JP2010159481A - Tinned material of copper alloy for printed board terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tinned material of copper or a copper alloy (hereinafter expressed as copper alloy) which has settling properties suitable as a base material of a printed wiring board terminal, inserted in a through hole of a printed board and mounted through a reflow soldering process. <P>SOLUTION: In the tinned material, each plating phase of a Cu-phase having a thickness of 0-2.0 μm, a Cu-Sn alloy phase having a thickness of 0.1-1.5 μm, and a Sn-phase having a thickness of 0.1-1.5 μm is formed in this order on the surface of a copper alloy having an average crystal grain diameter of 1.5-6.0 μm. Following relation: (D<SB>x</SB>-D<SB>Y</SB>)≥1 (unit:μm) is established between the crystal grain diameter D<SB>x</SB>of the copper alloy and the crystal grain diameter D<SB>Y</SB>of the plating phase directly above the copper alloy. The tinned material of the copper alloy has settling properties suitable for printed board terminals. In the tinned material of the copper alloy, the total concentration of C and S in the plating phase directly above the copper alloy may be within the range of 0.02-0.2 mass% and the copper alloy may contain 2-22 mass% of Zn. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a copper alloy tin plating material suitable as a material for a printed circuit board terminal to be inserted into a through hole of a printed circuit board and soldered through a reflow process. More specifically, the present invention relates to a copper alloy tin plating material that has suitable sagability as a material for printed circuit board terminals and is excellent in plating peeling resistance.

  In recent years, due to the downsizing of electronic and electrical components and the increase in the number of circuits, the miniaturization and high-density mounting of board terminals that supply electrical signals to circuits have progressed. Materials are being sought. In the case of a conductive material, there has been a problem of temperature rise due to Joule heat during energization due to miniaturization and high-density mounting. As the heat resistance of the copper alloy Sn plating strip, Patent Document 1 defines the components of the Cu—Sn plating intermediate layer and the crystal grain size (claim 4 of the same document). In Patent Document 2, a Zn-Sn based copper alloy Sn plating material is obtained as a printed circuit board terminal material excellent in solder mountability. In Patent Document 3, the crystal grain size of the Cu-Sn plating intermediate layer is specified. A plating strip excellent in bending workability and wear resistance is obtained. In Patent Document 4, a plating strip excellent in solderability and insertion property is obtained.

A printed circuit board is built in an electronic control unit of an automobile, and a male terminal (hereinafter referred to as a substrate terminal) is mounted on the printed circuit board. The substrate terminal is connected to an external electronic device or the like via a wire harness having a female terminal at one end. The printed circuit board terminal is inserted into a through hole of the printed circuit board, and solder-mounted on the printed circuit board through the steps of flux application, preheating, reflow soldering, cooling, and cleaning.
In the step of inserting the board terminal into the through hole of the printed board, it is ideal that the board terminal is inserted into the center of the through hole (see FIG. 1A). However, practically not all board terminals are inserted into the center of the through-hole, and some board terminals hit the inner periphery of the through-hole and are mounted with some deformation (FIG. 1). (See (b)). When solder mounting is performed with the substrate terminals deformed, an internal stress is generated in the solder portion in order to return to the original shape, and a mounting trouble in which a crack occurs in the solder portion due to this is predicted. However, the substrate terminal material using the conventional Sn plating material of brass (Cu—Zn-based copper alloy, C2600 or C2680) has high plastic deformability, and thus the above-mentioned trouble is difficult to occur.

JP 2003-293187 A Japanese Patent Application No. 2007-075466 Japanese Patent Application No. 2007-270206 Specification Japanese Patent Application No. 2007-284016

  However, it is not a conventional brass Sn plating material, but is excellent in the above heat resistance, bending workability, wear resistance, etc., and in the case of a substrate terminal manufactured with a plating material in which the crystal grain size of the Cu-Sn plating intermediate layer is adjusted. In this case, cracks are formed in the solder part, and mounting troubles frequently occur. Therefore, a copper alloy for a substrate terminal having excellent heat resistance, bending workability, wear resistance, etc. that does not generate cracks in the solder portion even when the substrate terminal is deformed, and has suitable sagability. A tin plating material was an object of the present invention.

The present inventors investigated the relationship between the crystal grain size of the copper alloy of the copper alloy tin plating material and the plating phase immediately above the copper alloy, and the C and S concentrations in the plating phase immediately above the copper alloy and the amount of sag. As a result, the larger the difference between the crystal grain size of the copper alloy and the crystal grain size of the plating phase immediately above it, the larger the amount of sag, and in addition, the C and S concentrations in the plating phase directly above the copper alloy We found that the higher the amount, the greater the amount of sag. That is, the present invention relates to the following inventions.
(1) An Sn plating material in which Cu phase, Cu—Sn alloy phase and Sn phase plating phases are formed in this order on the surface of copper or copper alloy having an average crystal grain size of 1.5 to 6.0 μm. The average thickness of the Cu phase is 0 to 2.0 μm, the average thickness of the Cu—Sn alloy phase is 0.1 to 1.5 μm, the average thickness of the Sn phase is 0.1 to 1.5 μm, and copper or (D _X −D _Y ) ≧ 1 (unit: μm) is established between the crystal grain size D _X of the copper alloy and the crystal grain size D _Y of the plating phase immediately above the copper or copper alloy, Copper alloy tin plating material suitable for printed circuit board terminals.
(2) The copper alloy tin-plated material according to (1) above, wherein the C and S concentrations in the plating phase immediately above copper or a copper alloy are 0.02 to 0.2 mass% in total.
(3) The copper alloy contains 2 to 22% by mass of Zn, and further contains at least one selected from the group of Ni, Cr, Co, Sn, Fe, Ag, and Mn as required. The copper alloy tin-plated material according to the above (1) or (2), wherein the copper alloy tin plating material is contained in an amount of 0.0 mass% or less, and the balance is composed of copper and inevitable impurities.

  The present invention provides a copper alloy tin plating material having a suitable sagability as a material of a printed wiring board terminal to be inserted through a through hole of a printed board and mounted through a reflow soldering process, and having excellent plating peeling resistance. Can be provided.

Schematic diagram (a) showing a state in which the board terminal is inserted into the center of the through hole of the printed circuit board, and schematic diagram showing a state in which the board terminal hits the inner peripheral portion of the through hole and is slightly deformed and mounted (b) ). It is explanatory drawing of the test which measures the amount of sagging. It is a profile of Sn and Cu concentration of Invention Example 1. 4 is a profile of C and S concentrations in Invention Example 1.

(1) Types of copper alloy Examples of the copper or copper alloy of the present invention (hereinafter collectively referred to as “copper alloy”) include C23000, C22000, C21000, and the like.
When the copper alloy of the present invention is a Cu-Zn alloy, Zn is preferably in the range of 2 to 22% by mass. Increasing the amount of Zn added increases the strength but decreases the conductivity. If the addition amount is less than 2% by mass, the strength is insufficient, and if it exceeds 22% by mass, the conductivity is insufficient.
In order to improve properties such as strength and heat resistance, one or more selected from the group of Ni, Cr, Co, Sn, Fe, Ag, and Mn can be added as necessary. However, since the electrical conductivity decreases as the amount added increases, the total amount added is 2.0% by mass or less.
The average crystal grain size of the copper alloy of the present invention is 1.5 to 6.0 μm in a cross section parallel to the rolling direction. When annealing is performed at a low temperature for a short time in order to make the average crystal grain size after final annealing less than 1.5 μm, unrecrystallized materials usually remain. Adopted industrially because it takes enough time to perform final annealing to obtain crystal grains with a crystal grain size of less than 1.5 μm and no unrecrystallized residue, and temperature control is required. Difficult to put into practical use. On the other hand, if the average crystal grain size exceeds 6.0 μm, sufficient strength cannot be obtained.

(2) Plating From the surface of the copper or copper alloy of the present invention to the base material, a plating film is composed of each phase of Sn phase, Cu—Sn alloy phase, and Cu phase. The plating film structure of the present invention can be obtained by performing electroplating in the order of Cu base plating and Sn plating and performing reflow treatment.
The average thickness of the Sn phase after reflowing is 0.1 to 1.5 μm. If the Sn phase is less than 0.1 μm, it causes plating peeling, and if it exceeds 1.5 μm, the insertion force increases.
The average thickness of the Cu—Sn alloy phase after reflowing is 0.1 to 1.5 μm. When the Cu—Sn alloy phase is less than 0.1 μm or exceeds 1.5 μm, it causes plating peeling.
The average thickness of the Cu phase after reflowing is set to 0 to 2.0 μm. The Cu base plating formed by electroplating is consumed for forming the Cu—Sn alloy phase during reflow, and its thickness may be zero. If the Cu phase exceeds 2.0 μm, it causes plating peeling.
The thickness of each plating at the time of electroplating is appropriately adjusted in the range of 0.4 to 2.2 μm for Sn plating and 0.1 to 2.2 μm for Cu plating, and then 230 to 600 ° C., 3 to The above-described plating structure can be obtained by performing a reflow process under an appropriate condition within a range of 30 seconds.

(3) Crystal grain size When an external force acts on the material (in the case of the present invention, the substrate terminal hits the inner periphery of the through hole and bends), the dislocation moves within the material and accumulates, thereby deforming the material. To do. In general, since the atomic arrangement of the crystal grain boundary of the metal structure is irregular as compared with the inside of the grain, dislocations accumulate preferentially at the crystal grain boundary. In particular, it is easy to accumulate in a place where the area of the crystal grain boundary is locally large, such as a grain boundary triple point.
Although the present invention is not limited by the following theory, when the crystal grain size of the metal crystal of the copper alloy that is the plating base material and the metal crystal of the plating phase are different, that is, the copper alloy that is the base material of the plating When (D _X -D _Y ) ≧ 1 holds between the crystal grain size D _X of the copper alloy and the crystal grain size D _Y of the plating phase immediately above the copper alloy, the interface between the copper alloy base material and the plating phase immediately above A coarse grain boundary like a grain boundary triple point is formed on one side. The area of the interface where the coarse crystal grain boundary is formed is larger than the grain boundary triple point existing in the copper alloy or the plating phase. Therefore, when an external force is applied, it is considered that dislocations accumulate in a portion where the local crystal grain boundary at the interface is coarse, and a suitable sag is obtained as a material for a printed circuit board terminal. On the other hand, when (D _X -D _Y ) is less than 1, coarse crystal grain boundaries are hardly formed at the interface, and the effects of the present invention cannot be obtained.
The method for controlling the crystal grain size of the copper alloy and the plating phase immediately above the copper alloy will be described below.

(A) Crystal grain size of copper alloy The copper alloy to which the present invention can be applied is manufactured through the steps of melting → casting → homogenization annealing → hot rolling → facing → cold rolling → recrystallization annealing → cold rolling. The At this time, the crystal grain size of the copper alloy can be controlled by adjusting the heating temperature or heating time of the recrystallization annealing. The higher the heating temperature and the longer the heating time, the coarser the crystal grain size. Conversely, the lower the heating temperature and the shorter the heating time, the finer the crystal grain size.
The crystal grain size of the copper alloy is preferably 1.5 to 6.0 μm. If it exceeds 6.0 μm, the desired strength cannot be obtained. On the other hand, when it is less than 1.5 μm, the bending workability is inferior.

(B) The crystal grain size of the plating phase immediately above the copper alloy The Cu base plating formed by electroplating is consumed for the formation of the Cu-Sn alloy phase during reflow, so the plating phase immediately above the copper alloy is the Cu-Sn alloy phase or It becomes a Cu phase. In any case, the crystal grain size of the Cu—Sn alloy phase and the Cu phase can be adjusted by controlling the size of the Cu electrodeposited grains during electroplating.
The crystal grain size of the plating phase is preferably 0.5 to 2.0 μm. If it exceeds 2.0 μm, the desired strength cannot be obtained. On the other hand, when it is less than 0.5 μm, the bending workability is inferior.
In order to make the crystal grain size of the plating phase just above the copper alloy fine, the Cu electrodeposited grains should be made small,
(A) increasing the current density;
(B) lowering the temperature of the plating bath;
(C) increasing the concentration of the plating bath;
(D) increasing the stirring speed of the plating bath solution;
(E) adding an appropriate surfactant to the plating bath;
Etc. are effective.

(4) C and S concentrations in the plating phase immediately above the copper alloy If C and S impurities are contained in the plating phase immediately above the copper alloy, dislocations accumulate and deform around the impurities when an external force is applied. It becomes easy.
When the total of C and S concentrations contained in the plating phase immediately above the copper alloy, which is the plating base material, is in the range of 0.02 to 0.2% by mass, a suitable sag is obtained as a material for printed circuit board terminals. It is done. If it is less than 0.02% by mass, the intended effect cannot be obtained, and if it exceeds 0.2% by mass, it causes plating peeling.
The reflow Sn plating is manufactured through the steps of alkaline electrolytic degreasing of copper base material → water washing → sulfuric acid washing → water washing → undercoat plating → water washing → Sn plating → water washing → reflow treatment. At this time, by adjusting the impurity removal conditions by alkaline electrolytic degreasing and pickling, C and S derived from impurities adhering to the surface of the copper base material are mixed in the plating phase, and the C and S of the plating phase immediately above the copper alloy are mixed. Concentration can be controlled.

In order to increase the C and S concentration of the plating phase directly above the copper alloy,
(A) lowering the current density of alkaline electrolytic degreasing,
(B) reducing the concentration of the degreasing agent;
(C) reducing the concentration of degreasing agent or sulfuric acid,
(D) shortening the alkaline electrolytic degreasing or pickling time;
(E) lowering the temperature of alkaline electrolytic degreasing or pickling,
Etc. are effective.

  Using a high-frequency melting furnace, 2 kg of electrolytic copper was melted in a graphite crucible having an inner diameter of 60 mm and a depth of 200 mm. After covering the molten metal surface with charcoal pieces, one selected from the group consisting of Zn and Ni, Cr, Co, Sn, Fe, Ag, and Mn was added. After adjusting the molten metal temperature to 1200 ° C., the molten metal was cast into a mold to produce an ingot having a width of 60 mm and a thickness of 30 mm. The ingot was heated at 850 ° C. for 3 hours and hot-rolled to a thickness of 8 mm. After grinding the oxide scale on the surface of the hot-rolled sheet with a grinder, cold rolling to a sheet thickness of 1 mm, recrystallization annealing, and cold rolling to a sheet thickness of 0.64 mm were performed. In the recrystallization annealing, the crystal grain size was controlled by heating the material at 750 ° C. in the atmosphere and adjusting the heating time. Moreover, in order to remove the oxide film produced | generated by annealing, the pickling in 10 mass% sulfuric acid-1 mass% peroxide aqueous solution and the mechanical polishing by # 1200 emery paper were performed in order. Table 1 shows the components of the copper alloy thus prepared.

Next, Sn plating was performed on these copper alloys by the following procedure.
(1) Electrolytic degreasing was performed under the following conditions using a sample as a cathode in an alkaline aqueous solution. Degreasing agent: Trademark “Pakuna P105” manufactured by Yuken Industry Co., Ltd. See Table 2 below for current density, degreasing agent concentration, temperature, and time.
(2) Pickling was performed using the sulfuric acid aqueous solution under the conditions shown in Table 2 below.
(3) Cu base plating was performed under the conditions shown in Table 3 below. Moreover, the plating thickness was changed by adjusting the electrodeposition time.
(4) Sn plating was performed under the following conditions. Plating bath composition: stannous oxide 41 g / L, phenolsulfonic acid 268 g / L, surfactant 5 g / L. Plating bath temperature: 50 ° C. Current density 9 A / dm ² . Moreover, the plating thickness was changed by adjusting the electrodeposition time.
(5) As a reflow treatment, the sample was inserted into a heating furnace having a temperature of 550 ° C. for 5 seconds and then cooled with water.

The following characteristics were evaluated with respect to the obtained copper alloy tin plating material.
(A) Plating thickness The thickness of each phase of Sn phase, Cu-Sn alloy phase, and Cu phase was determined. For the measurement, an electrolytic film thickness meter (CT-1 manufactured by Denso Co., Ltd.) was mainly used, and SEM observation from the cross section, GDS (glow discharge emission spectroscopy analyzer) analysis from the surface, and the like were used as needed.
(B) Sag amount A copper alloy tin plating material was pressed into a terminal shape having a thickness of 0.64 mm, a width of 0.64 mm, and a length of 30 mm. Using MODEL-1605N manufactured by Aiko Engineering Co., Ltd., one end of the terminal is fixed with a vise to a spring length of 20 mm, and the knife edge is pressed to the unfixed end until the displacement becomes 1.0 mm for 5 seconds. After holding, the load was removed. Thereafter, the difference between the terminal end position before the test and the position after the test was measured to obtain the amount of sag (see FIG. 2). The “sagging property suitable as a material for printed circuit board terminals” in the present invention means that the amount of sagging in the above test is 0.1 mm or more.

(C) Crystal grain size The crystal grain size of the copper alloy that is the plating base material is etched by mechanically polishing the rolled parallel perpendicular section of the sample to a mirror surface and immersing it in a 10 wt% ferric chloride aqueous solution for 30 seconds. The metal structure was observed with an optical microscope (magnification 400 times), and the crystal grain size was determined by the cutting method defined in JIS H 0501.
In the case of Cu-Sn alloy phase, the crystal grain size of the plating phase directly above the copper alloy is obtained by dissolving and removing the Sn phase on the plated surface of the copper alloy Sn plating material after reflow using an electrolytic film thickness meter. The Cu—Sn alloy phase was exposed on the surface, the metal structure was observed with an uneven SEM (ERA-8000) manufactured by ELIONIX, and the crystal grain size was determined by the cutting method defined in JIS H 0501. In the case of Cu phase, the electrolytic surface film thickness meter is used to dissolve and remove the Sn phase and Cu—Sn alloy phase, and the Cu phase is exposed on the plating surface. Similarly, the metal structure was observed to determine the crystal grain size.

(D) C and S concentrations After the reflowed sample is ultrasonically degreased in acetone, the concentration profiles of Sn, Cu, Ni, C, and S in the depth direction are obtained by GDS (glow discharge emission spectroscopic analyzer). It was. The measurement conditions are as follows.
-Apparatus: JY5000RF-PSS type made by JOBIN YBON-Current Method Program: CNBintel-12aa-0.
Mode: Set power = 40W.
-Atmospheric pressure: 775 Pa.
-Current value: 40 mA (700 V).
-Flash time: 20 s.
-Preheating time: 2 s.
Measurement time: analysis time = 30 s, sampling time = 0.020 s / point.
From the concentration profile data, the Sn, Cu, Ni concentration on the Sn surface, and the C and S concentrations of the plating phase immediately above the copper alloy were determined.

  3 and 4 show the Sn, Cu, C, and S concentration profiles of the following Invention Example 1 as typical GDS concentration profile data. From FIG. 3, it is recognized that the Cu—Sn alloy phase is just above the copper alloy of the plating base material, and the boundary surface exists at a depth of 1.7 μm where the inflection points of the Cu concentration and the Sn concentration coincide with each other. Furthermore, it is recognized that there is an interface between the Sn phase and the Cu—Sn alloy phase at a depth of 0.5 μm. Therefore, a Cu—Sn alloy phase exists in a depth range of 0.5 to 1.7 μm. From FIG. 4, the heights of the C and S peaks in this range are read, and the total is plated directly on the copper alloy. The C and S concentrations in the phase were taken. The C and S concentrations were similarly determined for other invention examples and comparative examples.

(E) Plating peelability A strip test piece having a width of 10 mm was sampled and subjected to 90 ° bending with a bending radius of 0.64 mm so that the bending axis was parallel to the rolling direction, and then at a temperature of 150 ° C. in the atmosphere. Heated up to 1000 hours. After heating, take out from the heating furnace, bend back, apply a tape (Sumitomo 3M, masking tape for plating, # 851A) to the outer periphery of the bend, peel off, and peel off with an optical microscope (50x magnification) The presence or absence was observed. In the evaluation, “◯” indicates that there is no plating peeling, and “×” indicates that there is plating peeling.

(F) Strength Based on JIS Z2241, a tensile test in the rolling parallel direction was performed to determine tensile strength (TS) and 0.2% yield strength (YS).
(G) Electrical conductivity Based on JIS H0505, electrical conductivity (EC;% IACS) was determined by volume resistivity measurement using a double bridge.

Example (Evaluation of sag and plating peel resistance regarding crystal grain size, C, and S concentration):
Table 4 shows the difference in crystal grain size between the copper alloy and the plating phase immediately above the copper alloy and the influence of the C and S concentrations in the plating phase immediately above the copper alloy on the sagability. All the examples in Table 4 used the copper alloy a in Table 1.
In Invention Examples 1 to 5 and Comparative Examples 1 to 3, when electroplating was performed with a Cu thickness of 0.3 μm and a Sn thickness of 0.8 μm, the thickness of the Sn phase after reflow was about 0.5 μm, Cu— The thickness of the Sn alloy phase was about 1.2 μm and was within the scope of the present invention. Since the Cu phase has disappeared, the plating phase on the copper alloy in these examples is a Cu-Sn alloy phase.
In Invention Examples 1 to 5, (D _X -D _Y ) was 1.0 μm or more, and the amount of sag exceeded 0.1 mm, indicating that sag was suitable as a material for printed circuit board terminals. Inventive Examples 1 and 2 had a total C and S concentration of 0.02% or more, and the amount of sag was larger than Inventive Examples 3 and 4.
In Invention Example 1 and Comparative Example 1, the Cu plating conditions are changed. Since the crystal grain size D _Y of the Cu-Sn alloy phase is a plating phase immediately above the copper alloy of Comparative Example 1 is coarse, (D _X -D _Y) becomes less than 1, the amount of sag is as less than 0.1mm became.
In Invention Example 2 and Comparative Example 2, the recrystallization annealing time is changed. In Comparative Example 2, since the crystal grain size D _X of the copper alloy was fine, (D _X -D _Y ) was less than 1 and the amount of sag was less than 0.1 mm.
In Comparative Example 3, since alkaline electrolytic degreasing and sulfuric acid pickling were insufficient, the total concentration of C and S exceeded 0.2%, and plating peeling occurred.

Example (Evaluation of Peeling Peeling on Plating Thickness):
Table 5 shows the influence of the plating thickness on the plating peelability. Table 2b shows the conditions for alkaline electrolytic degreasing and pickling, and Table 3b shows the conditions for Cu plating. All the examples in Table 5 use copper alloy a having a recrystallization annealing time of 30 s and an average crystal grain size D _x of 3.5 μm, and (D _X -D _Y ) is about the same as that of Invention Examples 1 to 5 The sum of the C and S concentrations was 0.02 to 0.2% by mass, and the amount of sag was about the same as that of Invention Examples 1 to 5 exceeding 0.1 mm.
Inventive Examples 6 to 10 are such that the Sn thickness after reflow is in the range of 0.1 to 1.5 μm, the thickness of the Cu—Sn alloy phase after reflow is in the range of 0.1 to 1.5 μm, and the Cu after reflow The phase thickness was in the range of 0-2.0 μm. Plating peeling did not occur in these alloys whose plating thickness was within the specified range.
In Comparative Example 4, the thickness of the Sn phase after reflow is less than 0.1 μm, in Comparative Example 5, the thickness of the Cu—Sn alloy phase after reflow exceeds 1.5 μm, and in Comparative Example 6, the thickness of the Cu phase after reflow is The thickness exceeded 2.0 μm. Plating peeling occurred in these alloys whose plating thickness was outside the specified range.

Example (strength and conductivity evaluation regarding component concentration):
Table 6 shows the influence of each component concentration on strength and conductivity. Table 2b shows the conditions for alkaline electrolytic degreasing and pickling, and Table 3b shows the conditions for Cu plating. In all the examples in Table 6, the average crystal grain size of the copper alloy is 1.5 to 6.0 μm, and the average thicknesses of the Cu phase, the Cu—Sn alloy phase, and the Sn phase are within the scope of the present invention. (D _X -D _Y ) is about the same as that of Invention Examples 1 to 5 with 1 or more, the total of C and S concentrations is 0.02 to 0.2% by mass, and the amount of sag is 0.1 mm. It was almost the same as Invention Examples 1-5.
In Invention Examples 11 to 18, the Zn concentration is in the range of 2 to 22%, and one concentration selected from the group of Ni, Cr, Co, Sn, Fe, Ag, and Mn is 2.0% or less. Met. These alloys, whose component concentrations were within the range defined in one embodiment of the present invention, had TS and YS of 400 MPa or more and EC of 30% IACS or more, and exhibited sufficient characteristics as a copper alloy for printed circuit boards.
In Comparative Example 7, one concentration selected from the group of Ni, Cr, Co, Sn, Fe, Ag, and Mn exceeded 2.0%, and in Comparative Example 8, the Zn concentration exceeded 22%. These alloys had an EC of less than 30% IACS. In Comparative Example 9, the Zn concentration was less than 2%, and TS and YS were less than 400 MPa. The properties of these copper alloys whose component concentrations were outside the range specified in one embodiment of the present invention were insufficient as printed circuit board copper alloys.

Claims (3)

An Sn plating material in which plating phases of Cu phase, Cu-Sn alloy phase and Sn phase are formed in this order on the surface of copper or copper alloy having an average crystal grain size of 1.5 to 6.0 μm, The average thickness of the Cu phase is 0 to 2.0 μm, the average thickness of the Cu—Sn alloy phase is 0.1 to 1.5 μm, the average thickness of the Sn phase is 0.1 to 1.5 μm, and the copper or copper alloy Printed circuit board terminals characterized in that (D _X -D _Y ) ≧ 1 (unit: μm) is established between the crystal grain size D _X and the crystal grain size D _Y of the plating phase immediately above the copper or copper alloy Copper alloy tin plating material suitable for use.   The copper alloy tin plating material according to claim 1, wherein the C and S concentrations in the plating phase immediately above copper or a copper alloy are 0.02 to 0.2 mass% in total.   The copper alloy contains 2 to 22% by mass of Zn, and if necessary, one or more selected from the group of Ni, Cr, Co, Sn, Fe, Ag, and Mn is 2.0% in total. The copper alloy tin-plated material according to claim 1, wherein the copper alloy tin-plated material is contained in copper and inevitable impurities.