TWI541366B - Cu-Ni-Si type copper alloy sheet excellent in deep drawing workability and a method for producing the same - Google Patents

Description

Cu-Ni-Si copper alloy plate excellent in deep drawing and workability and manufacturing method thereof

The present invention relates to a Cu-Ni-Si copper alloy sheet and a method for producing the same, which achieves a balance between deep drawing workability and solder heat peeling resistance and elastic limit value, and has little variation in fatigue resistance characteristics, and particularly has excellent deep drawing. It is suitable for use in electrical and electronic components because of its processability.

The present invention claims priority to the international application PCT/JP2011/062028, filed on May 25, 2011, the disclosure of which is incorporated herein.

With the reduction in size and thickness of electronic devices in recent years, terminals and connectors have become compact and thinner, requiring strength and bending workability, and replacing solid solution-strengthened copper such as phosphor bronze or brass. The alloy has a demand for a precipitation-strengthened copper alloy such as a copper-nickel-bismuth (Cu-Ni-Si-based) alloy, beryllium copper or titanium copper.

The copper-nickel-niobium alloy is an alloy of a nickel-deposited nickel compound which has a significant change in the solid solution limit of copper due to temperature, and is a kind of precipitation hardening type alloy which is hardened by quenching and tempering, and has excellent heat resistance or high temperature strength. The balance between strength and electrical conductivity is also excellent, and it has been widely used for various springs for electric conduction or electric wires for high tensile strength, and has recently been frequently used for electronic parts such as terminals and connectors.

In general, the strength and the bending workability are opposite. The copper-nickel-niobium alloy has also been studied from the past to maintain high strength and at the same time improve bending workability, and is aimed at adjusting the manufacturing steps, crystal grain size, and precipitates. of The number and shape, the collection organization are individually or mutually controlled to improve the bending workability.

In order to use a copper-nickel-niobium alloy in various environments in a predetermined environment in a strict environment, it is required to be easy to process, in particular, good deep drawability and solder heat-resistant peelability at high temperature use.

Patent Document 1 discloses a Cu-Ni-Si based alloy for electronic components having excellent balance between strength and bending workability, and Ni is 1.0 to 4.0% by mass and contains 1/6 to 1/4 of Ni with respect to Ni. The concentration of Si, the frequency of the twin boundary (Σ3 boundary) in the total crystal grain boundary is 15 to 60%.

Patent Document 2 discloses a copper-based precipitation type alloy sheet material having a tensile strength in a rolling direction, an angle formed in a direction of a rolling direction of 45°, and an angle of 90° with respect to a rolling direction. a copper-based precipitation type alloy plate for a contact material having a maximum value of each of the three tensile strengths of the tensile strength of the direction of 100 MPa or less, containing 2 to 4 mass% Ni and 0.4 to 1 mass% Si, if necessary At least one selected from the group consisting of Mg, Sn, Zn, and Cr is appropriately contained, and the remaining portion is composed of copper and unavoidable impurities. This copper-based precipitation type alloy sheet material is subjected to aging heat treatment on a solution-treated copper alloy sheet material, and then cold rolling is performed at a rolling reduction of 30% or less, and a multi-function switch for use in an electronic device or the like is used. The operational improvement.

Patent Document 3 discloses a copper-nickel-bismuth (Cu-Ni-Si-based) copper alloy sheet having a withstand strength of 700 N/mm ² or more, a conductivity of 35% IACS or more, and excellent bending workability. The copper alloy sheet includes: Ni: 2.5% (% by mass or less) and less than 6.0%, Si: 0.5% or more and less than 1.5%, and a mass ratio of Ni to Si of Ni/Si of 4 to 5, and Including Sn: 0.01% or more and less than 4%, the remaining portion is composed of Cu and unavoidable impurities, and the average crystal grain size is 10 μm or less, and the measurement result by the SEM-EBSP method is that the Cube orientation is {001}<100>. After the solution structure having a ratio of 50% or more is obtained by continuous annealing to obtain a solution-recrystallized structure, cold rolling at a processing rate of 20% or less and aging treatment at 400 to 600 ° C for 1 to 8 hours are performed, followed by processing. After 1 to 20% of the final cold rolling, it is produced by short-time annealing of 400 to 550 ° C × 30 seconds or less.

[Previous Technical Literature] [Patent Document]

Patent Document 1: Japanese Laid-Open Patent Publication No. 2009-263784

Patent Document 2: Japanese Laid-Open Patent Publication No. 2008-95186

Patent Document 3: Japanese Laid-Open Patent Publication No. 2006-283059

The conventional Cu-Ni-Si copper-nickel-niobium alloy has insufficient deep drawing workability, deep drawing workability, solder heat-resistant peelability, poor balance with elastic limit value, and fatigue resistance. The variation (unevenness) is large, and it is often found that it is not suitable as a material for electronic parts exposed to a long-term and severe environment of high temperature and high vibration.

In view of the circumstances, the present invention provides a Cu-Ni-Si copper alloy plate for use in electrical and electronic parts and a method for manufacturing the same, and achieve deep drawing The balance between the workability and the solder heat-resistant peeling property and the elastic limit value is small, and the variation (failure) of the fatigue resistance is small, and in particular, it has excellent deep drawability.

As a result of intensive studies, the present inventors have found that the Cu-Ni-Si-based copper alloy sheet of the present invention contains 1.0 to 3.0% by mass of Ni and contains a concentration of 1/6 to 1/4 of the mass% relative to Ni. Si, the remainder is composed of Cu and unavoidable impurities, and the arithmetic mean roughness Ra of the surface is 0.02 to 0.2 μm, and the absolute value of the value of each convex portion and concave portion when the surface roughness average line is used as a reference is used. The deviation is 0.1 μm or less, and the aspect ratio of the crystal grains in the alloy structure (the short diameter of the crystal grains / the long diameter of the crystal grains) is 0.4 to 0.6 to have a backscattered electron diffraction system. The average value of the total crystal grains of the GOS measured by the EBSD method by the scanning electron microscope is 1.2 to 1.5°, and the ratio of the total grain boundary length Lσ of the specific grain boundary to the total grain boundary length L of the crystal grain boundary (Lσ) /L) is 60 to 70%, the elastic limit value is 450 to 600 N/mm ² , and the solder heat resistance at 150 ° C for 1000 hours is good, and the variation in fatigue resistance (unevenness) is small, and the excellent deep drawing is exhibited. Processability.

Further, it was found that the average ratio of the aspect ratio of the crystal grains (the short diameter of the crystal grains/the long diameter of the crystal grains) is mainly about the solder heat-resistant peelability at 150 ° C for 1000 hours, and the average of the total crystal grains of the GOS. The value, mainly related to the elastic limit value, the ratio of the total special grain boundary length Lσ of the special grain boundary (Lσ/L), mainly related to the deep drawing workability, the arithmetic mean roughness Ra of the surface and the surface roughness average line as the reference Each of the convex and concave portions The standard deviation of the absolute value of the value, and the variation (inhomogeneity) of the fatigue resistance.

It has also been found that the average of the aspect ratio (the short diameter of the crystal grains/the long diameter of the crystal grains) of the crystal grains is basically affected by the processing rate at the time of final cold rolling at the time of production, GOS The average value of the total crystal grains is basically affected by the tension in the furnace of the copper alloy sheet during continuous low-temperature annealing at the time of manufacture, and the ratio (Lσ/L) of the total grain boundary length Lσ of the specific grain boundary is basically The upper surface is affected by the floating distance in the furnace of the copper alloy sheet during continuous low-temperature annealing at the time of manufacture, and the arithmetic mean roughness Ra of the surface and the surface roughness average line are used as the reference values of the convex portions and the concave portions. The standard deviation of the absolute value is basically affected by the tension applied to the copper alloy sheet at the time of final cold rolling at the time of manufacture and the surface roughness of the rolled roll.

According to the above findings, the Cu-Ni-Si-based copper alloy sheet of the present invention contains 1.0 to 3.0% by mass of Ni and contains Si at a concentration of 1/6 to 1/4 of the mass% concentration of Ni. The remaining portion is composed of Cu and unavoidable impurities, and the arithmetic mean roughness Ra of the surface is 0.02 to 0.2 μm, and the standard deviation of the absolute values of the values of the convex portions and the concave portions when the surface roughness average line is used as a reference is 0.1 μm or less, the aspect ratio of the crystal grains in the alloy structure (the short diameter of the crystal grains / the long diameter of the crystal grains) is 0.4 to 0.6, and is scanned with a backscattered electron diffraction system. The EBSD method performed by a type electron microscope measures the orientation of all pixels in the measurement area, and considers the boundary of the adjacent pixel between the pixels having a difference of 5° or more as the crystal grain boundary of the GOS. The average value is 1.2~1.5°, the ratio of the total grain boundary length Lσ of the special grain boundary to the total grain length L of the grain boundary (Lσ/L) is 60-70%, and the elastic limit value is 450~600N/mm. ^2, 150 ℃ 1000 hours and excellent solder heat release, fatigue resistance variation is small, It has excellent deep drawability pull processability.

Ni and Si are formed into fine particles of an intermetallic compound mainly composed of Ni ₂ Si by performing appropriate heat treatment. As a result, the strength of the alloy is remarkably increased while the electrical conductivity is also increased.

Ni is 1.0 to 3.0% by mass, preferably in the range of 1.5 to 2.5% by mass. If Ni is less than 1.0% by mass, sufficient strength cannot be obtained. On the other hand, if Ni exceeds 3.0% by mass, cracks may occur in hot rolling.

The added concentration (% by mass) of Si is 1/6 to 1/4 of the added concentration (% by mass) of Ni. If the added concentration of Si is less than 1/6 of the added concentration of Ni, the strength is lowered, and if it is more than 1/4 of the added concentration of Ni, not only the strength is not favored, but also the excessive conductivity of Si is lowered.

When the average value of the aspect ratio (the short diameter of the crystal grain/the long diameter of the crystal grain) of the crystal grain is less than 0.4 or more than 0.6, the solder heat-resistant peelability at 150 ° C for 1,000 hours is lowered.

If the average value of the total crystal grains of the GOS is less than 1.2° or exceeds 1.5°, the elastic limit value is lowered.

If the ratio (Lσ/L) of the total special grain boundary length Lσ of the special grain boundary is less than 60% or more than 70%, the deep drawability is lowered.

Fatigue resistance when the arithmetic mean roughness Ra of the surface exceeds 0.2 μm The variation in characteristics becomes large, and the arithmetic mean roughness Ra is less than 0.02 μm, the effect is saturated and the manufacturing cost is wasted.

When the standard deviation of the absolute values of the values of the convex portions and the concave portions when the surface roughness average line is used as a reference exceeds 0.1 μm, the variation in the fatigue resistance characteristics becomes large. Although the standard deviation is as small as possible, and considering the manufacturing cost or effect, it is preferably 0.03 μm or more.

The Cu-Ni-Si-based copper alloy sheet of the present invention further contains 0.2 to 0.8% by mass of Sn and 0.3 to 1.5% by mass of Zn.

Sn and Zn have an effect of improving strength and heat resistance, and Sn has an effect of improving stress relaxation resistance, and Zn has an effect of improving heat resistance of solder bonding. Sn is added in the range of 0.2 to 0.8% by mass, and Zn is in the range of 0.3 to 1.5% by mass. If it is less than the above range, the desired effect cannot be obtained, and if it exceeds the range, the conductivity is lowered.

The Cu-Ni-Si-based copper alloy sheet of the present invention further contains 0.001 to 0.2% by mass of Mg.

Mg has an effect of improving stress relaxation properties and hot workability, and when it exceeds 0.2% by mass, castability (decreased cast muscle quality), hot workability, and plating heat-resistant peelability are lowered.

The Cu-Ni-Si-based copper alloy sheet of the present invention further contains Fe: 0.007 to 0.25% by mass, P: 0.001 to 0.2% by mass, C: 0.0001 to 0.001% by mass, Cr: 0.001 to 0.3% by mass, and Zr: 0.001. One or two or more of 0.3% by mass.

Fe has an effect of improving hot rolling properties (an effect of suppressing surface cracks or edge cracks) and finely precipitating a compound of Ni and Si, and thus The effect of improving the heat-resistant adhesion of plating and the like has an effect of improving the reliability of the connector. When the content is less than 0.007%, the desired effect cannot be obtained for the above-mentioned action, and if the content exceeds 0.25, the content thereof exceeds 0.25. In the case of %, the hot rolling effect is saturated, and it tends to be lowered, and the conductivity is also adversely affected. Therefore, the content is determined to be 0.007 to 0.25%.

P has a function of preventing a decrease in elasticity due to bending processing, thereby enhancing the plugging and uncharging characteristics of the connector obtained by the molding process, and an effect of improving metal migration resistance, and the content thereof is less than 0.001%. On the other hand, if the content exceeds 0.2%, the solder heat-resistant peeling property is remarkably affected, so the content thereof is determined to be 0.001 to 0.2%.

C has an effect of improving the punching workability, and has an effect of improving the strength of the alloy by making the compound of Ni and Si fine, and the content is less than 0.0001%, the desired effect cannot be obtained, and the other If it exceeds 0.001%, it will have a bad influence on hot workability, so it is not suitable. Therefore, the C content is determined to be 0.0001 to 0.001%.

Cr and Zr have a strong affinity with C and easily contain C in the Cu alloy, and have a function of further miniaturizing the compound of Ni and Si to enhance the strength of the alloy, and further strengthening the strength by precipitation itself. The effect of the promotion, and even if the content of one or both of Cr and Zr is less than 0.001%, the effect of improving the strength of the alloy cannot be obtained. On the other hand, if it contains more than 0.3%, a large Cr and/or Zr may be produced. The precipitates are deteriorated, the plating property is deteriorated, and the punching workability is also deteriorated, and It is not suitable for affecting hot workability. Then, the content of one or both of Cr and Zr is determined to be 0.001 to 0.3%.

The method for producing a Cu-Ni-Si-based copper alloy sheet according to the present invention comprises the steps of hot rolling, cold rolling, solution processing, aging treatment, final cold rolling, and low temperature annealing in this order to produce a copper alloy sheet. At the time of the final cold rolling treatment, the processing rate is 10 to 30% and the tension applied to the copper alloy sheet is 90 to 150 N/mm ² , and is performed using a rolling roller having a grindstone having a particle size of #180 to 600; The continuous low-temperature annealing treatment is performed by applying a tensile force of 300 to 900 N/mm ^{2 to} the copper alloy sheet in the furnace and a floating distance of 10 to 20 mm for the copper alloy sheet in the furnace.

When the processing ratio at the final cold rolling is less than 10% or more than 30%, the average aspect ratio of the crystal grains (the short diameter of the crystal grains/the long diameter of the crystal grains) does not enter 0.4 to 0.6. range.

When the furnace internal tension applied to the copper alloy sheet during continuous low-temperature annealing is less than 300 N/mm ² or exceeds 900 N/mm ² , the average value of the total crystal grains of the GOS does not enter the range of 1.2° to 1.5°.

When the floating distance in the furnace of the copper alloy sheet during continuous low-temperature annealing is less than 10 mm or more than 20 mm, the ratio of the total grain boundary length Lσ of the special grain boundary to the total grain length L of the grain boundary (Lσ/L) is Will not enter the 60~70% range.

When the tension applied to the copper alloy sheet at the time of cold rolling is less than 90 N/mm ² , the standard deviation of the absolute values of the convex portions and the concave portions when the surface roughness average line is used as a reference exceeds 0.1 μm, when the tension exceeds At 150 N/mm ² , the effect is saturated and the manufacturing cost is wasted.

In the final cold rolling, if a rolling roll milled with a grindstone having a particle size of less than #180 is used, the arithmetic mean roughness Ra of the surface may exceed 0.2 μm, and if the particle size exceeds #600, the effect is saturated, and it is difficult to remove the resulting in the manufacturing step. Surface scars.

According to the present invention, a Cu-Ni-Si-based copper alloy sheet for use in electrical and electronic parts and a method for producing the same are provided, and a balance between deep drawing workability, solder heat-resistant peelability and elastic limit value, and variation in fatigue resistance characteristics are achieved. Less, especially with excellent deep drawability.

Hereinafter, embodiments of the present invention will be described.

[Component composition of copper alloy strips]

The copper alloy strip of the present invention has a mass % composition and contains 1.0 to 3.0% by mass of Ni, and contains Si at a concentration of 1/6 to 1/4 of the mass% concentration of Ni, and the balance is Cu and is inevitable. Impurities.

Ni and Si are formed into fine particles of an intermetallic compound mainly composed of Ni ₂ Si by performing appropriate heat treatment. As a result, the strength of the alloy is remarkably increased while the electrical conductivity is also increased.

Ni is 1.0 to 3.0% by mass, preferably in the range of 1.5 to 2.5% by mass. If Ni is less than 1.0% by mass, sufficient strength cannot be obtained. On the other hand, if Ni exceeds 3.0% by mass, cracks may occur in hot rolling.

The added concentration (% by mass) of Si is 1/6 to 1/4 of the added concentration (% by mass) of Ni. If the added concentration of Si is less than 1/6 of the added concentration of Ni, the strength is lowered, and if it is more than 1/4 of the added concentration of Ni, not only the strength is not favored, but also the excessive conductivity of Si is lowered.

The copper alloy may further contain 0.2 to 0.8% by mass of Sn and 0.3 to 1.5% by mass of Zn based on the basic composition.

Sn and Zn have an effect of improving strength and heat resistance, and Sn has an effect of improving stress relaxation resistance, and Zn has an effect of improving heat resistance of solder bonding. Sn is added in the range of 0.2 to 0.8% by mass, and Zn is in the range of 0.3 to 1.5% by mass. If it is less than the above range, the desired effect cannot be obtained, and if it exceeds the range, the conductivity is lowered.

The copper alloy may further contain 0.001 to 0.2% by mass of Mg based on the above basic composition.

Mg has an effect of improving stress relaxation properties and hot workability, and when it exceeds 0.2% by mass, castability (decreased cast muscle quality), hot workability, and plating heat-resistant peelability are lowered.

The copper alloy may further contain Fe: 0.007 to 0.25 mass%, P: 0.001 to 0.2 mass%, C: 0.0001 to 0.001 mass%, Cr: 0.001 to 0.3 mass%, and Zr: 0.001 to the basic composition. One or more of 0.3% by mass.

Fe has an effect of improving hot rolling properties (an effect of suppressing surface cracks or edge cracks) and a fine precipitation of a compound of Ni and Si. Therefore, the effect of improving the heat-resistant adhesion of plating is improved. The effect of the reliability is less than 0.007%, and the desired effect cannot be obtained for the above-described effects. On the other hand, if the content exceeds 0.25%, the hot rolling effect is saturated, and the tendency is lowered. It also has a bad influence on the conductivity, so the content is determined to be 0.007 to 0.25%.

P has a function of preventing a decrease in elasticity due to bending processing, thereby enhancing the plugging and uncharging characteristics of the connector obtained by the molding process, and an effect of improving metal migration resistance, and the content thereof is less than 0.001%. On the other hand, if the content exceeds 0.2%, the solder heat-resistant peeling property is remarkably affected, so the content thereof is determined to be 0.001 to 0.2%.

C has an effect of improving the punching workability, and has an effect of improving the strength of the alloy by making the compound of Ni and Si fine, and the content is less than 0.0001%, the desired effect cannot be obtained, and the other If it exceeds 0.001%, it will have a bad influence on hot workability, so it is not suitable. Therefore, the C content is determined to be 0.0001 to 0.001%.

Cr and Zr have a strong affinity with C and easily contain C in the Cu alloy, and have a function of further miniaturizing the compound of Ni and Si to enhance the strength of the alloy, and further strengthening the strength by precipitation itself. The effect of the promotion, and even if the content of one or both of Cr and Zr is less than 0.001%, the effect of improving the strength of the alloy cannot be obtained. On the other hand, if it contains more than 0.3%, a large Cr and/or Zr may be produced. Since the precipitates are deteriorated, the plating property is deteriorated, the punching workability is also deteriorated, and the hot workability is affected, so that it is not suitable. Then one or two of Cr and Zr The content is determined to be 0.001 to 0.3%.

Further, the Cu-Ni-Si-based copper alloy strip has an arithmetic mean roughness Ra of 0.02 to 0.2 μm on the surface, and a standard deviation of absolute values of the values of the convex portions and the concave portions when the surface roughness average line is used as a reference is 0.1. Below μm, the aspect ratio of the crystal grains in the alloy structure (the short diameter of the crystal grains / the long diameter of the crystal grains) is 0.4 to 0.6, and is a scanning type having a backscattered electron diffraction system. The EBSD method performed by an electron microscope measures the orientation of all pixels in the measurement area, and considers the average of the total crystal grains of the GOS when the boundary between the adjacent pixels is 5 or more as the grain boundary. The ratio of the total grain boundary length Lσ of the special grain boundary to the total grain length L of the grain boundary (Lσ/L) is from 60 to 70%, and the elastic limit value is from 450 to 600 N/mm ² , which is 1.2 to 1.5°. The solder heat-resistant peelability at 150 ° C for 1,000 hours is good, and the variation in fatigue resistance is small, and excellent deep drawability is exhibited.

[Arithmetic mean roughness Ra, standard deviation of the absolute values of the values of the convex portions and the concave portions when the surface roughness average line is used as a reference]

The arithmetic mean roughness Ra of the surface of the copper alloy sheet was determined in the following manner.

The stylus type surface roughness measuring device (SE-30D) manufactured by Otaru Research Laboratory Co., Ltd. of Japan was used to obtain an outline according to JIS B0651-1996, and the arithmetic mean roughness (Ra) was calculated from the outline of the profile (JIS). B0601-1994).

When the copper alloy plate surface roughness average line is used as a reference, each convex portion and The standard deviation of the absolute value of the value of the concave portion was obtained in the following manner.

The stylus type surface roughness measuring device (SE-30D) manufactured by Otaru Institute of Japan Co., Ltd. was used to obtain the profile according to JIS B0651-1996, and the surface roughness average line was actually measured based on the profile of the surface. The absolute value of the value of each convex portion and concave portion is calculated as the standard deviation.

[aspect ratio, GOS, Lσ/L]

The average value of the aspect ratio (the short diameter of the crystal grains / the long diameter of the crystal grains) of the crystal grains in the alloy structure was determined in the following manner.

As a pretreatment, a sample of 10 mm × 10 mm was immersed in 10% sulfuric acid for 10 minutes, and then washed with water, and the water was sprayed off by a jet, and the sample sprayed with water was made by Hitachi-hitec Co., Ltd. The surface polishing (ion milling) apparatus performs surface treatment with an acceleration voltage of 5 kV, an incident angle of 5°, and an irradiation time of one hour.

Next, the surface of the sample was observed by a scanning electron microscope S-3400N manufactured by Hitachi-Hitec Co., Ltd. having an EBSD system manufactured by TSL Corporation. The observation conditions were an acceleration voltage of 25 kV and a measurement area (rolling direction) of 150 μm × 150 μm.

Next, the orientation of all the pixels in the measurement area is measured with a resolution of 0.5 μm, and a boundary having a difference in orientation between pixels of 5° or more is defined as a crystal grain boundary, and two or more pixels surrounded by a crystal grain boundary are defined. When the collection is a crystal grain, the length in the long axis direction of each crystal grain is regarded as a, the length in the short axis direction is regarded as b, and the value obtained by dividing b by a is defined as The aspect ratio is obtained by calculating the aspect ratio of all the crystal grains in the measurement area, and calculating the average value.

When the average value of the aspect ratio (the short diameter of the crystal grain/the long diameter of the crystal grain) of the crystal grain is less than 0.4 or more than 0.6, the solder heat-resistant peelability at 150 ° C for 1,000 hours is lowered.

The average value of the total crystal grains of the GOS measured by the EBSD method using a scanning electron microscope having a backscattered electron diffraction system was determined in the following manner.

As a pretreatment, a sample of 10 mm × 10 mm was immersed in 10% sulfuric acid for 10 minutes, and then washed with water, and the water was sprayed off by a jet, and the sample sprayed with water was made by Hitachi-hitec Co., Ltd. The surface polishing (ion milling) apparatus performs surface treatment with an acceleration voltage of 5 kV, an incident angle of 5°, and an irradiation time of one hour.

Next, the surface of the sample was observed by a scanning electron microscope S-3400N manufactured by Hitachi-Hitec Co., Ltd. having an EBSD system manufactured by TSL Corporation. The observation conditions were an acceleration voltage of 25 kV and a measurement area of 150 μm × 150 μm.

According to the observation result, the average value of the average azimuth difference between all pixels in the crystal grains of the whole crystal grains was determined under the following conditions.

The orientation of all the pixels in the measurement area was measured at a resolution of 0.5 μm, and a boundary in which the azimuth difference between adjacent pixels was 5 or more was regarded as a crystal grain boundary.

Next, for each of the crystal grains surrounded by the crystal grain boundaries, the average value of the azimuth differences between the whole pixels in the crystal grains is calculated by the formula (1). (GOS: Grain Orientation Spread), the average value of all the values is taken as the average azimuth difference between the whole pixels in the crystal grains of the whole crystal grains, that is, the average value of the whole crystal grains as the GOS. Two or more pixels are connected as crystal grains.

In the above formula, i and j represent the numbers of the pixels in the crystal grains.

N represents the number of pixels in the crystal grain.

α _ij represents the difference in orientation of the pixels i and j.

The average value of the total crystal grains of the GOS, which is less than 1.2° or exceeds 1.5°, causes a decrease in the elastic limit value.

The ratio of the total grain boundary length Lσ of the specific grain boundary measured by the EBSD method with a backscattered electron diffraction system to the total grain boundary length L of the grain boundary (Lσ/L), below The method is obtained. The special grain boundary, in crystallography, is a Σ value defined by CSL theory (Krongerg et. al.: Trans. Met. Soc. AIME, 185, 501 (1949)) and has a grain boundary of 3≦Σ≦29 (corresponding grain) Boundary) The lattice orientation defect Dq defined as the original corresponding portion of the grain boundary corresponds to the crystal grain boundary of Dq ≦ 15 ° / Σ ^1/2 (DGBrandon: Acta. Metallurgica. Vol. 14, p1479, 1966).

As a pretreatment, a sample of 10 mm × 10 mm was immersed in 10% sulfuric acid for 10 minutes, then washed with water, and after the water was sprayed by a jet, The sample after water scatter was subjected to a surface treatment by a surface polishing (ion polishing) apparatus manufactured by Hitachi-hitec Co., Ltd. at an acceleration voltage of 5 kV, an incident angle of 5°, and an irradiation time of one hour.

Next, the surface of the sample was observed by a scanning electron microscope S-3400N manufactured by Hitachi-Hitec Co., Ltd. having an EBSD system manufactured by TSL Corporation. The observation conditions were an acceleration voltage of 25 kV and a measurement area of 150 μm × 150 μm.

The orientation of all the pixels in the measurement area was measured at a resolution of 0.5 μm, and a boundary in which the azimuth difference between adjacent pixels was 5 or more was regarded as a crystal grain boundary.

Next, the total grain boundary length L of the crystal grain boundary in the measurement range is measured, and the position of the crystal grain boundary of the specific grain boundary is determined at the interface of the adjacent crystal grain, and the full special grain boundary length Lσ of the specific grain boundary is obtained. The ratio of the grain boundary length Lσ/L of the total grain boundary length L of the crystal grain boundary measured as described above is a specific grain boundary length ratio.

If the ratio (Lσ/L) of the total special grain boundary length Lσ of the special grain boundary is less than 60% or more than 70%, the deep drawability is lowered.

〔Production method〕

The method for producing a Cu-Ni-Si-based copper alloy sheet according to the present invention comprises the steps of hot rolling, cold rolling, solution processing, aging treatment, final cold rolling, and low temperature annealing in this order to produce a copper alloy sheet. At the time of the final cold rolling treatment, the processing rate is 10 to 30% and the tension applied to the copper alloy sheet is 90 to 150 N/mm ² , and is carried out using a rolling roller having a grindstone having a particle size of #180 to 600; The continuous low-temperature annealing treatment is performed by applying a tensile force of 300 to 900 N/mm ^{2 to} the copper alloy sheet in the furnace and a floating distance of 10 to 20 mm for the copper alloy sheet in the furnace.

When the processing ratio at the final cold rolling is less than 10% or more than 30%, the average aspect ratio of the crystal grains (the short diameter of the crystal grains/the long diameter of the crystal grains) does not enter 0.4 to 0.6. The range will result in a decrease in solder heat-resistant peelability.

When the furnace tension applied to the copper alloy sheet during continuous low-temperature annealing is less than 300 N/mm ² or exceeds 900 N/mm ² , the average value of the total crystal grains of Gos does not enter the range of 1.2° to 1.5°, which may result in elastic limit. The value is reduced.

When the floating distance in the furnace of the copper alloy sheet during continuous low-temperature annealing is less than 10 mm or more than 20 mm, the ratio of the total grain boundary length Lσ of the special grain boundary to the total grain length L of the grain boundary (Lσ/L) is It will not enter the range of 60~70%, which will result in lower processing of deep drawing.

When the tension applied to the copper alloy sheet at the time of cold rolling is less than 90 N/mm ² , the standard deviation of the absolute values of the convex portions and the concave portions when the surface roughness average line is used as a reference exceeds 0.1 μm, when the tension exceeds At 150 N/mm ² , the effect is saturated and the manufacturing cost is wasted.

In the final cold rolling, if a rolling roll milled with a grindstone having a particle size of less than #180 is used, the arithmetic mean roughness Ra of the surface may exceed 0.2 μm, and if the particle size exceeds #600, the effect is saturated, and it is difficult to remove the resulting in the manufacturing step. Surface scars.

Figure 1 shows the continuous low temperature used in the manufacturing method of the present invention. An example of an annealing device. The copper alloy sheet F which has been subjected to final cold rolling and wound around the feed reel 11 is subjected to a predetermined tension by the tension control device 12 and the tension control device 14, and is subjected to low temperature annealing at a predetermined temperature and time in the transverse mold annealing furnace 13 via The lapping and pickling device 15 is wound around the tension reel 16.

The so-called in-furnace floating distance of the copper alloy sheet F at the time of continuous low-temperature annealing of the present invention is a wave height value of the copper alloy sheet F which fluctuates by the hot air G in the furnace as shown in Fig. 2 . In Fig. 2, the copper alloy sheet F fluctuates with a wave of the span L, and the height from the center of the wave is the floating distance H. This floating distance H is controlled by the tension applied to the copper alloy sheet F by the tension control devices 12 and 14, and the discharge amount of the hot air G blown onto the copper alloy sheet F in the annealing furnace 13.

As an example of a specific manufacturing method, the following method is mentioned.

The material was blended into a Cu-Ni-Si-based copper alloy sheet of the invention, and a copper alloy ingot was obtained by melt-casting using a low-frequency dissolution furnace in a reducing environment. Next, the copper alloy ingot was heated to 900 to 980 ° C, hot rolled to obtain a hot rolled sheet having an appropriate thickness, and the hot rolled sheet was water-cooled, and then both surfaces were appropriately subjected to face milling. Then, cold rolling is performed at a rolling ratio of 60 to 90% to prepare a cold-rolled sheet having an appropriate thickness, and then continuous annealing is performed at 710 to 750 ° C for 7 to 15 seconds. Next, after completion of the continuous annealing treatment, the copper plate is subjected to pickling and surface polishing, and then cold-rolled at a rolling ratio of 60 to 90% to prepare a cold-rolled sheet having an appropriate thickness. Next, the cold-rolled sheet is held at 710 to 780 ° C for 7 to 15 seconds, and then rapidly cooled and subjected to a solution treatment, and then held at 430 to 470 ° C for 3 hours to carry out precipitation aging treatment, followed by pickling treatment. And the processing rate is 10 to 30%, the tension applied to the copper alloy sheet is 90 to 150 N/mm ² , and the final cold rolling is performed using a rolling roller milled with a grindstone of #180 to 600, and the copper in the furnace is applied. The tension applied by the alloy plate is 300 to 900 N/mm ² , and the floating distance of the copper alloy plate in the furnace is 10 to 20 mm to perform continuous low temperature annealing.

[Examples]

The materials were prepared into the components shown in Table 1, and dissolved in a low-frequency melting furnace in a reducing environment, followed by casting to produce a copper alloy ingot having a thickness of 80 mm, a width of 200 mm, and a length of 800 mm. After heating the copper alloy ingot to 900 to 980 ° C, a hot rolled sheet having a thickness of 11 mm was hot rolled, and the hot rolled sheet was water-cooled, and then both sides were subjected to face milling of 0.5 mm. Then, cold rolling was performed at a rolling ratio of 87% to obtain a cold-rolled sheet having a thickness of 1.3 mm, and then subjected to continuous annealing at 710 to 750 ° C for 7 to 15 seconds, followed by pickling, surface grinding, and rolling. The rate of 77% was cold rolled to produce a cold rolled sheet having a thickness of 0.3 mm.

After the cold-rolled sheet is held at 710 to 780 ° C for 7 to 15 seconds, it is rapidly cooled and subjected to a solution treatment, and then held at 430 to 470 ° C for 3 hours to carry out precipitation aging treatment, and after pickling treatment, The conditions shown in 1 were subjected to final cold rolling and continuous low temperature annealing to produce a copper alloy sheet.

Then, for each of the obtained samples, the arithmetic mean roughness Ra, the standard deviation of the absolute values of the values of the convex portions and the concave portions when the surface roughness average line is used as a reference, the aspect ratio, and the GOS were measured. The average value of the total crystal grains, the ratio of the total grain boundary length Lσ of the specific grain boundary to the total grain length L of the grain boundary (Lσ/L), the deep drawing processability, the elastic limit value, and the solder heat resistance peelability , the average value of fatigue characteristics, and the standard deviation of fatigue characteristics.

The arithmetic mean roughness Ra of the surface of the copper alloy sheet was determined in the following manner.

The stylus type surface roughness measuring device (SE-30D) manufactured by Otaru Research Laboratory Co., Ltd. of Japan was used to obtain an outline according to JIS B0651-1996, and the arithmetic mean roughness (Ra) was calculated from the outline of the profile (JIS). B0601-1994).

The standard deviation of the absolute values of the values of the convex portions and the concave portions when the surface roughness average line of the copper alloy sheet is used as a reference is obtained as follows.

The stylus type surface roughness measuring device (SE-30D) manufactured by Otaru Institute of Japan Co., Ltd. was used to obtain the profile according to JIS B0651-1996, and the surface roughness average line was actually measured based on the profile of the surface. The absolute value of the value of each convex portion and concave portion is calculated as the standard deviation.

The average of the aspect ratio (the short diameter of the crystal grains/the long diameter of the crystal grains) was determined in the following manner.

As a pretreatment, a sample of 10 mm × 10 mm was immersed in 10% sulfuric acid for 10 minutes, then washed with water, and after the water was sprayed by a jet, The sample after water scatter was subjected to a surface treatment by a surface polishing (ion polishing) apparatus manufactured by Hitachi-hitec Co., Ltd. at an acceleration voltage of 5 kV, an incident angle of 5°, and an irradiation time of one hour.

Next, the surface of the sample was observed by a scanning electron microscope S-3400N manufactured by Hitachi-Hitec Co., Ltd. having an EBSD system manufactured by TSL Corporation. The observation conditions were an acceleration voltage of 25 kV and a measurement area (rolling direction) of 150 μm × 150 μm.

Next, the orientation of all the pixels in the measurement area is measured with a resolution of 0.5 μm, and a boundary having a difference in orientation between pixels of 5° or more is defined as a crystal grain boundary, and two or more pixels surrounded by a crystal grain boundary are defined. When the collection is a crystal grain, the length in the long-axis direction of each crystal grain is regarded as a, the length in the short-axis direction is regarded as b, and the value obtained by dividing b by a is defined as an aspect ratio, and the measurement area is determined. The aspect ratio of all the crystal grains in the inside was obtained, and the average value was calculated.

The average value of the total crystal grains of GOS was determined in the following manner.

As a pretreatment, a sample of 10 mm × 10 mm was immersed in 10% sulfuric acid for 10 minutes, and then washed with water, and the water was sprayed off by a jet, and the sample sprayed with water was made by Hitachi-hitec Co., Ltd. The surface polishing (ion milling) apparatus performs surface treatment with an acceleration voltage of 5 kV, an incident angle of 5°, and an irradiation time of one hour.

Next, the surface of the sample was observed by a scanning electron microscope S-3400N manufactured by Hitachi-Hitec Co., Ltd. having an EBSD system manufactured by TSL Corporation. The observation conditions were an acceleration voltage of 25 kV and a measurement area of 150 μm × 150 μm.

According to the observation result, the average value of the average azimuth difference between all pixels in the crystal grains of the whole crystal grains was determined under the following conditions.

The orientation of all the pixels in the measurement area was measured at a resolution of 0.5 μm, and a boundary in which the azimuth difference between adjacent pixels was 5 or more was regarded as a crystal grain boundary.

Next, for each of the crystal grains surrounded by the crystal grain boundary, the average value (GOS: Grain Orientation Spread) of the azimuth difference between the whole pixels in the crystal grain is calculated by the formula (1), and the average value of all the values is taken as The average azimuth difference between all pixels in the crystal grains of the whole crystal grains, that is, the average value of the whole crystal grains as the GOS. Two or more pixels are connected as crystal grains.

In the above formula, i and j represent the numbers of the pixels in the crystal grains.

N represents the number of pixels in the crystal grain.

α _ij represents the difference in orientation of the pixels i and j.

The ratio (Lσ/L) of the total grain boundary length Lσ of the specific grain boundary to the total grain boundary length L of the crystal grain boundary was determined in the following manner.

As a pretreatment, a sample of 10 mm × 10 mm was immersed in 10% sulfuric acid for 10 minutes, and then washed with water, and the water was sprayed off by a jet, and the sample sprayed with water was made by Hitachi-hitec Co., Ltd. Planar grinding (ion grinding) device with an accelerating voltage of 5kV and an incident angle of 5° The surface treatment was performed by shooting for one hour.

Next, the surface of the sample was observed by a scanning electron microscope S-3400N manufactured by Hitachi-Hitec Co., Ltd. having an EBSD system manufactured by TSL Corporation. The observation conditions were an acceleration voltage of 25 kV and a measurement area of 150 μm × 150 μm.

The orientation of all the pixels in the measurement area was measured at a resolution of 0.5 μm, and a boundary in which the azimuth difference between adjacent pixels was 5 or more was regarded as a crystal grain boundary.

Next, the total grain boundary length L of the crystal grain boundary in the measurement range is measured, and the position of the crystal grain boundary of the specific grain boundary is determined at the interface of the adjacent crystal grain, and the full special grain boundary length Lσ of the specific grain boundary is obtained. The ratio of the grain boundary length Lσ/L of the total grain boundary length L of the crystal grain boundary measured as described above is a specific grain boundary length ratio.

The deep drawability was determined in the following manner.

Using a tester manufactured by Erichsen Co., Ltd., a punching diameter: Φ10 mm, a lubricant: a condition of a lubricating oil, a cover cylinder was produced, and the appearance was observed, and a good one was ○, and a crack or crack at the edge was ×.

The elastic limit value was obtained in the following manner.

According to JIS-H3130, the permanent deflection amount was measured by a torque test, and Kb0.1 of R.T. (the maximum surface stress value of the fixed end corresponding to the permanent deflection amount of 0.1 mm) was calculated.

The solder heat-resistant peelability was determined in the following manner.

Each of the obtained samples was cut into a thin shape having a width of 10 mm and a length of 50 mm, and immersed in a 60% Sn-40% Pb solder at 230 ° C ± 5 ° C. Seconds. The flux uses 25% rosin ethanol. This material was heated at 150 ° C for 1000 hours, bent at 90 ° with the same bending radius as the sheet thickness, and after being reduced, the solder of the bent portion was visually observed for peeling.

The average value of the fatigue characteristics and the standard deviation of the fatigue characteristics were obtained in the following manner.

In the fatigue test, a thin and long test piece having a width of 10 mm in the parallel direction with respect to the rolling direction was carried out in accordance with JIS Z2273. It was measured that the maximum additional stress (stress at the fixed end) on the surface of the test piece was a fatigue life of 400 MPa (the number of times of repeated vibrations until the test piece was broken). The measurement was carried out four times under the same conditions, and the standard deviation of the measured values of four times was calculated.

The results of this measurement are shown in Table 2.

According to Table 2, in the Cu-Ni-Si-based copper alloy of the present invention, the deep drawing processability and the solder heat-resistant peeling property are balanced with the elastic limit value, and the fatigue resistance variation is small, and in particular, the deep drawing processability is excellent. It is suitable for use in electronic parts exposed to high temperature and high vibration for a long time in harsh environments.

The above description of the manufacturing method of the embodiment of the present invention is not limited to the description, and various modifications can be made without departing from the spirit and scope of the invention.

[Industrial Availability]

The Cu-Ni-Si-based copper alloy sheet of the present invention is suitable for use in electronic parts such as terminals and connectors exposed to a long-term and severe use environment of high temperature and high vibration.

11‧‧‧Feed reel

12‧‧‧Tension control device

13‧‧‧ transverse die annealing furnace

14‧‧‧Tension control device

15‧‧‧ grinding and pickling equipment

16‧‧‧Tension reel

F‧‧‧ copper alloy plate

G‧‧‧ hot air

Fig. 1 is a schematic view showing an example of a continuous low-temperature annealing apparatus used in the method for producing a Cu-Ni-Si-based copper alloy sheet of the present invention.

Fig. 2 is a schematic view for explaining a floating distance of a copper plate in a continuous low-temperature annealing furnace used in the method for producing a Cu-Ni-Si-based copper alloy sheet of the present invention.

Claims (6)

A Cu-Ni-Si copper alloy plate containing 1.0 to 3.0% by mass of Ni, containing Si at a concentration of 1/6 to 1/4 of the mass% of Ni, and the balance being Cu and unavoidable impurities The arithmetic mean roughness Ra of the surface is 0.02 to 0.2 μm, and the standard deviation of the absolute values of the values of the convex portions and the concave portions when the surface roughness average line is used as a reference is 0.1 μm or less, and crystal grains in the alloy structure are formed. The aspect ratio (the short diameter of the crystal grains / the long diameter of the crystal grains) has an average value of 0.4 to 0.6, and is performed by an EBSD method using a scanning electron microscope with a backscattered electron diffraction system. The orientation of all pixels in the measurement area is measured, and the average of the total crystal grains of the GOS when the boundary between the adjacent pixels is 5° or more is regarded as the grain boundary. The average grain size is 1.2 to 1.5°. The ratio of the full special grain boundary length Lσ to the full grain boundary length L of the grain boundary (Lσ/L) is 60-70%, the elastic limit value is 450-600 N/mm ² , and the heat-resistant peeling of the solder is 150 ° C for 1000 hours. Good properties, little variation in fatigue resistance, and excellent deep drawability. The Cu-Ni-Si-based copper alloy sheet according to claim 1 further contains 0.2 to 0.8% by mass of Sn and 0.3 to 1.5% by mass of Zn. The Cu-Ni-Si-based copper alloy sheet according to claim 1 further contains 0.001 to 0.2% by mass of Mg. The Cu-Ni-Si-based copper alloy sheet according to the second aspect of the patent application further contains 0.001 to 0.2% by mass of Mg. For example, the Cu-Ni-Si system of the patent scope 1, 2, 3 or 4 The copper alloy sheet further contains one of Fe: 0.007 to 0.25% by mass, P: 0.001 to 0.2% by mass, C: 0.0001 to 0.001% by mass, Cr: 0.001 to 0.3% by mass, and Zr: 0.001 to 0.3% by mass or Two or more. A method for producing a Cu-Ni-Si-based copper alloy sheet according to the first aspect of the invention is the method for producing a copper alloy sheet according to the first aspect of the invention, which comprises the steps of hot rolling, cold rolling, solution treatment, and aging treatment. In the final cold rolling and low temperature annealing step, when the copper alloy sheet is manufactured, the final cold rolling treatment is performed at a processing rate of 10 to 30% and the tension applied to the copper alloy sheet is 90 to 150 N/mm ² , and the particle size is # 180~600 grindstone-rolled rolling rolls are used; continuous low-temperature annealing treatment, the tension applied to the copper alloy plate in the furnace is 300~900N/mm ² , and the floating distance of the copper alloy plate in the furnace is 10 ~20mm to implement.