JP5054160B2 - Cu-Mg-P-based copper alloy strip and method for producing the same - Google Patents

Description

  The present invention is a Cu-Mg-P copper alloy strip suitable for electrical and electronic parts such as connectors, lead frames, relays, switches, etc., and in particular, tensile strength, spring limit value, and double swing plane bending fatigue characteristics. The present invention relates to a Cu-Mg-P-based copper alloy strip that is balanced at a high level and a method for producing the same.

In recent years, electronic devices such as mobile phones and notebook PCs have become smaller, thinner, and lighter, and parts such as terminals and connectors used are smaller and have a smaller pitch between electrodes. The stress repeatedly applied to these parts also tends to increase.
Under these circumstances, the copper alloy materials used for these parts are required to be thinner, and because of the need to maintain various reliability as parts, they have higher strength and balance with spring limit values. There is a demand for a material that can be removed and has excellent fatigue properties.
On the other hand, due to the increase in the number of electrodes and the increase in energization current due to the higher functionality of equipment, the generated Joule heat has become excessive, and there is an increasing demand for materials having higher conductivity than before. Such a high conductivity material is strongly demanded for a terminal / connector material for automobiles in which an increase in energization current is rapidly progressing.
Conventionally, brass or phosphor bronze has been generally used as a material for such terminals and connectors, but it does not sufficiently meet the above requirements. Brass lacks strength, springiness and electrical conductivity, so it cannot cope with downsizing of connectors and increase in energization current, and phosphor bronze has higher strength and higher springiness, but its conductivity is 20% Since it is as low as about IACS, there is a disadvantage that it cannot cope with an increase in energization current and is inferior in migration resistance. Migration is a phenomenon in which Cu on the anode side is ionized and deposited on the cathode side when condensation occurs between the electrodes, eventually leading to a short circuit between the electrodes. It is used in a high humidity environment like an automobile. This is a problem with a connector that requires attention, and even with a connector whose pitch between electrodes has become narrow due to miniaturization.

  As a copper alloy for improving the problems of brass and phosphor bronze, the applicant described in Patent Document 1 in terms of weight%, Mg: 0.1 to 1.0%, P: 0.001 to 0.02%. In which the rest is made of Cu and inevitable impurities, the surface crystal grains have an oval shape, the average minor axis of the oval crystal grains is 5 to 20 μm, and the average major axis / average minor axis In order to form such an oval crystal grain having a value of 1.5 to 6.0, the average crystal grain size is in the range of 5 to 20 μm in the final annealing immediately before the final cold rolling. Then, a copper alloy strip is disclosed in which the rolling rate is set in the range of 30 to 85% in the final cold rolling step, thereby reducing the wear of the stamping die during stamping.

  In addition, the applicant has disclosed in Patent Document 2 a conventional copper alloy containing Mg: 0.3-2% by weight, P: 0.001-0.1% by weight, with the remainder consisting of Cu and inevitable impurities. In the thin plate, the P content is regulated to 0.001 to 0.02 wt%, the oxygen content is 0.0002 to 0.001 wt%, and the C content is 0.0002 to 0.0013 wt% By adjusting, the particle size of the oxide particles containing Mg dispersed in the substrate is adjusted to 3 μm or less, and thereby, the decrease in the spring limit value after bending is less than that of the conventional copper alloy thin plate. When a connector is manufactured from a copper alloy thin plate, the obtained connector shows much better connection strength than before, and it will not be detached even if used in a high-vibration environment such as around an automobile engine. The knowledge is disclosed.

JP-A-6-340938 JP-A-9-157774

According to the invention disclosed in Patent Document 1 and Patent Document 2 described above, a copper alloy having excellent strength, conductivity, and the like has been obtained.
However, as the functionality of electric / electronic devices becomes more and more remarkable, the performance improvement of these copper alloys has been strongly demanded. In particular, it is important for copper alloys used in connectors and the like to be able to be used at high stress without causing settling in the use state, and to have good fatigue characteristics in a high-vibration environment at high temperatures. Therefore, there is an increasing demand for a Cu—Mg—P-based copper alloy strip having a high balance between the tensile strength, the spring limit value, and the double swing plane bending fatigue characteristics.
In each of the above patent documents, the copper alloy composition and the shape of the surface crystal grains are defined, but the tensile strength, spring limit value characteristics, and double-bending plane bending fatigue are taken into account when analyzing the fine structure of the crystal grains. The relationship with characteristics is not mentioned.

  In view of such a situation, the present invention provides a Cu-Mg-P-based copper alloy strip having a high balance between tensile strength, spring limit value, and double swing plane bending fatigue characteristics, and a method for manufacturing the same. Is.

Conventionally, plastic deformation of crystal grains has been performed by observing the structure of the surface, and a recent technique that can be applied to strain evaluation of crystal grains is a backscattered electron diffraction (EBSD) method. This EBSD method is a means for obtaining a crystal orientation from an electron beam diffraction image (Kikuchi line) obtained from a sample surface by placing a test piece in a scanning electron microscope (SEM). If there is, the direction can be easily measured. With recent improvements in computer processing power, even in polycrystalline metal materials, if about 100 crystal grains exist in a target area of about several millimeters, their orientations are evaluated within a practical time. The crystal grain boundary can be extracted from the evaluated crystal orientation data by an image processing technique using a computer.
If a part to be modeled by searching for crystal particles of a desired condition from the image extracted in this way is selected, automatic processing becomes possible. Further, since the crystal orientation data is associated with each part (actually a pixel) of the image, the crystal orientation data corresponding to the image of the selected part can be extracted from the file.

  As a result of intensive studies, the present inventors have observed the surface of a Cu—Mg—P-based copper alloy using an EBSD method with a scanning electron microscope with a backscattered electron diffraction image system. However, when the orientation of all the pixels in the measurement area is measured and a boundary where the orientation difference between adjacent pixels is 5 ° or more is regarded as a grain boundary, the average orientation difference between all the pixels in the crystal grain is 4 The ratio of the area of crystal grains that is less than ° to the total measured area and the area average GAM of crystal grains existing in the measured area are both the tensile strength and the spring limit value characteristics of the Cu-Mg-P-based copper alloy. It was found that there is a close relationship with plane bending fatigue properties.

The area average GAM of crystal grains existing within the measurement area as used in the present invention is calculated by the following method.
GAM is the average value of misorientation between adjacent measurement points (pixels) in the same crystal grain. When the difference in orientation at the boundary i between adjacent measurement points is expressed by equation (1), the boundary between pixels in the crystal grain is When m exist, the GAM value of this crystal grain is expressed by the equation (2).

When the value of the GAM in individual grains (GAM) _k, the area of each crystal grain and S _k, if there are M grain within the measurement range, area average GAM is expressed by equation (3) The

The copper alloy strip of the present invention is a copper alloy strip having a composition of Mg: 0.3-2%, P: 0.001-0.1%, the balance being Cu and inevitable impurities. Yes, with the EBSD method using a scanning electron microscope with a backscattered electron diffraction image system, the orientation of all pixels within the measurement area of the surface of the copper alloy strip is measured at a step size of 0.5 μm, and adjacent pixels When the boundary where the difference in orientation between them is 5 ° or more is regarded as a crystal grain boundary, the area ratio of crystal grains in which the average orientation difference between all pixels in the crystal grains is less than 4 ° is 45% of the measured area. The area average GAM of the crystal grains existing in the measurement area is 2.2 to 3.0 °, the tensile strength is 641 to 708 N / mm ² , and the spring limit value is 472 to 55%. It was 503N / mm ^2, both in the number of repetitions of 1 × 10 ⁶ times Ri plane bending fatigue limit is characterized in that it is a 300~350N / mm ^2.

When the area ratio of the crystal grains in which the average orientation difference between all the pixels in the crystal grains is less than 4 ° is less than 45% or more than 55% of the measurement area, both the tensile strength and the spring limit value are lowered. When the area average GAM of the crystal grains present in the measurement area is less than 2.2 ° or exceeds 3.0 °, the double-bending plane bending fatigue characteristics tend to be deteriorated.
That is, the area ratio of the crystal grains in which the average orientation difference between all the pixels in the crystal grains is less than 4 ° is 45 to 55%, and the area average GAM of the crystal grains existing in the measurement area is 2.2 to 3%. By being 0.0 °, the tensile strength is 641 to 708 N / mm ² , the spring limit value is 472 to 503 N / mm ² , and the double-bending plane bending fatigue limit at 300 times of 1 × 10 ⁶ is 300 to 350 N / mm ² , and the tensile strength, spring limit value, and double swing plane bending fatigue characteristics are balanced at a high level.

Furthermore, the copper alloy strip of the present invention may contain 0.001 to 0.03% of Zr by mass%.
Addition of 0.001 to 0.03% of Zr contributes to improvement of tensile strength and spring limit value.

  The manufacturing method of the copper alloy strip according to the present invention has a hot rolling start temperature of 700 ° C to 700 ° C when manufacturing a copper alloy in a process including hot rolling, solution treatment, finish cold rolling, and low temperature annealing in this order. At 800 ° C., the total hot rolling rate is 90% or more, the average rolling rate per pass is 10% to 35%, the hot rolling is performed, and the Vickers hardness of the copper alloy plate after the solution treatment is performed. Is adjusted to 80 to 100 Hv, the total rolling rate in the finish cold rolling is performed at 50 to 80%, and the low temperature annealing is performed at 250 to 450 ° C. for 30 to 180 seconds.

In order to stabilize the copper alloy structure and balance the tensile strength and the spring limit value at a high level, hot rolling is performed so that the Vickers hardness of the copper alloy plate after the solution treatment is 80 to 100 Hv, It is necessary to appropriately adjust various conditions of cold rolling and solution treatment, and further, within the measurement area of the surface of the copper alloy strip by the EBSD method using a scanning electron microscope with a backscattered electron diffraction image system. A crystal whose average orientation difference between all pixels in a crystal grain is less than 4 ° when the orientation of all pixels is measured and a boundary where the orientation difference between adjacent pixels is 5 ° or more is regarded as a grain boundary. The area ratio of the grains is 45 to 55% of the measurement area, the area average GAM of the crystal grains existing in the measurement area is 2.2 to 3.0 °, and the tensile strength is 641 to 708 N / mm2 and the spring limit is 472 to 503 A / mm @ 2, the Reversed Plane Bending fatigue limit in 1 × 10 ⁶ times is to 300~350N / mm ² performs the total rolling reduction in the finish cold rolling at 50-80%, the low-temperature annealing 250 It is necessary to carry out at ~ 450 ° C for 30 to 180 seconds.

  According to the present invention, it is possible to obtain a Cu-Mg-P-based copper alloy strip having a high balance between tensile strength, spring limit value, and double swing plane bending fatigue characteristics.

Hereinafter, embodiments of the present invention will be described.
The copper alloy strip of the present invention has a composition in which Mg is 0.3 to 2%, P is 0.001 to 0.1%, and the balance is Cu and inevitable impurities.
Mg improves the strength without being dissolved in the Cu substrate and impairing conductivity. Further, P has a deoxidizing action at the time of melt casting, and improves the strength in the state of coexisting with the Mg component. By containing these Mg and P in the above range, the characteristics can be effectively exhibited.
Moreover, it is good also as what contains 0.001-0.03% of Zr by mass%, and addition of Zr of this range is effective for improvement of tensile strength and a spring limit value.

This copper alloy strip is measured by the EBSD method using a scanning electron microscope with a backscattered electron diffraction image system, with the step size of 0.5 μm and the orientation of all pixels within the measurement area of the surface of the copper alloy strip. When the boundary where the orientation difference between adjacent pixels is 5 ° or more is regarded as a grain boundary, the area ratio of the crystal grains where the average orientation difference between all the pixels in the crystal grain is less than 4 ° is It is 45 to 55% of the measurement area, the area average GAM of the crystal grains existing in the measurement area is 2.2 to 3.0 °, the tensile strength is 641 to 708 N / mm ² , and the spring limit The value is 472 to 503 N / mm ² , and the double swing plane bending fatigue limit is 300 to 350 N / mm ² at the number of repetitions of 1 × 10 ⁶ times.

The area ratio of the crystal grains in which the average orientation difference between all the pixels in the crystal grains is less than 4 ° was determined as follows.
As a pretreatment, a 10 mm × 10 mm sample taken from a rolled material is immersed in 10% sulfuric acid for 10 minutes, then washed with water and sprinkled by air blow, and then the water sprayed sample is a flat milling (ion milling) device manufactured by Hitachi High-Technologies Corporation. The surface treatment was performed at an acceleration voltage of 5 kV, an incident angle of 5 °, and an irradiation time of 1 hour.
Next, the sample surface was observed with a scanning electron microscope S-3400N manufactured by Hitachi High-Technologies Corporation equipped with an EBSD system manufactured by TSL. The observation conditions were an acceleration voltage of 25 kV and a measurement area of 150 μm × 150 μm (including 5000 or more crystal grains).
From the observation results, the area ratio with respect to the total measurement area of the crystal grains in which the average orientation difference between all the pixels in the crystal grains is less than 4 ° was obtained under the following conditions.
At a step size of 0.5 μm, the orientation of all pixels within the measurement area range was measured, and a boundary where the orientation difference between adjacent pixels was 5 ° or more was regarded as a crystal grain boundary. Next, for each crystal grain surrounded by the crystal grain boundary, an average value (GOS: Grain Orientation Spread) of the orientation difference between all the pixels in the crystal grain is calculated by the equation (4), and the average value is 4 The area of the crystal grains of less than 0 ° was calculated and divided by the total measured area, and the ratio of the area of the crystal grains having an average orientation difference within the crystal grains of less than 4 ° to the total crystal grains was determined. In addition, what connected 2 pixels or more was made into the crystal grain.

In the above formula, i and j indicate the numbers of pixels in the crystal grains.
n indicates the number of pixels in the crystal grains.
α _ij represents the difference in orientation between pixels i and j.

Moreover, the area average GAM of the crystal grain which exists in a measurement area was calculated | required as follows.
As a pretreatment, a 10 mm × 10 mm sample taken from a rolled material is immersed in 10% sulfuric acid for 10 minutes, then washed with water and sprinkled by air blow, and then the water sprayed sample is a flat milling (ion milling) device manufactured by Hitachi High-Technologies Corporation. The surface treatment was performed at an acceleration voltage of 5 kV, an incident angle of 5 °, and an irradiation time of 1 hour.
Next, the sample surface was observed with a scanning electron microscope S-3400N manufactured by Hitachi High-Technologies Corporation equipped with an EBSD system manufactured by TSL. The observation conditions were an acceleration voltage of 25 kV and a measurement area of 150 μm × 150 μm (including 5000 or more crystal grains).
From the observation results, the area average GAM of the crystal grains existing in the measurement area was determined under the following conditions.
At a step size of 0.5 μm, the orientation of all pixels within the measurement area range was measured, and a boundary where the orientation difference between adjacent pixels was 5 ° or more was regarded as a crystal grain boundary.
GAM is the average value of misorientation between adjacent measurement points (pixels) in the same crystal grain. When the difference in orientation at the boundary i between adjacent measurement points is expressed by equation (1), the boundary between pixels in the crystal grain is When m exist, the GAM value of this crystal grain is expressed by the equation (2).

When the value of the GAM in individual grains (GAM) _k, the area of each crystal grain and S _k, if there are M grain within the measurement range, area average GAM is expressed by equation (3) The

The area ratio of the crystal grains in which the average orientation difference between all the pixels in the crystal grains is less than 4 ° thus obtained is 45 to 55% of the measurement area, and the area of the crystal grains existing in the measurement area The copper alloy strip of the present invention having an average GAM of 2.2 to 3.0 ° is less prone to accumulate strain in crystal grains, is less prone to cracking, and has both tensile strength and spring limit value. Balances the swing plane bending fatigue characteristics at a high level.

The copper alloy strip having such a configuration can be manufactured, for example, by the following manufacturing process.
“Melting / Casting → Hot Rolling → Cold Rolling → Solution Treatment → Finish Cold Rolling → Low Temperature Annealing”
Although not described in the above process, chamfering may be performed as necessary after hot rolling, and pickling, polishing, or further degreasing may be performed as necessary after each heat treatment. .
Hereinafter, main steps will be described in detail.

[Hot rolling / cold rolling / solution treatment]
In order to stabilize the copper alloy structure and to balance the tensile strength, the spring limit value and the double swing plane bending fatigue characteristics at a high level, the Vickers hardness of the copper alloy plate after the solution treatment is 80 to 100 Hv. Thus, it is necessary to appropriately adjust various conditions for hot rolling, cold rolling, and solution treatment.
In particular, in hot rolling, the rolling start temperature is set to 700 ° C. to 800 ° C., the total rolling rate is set to 90% or more, and the hot rolling is performed so that the average rolling rate per pass is 10% to 35%. is important. If the average rolling rate per pass is less than 10%, the workability in the subsequent process is deteriorated, and if it exceeds 35%, material cracking is likely to occur. If the total rolling ratio is less than 90%, the additive elements are not uniformly dispersed and material cracking is likely to occur. When the rolling start temperature is less than 700 ° C., the additive elements are not uniformly dispersed, and material cracking is likely to occur. When the rolling start temperature exceeds 800 ° C., the heat cost increases, resulting in economical waste.

(Finish cold rolling)
Finish cold rolling is carried out at a total rolling rate of 50 to 80%. When the total rolling reduction is less than 50%, the area average GAM of the crystal grains existing in the measurement area is less than 2.2 °, and when it exceeds 80%, the area average GAM of the crystal grains existing in the measurement area is 3. Exceeding 0 °, both cause a decrease in the double-bending plane bending fatigue characteristics.

[Low temperature annealing]
After the finish cold rolling, low temperature annealing at 250 to 450 ° C. for 30 to 180 seconds is performed to further stabilize the copper alloy structure, resulting in high tensile strength, spring limit value, and double swing plane bending fatigue characteristics. Measure the azimuth of all pixels within the measurement area of the surface of the copper alloy strip by the EBSD method using a scanning electron microscope with a backscattered electron diffraction image system, and balance the azimuth difference between adjacent pixels. When the boundary where the angle is 5 ° or more is regarded as a crystal grain boundary, the area ratio of crystal grains having an average orientation difference between all the pixels in the crystal grains of less than 4 ° is 45 to 55% of the measurement area. Yes, the area average GAM of the crystal grains existing in the measurement area is 2.2 to 3.0 °.
When the low-temperature annealing temperature is less than 250 ° C., the spring limit value characteristics are not improved, and when it exceeds 450 ° C., a brittle and coarse Mg compound is formed and the tensile strength is lowered. Similarly, if the low-temperature annealing time is less than 30 seconds, the spring limit value characteristics are not improved, and if it exceeds 180 seconds, a brittle and coarse Mg compound is formed, and the tendency to decrease the tensile strength becomes strong.

Hereinafter, the characteristics of the examples of the present invention will be described in comparison with comparative examples.
A copper alloy having the composition shown in Table 1 was melted in a reducing atmosphere using an electric furnace to produce an ingot having a thickness of 150 mm, a width of 500 mm, and a length of 3000 mm. This molten ingot was hot-rolled at the rolling start temperature shown in Table 1, the total rolling rate, and the average rolling rate per pass to obtain a copper alloy plate having a thickness of 7.5 mm to 18 mm. After removing 0.5 mm of oxide scale on both surfaces of this copper alloy plate with a mill, cold rolling with a rolling rate of 85% to 95% is performed, and a solution treatment is performed at 750 ° C.,
Finish cold rolling shown in Table 1 is performed to produce a 0.2 mm cold rolled strip, and then low temperature annealing shown in Table 1 is performed, and Examples 1 to 10 and Comparative Examples 1 to 1 in Table 1 are performed. A Cu—Mg—P-based copper alloy strip shown in FIG.
Moreover, the Vickers hardness of the copper alloy plate after the solution treatment shown in Table 1 was measured based on JIS-Z2244.

The following various tests were performed with each sample in Table 1, and the results are summarized in Table 2.
(Area ratio)
As a pretreatment, a 10 mm × 10 mm sample taken from a rolled material is immersed in 10% sulfuric acid for 10 minutes, then washed with water and sprinkled by air blow, and then the water sprayed sample is a flat milling (ion milling) device manufactured by Hitachi High-Technologies Corporation. The surface treatment was performed at an acceleration voltage of 5 kV, an incident angle of 5 °, and an irradiation time of 1 hour.
Next, the sample surface was observed with a scanning electron microscope S-3400N manufactured by Hitachi High-Technologies Corporation equipped with an EBSD system manufactured by TSL. The observation conditions were an acceleration voltage of 25 kV and a measurement area of 150 μm × 150 μm (including 5000 or more crystal grains).
From the observation results, the area ratio with respect to the total measurement area of the crystal grains in which the average orientation difference between all the pixels in the crystal grains is less than 4 ° was obtained under the following conditions.
At a step size of 0.5 μm, the orientation of all pixels within the measurement area range was measured, and a boundary where the orientation difference between adjacent pixels was 5 ° or more was regarded as a crystal grain boundary. Next, for each crystal grain surrounded by the crystal grain boundary, the average value of the orientation difference between all the pixels in the crystal grain is calculated by the above-mentioned formula 1, and the area of the crystal grain whose average value is less than 4 ° Was calculated and divided by the total measurement area to determine the ratio of the area of the crystal grains having an average orientation difference within the crystal grains of less than 4 ° to the total crystal grains. In addition, what connected 2 pixels or more was made into the crystal grain.
The measurement location was changed by this method and measurement was performed 5 times, and the average value of the respective area ratios was defined as the area ratio.

(Area average GAM)
As a pretreatment, a 10 mm × 10 mm sample taken from a rolled material is immersed in 10% sulfuric acid for 10 minutes, then washed with water and sprinkled by air blow, and then the water sprayed sample is a flat milling (ion milling) device manufactured by Hitachi High-Technologies Corporation. The surface treatment was performed at an acceleration voltage of 5 kV, an incident angle of 5 °, and an irradiation time of 1 hour.
Next, the sample surface was observed with a scanning electron microscope S-3400N manufactured by Hitachi High-Technologies Corporation equipped with an EBSD system manufactured by TSL. The observation conditions were an acceleration voltage of 25 kV and a measurement area of 150 μm × 150 μm (including 5000 or more crystal grains).
From the observation results, the average value of the orientation difference between adjacent pixels in the same crystal grain was determined as follows.
At a step size of 0.5 μm, the orientation of all pixels within the measurement area range was measured, and a boundary where the orientation difference between adjacent pixels was 5 ° or more was regarded as a crystal grain boundary. Next, for each crystal grain surrounded by the crystal grain boundary, the area average GAM of the crystal grain was calculated by the above equation (3). In addition, what connected 2 pixels or more was made into the crystal grain.

(Mechanical strength)
It measured with the JIS5 test piece.
(Spring limit value)
Based on JIS-H3130, the amount of permanent deflection is measured by a moment type test. T.A. Kb0.1 (maximum surface stress value at the fixed end corresponding to a permanent deflection of 0.1 mm) was calculated.
(conductivity)
It measured based on JIS-H0505.
(Fatigue properties)
In accordance with JISZ2273 (1978), a fatigue test of double swing plane bending was performed. A strip-shaped sample with a width of 10 mm was taken so that the length direction of the sample coincided with the rolling direction, the maximum stress (σ) applied to the sample surface was changed stepwise, and the sample was broken at each maximum stress. The number of repetitions (Nf) was measured, and an SN diagram was created.
From this SN diagram, the maximum allowable cyclic stress σ (A10 ⁶ ) = fatigue limit that does not break at a repetition number of 1 × 10 ⁶ times was determined.

From these results, the orientation of all the pixels within the measurement area of the surface of the copper alloy strip was measured with an EBSD method using a scanning electron microscope with a backscattered electron diffraction image system at a step size of 0.5 μm. When the boundary where the orientation difference between pixels is 5 ° or more is regarded as a grain boundary, the area ratio of the crystal grains where the average orientation difference between all the pixels in the crystal grain is less than 4 ° is the measured area It is 45 to 55%, and the area average GAM of the crystal grains existing in the measurement area is 2.2 to 3.0 °. The mass% is Mg: 0.3 to 2%, P: 0.001. The copper alloy strip of the present invention having a composition of 0.1%, the balance being Cu and inevitable impurities, has a tensile strength of 641 to 708 N / mm ² and a spring limit value of 472 to 503 N / mm ² . There, bending Reversed plane in the number of repetitions of 1 × 10 ⁶ times Re limit is 300~350N / mm ^2, and the tensile strength, and spring limit value, it can be seen that the two swing fatigue properties are balanced at a high level.
Among them, the one added with Zr has improved tensile strength and spring limit value.

  From these facts, the Cu-Mg-P-based copper alloy of the present invention is used for electrical and electronic parts such as connectors, lead frames, relays, switches, etc., in which the spring limit value characteristics and the swing fatigue characteristics are particularly important. It turns out that it is suitable for.

As mentioned above, although the manufacturing method of embodiment of this invention was demonstrated, this invention is not limited to this description, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, although the manufacturing process in the order of “melting / casting → hot rolling → cold rolling → solution treatment → finishing cold rolling → low temperature annealing” was shown, hot rolling, solution treatment, finish cold rolling The low temperature annealing may be performed in this order. In that case, the rolling start temperature of hot rolling, the total rolling rate in hot rolling, the average rolling rate per pass, the total rolling rate in finish cold rolling As for conditions other than the temperature and time of low-temperature annealing, general production conditions may be applied.

Claims (3)

It is a copper alloy strip having a composition by mass%, Mg: 0.3-2%, P: 0.001-0.1%, the balance being Cu and inevitable impurities, with backscattered electron diffraction image system Measure the orientation of all the pixels within the measurement area of the surface of the copper alloy strip with a step size of 0.5 μm by the EBSD method using a scanning electron microscope, and the orientation difference between adjacent pixels is 5 ° or more. When the boundary is regarded as a crystal grain boundary, the area ratio of crystal grains in which the average orientation difference between all pixels in the crystal grains is less than 4 ° is 45 to 55% of the measurement area, and the measurement area The area average GAM of the crystal grains existing in the inside is 2.2 to 3.0 °, the tensile strength is 641 to 708 N / mm ² , the spring limit value is 472 to 503 N / mm ² , and 1 × 10 ⁶ times both pretend plane bending fatigue limit in the number of repetitions of the Copper alloy strip material, which is a 00~350N / mm ^2.   The copper alloy strip according to claim 1, containing 0.001 to 0.03% of Zr by mass%.   It is a manufacturing method of the copper alloy strip of Claim 1 or 2, Comprising: When manufacturing a copper alloy in the process including hot rolling, solution treatment, finish cold rolling, and low temperature annealing in this order, The rolling start temperature is 700 ° C. to 800 ° C., the total hot rolling rate is 90% or more, the hot rolling is performed with the average rolling rate per pass being 10% to 35%, and after the solution treatment The Vickers hardness of the copper alloy plate is adjusted to 80 to 100 Hv, the total rolling rate in the finish cold rolling is performed at 50 to 80%, and the low temperature annealing is performed at 250 to 450 ° C. for 30 to 180 seconds. A method for producing a copper alloy strip characterized by comprising: