forming at ~30A / dm ² becomes electroplating.   The method for producing a conductive member according to claim 1, wherein sludge removing means and bubble removing means are used when the plating layer is formed of the Sn or Sn alloy.   The method for producing a conductive member according to claim 1, wherein the reflow treatment is performed after 1 to 30 minutes have elapsed since the plating layer was formed.   The reflow treatment includes a heating step of heating the plating layer to a peak temperature of 240 to 300 ° C. at a temperature rising rate of 10 to 90 ° C./second, and a cooling rate of 30 ° C./second or less after reaching the peak temperature. The primary cooling step of cooling for 1 to 30 seconds and the secondary cooling step of cooling at a cooling rate of 50 to 250 ° C./second after the primary cooling are provided. The manufacturing method of the electrically-conductive member.   The electrically-conductive member manufactured by the manufacturing method as described in any one of Claim 1 to 4.

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