JP2013076122A - Sn-plated material and method for manufacturing the same - Google Patents

Abstract

An object of the present invention is to provide a Sn plated material having a low coefficient of friction and excellent solder wettability and contact reliability, and a method for producing the Sn plated material at a low cost.
In a Sn plating material in which a Cu-Sn compound layer is formed on a substrate made of copper or a copper alloy, and a pure Sn layer is formed on the Cu-Sn compound layer, the thickness of the pure Sn layer is 0.3 to 1.5 μm, the average crystal grain size of the Cu—Sn compound in a plane substantially parallel to the interface between the layers of the Sn plating material is 1.3 μm or more, and the arithmetic average roughness of the surface of the Sn plating material Ra is 0.15 μm or more.
[Selection figure] None

Description

  The present invention relates to an Sn plating material and a method for manufacturing the same, and more particularly, to an Sn plating material used as a material for a connection terminal that can be inserted and removed and a method for manufacturing the same.

  Conventionally, an Sn plated material obtained by applying Sn plating to the outermost layer of a conductor material such as copper or copper alloy has been used as a material for a connection terminal that can be inserted and removed. In particular, Sn plating materials have low contact resistance, and from the viewpoints of contact reliability, corrosion resistance, solderability, economy, etc., control boards for industrial equipment such as automobiles, mobile phones, personal computers and other industrial equipment such as robots, Used as a material for terminals and bus bars of connectors, lead frames, relays, switches, etc.

  In general, such Sn plating is performed by electroplating, and a reflow process (Sn melting process) is performed immediately after electroplating in order to remove internal stress of the Sn plating material and suppress the generation of whiskers. It has been broken. When the reflow treatment is performed after Sn plating in this way, a part of Sn diffuses into the material and the base component to form a compound layer, and a Sn layer (hereinafter referred to as “pure”) having a soft molten and solidified structure on this compound layer. Sn layer ") is formed. This pure Sn layer plays an extremely important role in order to obtain excellent contact reliability, corrosion resistance and solderability.

  However, since the pure Sn layer is soft and easily deformed, if the Sn-plated material subjected to reflow processing is used as a material such as a connection terminal that can be inserted and removed, the surface is scraped when the connection terminal is inserted and the friction coefficient is increased. There is a problem that power becomes high. In connection terminals of automobiles and the like, the number of terminals is increasing, and the insertion force at the time of assembly increases in proportion to the number of terminals, and the work load becomes a problem.

  In order to solve such problems, in the Sn plating material subjected to reflow treatment, the film thickness of the pure Sn layer, which is a soft layer, is reduced, and a compound layer such as a hard Cu—Sn compound layer is ground by reflow treatment. Thus, the friction coefficient is reduced. However, when the pure Sn layer is thinned, the material and the base component diffuse quickly to the outermost surface due to changes over time, and heat resistance and contact reliability are lowered. Therefore, a method of inserting a Ni layer as a diffusion suppressing layer under the Cu—Sn compound layer has been proposed (see, for example, Patent Document 1).

  Further, a base plating layer made of Ni or Ni alloy, an intermediate plating layer made of Cu-Sn alloy, and a surface plating layer made of Sn or Sn alloy are formed in this order on the surface of copper or copper alloy, The average crystal grain size of the Cu—Sn alloy forming the plating layer is 0.05 μm or more and less than 0.5 μm when the cross section of this plating layer is observed, and the average roughness Ra of the surface of the intermediate plating layer is 0 A method of improving the heat resistance of the Sn plating material and reducing the insertion force by setting the thickness to 0.1 to 0.5 μm has been proposed (for example, see Patent Document 2).

  Furthermore, on the surface of the base material made of a copper alloy containing 0.3 to 15% by mass of Ni, the surface layer side Sn layer having a thickness of 0.5 μm or less and the average cross section of the lower layer by reflow or hot Sn plating By forming a Sn plating layer having a diameter of 0.05 to 1.0 μm and a columnar crystal Cu—Sn alloy layer having an average aspect ratio of 1 or more and having a thickness of 0.2 to 2.0 μm, an Sn plating copper alloy A method of reducing the insertion force while maintaining the contact reliability of the material has been proposed (see, for example, Patent Document 3).

JP 2003-147579 A (paragraph number 0007) JP 2009-108389 A (paragraph number 0013-0025) JP 2002-298963 A (paragraph numbers 0004-0005)

  However, in the methods of Patent Documents 1 and 2, the number of processes is increased by the Ni plating process, and the management cost and initial cost of the plating line are increased. Further, when the pure Sn layer is a thin layer having a thickness of 0.2 μm or less, the insertion force can be lowered, but a portion where the Cu—Sn compound layer is exposed is generated, and solderability and corrosion resistance are deteriorated.

  Moreover, in the method of patent document 3, the kind of base material is limited to the copper alloy containing Ni, and manufacturing cost becomes high.

  Therefore, in view of such conventional problems, the present invention provides a Sn plating material having a low coefficient of friction and excellent solder wettability and contact reliability, and a method for producing the Sn plating material at a low cost. With the goal.

  As a result of intensive studies to solve the above problems, the present inventors have formed a Cu—Sn compound layer (diffusion layer) on a substrate made of copper or a copper alloy, and pure Cu is formed on this Cu—Sn compound layer. In the Sn plating material on which the Sn layer is formed, the thickness of the pure Sn layer is 0.3 to 1.5 μm, and the average crystal grain size of the Cu—Sn compound in the plane substantially parallel to the interface between the layers of the Sn plating material is By making the arithmetic average roughness Ra of the surface of the Sn plating material 1.3 μm or more and 0.15 μm or more, a Sn plating material having a low friction coefficient and excellent solder wettability and contact reliability can be manufactured at a low cost. As a result, the present invention has been completed.

  In other words, the Sn plating material according to the present invention is a Sn plating material in which a Cu—Sn compound layer is formed on a base material made of copper or a copper alloy, and a pure Sn layer is formed on the Cu—Sn compound layer. The Sn layer has a thickness of 0.3 to 1.5 μm, the average crystal grain size of the Cu—Sn compound in a plane substantially parallel to the interface between the layers of the Sn plating material is 1.3 μm or more, and the Sn plating material The arithmetic average roughness Ra of the surface is 0.15 μm or more.

  The interface between the layers of the Sn plating material and the average crystal grain size of the Cu—Sn compound (the lateral length of the crystal grains of the Cu—Sn compound) in a plane substantially parallel to the interface between the layers of the Sn plating material. The ratio (vertical length / horizontal length) of the average value (vertical length of the crystal grains of the Cu-Sn compound) of the maximum height of each crystal grain of the Cu-Sn compound in the vertical cross section is 0. .5 or less is preferable.

  In addition, in a predetermined region on a cross section substantially perpendicular to the interface between the layers of the Sn plating material, the width of each crystal grain of the Cu—Sn compound (the length in a direction substantially parallel to the interface between the layers) is 0. The ratio of coarse crystal grains to the sum of fine crystal grains and coarse crystal grains is ΣRy × 100 / (, where ΣRx is the number of fine crystal grains of 0.7 μm or less and ΣRy is the number of coarse crystal grains of 1.3 μm or greater. (ΣRx + ΣRy) is preferably 25 to 60%.

Furthermore, it is preferable that lubricating oil is applied to the surface of the pure Sn layer of the Sn plating material, and the amount of the lubricating oil applied is preferably 0.2 mg / dm ² or more.

  Moreover, the manufacturing method of the Sn plating material by this invention forms an Sn layer on the base material which consists of copper or a copper alloy by electroplating, and after drying the surface of Sn layer, the surface of Sn layer is heated. In the method for producing a Sn plating material, in which a Cu—Sn compound layer is formed on a base material by cooling after melting Sn, and a pure Sn layer is formed thereon, electroplating is performed at 0.1 g / L. Cu-- formed between the base material and the pure Sn layer is performed by using the Sn plating bath containing the above Sn oxide, performing cooling by cooling the air after it is melted and holding it by air cooling. The average crystal grain size of the Cu—Sn compound on the surface substantially parallel to the interface between the layers of the Sn plating layer of the Sn compound layer is 1.3 μm or more, and the arithmetic average roughness Ra of the surface of the Sn plating material is 0.15 μm. So that the electroplating The current density and the air cooling holding time are set, and the energization time of electroplating is set so that the thickness of the Sn layer formed on the substrate by electroplating is 0.8 to 1.8 μm. .

Moreover, the manufacturing method of the Sn plating material by this invention forms an Sn layer on the base material which consists of copper or a copper alloy by electroplating, and after drying the surface of Sn layer, the surface of Sn layer is heated. In the method for producing a Sn plating material, in which a Cu—Sn compound layer is formed on a base material by cooling after melting Sn, and a pure Sn layer is formed thereon, electroplating is performed at 0.1 g / L. The Sn plating bath containing the above Sn oxide is used, and the cooling after melting Sn is carried out by cooling with air and then water cooling, and the current density of electroplating is a (A / dm ² ), air cooling. When holding time b (seconds), current density and air cooling holding time are set so as to satisfy 1 ≦ a ≦ 5, 1 ≦ b ≦ 5, and b ≧ a−1.5, and formed on the substrate by electroplating. The thickness of the Sn layer will be 0.8-1.8 μm Thus, the energization time of electroplating is set.

In the method for producing the Sn plating material, it is preferable to set the energization time for electroplating so that the thickness of the Sn layer formed on the substrate by electroplating is 0.9 to 1.6 μm. Moreover, it is preferable to apply a lubricating oil to the surface after cooling after melting Sn, and the application amount of the lubricating oil is preferably 0.2 mg / dm ² or more.

  According to the present invention, an Sn plating material having a low friction coefficient and excellent solder wettability and contact reliability can be manufactured at low cost.

  In the embodiment of the Sn plating material according to the present invention, a Cu—Sn compound layer (diffusion layer) is formed on a base material made of copper or a copper alloy, and a pure Sn layer is formed on this Cu—Sn compound layer. In the Sn plating material, the thickness of the pure Sn layer is 0.3 to 1.5 μm, and the average crystal grain size of the Cu—Sn compound in a plane substantially parallel to the interface between the layers of the Sn plating material is 1.3 μm or more. And the arithmetic average roughness Ra of the surface of the Sn plating material is 0.15 μm or more.

  Thus, when the average crystal grain size of the Cu—Sn compound is grown coarsely, there is an effect of reducing the friction coefficient. When the Sn plating material is used as a material for a connection terminal that can be inserted and removed, pure Sn at the time of insertion is used. The effect of reducing the insertion force by suppressing the surface of the layer from being cut can be obtained. Further, since it is not necessary to make the pure Sn layer thin, the heat resistance and contact reliability of the Sn plating material can be maintained.

  When the average crystal grain size of the Cu—Sn compound is less than 1.3 μm, the effect of reducing the friction coefficient becomes insufficient, so the average crystal grain size of the Cu—Sn compound is 1.3 μm or more, and 1.3 to It is preferably 3 μm, and more preferably 1.5 to 2.0 μm. Moreover, when the arithmetic average roughness Ra of the surface of the Sn plating material is less than 0.15 μm, the surface roughness is insufficient, and the effect of reducing the friction coefficient becomes insufficient. The roughness Ra is 0.15 μm or more, and preferably 0.15 to 0.3 μm.

  Moreover, when the thickness of the pure Sn layer of the Sn plating material is less than 0.3 μm, the original characteristics as the Sn plating material cannot be exhibited, and when it exceeds 1.5 μm, the arithmetic average roughness of the surface of the Sn plating material Since the surface roughness Ra is less than 0.15 μm, the surface roughness is insufficient, and the effect of reducing the friction coefficient is insufficient. Therefore, the thickness of the pure Sn layer of the Sn plating material is 0.3 to 1. 5 μm, preferably 0.4 to 1.2 μm.

  The interface between the layers of the Sn plating material and the average crystal grain size of the Cu—Sn compound (the lateral length of the crystal grains of the Cu—Sn compound) in a plane substantially parallel to the interface between the layers of the Sn plating material. The ratio (vertical length / horizontal length) of the average value (vertical length of the crystal grains of the Cu-Sn compound) of the maximum height of each crystal grain of the Cu-Sn compound in the vertical cross section is 0. .5 or less is preferable. If this ratio exceeds 0.5, the effect of reducing the friction coefficient becomes insufficient, and therefore it is preferably 0.5 or less.

  In addition, in a predetermined region on a cross section substantially perpendicular to the interface between the layers of the Sn plating material, the width of each crystal grain of the Cu—Sn compound (the length in a direction substantially parallel to the interface between the layers) is 0. The ratio of coarse crystal grains to the sum of fine crystal grains and coarse crystal grains is ΣRy × 100 / (, where ΣRx is the number of fine crystal grains of 0.7 μm or less and ΣRy is the number of coarse crystal grains of 1.3 μm or greater. (ΣRx + ΣRy) is preferably 25 to 60%. When the presence ratio of the coarse crystal grains is less than 25% or exceeds 60%, the Cu—Sn compound crystal grains are arranged substantially uniformly, and the effect of reducing the friction coefficient is insufficient. The proportion of coarse crystal grains is preferably 25 to 60%, and more preferably 30 to 50%.

Moreover, it is preferable that the lubricating oil is applied to the surface of the pure Sn layer of the Sn plating material, and the applied amount of the lubricating oil is preferably 0.2 mg / dm ² or more. Thus, when lubricating oil is applied to the surface of the Sn layer of the Sn plating material, the lubricating oil is held in the concavo-convex structure on the surface of the pure Sn layer formed by the coarsening of the crystal grains of the Cu-Sn compound of the Sn plating material. Thus, although the effect of further reducing the friction coefficient of the Sn plating material can be obtained, the effect cannot be sufficiently exhibited when the amount of the lubricating oil applied is less than 0.2 mg / dm ² .

  Moreover, in embodiment of the manufacturing method of Sn plating material by this invention, after forming Sn layer on the base material which consists of copper or a copper alloy by electroplating, and drying the surface of Sn layer, the surface of Sn layer In the method for producing a Sn plating material, a Cu—Sn compound layer is formed on a base material and then a pure Sn layer is formed on the substrate by cooling Sn after melting Sn and electroplating. . Performed by using Sn plating bath containing Sn oxide of 1 g / L or more, and after cooling Sn after cooling with air and then cooling with water to form between substrate and pure Sn layer The average crystal grain size of the Cu-Sn compound in a surface substantially parallel to the interface between the layers of the Sn plating material of the Cu-Sn compound layer is 1.3 μm or more, and the arithmetic average roughness Ra of the surface of the Sn plating material To be over 0.15 μm The current density and air cooling holding time of electroplating are set, and the thickness of the Sn layer formed on the substrate by electroplating (the electrodeposition thickness of the Sn plating layer) is 0.8 to 1.8 μm. Set the energization time for electroplating.

Specifically, an Sn layer is formed on a base material made of copper or a copper alloy by electroplating, the surface of the Sn layer is dried, the surface of the Sn layer is heated to melt Sn, and then cooled. In the manufacturing method of Sn plating material which forms a Cu-Sn compound layer on a base material and forms a pure Sn layer on it by this, electroplating is Sn containing 0.1 g / L or more of Sn oxide When using a plating bath, cooling after melting Sn is held by air cooling and then water cooling, and the current density of electroplating is a (A / dm ² ) and air cooling holding time b (seconds). 1 ≦ a ≦ 5, 1 ≦ b ≦ 5, b ≧ a−1.5 so that the current density and air cooling holding time are set, and the thickness of the Sn layer formed on the substrate by electroplating is Set the electroplating energization time so that it becomes 0.8-1.8μm The

  The Sn plating bath contains 0.1 g / L or more of Sn oxide, and preferably contains 0.2 g / L or more of Sn oxide. When Sn plating bath contains Sn oxide, Sn oxide is involved in the inside, surface and grain boundary of Sn crystal during electroplating, and Sn electrodeposition is inhibited by the presence of Sn oxide, Since Sn electrodeposition is nucleated non-uniformly, crystal grains of electrodeposited Sn can be generated coarsely and non-uniformly. Further, the Sn plating bath contains tin sulfate, and Sn oxide is produced in the Sn plating bath by blowing air into the Sn plating bath or by stirring or circulating the Sn plating bath and contacting with the atmosphere. preferable.

When the current density is higher than 5 A / dm ² , Sn electrodeposition is uniformly nucleated, so that the crystal grains of electrodeposited Sn grow finely and uniformly, but the current density is 1 to 5 A / dm ² , preferably 1 If it is set to 0.5 to 3 A / dm ² , Sn electrodeposition is nucleated non-uniformly, so that the crystal grains of electrodeposited Sn can be generated coarsely and non-uniformly.

  Further, when the air cooling holding time is longer than 5 seconds, the crystal grain size of the Cu—Sn compound becomes too coarse and exceeds 5 μm, the grain boundary is reduced and the surface roughness of the Sn plating material becomes too small. Since the ratio of the presence of grains becomes too small and the effect of reducing the friction coefficient becomes insufficient, the air-cooling holding time is used to appropriately coarsen the crystal grain size of the Cu-Sn compound and to generate it nonuniformly. Is 1-5 seconds, preferably 2-4 seconds.

  In addition, the reflow process (Sn melting process) of Sn plating material can be performed by hold | maintaining Sn plating material at 235-280 degreeC, Preferably it is 245-270 degreeC for 10 to 20 seconds.

  In the above Sn plating material manufacturing method, when the thickness of the Sn layer formed by electroplating (electrodeposition thickness) is greater than 1.8 μm, the Sn plating material can be adjusted even if the current density and air cooling holding time are adjusted. Since the arithmetic average roughness Ra of the surface cannot be 0.15 μm or more, the thickness of the Sn layer formed by electroplating is set to 0.8 to 1.8 μm, and 0.9 to 1.6 μm. Is preferred.

Moreover, in embodiment of the manufacturing method of said Sn plating material, after making Sn cool, after cooling, it is preferable to apply | coat lubricating oil to the surface, and the application quantity of lubricating oil is 0.2 mg / dm < ² > or more Is preferred. In order to further reduce the friction coefficient of the Sn plating material, it is preferable that the lubricating oil is applied to the surface of the Sn layer. However, when the applied amount of the lubricating oil is less than 0.2 mg / dm ² , the effect is sufficiently obtained. I can't demonstrate it.

  Hereinafter, examples of the Sn plating material and the manufacturing method thereof according to the present invention will be described in detail.

[Example 1]
First, as a material (material to be plated), a pure copper plate having a Vickers hardness of 105 (measured with a test load of 0.5 kgf using a Vickers hardness meter manufactured by Mitutoyo Corporation) and having a length of 100 mm × width of 60 mm × thickness of 0.4 mm (Oxygen-free copper C1020) was prepared and washed as a pretreatment after electrolytic degreasing and then pickled and then washed with water.

In addition, air is supplied at a flow rate of 1 L / min to 1 L of an aqueous solution containing Sn (SnSO ₄ ) 60 g / L, 75 g / L sulfuric acid (H ₂ SO ₄ ), 30 g / L cresolsulfonic acid, and 1 g / L β-naphthol. An Sn plating bath was prepared by blowing for 30 minutes to produce 0.2 g / L of Sn oxide. Note that it was confirmed by an electron beam microanalyzer (EPMA) that the generated substance was a substance composed of Sn and oxygen (O) (a mixture of SnO and SnO ₂ ). The amount of Sn oxide produced in the Sn plating bath is adjusted to the amount of air blown (L / min) and the time of blowing (min) to produce Sn oxide, and then filtered paper (GAV manufactured by ADVANTEC). The solid content in the liquid was collected by filtration through −100 (retained particle diameter: 1.0 mm), dried by a fan for 24 hours, and quantified by measuring the weight.

Next, the pre-processed material and the Sn plate are separated by 100 mm and placed in a 2 L beaker, the above Sn plating bath 1 L is placed in the beaker, the stirrer in the beaker is rotated at 300 rpm, and the Sn plating bath is stirred. The temperature of the liquid was controlled at 20 ° C., and the material and the Sn plate were respectively used as a cathode and an anode, and a current density of 3 A / dm ² was applied for 50 seconds. Formed.

  The Sn plating material in which the Sn plating layer was formed on the material in this manner was washed with water and the surface of the Sn plating material was dried, and then the Sn plating material was reflowed (Sn melting treatment). In this reflow treatment, the Sn plating material is heated at 250 ° C. for 10 seconds in an air atmosphere by a near infrared heater (manufactured by HYBEC) to melt the surface of the Sn plating layer, and then the near infrared heater is stopped for 2 seconds. By maintaining in an air atmosphere, it was kept air-cooled, and immediately after that, it was immersed in a water bath at a temperature of 20 ° C. and cooled.

  In addition, about the Sn plating material before a reflow process, the thickness (electrodeposition thickness) of Sn plating layer was measured and the crystal grain size of electrodeposition Sn was calculated | required. The thickness (electrodeposition thickness) of the Sn plating layer was measured using a fluorescent X-ray film thickness meter (manufactured by Seiko Instruments Inc.), and the crystal grain size of electrodeposited Sn was measured by an electron beam microanalyzer (EPMA). Using the obtained secondary electron image (SEI), the surface of the Sn plating layer was magnified 5000 times and determined according to the cutting method of JIS H0501. As a result, the electrodeposition thickness was 1.0 μm, and the crystal grain size of electrodeposited Sn was 1.3 μm.

  Table 1 shows the manufacturing conditions for the Sn-plated material after the reflow treatment thus prepared, the electrodeposition thickness of the Sn-plated layer of the Sn-plated material before the reflow treatment, and the crystal grain size of the electrodeposited Sn.

  Moreover, about the Sn plating material after a reflow process, the thickness of the pure Sn layer and the thickness of the Cu-Sn compound layer were measured. The thickness of the pure Sn layer was measured using an electrolytic film thickness meter (TH11 manufactured by Chuo Seisakusho) according to the electrolytic test method of JIS H8501. Further, the thickness of the Cu—Sn compound layer is measured using an electrolytic film thickness meter in the same manner as the pure Sn layer, and the value displayed by measuring again after the measurement of the thickness of the pure Sn layer is expressed as Cu. -The thickness of the Sn compound layer. As a result, the thickness of the pure Sn layer was 0.7 μm, and the thickness of the Cu—Sn compound layer was 0.8 μm. A focused ion beam (FIB) is used to expose a cross section that is substantially perpendicular to the surface of the Sn plating material (a cross section that is substantially perpendicular to the interface between the layers of the Sn plating material) and to observe the cross section with a scanning ion microscope (SIM). As a result, the thicknesses of the pure Sn layer and the Cu—Sn compound layer were both the same as the thickness measured by the electrolytic film thickness meter.

  Further, for the Sn plating material after the reflow treatment, a surface substantially parallel to the surface of the Sn plating material (substantially the interface between each layer of the Sn plating material) by dissolving the pure Sn layer using the electrolytic film thickness meter. The Cu—Sn compound layer is exposed on a parallel plane, and the surface is observed with a scanning ion microscope (SIM) at a magnification of 5000 times, and the average crystal grain size of the Cu—Sn compound is determined according to the cutting method of JIS H0501. Asked. As a result, the average crystal grain size of the Cu—Sn compound was 1.6 μm.

  Further, for the Sn plating material after the reflow treatment, a focused ion beam (FIB) is used to expose a cross section substantially perpendicular to the surface of the Sn plating material (a cross section substantially perpendicular to the interface between the layers of the Sn plating material), Cross-section observation is performed with a scanning ion microscope (SIM) at a magnification of 2000 times, and each crystal grain of the Cu—Sn compound is observed in a 60 μm long region in a direction substantially parallel to the interface between the layers of the Sn plating material. The width (the length in the direction substantially parallel to the interface between each layer) is measured, and the number of fine crystal grains whose width is 0.7 μm or less is ΣRx, and the number of coarse crystal grains of 1.3 μm or more is ΣRy. The ratio (%) of the presence of coarse crystal grains to the sum of crystal grains and coarse crystal grains was calculated from ΣRy × 100 / (ΣRx + ΣRy). As a result, 39 ΣRx and 21 ΣRy were present, and the abundance ratio ΣRy × 100 / (ΣRx + ΣRy) of the coarse crystal grains of the Cu—Sn compound was 35%.

  Further, for the Sn plating material after the reflow treatment, a focused ion beam (FIB) is used to expose a cross section substantially perpendicular to the surface of the Sn plating material (a cross section substantially perpendicular to the interface between the layers of the Sn plating material), The cross-section is observed with a scanning ion microscope (SIM) at a magnification of 5000 times, and in the region of 20 μm in length in a direction substantially parallel to the interface between the Sn plating materials, the interface between the Sn plating materials is approximately The maximum height of each crystal grain of the Cu—Sn compound in the vertical direction was measured, and the average value of the maximum heights of all the crystal grains was defined as the vertical length of the crystal grains of the Cu—Sn compound. On the other hand, with respect to the Sn plating material after the reflow treatment, the Cu—Sn compound layer is exposed on a surface substantially parallel to the surface of the Sn plating material (a surface substantially parallel to the interface between the layers of the Sn plating material), and a scanning ion microscope ( The surface was observed with a magnification of 5000 times by SIM), and the average crystal grain size determined according to the cutting method of JIS H0501 was defined as the lateral length of the Cu-Sn compound crystal grains. When the aspect ratio (vertical length / horizontal length) of the crystal grains of the Cu-Sn compound was calculated from the vertical length and the horizontal length of the Cu-Sn compound crystal grains thus determined, It was 0.35.

  Further, as the surface roughness of the Sn-plated material after the reflow treatment, the arithmetic average roughness (which is a parameter representing the surface roughness) according to JIS B0601 from the measurement result by an ultra-deep microscope (VK-8500 manufactured by KEYENCE). Ra was calculated. As a result, the arithmetic average roughness Ra was 0.15 μm.

These results are shown in Table 2.

  Moreover, the surface friction coefficient was calculated about the Sn plating material after a reflow process, and the contact reliability after leaving at high temperature was evaluated.

  The friction coefficient (μ) is obtained by indenting (R = 1.5 mm) one of the two flat test pieces cut out from the Sn-plated material after the reflow treatment to form a convex indenter. Using the test piece as the base-side evaluation sample, using a load cell, the indenter was slid 7 mm at a moving speed of 60 mm / min while pressing the indenter against the surface of the evaluation sample with a load of 300 gf. The average value (F) of the force applied in the horizontal direction was measured and divided by the applied load (N), and calculated from μ = F / N. As a result, the friction coefficient was 0.18.

  The evaluation of solder wettability was performed by using a tester having a width of 10 mm and a length of 60 mm punched out from the Sn-plated material after reflow treatment at 85 ° C. using a solder checker (SAT-5200 manufactured by Reska Co., Ltd.). After being left in an environment of 85% humidity for 24 hours, an inactive flux is applied and immersed in a Pb-free solder (Sn-3 mass% Ag-0.5 mass% Cu) bath at a rate of 4 mm / s. Then, by immersing a 4 mm long portion for 10 seconds and observing the appearance of the plated surface, the area of the portion wetted by the solder (solder wetting ratio) relative to the surface area immersed in the solder of the test piece was obtained. As a result, the solder wettability was 98% and the solder wettability was good.

  Evaluation of contact reliability after leaving at high temperature is carried out by holding a test piece cut out from the Sn-plated material after the reflow treatment in a constant temperature bath at 120 ° C. for 120 hours in an air atmosphere and then taking it out from the constant temperature bath, and then measuring the chamber at 20 ° C. The contact resistance value on the surface of the test piece (contact resistance value after standing at high temperature) was measured. The contact resistance value was measured using a micro-ohm meter (manufactured by Yamazaki Seiki Laboratory Co., Ltd.), an open-circuit voltage of 20 mV, a current of 10 mA, a U-shaped wire probe with a diameter of 0.5 mm, a maximum load of 100 gf, and sliding ( Measurement was performed 5 times under the condition of 1 mm / 100 gf) to obtain an average value (when a maximum load of 100 gf was applied). As a result, the contact resistance value after standing at high temperature was 1.2 mΩ, and the contact reliability was good.

  These results are shown in Table 3. In Table 4, the case where the solder wettability is 90% or more and the solder wettability is good is indicated by ◯, the case where the solder wettability is less than 90% and the solder wettability is not good is indicated by x, and the contact resistance after being left at high temperature The case where the value is 2 mΩ or less and the contact reliability is good is indicated by ◯, and the case where the contact resistance value after standing at high temperature is higher than 2 mΩ and the contact reliability is not good is indicated by x.

[Example 2]
A Sn plating material after reflow treatment was produced in the same manner as in Example 1 except that the current density was 2 seconds at a current density of 2 A / dm ² and the air cooling holding time after heating and melting the Sn plating layer was 1 second. . In addition, when the electrodeposition thickness of the Sn plating layer of the Sn plating material before the reflow treatment was measured and the grain size of the electrodeposited Sn was determined by the same method as in Example 1, the electrodeposition thickness was 1. The crystal grain size of 0 μm and electrodeposited Sn was 1.6 μm. Table 1 shows the manufacturing conditions of the Sn plating material after the reflow treatment thus prepared, the electrodeposition thickness of the Sn plating layer before the reflow treatment, and the crystal grain size of the electrodeposited Sn.

  Moreover, about the Sn plating material after a reflow process, the thickness of a pure Sn layer and the thickness of a Cu-Sn compound layer are measured by the method similar to Example 1, and the average crystal grain diameter of a Cu-Sn compound is calculated | required. The ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) is calculated from the number of fine crystal grains ΣRx and the number of coarse crystal grains ΣRy of the Cu—Sn compound, and the aspect ratio of the crystal grains of the Cu—Sn compound is calculated. The arithmetic average roughness Ra of the surface of the Sn plating material was calculated. As a result, the thickness of the pure Sn layer was 0.6 μm, the thickness of the Cu—Sn compound layer was 0.9 μm, and the average crystal grain size of the Cu—Sn compound was 1.5 μm. The number of fine crystal grains ΣRx of the Cu—Sn compound was 22, the number of coarse crystal grains ΣRy was 22, and the existence ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) was 50%. Moreover, the aspect ratio of the crystal grain of the Cu-Sn compound was 0.45, and the arithmetic average roughness Ra of the surface of the Sn plating material was 0.21. These results are shown in Table 2.

  Further, for the Sn plated material after the reflow treatment, the surface friction coefficient was calculated by the same method as in Example 1, and the solder wettability and the contact reliability after being left at high temperature were evaluated. As a result, the coefficient of friction was 0.20, the solder wettability was 95%, the solder wettability was good, the contact resistance value after standing at high temperature was 0.8 mΩ, and the contact reliability was good. These results are shown in Table 3.

[Example 3]
Air is flown for 150 minutes at a flow rate of 1 L / min into a 1 L aqueous solution containing 60 g / L of Sn (SnSO ₄ ) sulfate, 75 g / L of sulfuric acid (H ₂ SO ₄ ), 30 g / L of cresolsulfonic acid and 1 g / L of β-naphthol. A Sn plating bath was produced by blowing to produce 1.0 g / L of Sn oxide, energized for 30 seconds at a current density of 5 A / dm ² , and the air cooling holding time after heating and melting the Sn plating layer was set to 4 seconds. Except for the above, an Sn plated material after the reflow treatment was produced in the same manner as in Example 1. In addition, when the electrodeposition thickness of the Sn plating layer of the Sn plating material before the reflow treatment was measured and the grain size of the electrodeposited Sn was determined by the same method as in Example 1, the electrodeposition thickness was 1. The crystal grain size of 0 μm and electrodeposited Sn was 1.0 μm. Table 1 shows the manufacturing conditions of the Sn plating material after the reflow treatment thus prepared, the electrodeposition thickness of the Sn plating layer before the reflow treatment, and the crystal grain size of the electrodeposited Sn.

  Moreover, about the Sn plating material after a reflow process, the thickness of a pure Sn layer and the thickness of a Cu-Sn compound layer are measured by the method similar to Example 1, and the average crystal grain diameter of a Cu-Sn compound is calculated | required. The ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) is calculated from the number of fine crystal grains ΣRx and the number of coarse crystal grains ΣRy of the Cu—Sn compound, and the aspect ratio of the crystal grains of the Cu—Sn compound is calculated. The arithmetic average roughness Ra of the surface of the Sn plating material was calculated. As a result, the thickness of the pure Sn layer was 0.5 μm, the thickness of the Cu—Sn compound layer was 1.1 μm, and the average crystal grain size of the Cu—Sn compound was 2.1 μm. The number of fine crystal grains ΣRx of the Cu—Sn compound was 42, the number of coarse crystal grains ΣRy was 15, and the presence ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) was 25%. Moreover, the aspect ratio of the crystal grain of the Cu-Sn compound was 0.30, and the arithmetic mean roughness Ra of the surface of the Sn plating material was 0.19. These results are shown in Table 2.

  Further, for the Sn plated material after the reflow treatment, the surface friction coefficient was calculated by the same method as in Example 1, and the solder wettability and the contact reliability after being left at high temperature were evaluated. As a result, the coefficient of friction was 0.21, the solder wettability was 97%, and the solder wettability was good. The contact resistance value after standing at high temperature was 1.4 mΩ, and the contact reliability was good. These results are shown in Table 3.

[Example 4]
A Sn-plated material after reflow treatment was produced in the same manner as in Example 1 except that the energization time was 75 seconds. In addition, when the electrodeposition thickness of the Sn plating layer of the Sn plating material before the reflow treatment was measured and the grain size of the electrodeposited Sn was determined by the same method as in Example 1, the electrodeposition thickness was 1. The crystal grain size of 5 μm and electrodeposited Sn was 1.3 μm. Table 1 shows the manufacturing conditions of the Sn plating material after the reflow treatment thus prepared, the electrodeposition thickness of the Sn plating layer before the reflow treatment, and the crystal grain size of the electrodeposited Sn.

  Moreover, about the Sn plating material after a reflow process, the thickness of a pure Sn layer and the thickness of a Cu-Sn compound layer are measured by the method similar to Example 1, and the average crystal grain diameter of a Cu-Sn compound is calculated | required. The ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) is calculated from the number of fine crystal grains ΣRx and the number of coarse crystal grains ΣRy of the Cu—Sn compound, and the aspect ratio of the crystal grains of the Cu—Sn compound is calculated. The arithmetic average roughness Ra of the surface of the Sn plating material was calculated. As a result, the thickness of the pure Sn layer was 1.0 μm, the thickness of the Cu—Sn compound layer was 1.0 μm, and the average crystal grain size of the Cu—Sn compound was 1.6 μm. The number of fine crystal grains ΣRx of the Cu—Sn compound was 37, the number of coarse crystal grains ΣRy was 20, and the existence ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) was 35%. Moreover, the aspect ratio of the crystal grain of the Cu-Sn compound was 0.40, and the arithmetic average roughness Ra of the surface of the Sn plating material was 0.17. These results are shown in Table 2.

  Further, for the Sn plated material after the reflow treatment, the surface friction coefficient was calculated by the same method as in Example 1, and the solder wettability and the contact reliability after being left at high temperature were evaluated. As a result, the coefficient of friction was 0.18, the solder wettability was 94%, the solder wettability was good, the contact resistance value after standing at high temperature was 0.8 mΩ, and the contact reliability was good. These results are shown in Table 3.

[Examples 5 to 6]
On the surface of the Sn plating material after the reflow treatment, lubricating oil (Unipress PA5 manufactured by JX Nippon Mining & Energy Co., Ltd.) used for plastic working such as pressing and cutting is 0.2 mg / dm ² (Example 5). ) And 20 mg / dm ² (Example 6) An Sn plated material after reflow treatment and lubricant application was produced by the same method as in Example 1 except that it was applied. In addition, when the electrodeposition thickness of the Sn plating layer of the Sn plating material before the reflow treatment was measured and the grain size of the electrodeposited Sn was determined by the same method as in Example 1, the electrodeposition thickness was 1. The crystal grain size of 0 μm and electrodeposited Sn was 1.3 μm. Table 1 shows the manufacturing conditions of the Sn-plated material after the reflow treatment and lubricant application thus prepared, the electrodeposition thickness of the Sn plating layer before the reflow treatment, and the crystal grain size of the electrodeposited Sn.

  Further, with respect to the Sn plating material after the reflow treatment and the lubricant application, the thickness of the pure Sn layer and the thickness of the Cu—Sn compound layer were measured by the same method as in Example 1, and the average crystal of the Cu—Sn compound was measured. The grain size is obtained, the abundance ratio ΣRy × 100 / (ΣRx + ΣRy) of the coarse crystal grains is calculated from the number ΣRx of the fine crystal grains of the Cu—Sn compound and the number ΣRy of the coarse crystal grains. The ratio was calculated, and the arithmetic average roughness Ra of the surface of the Sn plating material was calculated. As a result, the thickness of the pure Sn layer was 0.7 μm, the thickness of the Cu—Sn compound layer was 0.8 μm, and the average crystal grain size of the Cu—Sn compound was 1.6 μm. Further, the number of fine crystal grains ΣRx of the Cu—Sn compound was 39, the number of coarse crystal grains ΣRy was 21, and the existence ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) was 15%. Moreover, the aspect ratio of the crystal grain of the Cu-Sn compound was 0.35, and the arithmetic average roughness Ra of the surface of the Sn plating material was 0.15. These results are shown in Table 2.

  For the Sn plating material after reflow treatment and lubricant application, the surface friction coefficient was calculated by the same method as in Example 1, and the solder wettability and the contact reliability after being left at high temperature were evaluated. As a result, the coefficient of friction was 0.12, the solder wettability was 93% and the solder wettability was good, the contact resistance value after standing at high temperature was 1.3 mΩ, and the contact reliability was good. These results are shown in Table 3.

[Comparative Example 1]
A Sn-plated material after the reflow treatment was produced in the same manner as in Example 1 except that the energization time was set to 35 seconds. In addition, when the electrodeposition thickness of the Sn plating layer of the Sn plating material before the reflow treatment was measured by the same method as in Example 1 and the grain size of the electrodeposited Sn was determined, the electrodeposition thickness was 0. The crystal grain size of 7 μm and electrodeposited Sn was 1.3 μm. Table 1 shows the manufacturing conditions of the Sn plating material after the reflow treatment thus prepared, the electrodeposition thickness of the Sn plating layer before the reflow treatment, and the crystal grain size of the electrodeposited Sn.

  Moreover, about the Sn plating material after a reflow process, the thickness of a pure Sn layer and the thickness of a Cu-Sn compound layer are measured by the method similar to Example 1, and the average crystal grain diameter of a Cu-Sn compound is calculated | required. The ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) is calculated from the number of fine crystal grains ΣRx and the number of coarse crystal grains ΣRy of the Cu—Sn compound, and the aspect ratio of the crystal grains of the Cu—Sn compound is calculated. The arithmetic average roughness Ra of the surface of the Sn plating material was calculated. As a result, the thickness of the pure Sn layer was 0.1 μm, the thickness of the Cu—Sn compound layer was 0.8 μm, and the average crystal grain size of the Cu—Sn compound was 1.6 μm. The number of fine crystal grains ΣRx of the Cu—Sn compound was 42, the number of coarse crystal grains ΣRy was 14, and the existence ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) was 15%. Moreover, the aspect ratio of the crystal grain of the Cu-Sn compound was 0.40, and the arithmetic average roughness Ra of the surface of the Sn plating material was 0.15. These results are shown in Table 2.

  Further, for the Sn plated material after the reflow treatment, the surface friction coefficient was calculated by the same method as in Example 1, and the solder wettability and the contact reliability after being left at high temperature were evaluated. As a result, the coefficient of friction was 0.18, the solder wettability was 85%, the solder wettability was not good, the contact resistance value after standing at high temperature was 3.7 mΩ, and the contact reliability was not good. These results are shown in Table 3.

[Comparative Example 2]
A Sn plating material after reflow treatment was produced in the same manner as in Example 1 except that the current density was 5 A / dm ² and the current was passed for 30 seconds, and the air cooling holding time after heating and melting the Sn plating layer was 1 second. . In addition, when the electrodeposition thickness of the Sn plating layer of the Sn plating material before the reflow treatment was measured and the grain size of the electrodeposited Sn was determined by the same method as in Example 1, the electrodeposition thickness was 1. The crystal grain size of 0 μm and electrodeposited Sn was 1.0 μm. Table 1 shows the manufacturing conditions of the Sn plating material after the reflow treatment thus prepared, the electrodeposition thickness of the Sn plating layer before the reflow treatment, and the crystal grain size of the electrodeposited Sn.

  Moreover, about the Sn plating material after a reflow process, the thickness of a pure Sn layer and the thickness of a Cu-Sn compound layer are measured by the method similar to Example 1, and the average crystal grain diameter of a Cu-Sn compound is calculated | required. The ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) is calculated from the number of fine crystal grains ΣRx and the number of coarse crystal grains ΣRy of the Cu—Sn compound, and the aspect ratio of the crystal grains of the Cu—Sn compound is calculated. The arithmetic average roughness Ra of the surface of the Sn plating material was calculated. As a result, the thickness of the pure Sn layer was 0.6 μm, the thickness of the Cu—Sn compound layer was 0.8 μm, and the average crystal grain size of the Cu—Sn compound was 1.1 μm. The number of fine crystal grains ΣRx of the Cu—Sn compound was 19, the number of coarse crystal grains ΣRy was 1, and the existence ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) was 5%. Further, the aspect ratio of the crystal grains of the Cu—Sn compound was 0.65, and the arithmetic average roughness Ra of the surface of the Sn plating material was 0.08. These results are shown in Table 2.

  Further, for the Sn plated material after the reflow treatment, the surface friction coefficient was calculated by the same method as in Example 1, and the solder wettability and the contact reliability after being left at high temperature were evaluated. As a result, the coefficient of friction was 0.36, the solder wettability was 75% and the solder wettability was good, the contact resistance value after standing at high temperature was 1.5 mΩ, and the contact reliability was good. These results are shown in Table 3.

[Comparative Example 3]
A Sn plating material after reflow treatment was produced in the same manner as in Example 1 except that the current density was 4 A / dm ² for 37 seconds and the air cooling holding time after heating and melting the Sn plating layer was 1 second. . In addition, when the electrodeposition thickness of the Sn plating layer of the Sn plating material before the reflow treatment was measured and the grain size of the electrodeposited Sn was determined by the same method as in Example 1, the electrodeposition thickness was 1. The crystal grain size of 0 μm and electrodeposited Sn was 1.3 μm. Table 1 shows the manufacturing conditions of the Sn plating material after the reflow treatment thus prepared, the electrodeposition thickness of the Sn plating layer before the reflow treatment, and the crystal grain size of the electrodeposited Sn.

  Moreover, about the Sn plating material after a reflow process, the thickness of a pure Sn layer and the thickness of a Cu-Sn compound layer are measured by the method similar to Example 1, and the average crystal grain diameter of a Cu-Sn compound is calculated | required. The ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) is calculated from the number of fine crystal grains ΣRx and the number of coarse crystal grains ΣRy of the Cu—Sn compound, and the aspect ratio of the crystal grains of the Cu—Sn compound is calculated. The arithmetic average roughness Ra of the surface of the Sn plating material was calculated. As a result, the thickness of the pure Sn layer was 0.7 μm, the thickness of the Cu—Sn compound layer was 1.0 μm, and the average crystal grain size of the Cu—Sn compound was 1.5 μm. The number of fine crystal grains ΣRx of the Cu—Sn compound was 39, the number of coarse crystal grains ΣRy was 21, and the existence ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) was 35%. Moreover, the aspect ratio of the crystal grain of the Cu-Sn compound was 0.40, and the arithmetic average roughness Ra of the surface of the Sn plating material was 0.09. These results are shown in Table 2.

  Further, for the Sn plated material after the reflow treatment, the surface friction coefficient was calculated by the same method as in Example 1, and the solder wettability and the contact reliability after being left at high temperature were evaluated. As a result, the coefficient of friction was 0.35, the solder wettability was 95%, the solder wettability was good, the contact resistance value after standing at high temperature was 1.5 mΩ, and the contact reliability was good. These results are shown in Table 3.

[Comparative Example 4]
An Sn plated material after the reflow treatment was produced in the same manner as in Example 1 except that the energization time was 37 seconds. In addition, when the electrodeposition thickness of the Sn plating layer of the Sn plating material before the reflow treatment was measured and the grain size of the electrodeposited Sn was determined by the same method as in Example 1, the electrodeposition thickness was 2. The crystal grain size of 0 μm and electrodeposited Sn was 1.3 μm. Table 1 shows the manufacturing conditions of the Sn plating material after the reflow treatment thus prepared, the electrodeposition thickness of the Sn plating layer before the reflow treatment, and the crystal grain size of the electrodeposited Sn.

  Moreover, about the Sn plating material after a reflow process, the thickness of a pure Sn layer and the thickness of a Cu-Sn compound layer are measured by the method similar to Example 1, and the average crystal grain diameter of a Cu-Sn compound is calculated | required. The ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) is calculated from the number of fine crystal grains ΣRx and the number of coarse crystal grains ΣRy of the Cu—Sn compound, and the aspect ratio of the crystal grains of the Cu—Sn compound is calculated. The arithmetic average roughness Ra of the surface of the Sn plating material was calculated. As a result, the thickness of the pure Sn layer was 1.4 μm, the thickness of the Cu—Sn compound layer was 1.2 μm, and the average crystal grain size of the Cu—Sn compound was 1.6 μm. The number of fine crystal grains ΣRx of the Cu—Sn compound was 37, the number of coarse crystal grains ΣRy was 20, and the existence ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) was 35%. Moreover, the aspect ratio of the crystal grain of the Cu-Sn compound was 0.45, and the arithmetic average roughness Ra of the surface of the Sn plating material was 0.12. These results are shown in Table 2.

  Further, for the Sn plated material after the reflow treatment, the surface friction coefficient was calculated by the same method as in Example 1, and the solder wettability and the contact reliability after being left at high temperature were evaluated. As a result, the coefficient of friction was 0.40, the solder wettability was 94%, the solder wettability was good, the contact resistance value after standing at high temperature was 0.7 mΩ, and the contact reliability was good. These results are shown in Table 3.

[Comparative Example 5]
An Sn-plated material after the reflow treatment was produced in the same manner as in Example 1 except that the air-cooled holding time after heating and melting the Sn plating layer was 1 second. In addition, when the electrodeposition thickness of the Sn plating layer of the Sn plating material before the reflow treatment was measured and the grain size of the electrodeposited Sn was determined by the same method as in Example 1, the electrodeposition thickness was 1. The crystal grain size of 0 μm and electrodeposited Sn was 1.3 μm. Table 1 shows the manufacturing conditions of the Sn plating material after the reflow treatment thus prepared, the electrodeposition thickness of the Sn plating layer before the reflow treatment, and the crystal grain size of the electrodeposited Sn.

  Moreover, about the Sn plating material after a reflow process, the thickness of a pure Sn layer and the thickness of a Cu-Sn compound layer are measured by the method similar to Example 1, and the average crystal grain diameter of a Cu-Sn compound is calculated | required. The ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) is calculated from the number of fine crystal grains ΣRx and the number of coarse crystal grains ΣRy of the Cu—Sn compound, and the aspect ratio of the crystal grains of the Cu—Sn compound is calculated. The arithmetic average roughness Ra of the surface of the Sn plating material was calculated. As a result, the thickness of the pure Sn layer was 0.7 μm, the thickness of the Cu—Sn compound layer was 0.8 μm, and the average crystal grain size of the Cu—Sn compound was 1.1 μm. Further, the number of fine crystal grains ΣRx of the Cu—Sn compound was 38, the number of coarse crystal grains ΣRy was 2, and the existence ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) was 5%. Moreover, the aspect ratio of the crystal grain of the Cu-Sn compound was 0.60, and arithmetic mean roughness Ra of the surface of Sn plating material was 0.19. These results are shown in Table 2.

  Further, for the Sn plated material after the reflow treatment, the surface friction coefficient was calculated by the same method as in Example 1, and the solder wettability and the contact reliability after being left at high temperature were evaluated. As a result, the coefficient of friction was 0.34, the solder wettability was 93% and the solder wettability was good, the contact resistance value after standing at high temperature was 1.7 mΩ, and the contact reliability was good. These results are shown in Table 3.

[Comparative Example 6]
Except that the surface of the Sn-plated material after the reflow treatment was coated with 0.2 mg / dm ² of lubricating oil (Unipress PA5 manufactured by JX Nippon Oil & Energy Corporation) used for plastic processing such as pressing and cutting. By the same method as in Example 2, a Sn plating material after reflow treatment and application of lubricating oil was produced. In addition, when the electrodeposition thickness of the Sn plating layer of the Sn plating material before the reflow treatment was measured and the grain size of the electrodeposited Sn was determined by the same method as in Example 1, the electrodeposition thickness was 1. The crystal grain size of 0 μm and electrodeposited Sn was 1.0 μm. Table 1 shows the manufacturing conditions of the Sn-plated material after the reflow treatment and lubricant application thus prepared, the electrodeposition thickness of the Sn plating layer before the reflow treatment, and the crystal grain size of the electrodeposited Sn.

  Further, with respect to the Sn plating material after the reflow treatment and the lubricant application, the thickness of the pure Sn layer and the thickness of the Cu—Sn compound layer were measured by the same method as in Example 1, and the average crystal of the Cu—Sn compound was measured. The grain size is obtained, the abundance ratio ΣRy × 100 / (ΣRx + ΣRy) of the coarse crystal grains is calculated from the number ΣRx of the fine crystal grains of the Cu—Sn compound and the number ΣRy of the coarse crystal grains. The ratio was calculated, and the arithmetic average roughness Ra of the surface of the Sn plating material was calculated. As a result, the thickness of the pure Sn layer was 0.6 μm, the thickness of the Cu—Sn compound layer was 0.8 μm, and the average crystal grain size of the Cu—Sn compound was 1.1 μm. The number of fine crystal grains ΣRx of the Cu—Sn compound was 19, the number of coarse crystal grains ΣRy was 1, and the existence ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) was 5%. Further, the aspect ratio of the crystal grains of the Cu—Sn compound was 0.65, and the arithmetic average roughness Ra of the surface of the Sn plating material was 0.08. These results are shown in Table 2.

  For the Sn plating material after reflow treatment and lubricant application, the surface friction coefficient was calculated by the same method as in Example 1, and the solder wettability and the contact reliability after being left at high temperature were evaluated. As a result, the coefficient of friction was 0.26, the solder wettability was 95% and the solder wettability was good, the contact resistance value after standing at high temperature was 0.9 mΩ, and the contact reliability was good. These results are shown in Table 3.

[Comparative Example 7]
An Sn-plated material after the reflow treatment was produced in the same manner as in Example 3 except that the air-cooled holding time after heating and melting the Sn plating layer was 1 second. In addition, when the electrodeposition thickness of the Sn plating layer of the Sn plating material before the reflow treatment was measured and the grain size of the electrodeposited Sn was determined by the same method as in Example 1, the electrodeposition thickness was 1. The crystal grain size of 0 μm and electrodeposited Sn was 1.0 μm. Table 1 shows the manufacturing conditions of the Sn plating material after the reflow treatment thus prepared, the electrodeposition thickness of the Sn plating layer before the reflow treatment, and the crystal grain size of the electrodeposited Sn.

  Moreover, about the Sn plating material after a reflow process, the thickness of a pure Sn layer and the thickness of a Cu-Sn compound layer are measured by the method similar to Example 1, and the average crystal grain diameter of a Cu-Sn compound is calculated | required. The ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) is calculated from the number of fine crystal grains ΣRx and the number of coarse crystal grains ΣRy of the Cu—Sn compound, and the aspect ratio of the crystal grains of the Cu—Sn compound is calculated. The arithmetic average roughness Ra of the surface of the Sn plating material was calculated. As a result, the thickness of the pure Sn layer was 0.7 μm, the thickness of the Cu—Sn compound layer was 0.9 μm, and the average crystal grain size of the Cu—Sn compound was 1.3 μm. Further, the number of fine crystal grains ΣRx of the Cu—Sn compound was 10, the number of coarse crystal grains ΣRy was 30, and the presence ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) was 75%. Moreover, the aspect ratio of the crystal grain of the Cu-Sn compound was 0.45, and the arithmetic average roughness Ra of the surface of the Sn plating material was 0.11. These results are shown in Table 2.

  Further, for the Sn plated material after the reflow treatment, the surface friction coefficient was calculated by the same method as in Example 1, and the solder wettability and the contact reliability after being left at high temperature were evaluated. As a result, the coefficient of friction was 0.31, the solder wettability was 91% and the solder wettability was good, the contact resistance value after standing at high temperature was 1.2 mΩ, and the contact reliability was good. These results are shown in Table 3.

[Comparative Example 8]
Sn plating bath (including Sn oxide) composed of 1 L aqueous solution containing sulfuric acid Sn (SnSO ₄ ) 60 g / L, sulfuric acid (H ₂ SO ₄ ) 75 g / L, cresolsulfonic acid 30 g / L and β-naphthol 1 g / L An Sn plating material after the reflow treatment was prepared in the same manner as in Example 3 except that a non-Sn plating bath was used. In addition, when the electrodeposition thickness of the Sn plating layer of the Sn plating material before the reflow treatment was measured and the grain size of the electrodeposited Sn was determined by the same method as in Example 1, the electrodeposition thickness was 1. The crystal grain size of 0 μm and electrodeposited Sn was 1.1 μm. Table 1 shows the manufacturing conditions of the Sn plating material after the reflow treatment thus prepared, the electrodeposition thickness of the Sn plating layer before the reflow treatment, and the crystal grain size of the electrodeposited Sn.

  Moreover, about the Sn plating material after a reflow process, the thickness of a pure Sn layer and the thickness of a Cu-Sn compound layer are measured by the method similar to Example 1, and the average crystal grain diameter of a Cu-Sn compound is calculated | required. The ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) is calculated from the number of fine crystal grains ΣRx and the number of coarse crystal grains ΣRy of the Cu—Sn compound, and the aspect ratio of the crystal grains of the Cu—Sn compound is calculated. The arithmetic average roughness Ra of the surface of the Sn plating material was calculated. As a result, the thickness of the pure Sn layer was 0.7 μm, the thickness of the Cu—Sn compound layer was 1.0 μm, and the average crystal grain size of the Cu—Sn compound was 1.5 μm. The number of fine crystal grains ΣRx of the Cu—Sn compound was 8, the number of coarse crystal grains ΣRy was 35, and the existence ratio of coarse crystal grains ΣRy × 100 / (ΣRx + ΣRy) was 81%. Moreover, the aspect ratio of the crystal grain of the Cu-Sn compound was 0.55, and the arithmetic average roughness Ra of the surface of the Sn plating material was 0.12. These results are shown in Table 2.

  Further, for the Sn plated material after the reflow treatment, the surface friction coefficient was calculated by the same method as in Example 1, and the solder wettability and the contact reliability after being left at high temperature were evaluated. As a result, the coefficient of friction was 0.36, the solder wettability was 95%, the solder wettability was good, the contact resistance value after standing at high temperature was 1.4 mΩ, and the contact reliability was good. These results are shown in Table 3.

Claims (10)

In a Sn plating material in which a Cu—Sn compound layer is formed on a base material made of copper or a copper alloy and a pure Sn layer is formed on this Cu—Sn compound layer, the thickness of the pure Sn layer is 0.3 to 1.5 μm, the average crystal grain size of the Cu—Sn compound in a plane substantially parallel to the interface between the layers of the Sn plating material is 1.3 μm or more, and the arithmetic average roughness Ra of the surface of the Sn plating material is 0 Sn plating material characterized by being 15 micrometers or more. The interface between the layers of the Sn plating material with respect to the average crystal grain size of the Cu—Sn compound (the lateral length of the crystal grains of the Cu—Sn compound) in a plane substantially parallel to the interface between the layers of the Sn plating material The ratio (vertical length / horizontal length) of the average value (vertical length of the crystal grains of the Cu-Sn compound) of the maximum height of each crystal grain of the Cu-Sn compound in a substantially vertical cross section is The Sn plating material according to claim 1, wherein the Sn plating material is 0.5 or less. In a predetermined region on a cross section substantially perpendicular to the interface between the layers of the Sn plating material, the width of each crystal grain of Cu—Sn compound (length in a direction substantially parallel to the interface between the layers) is 0.7 μm. The ratio of coarse crystal grains to the sum of fine crystal grains and coarse crystal grains is ΣRy × 100 / (ΣRx + ΣRy) where the number of fine crystal grains below is ΣRx and the number of coarse crystal grains of 1.3 μm or more is ΣRy. The Sn plating material according to claim 1, wherein the Sn plating material is 25 to 60%. The Sn plating material according to any one of claims 1 to 3, wherein a lubricating oil is applied to a surface of the pure Sn layer. The Sn plating material according to claim 4, wherein an application amount of the lubricating oil is 0.2 mg / dm ² or more. By forming a Sn layer on a substrate made of copper or a copper alloy by electroplating, drying the surface of the Sn layer, heating the surface of the Sn layer to melt Sn, and then cooling the substrate, In the manufacturing method of Sn plating material which forms a Cu-Sn compound layer on it and forms a pure Sn layer on it, electroplating uses Sn plating bath containing 0.1 g / L or more of Sn oxide. And the cooling after melting Sn is carried out by air cooling and cooling with water, and the interface between each layer of the Sn plating material of the Cu-Sn compound layer formed between the substrate and the pure Sn layer Current density and air cooling of electroplating so that the average crystal grain size of the Cu—Sn compound on the substantially parallel plane is 1.3 μm or more and the arithmetic average roughness Ra of the surface of the Sn plating material is 0.15 μm or more. Set retention time for electroplating A method for producing an Sn-plated material, wherein the energization time of electroplating is set so that the thickness of the Sn layer formed on the substrate becomes 0.8 to 1.8 μm. By forming a Sn layer on a substrate made of copper or a copper alloy by electroplating, drying the surface of the Sn layer, heating the surface of the Sn layer to melt Sn, and then cooling the substrate, In the manufacturing method of Sn plating material which forms a Cu-Sn compound layer on it and forms a pure Sn layer on it, electroplating uses Sn plating bath containing 0.1 g / L or more of Sn oxide. If the current density of electroplating is a (A / dm ² ) and the air cooling holding time b (seconds), 1 ≦ a ≦ 5, current density and air cooling holding time are set so as to satisfy 1 ≦ b ≦ 5, b ≧ a−1.5, and the thickness of the Sn layer formed on the substrate by electroplating is 0.8-1 .Electrical plating energizing time is set to 8μm The manufacturing method of Sn plating material. The energization time of electroplating is set so that the thickness of the Sn layer formed on the substrate by electroplating is 0.9 to 1.6 μm. Manufacturing method of Sn plating material. The method for producing a Sn-plated material according to any one of claims 6 to 8, wherein after the Sn is melted and cooled, a lubricating oil is applied to the surface. The method for producing a Sn-plated material according to claim 9, wherein an application amount of the lubricating oil is 0.2 mg / dm ² or more.