CN102906288A - Cu-Co-Si type copper alloy rolled plate and electric parts using same - Google Patents

Abstract

Provided is a rolled Cu-Co-Si copper alloy sheet which has excellent workability by pressing, bendability, and strength. The rolled Cu-Co-Si copper alloy sheet contains 0.5-3.0 mass% Co and 0.1-1.0 mass% Si, with the remainder comprising Cu and incidental impurities. When the sheet is examined by X-ray diffractometry for crystal orientation in the range of from the surface of the sheet to a depth of 5 [mu]m therefrom, the sheared texture in an area which corresponds to the a=0-10 degree region on the {111} normal pole figure (where a is an axis which is perpendicular to the rotation axis of the goniometer for diffraction defined in the Schlutz method) has a pole density of 1.5-8.

Description

Cu-Co-Si type copper alloy rolled plate and electric parts using same

technical field

The present invention relates to a copper alloy that is excellent in strength and conductivity and can be suitably applied to, for example, spring materials for electronic machines.

Background technique

For terminals, connectors, switches, relays, etc., spring materials for electric and electronic equipment (materials for connectors) are required to have excellent spring properties, bending workability, and electrical conductivity, and phosphor bronze and the like have been used conventionally. However, due to the demand for further miniaturization of electronic components in recent years, precipitation-strengthened copper alloys such as Corson alloys, beryllium copper, and titanium copper have been developed to replace conventional solid-solution-strengthened copper alloys such as phosphor bronze and brass. Among them, Corson alloys are increasingly used in electronic parts because of their high balance between strength and electrical conductivity.

Such terminals, connectors, and the like are formed into desired shapes from copper alloy raw materials by press working, but as electronic components become smaller, dimensional accuracy after stamping becomes important.

As a technique for improving the press workability of the copper alloy for electronic machines, a technique of covering the surface of the copper alloy with a Cu layer is disclosed (see Patent Document 1). In addition, techniques for improving press workability by specifying the orientation of the texture of copper alloys have been proposed (see Patent Documents 2 to 4).

In particular, the suppression of dents and burrs, which have been a problem in press processing, has been dealt with by adjusting the mold. low material.

Patent Document 1: Japanese Patent Laid-Open No. 2006-272889

Patent Document 2: Japanese Patent Laid-Open No. 2007-186799

Patent Document 3: Japanese Patent No. 3800279

Patent Document 4: Japanese Patent No. 4009981.

Contents of the invention

The problem to be solved by the invention

However, it is known that usually during cold rolling, lattice rotation occurs along with plastic deformation of the material to form a texture, but the surface region of the material in contact with the rolls during rolling forms a texture different from that of the central portion of the material. The reason for this is that in the center of the material, the material is deformed by the compressive stress in the thickness direction and the tensile stress in the rolling direction to form a so-called rolled texture. The surface texture (shear texture) is formed by shear deformation under the influence of the friction force of the roller.

However, as a result of research conducted by the present inventors, it has been clarified that press workability is greatly improved by increasing the extreme density of the shear texture at a depth of 5 μm from the surface of the Cu—Co—Si alloy rolled sheet.

However, in the case of the conventional copper alloy rolled sheet, the portion where the extreme density of the shear texture is high is limited to the outermost surface of the sheet, and the press workability is not sufficient.

FIG. 1 schematically shows the extreme density of the shear texture of the copper alloy rolled sheet of the present invention and the conventional copper alloy rolled sheet. In the conventional copper alloy rolling, the extreme density of the shear texture on the outermost surface of the plate also reached 1.5 or more, but as it penetrated into the interior, the extreme density decreased sharply, and at a depth of 5 μm from the surface of the plate, the extreme density became Less than 1.5.

As described above, the present invention is made to solve the above-mentioned problems, and an object of the present invention is to provide a Cu—Co—Si based copper alloy rolled sheet excellent in press workability, bending workability, and strength.

means of solving problems

The Cu-Co-Si type copper alloy rolled sheet of the present invention is a copper alloy rolled sheet containing 0.5~3.0% by mass of Co, 0.1~1.0% by mass of Si, and the balance contains Cu and unavoidable impurities. When the X-ray diffraction method measures the crystal orientation from the surface of the plate to a depth of 5 μm, it corresponds to α=0~10° on the {111} pole figure (where α: is the same as the diffraction goniometer specified in the Schulz method The pole density of the shear texture in the region where the rotation axis is perpendicular to the axis) is 1.5 or more and 8 or less.

It is preferable to further contain a total of 0.05 to 2.0 mass % of one or more selected from Cr, Ni, Mg, Sn, Zn, and Mn, and Cr is 0.3 mass % or less, Ni is less than 1 mass %, and Mg 0.2 mass % or less, Sn is 1 mass % or less, Zn is 1 mass % or less, and Mn is 0.15 mass % or less.

The ten-point average roughness of the plate surface is preferably 0.4 to 1.2 μm.

The electrical component of the present invention uses the Cu-Co-Si-based copper alloy rolled sheet described above.

The effect of the invention

According to the present invention, a Cu—Co—Si based copper alloy rolled sheet excellent in press workability, bendability, and strength can be obtained.

Description of drawings

[ Fig. 1 ] A schematic diagram showing the pole density of the shear texture of the copper alloy rolled sheet of the present invention and the conventional copper alloy rolled sheet.

Detailed ways

Embodiments of the Cu—Co—Si based copper alloy rolled sheet according to the present invention will be described below. In addition, in this invention, unless otherwise specified, % is considered to represent mass % (weight %).

(composition)

[Co and Si]

The concentration of Co in the copper alloy rolled sheet is 0.5 to 3.0%, and the concentration of Si is 0.1 to 1.0%. Co and Si form a solid solution when the copper alloy is melted, and are aged and precipitated by heat treatment after the solution treatment to form fine particles of an intermetallic compound mainly composed of Co and Si. As a result, the strength of the copper alloy is significantly increased, and the electrical conductivity is also improved.

If the concentration of Co is less than 0.5%, sufficient strength of the copper alloy cannot be obtained, and if it exceeds 3.0%, cracks will occur during hot rolling. If the concentration of Si is less than 0.1%, sufficient strength of the copper alloy cannot be obtained, and if it exceeds 1.0%, the conductivity will decrease.

[Cr, Ni, Mg, Sn, Zn and Mn]

The copper alloy rolled sheet may further contain 0.05 to 2.0% in total of one or more selected from Cr, Ni, Mg, Sn, Zn, and Mn.

If the total of these elements is less than 0.05%, the effect of improving the properties of the copper alloy such as stress relaxation characteristics, hot workability, strength, and heat resistance as shown below cannot be obtained, and if it exceeds 2.0%, the electrical conductivity may decrease.

Here, Mg has the effect of improving the stress relaxation characteristics and hot workability of the copper alloy, but if it is less than 0.05%, the above effects cannot be obtained, and if it exceeds 0.2%, there will be a decrease in castability (cast skin quality) and a decrease in hot workability. In the case where the property and plating heat-resistant detachment are lowered, the concentration of Mg is preferably 0.05 to 0.2%.

Cr has the effect of improving hot workability and the effect of improving strength, but if it is less than 0.05%, the above effects cannot be obtained, and if it exceeds 0.3%, the conductivity will decrease.

Ni has the effect of improving the strength of the copper alloy, and the concentration of Ni is preferably 0.2% or more and less than 1%. If Ni is less than 0.2%, the above-mentioned effect cannot be obtained, and if it exceeds 1%, the conductivity will decrease.

Sn and Zn have the effects of improving the strength and heat resistance of copper alloys. In addition, Sn improves the stress relaxation resistance of copper alloys, and Zn improves the heat peeling resistance of copper alloys when Sn is plated. The concentration of Sn is preferably 0.2 to 1%, and the concentration of Zn is preferably 0.2 to 1%. If the concentration of Sn or Zn is less than 0.2%, the above effects cannot be obtained, and if it exceeds 1%, the conductivity will decrease.

Mn has the effect of improving hot workability in addition to the effect of improving strength by solid solution strengthening. If Mn is less than 0.05%, the above effects cannot be obtained, and if it exceeds 0.15%, the conductivity will decrease, so the concentration of Mn is preferably 0.05 to 0.15%.

(polar density of shear texture)

It is known that usually during cold rolling, the crystal lattice rotates to form a texture along with the plastic deformation of the material, but there is a difference in the texture formed between the surface layer region of the material and the central part of the material in contact with the roll during rolling (above Shiro et al., Journal of the Japan Society for Metals, p33, volume 36, 1972; edited by Isamu Goku, "Progress in Metal Plastic Processing" (Progress in Metal Plastic Processing), p499, Corona Corporation (コロナ社), 1978). The reason for this is that in the center of the material, the material is deformed by the biaxial stress of the combination of the compressive stress in the thickness direction and the tensile stress in the rolling direction. The shear deformation due to the influence of friction is called surface texture (shear texture), which is different from rolling texture. For example, it is known that under optimal conditions, Al plates form a surface texture from both sides of the plate to 30% of the plate thickness, and change rapidly to the internal structure through a thin transition layer. As a result of research conducted by the present inventors, it has become clear that in copper alloy rolled sheets, the surface texture can be formed by about 10 to 20% of the sheet thickness by controlling the preparation conditions. As a result of further research, it became clear that in copper alloy rolled sheets, press workability is changed by controlling the surface texture (shear texture).

In the present invention, when the crystal orientation is measured from the plate surface to a depth of 5 μm by X-ray diffraction method, it will be equivalent to α=0~10° on the {111} pole figure (wherein, α: same as Schultz The polar density of the shear texture in the area where the axis of rotation of the goniometer for diffraction is perpendicular to the axis specified in the law is specified to be 1.5 or more and 8 or less.

Here, the reason for investigating the relationship between the surface texture and press workability using the Cu-Co-Si-based copper alloy rolled sheet of the present invention is to investigate the relationship between the surface texture and the press workability for a depth of 5 μm from the surface of the sheet. If the surface texture is different, there is a significant difference in the press workability, so the depth is used as the measurement object.

As above, the pole density of the shear texture was determined. Therefore, it became clear that when a rolled sheet having a shear texture pole density of 1.5 to 8 is subjected to stamping, the indentation of the material produced after stamping is smaller than that of the conventional material, and the burrs are lower than the conventional material.

If the pole density of the shear texture at a depth of 5 μm from the sheet surface is less than 1.5, the shear texture cannot be sufficiently formed, and the dent becomes large, and the burr becomes high, and the press workability does not improve. On the other hand, it is difficult for the pole density of the shear texture to exceed 8 industrially, so eight is the upper limit of the pole density. In the range of the pole density of 1.5 or more to 3 or less, the pole density of the shear texture is increased, and the press workability is correspondingly improved (indentation becomes smaller, and the burrs are reduced), but if the pole density exceeds 3, the press workability The degree of improvement slows down, and if the pole density exceeds 5, there is no difference in press workability. In addition, in order to obtain a high pole density exceeding 5, it is necessary to use a high-viscosity rolling oil or to increase the rolling speed, which increases the surface roughness of the material. On the other hand, if the pole density exceeds 4.5, wrinkles will be generated in the bent portion. Therefore, the pole density is preferably 1.8 to 5, more preferably 2.0 to 4.5.

It should be noted that, in the case of the conventional copper alloy rolled sheet, since the extremely dense portion of the shear texture is limited to the outermost surface of the sheet, it cannot be said that the press workability is sufficient. FIG. 1 schematically shows the extreme density of the shear texture of the copper alloy rolled sheet of the present invention and the conventional copper alloy rolled sheet. In the conventional copper alloy rolling, the extreme density of the shear texture on the outermost surface of the plate also reached 1.5 or more, but as it penetrated into the interior, the extreme density decreased sharply, and at a depth of 5 μm from the surface of the plate, the extreme density became Less than 1.5.

As a method of controlling the extreme density of the shear texture to a depth of 5 μm from the surface of the sheet to be 1.5 or more and 8 or less, the method of increasing the frictional force between the roll and the copper alloy rolling raw material at the time of final cold rolling is mentioned. method. Specifically, at the time of final cold rolling, 1) increasing the viscosity of rolling oil, 2) increasing the roughness of the roll, and 3) increasing the rolling speed (reducing the roll diameter).

Usually, the viscosity of rolling oil during cold rolling is about 0.03 to 0.06 cm ² /s, and by setting the viscosity of rolling oil during final cold rolling to 0.06 cm ² /s or more, the shear texture can be made extremely The density is 1.5 or more and 8 or less.

In the copper alloy rolled sheet of the present invention, solid-solution Co and Si are heat-treated to age-precipitate, but the order of the aging treatment and the above-mentioned final cold rolling may come first.

In the copper alloy rolled sheet of the present invention, the ten-point average roughness of the sheet surface is preferably 0.4 to 1.2 μm. If the ten-point average roughness of the plate surface is less than 0.4 μm, sufficient lubricating oil cannot be supplied between the mold and the material during pressing, and the proportion of fractured surfaces or burrs may increase. In addition, in the case of producing a copper alloy rolled sheet by a usual method, the ten-point average roughness of the sheet surface does not exceed 1.2 μm.

(Preparation)

The preparation process of the copper alloy rolled sheet of the present invention is as follows. First, electrolytic copper or oxygen-free copper is used as the main raw material, and the above-mentioned chemical components are added to the composition, which is covered with charcoal and subjected to atmospheric melting to prepare an ingot. After the ingot is hot rolled, heat treatment and cold rolling are repeated to prepare the desired strip or foil. Heat treatment includes solution treatment and aging treatment. In solution treatment, the material is heated in a high-temperature zone of 800~1080°C, which is relatively high compared with Cu-Ni-Si-like Corson alloys, so that the constituent elements of the precipitates (Co- Si and subcomponents) are solid-dissolved in the parent phase. The optimum solution treatment temperature varies with the concentration of Co and Si, and the higher the concentration of Co and Si, the higher the solution treatment temperature. Then, aging treatment is carried out in the temperature range of 300~600°C to precipitate fine compounds from the parent phase and improve the strength. In order to obtain higher strength before or after aging, cold rolling is often performed. In addition, strain relief annealing is often performed after cold rolling.

The copper alloy rolled sheet of the present invention can be made into various forms such as spring material (bar) and foil. For example, when the copper alloy of the present invention is made into a strip for a spring material, it can be applied to electric parts such as lead frames, connectors, pins, terminals, relays, and switches. As a connector, it can be applied to all known shapes and structures, and generally includes male (jack, plug) and female (socket, receptacle). Terminals are often provided with, for example, a series of multiple pins arranged side by side, and are bent appropriately to form a spring shape in order to make electrical contact between the terminals when mated with other connectors. In addition, usually, terminals of connectors are composed of the rolled copper alloy sheet of the present invention.

Example

Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to them.

<Example 1>

1. Preparation of samples

2.0% of Co and 0.45% of Si were respectively added to the electrolytic copper, melted in an atmospheric melting furnace covered with charcoal, and the melt was stirred. Then, an ingot was cast at a casting temperature of 1250° C., annealed at a temperature of 1000° C. for 3 hours, and then hot rolled to a plate thickness of 11 mm. After removing scale on the surface layer of the hot-rolled material by face cutting, it was cold-rolled to a plate thickness of 0.24 mm, and solution treatment was performed at 1050° C. for 1 minute to obtain a rolled plate sample. Next, aging treatment was implemented on the condition of 510 degreeC for 10 hours, and the final cold rolling was performed to 0.2 mm after that. The rolling speed and the viscosity of the rolling oil in the final cold rolling were changed as shown in Table 1 to adjust the extreme density of the shear texture.

2. Determination of the pole density of the shear texture

Using an X-ray diffractometer (RINT2500 manufactured by Rigaku Corporation), the {111} positive pole of each sample was measured by the reflection method to prepare a {111} pole figure. However, in the reflection method, if the incident angle of X-rays with respect to the sample surface becomes shallow, the measurement becomes difficult, so the angle range that can actually be measured on the pole figure is 0°≤α≤75°, 0°≤β ≤360° (wherein, α: an axis perpendicular to the rotation axis of the diffractive goniometer specified in the Schulz method, and β: an axis parallel to the above-mentioned rotation axis).

In the measurement, the rotation intervals Δα and Δβ between α and β are set to 5°, scanning is performed within the above-mentioned angle range, and the X-ray intensity of 16×73=1168 points is measured. At this time, the state without texture (that is, the state in which the crystal orientation is random) was counted as 1, and the intensity of the texture on the pole figure was normalized. The {111} positive pole point measurement of the copper powder sample was performed as a state where the crystal orientation was random, and it was counted as 1.

It should be noted that, as X-ray irradiation conditions, a Cr bulb was used, the tube voltage was set to 40 kV, and the tube current was set to 100 mA, and the {111} pole figure was measured by the Schulz reflection method. In the case of using a Cr tube, if the X-ray diffraction intensity of an infinitely thick sample is defined as 100%, the X-ray diffraction intensity at a depth of 5 μm from the surface of the plate is theoretically equivalent to 92%. That is, since more than 90% of the information of the obtained {111} pole figure is composed of the X-ray diffraction information of the surface texture formed on the surface of the sample, it is judged as measuring the surface texture formed at a depth of 5 μm from the surface of the plate. method is sufficient.

As above, measure the pole density corresponding to the crystal orientation in the range of α=0°~10° on the {111} pole figure of the shear texture, and define the maximum value of the pole density in this range as the shear texture extreme density.

3. Size of indentation

For each sample, the die gap was set at 10%, a wire with a length of 30 mm and a width of 0.5 mm was punched at a punching speed of 250 spm, and a cross section of the punched material was photographed with a confocal microscope. In the captured image, the part with the highest height on the side of the punching start surface (the part far from the punching position in the center of the punched material) and the part with the lowest height (the part that is lowered for the punching position and material depression) ) height difference is defined as the size of the indentation.

If the size of the dent was within 30 μm, it was determined that the dent was small and good.

4. The height of the burr

For each sample, the die gap was set at 10%, a wire with a length of 30 mm and a width of 0.5 mm was punched at a punching speed of 250 spm, and a cross section of the punched material was photographed with a confocal microscope. In the captured image, the difference in height between the portion with the highest height and the portion with the lowest height on the side of the punched finish surface was defined as the height of the burr.

If the height of the burrs is within 10 μm, it is judged that the burrs are low and good.

5. Bending workability

According to the Japan Copper Association (JBMA) technical standard T307 (1999), the bending radius is set to 0.15mm, and the bending axis is parallel to the rolling direction to perform the bending test. Corresponding to the 5-level evaluation A~E of the same technical standard, the evaluation shall be carried out according to the following standards.

○: A (good) of the same technical standard

△: B (small folds) and C (large folds) of the same technical standard

×: D (small crack) and E (large crack) of the same technical standard.

6. Tensile strength

About each sample, the tensile test was performed in the direction parallel to the rolling direction according to JISZ2241, and the tensile strength was calculated|required. When the tensile strength is (650 MPa) or more, it is good as a spring material.

Table 1 shows the obtained results.

[Table 1]

As can be seen from Table 1, in the case of Invention Examples 1 to 11, the dents are small, the burrs are low, the press workability is excellent, and the bending workability is also good. In addition, the tensile strength is also high.

On the other hand, in the case of Comparative Example 1 in which the rolling speed at the time of final cold rolling was less than 160 mpm, the pole density of the shear texture was less than 1.5, the sinking was large, the burrs were high, and the press workability deteriorated.

In the case of Comparative Example 2, the viscosity of the rolling oil was as low as 0.03 cm ² /s or less, the extreme density of the shear texture was less than 1.5, the sinking was large, the burrs were high, and the press workability deteriorated.

In the case of Comparative Example 3, the rolling speed was less than 160 mpm, and the viscosity of the rolling oil was also as low as 0.03 cm ² /s or less, and the extreme density of the shear texture became less than 1.5, with large dents, high burrs, and high pressure. Workability deteriorates. In addition, the range of suitable solution temperature fluctuates with the composition of a copper alloy rolled sheet, and is not limited to 1050 degreeC applied in the example of the invention.

<Example 2>

Co, Si, Mg, Sn, Zn, Mn, Ni, and Cr were added to the electrolytic copper at the ratios shown in Table 2, melted in an atmospheric melting furnace, and the melt was stirred. Then, an ingot was cast at a casting temperature of 1250° C., annealed at 1000° C. for 3 hours, and then hot rolled to a plate thickness of 11 mm. After removing scale on the surface of the hot-rolled material by face cutting, it was cold-rolled to a plate thickness of 0.24 mm, and then solution treated at the solution temperature in Table 3 for 1 minute to obtain a rolled plate sample. Next, aging treatment was implemented on the condition of 510 degreeC for 10 hours, and the final cold rolling was implemented to 0.2 mm after that. The rolling speed and the viscosity of rolling oil at the time of final cold rolling were set to the values shown in Table 3. For each sample, the same evaluation as in Example 1 was performed except for the tensile strength. Since the tensile strength is largely influenced by the composition, it was judged that 550 MPa or more was good in strength. The components of each sample and the obtained results are shown in Table 2 and Table 3, respectively.

[Table 2]

[table 3]

It can be seen from Table 3 that the samples of Invention Examples 12 to 26 have small dents, low burrs, excellent press workability, and good bending workability. In addition, the tensile strength was also good.

In the case of Comparative Example 4 in which Co was less than 0.5% by mass, although the press workability was good, the strength decreased. In the case of Comparative Example 5 in which Co exceeded 3.0% by mass, cracks occurred during hot rolling, and a sample could not be prepared.

Claims (4)

1. Cu-Co-Si class copper alloy milled sheet, described copper alloy milled sheet is for containing the Co of 0.5 ~ 3.0 quality %, the Si of 0.1 ~ 1.0 quality %, surplus comprises Cu and the inevitably copper alloy milled sheet of impurity, wherein, when measuring the slave plate surface and play crystalline orientation to the degree of depth of 5 μ m by X-ray diffraction method, be equivalent to the utmost point density of the shear texture in the zone of the α on the 111} utmost point figure=0 ~ 10 ° is more than 1.5 and below 8, wherein α: with the diffraction of stipulating in the schultze method with the vertical axle of the turning axle of goniometer.

2. the Cu-Co-Si class copper alloy milled sheet of claim 1, wherein, further contain add up to 0.05 ~ 2.0 quality % be selected among Cr, Ni, Mg, Sn, Zn and the Mn more than a kind, and Cr is defined as below the 0.3 quality %, Ni is defined as less than 1 quality %, Mg is defined as below the 0.2 quality %, Sn is defined as below the 1 quality %, Zn is defined as below the 1 quality %, Mn is defined as below the 0.15 quality %.

3. claim 1 or 2 Cu-Co-Si class copper alloy milled sheet, wherein, 10 mean roughness on plate surface are 0.4 ~ 1.2 μ m.

4. electric parts, described electric parts right to use require in 1 ~ 3 each Cu-Co-Si class copper alloy milled sheet.

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