JP6339361B2 - Copper alloy sheet and manufacturing method thereof - Google Patents

Description

  The present invention relates to a lead frame, a connector, a terminal material, etc. for electrical and electronic equipment, a connector for automobile use, and other terminal materials, a copper alloy plate material applied to a relay, a switch, a socket, and the like, and a method for manufacturing the same. .

  Properties required for copper alloy sheets used in electrical and electronic equipment include conductivity, yield strength (yield stress), tensile strength, bending workability, fatigue resistance, stress relaxation characteristics, Young's modulus, etc. . In recent years, with the miniaturization, weight reduction, high functionality, high density mounting, and high usage environment of electric / electronic devices, these required characteristics are increasing.

  Particularly, in recent ultra-small terminals, it is required to take a large or constant displacement in a smaller space than before, and therefore, a material having a lower Young's modulus than ever is required.

  Conventionally, as materials for electric and electronic devices, copper-based materials such as phosphor bronze, red brass, brass and the like are widely used in addition to iron-based materials. These copper alloys have improved strength by a combination of solid solution strengthening of Sn and Zn and work hardening by cold working such as rolling and wire drawing. However, the copper alloy material reinforced by this method tends to have insufficient electrical conductivity. Moreover, since high strength is obtained by performing processing such as cold rolling at a high processing rate, bending workability may be insufficient.

  Therefore, as a strengthening method replacing solid solution strengthening or work hardening, there is precipitation strengthening in which a fine second phase is precipitated in the copper alloy. This strengthening method has a merit of improving the conductivity at the same time in addition to increasing the strength, and is therefore performed in many alloy systems.

  Under such circumstances, Cu—Ni—Si based alloys (Corson based alloys) are used for electrical and electronic equipment. Cu-Ni-Si-based alloys are alloys that are strengthened mainly by precipitation strengthening or work hardening. Therefore, in a Cu-Ni-Si alloy, control of Young's modulus and improvement in stress relaxation resistance and fatigue resistance are required.

  However, with the recent miniaturization of parts used in electrical and electronic equipment and automobiles, the copper alloy sheet used has been bent to a higher strength material with a smaller radius. Therefore, there is a strong demand for copper alloy sheet materials having excellent proof stress. Furthermore, since a certain spring property and sag resistance are required in a small space, a low Young's modulus is strongly required for the material in order to exert a reliable contact pressure with a constant displacement. In this regard, in the conventional Cu—Ni—Si-based alloy, high strength was obtained by increasing the rolling rate and obtaining large work hardening. However, with this method, it is difficult to control the Young's modulus, and the desired Young's modulus characteristics cannot be obtained.

  In addition, with the progress of miniaturization of electronic components such as connectors, dimensional accuracy of terminals and tolerances for press working have been strictly demanded. By reducing the Young's modulus of the copper alloy sheet, it is possible to reduce the influence of dimensional fluctuations on the contact contact pressure, which facilitates component design. For this reason, copper alloy parts are required to have a low Young's modulus (longitudinal elastic modulus), and a copper alloy sheet material having a Young's modulus of 125 GPa or less and a deflection coefficient of 115 GPa or less is required.

  Further, in a high current connector or the like, there is a problem that the material itself self-heats due to Joule heat generated by current flowing through the member, and stress is relieved. There is also a problem that the initial contact pressure cannot be maintained due to the “sag” during use. Therefore, the material is required to have excellent stress relaxation resistance.

  In addition, when used as a part used in an electronic device or an automobile, vibration is applied depending on the use situation, and repeated stress is applied to the material. If a constant load stress is continuously applied to the material, a crack is generated in the plate material, leading to a break. Therefore, the material is required to have excellent fatigue resistance.

  Several proposals have been made to solve this demand for improvement in low Young's modulus, stress relaxation resistance, and fatigue resistance in the width direction (TD) of the rolled sheet by controlling the crystal orientation of the alloy material. Yes. For example, in Patent Documents 1 and 2, by controlling the X-ray diffraction intensity of the Cube orientation of the texture in the alloy and the area ratio of the Cube orientation crystal grains, 0.2% proof stress, stress relaxation resistance and bending workability are controlled. Has improved. In Patent Document 3, strength anisotropy is improved by controlling the flatness of all crystal grains in the longitudinal section of the plate material. In Patent Document 4, the deflection coefficient in the vertical direction of rolling is lowered by increasing the Cube orientation and reducing the NDRDW orientation.

  In the technique described in Patent Document 1, the average particle diameter of Ni—Si-based precipitates and the X-ray diffraction peak intensity of the I {200} crystal plane are increased above a certain level. Further, by increasing the twin density in the crystal grains, the 0.2% proof stress, bending workability, and stress relaxation resistance are improved, but the Young's modulus characteristics are not improved. In addition, in the manufacturing method described in Patent Document 1, it is presumed that the Young's modulus decreases because the (100) planes facing TD are accumulated. However, there is no description of what Young's modulus actually becomes. Absent.

  In the technique described in Patent Document 2, conductivity, 0.2% proof stress, bending workability and stress relaxation resistance are improved by increasing the Cube orientation area ratio and twin boundary density in the crystal by texture control. Although improved, Young's modulus is not controlled, and the effect of improving characteristics is limited.

  In the technique described in Patent Document 3, although the strength anisotropy is improved by controlling the flatness of all crystal grains from the observation of the structure of the longitudinal section of the plate material, the strength is 700 MPa or more, and the upper limit is 820 MPa. Still, the Young's modulus is not controlled.

  In the technique described in Patent Document 4, the deflection coefficient in the vertical direction of rolling is controlled by controlling the texture. However, this is control of the texture system that orients a specific crystal plane, and is obtained by the present invention. It is very different from the metal structure.

  Non-Patent Document 1 shows an average Young's modulus of a material composed of a parent phase and a second phase.

  The Young's modulus is measured by a method of calculating from the slope of the elastic region of the stress-strain diagram by the tensile test, the slope of the elastic region of the stress-strain diagram when the beam (cantilever) is bent. There are two methods of calculating from the above.

Furthermore, the Young's modulus of the copper alloy sheet is also described in Patent Document 5 and Patent Document 6.
Patent Document 5 describes a copper alloy sheet material having a small Young's modulus of 110 GPa or less, for example, by controlling the area ratio of the Cube orientation (100) plane facing the rolling direction (RD) to 30% or more. However, although this patent document 5 makes it a subject to reduce a Young's modulus, it does not describe focusing on the Young's modulus of a TD direction and controlling this low.

  Patent Document 6 discloses that a precipitation-free zone (PFZ) having a predetermined width is formed in the vicinity of a grain boundary in a copper alloy at the time of aging treatment, tensile strength (TS (LD)) in the rolling parallel direction, and Ni content. By controlling the average crystal grain size of the base material, the width of the precipitation-free zone (PFZ), and the particle diameter of the compound on the grain boundary to satisfy a predetermined relationship, the Young's modulus is 130 GPa in the embodiment. A copper alloy sheet is described. However, this Patent Document 6 does not mention the Young's modulus in the TD direction, and does not describe controlling the Young's modulus in the TD direction to be low.

JP 2011-84764 A JP 2011-231393 A JP 2011-17070 A Japanese Patent No. 5117602 International Publication WO2011 / 068134A1 International Publication WO2009 / 104615A1

Onaka et al .: Journal of the Japan Institute of Metals, Vol. 63, no. 10 (1999), pp 1283-1289

Thus, conventionally, a copper alloy sheet material in which the Young's modulus in the TD direction is controlled to be low has not been known, and the provision thereof has been required.
In view of the problems as described above, an object of the present invention is to provide a lead frame and a connector for electrical and electronic equipment that have a low Young's modulus in the TD direction, a high proof stress in the TD direction, and excellent fatigue resistance. It is intended to provide a copper alloy plate material suitable for connectors for automobiles, other terminal materials, other terminal materials, relays, switches, sockets, and the like.

  The present inventors have made various studies and studied a copper alloy sheet suitable for electric / electronic component applications. As a result, the present inventors, in the Cu-Ni-Si-based copper alloy plate material, the density of flat crystal grains having an aspect ratio of 0.3 or less oriented in a predetermined direction, and further, between adjacent crystal grains It has been found that the Young's modulus in the vertical direction of rolling (TD) can be controlled to be low by using a metal structure in which the length per unit area of the crystal grain boundary having a deviation angle of 30 ° or more is appropriately controlled. In addition, the present inventors have found a method for producing a copper alloy plate material having a specific process for realizing the predetermined metal structure. The present invention has been completed based on these findings.

That is, according to the present invention, the following means are provided.
(1) Ni is 1.0 to 5.0 mass%, Si is 0.1 to 2.0 mass%, B is 0.10 mass% or less, Mg is 1.80 mass% or less, and P is 0.00. 05 mass% or less, Cr 0.50 mass% or less, Mn 0.16 mass% or less, Fe 0.05 mass% or less, Co 0.05 mass% or less, Zn 0.51 mass% or less, Zr 0.10 wt% or less, at least one selected from 0.05 wt% or less and Sn and Ag from the group consisting of 0.50 wt% or less to 0.1 0 to 3.0 wt% in total The balance is a copper alloy sheet made of copper and inevitable impurities,
In the analysis on the rolling surface, the crystal grains having an aspect ratio represented by the ratio of the minor axis / major axis of the crystal grains of 0.3 or less and oriented within ± 30 ° from the TD direction and a density of 0.030 cells / [mu] m ² or less, and the length per unit area of the displacement angle between adjacent crystal grains is 30 ° or more grain boundaries is 0.8 [mu] m / [mu] m ² or less A copper alloy sheet characterized by the above .
(2 ) The Young's modulus in the TD direction measured by a tensile test, which indicates the amount of displacement when a certain stress is applied to the plate material, is 125 GPa or less, the deflection coefficient in the TD direction measured by the deflection test is 115 GPa or less, TD The proof stress in the direction is 600 MPa or more, the electrical conductivity is 20% IACS or more, and the stress relaxation rate (SR) after holding at 150 ° C. for 1000 hours is 20% or less as stress relaxation characteristics (1 ) The copper alloy sheet material described.
(3) fatigue resistance of the leaf spring fatigue test, the load stress 500MPa or more, the copper alloy sheet according to the repeat count is not less than 10 ⁶ times (1) or (2).
( 4 ) Ni is 1.0 to 5.0 mass%, Si is 0.1 to 2.0 mass%, B is 0.10 mass% or less, Mg is 1.80 mass% or less, and P is 0.00. 05 mass% or less, Cr 0.50 mass% or less, Mn 0.16 mass% or less, Fe 0.05 mass% or less, Co 0.05 mass% or less, Zn 0.51 mass% or less, Containing at least one selected from the group consisting of 0.10 mass% or less of Zr, 0.05 mass% or less of Ag, and 0.50 mass% or less of Sn in a total of 0.1 to 3.0 mass%, A method for producing a copper alloy sheet comprising copper and inevitable impurities, the copper alloy material comprising an alloy component composition giving the copper alloy sheet,
Casting [process 1],
Cold rolling 1 with a processing rate of 10% or less [Step 2],
Pre-annealing at a holding temperature of 300 to 700 ° C. and a holding time of 1 minute to 5 hours [Step 3],
Homogenization heat treatment at a holding temperature of 700 ° C. or higher for 5 minutes to 20 hours [Step 4],
Hot rolling [step 5],
Water quenching [Step 6],
Chamfering [process 7],
Cold rolling 2 with a processing rate of 50% or more [Step 8],
Intermediate solution heat treatment [Step 9] with a temperature rising rate of 5 to 15 ° C./second, a holding temperature of 300 to 700 ° C., and a holding time of 1 second to 10 hours,
Cold rolling 3 [Process 10] with a processing rate of 10 to 99%,
Solution heat treatment [step 11] having an ultimate temperature of 700 to 1020 ° C. and a holding time of 1 second to 60 seconds,
Aging precipitation heat treatment [Step 12] with a holding temperature of 300 to 600 ° C. and a holding time of 10 minutes to 20 hours,
Pickling [Step 13] and finish cold rolling with a rolling rate of 8 to 80% [Step 14]
The method of manufacturing the copper alloy sheet | seat of any one of (1)-( 3 ) characterized by performing each process of these in this order .
(5) In the following the finish cold rolling [step 14], holding temperature 300 to 600 ° C., the retention time stress relief annealing of 1 to 60 seconds [Step 15] subjecting (4) of the copper alloy sheet according to Production method.

The copper alloy sheet of the present invention is a crystal grain having a predetermined alloy composition and an aspect ratio of 0.3 or less, and the density of crystal grains whose major axis is within ± 30 ° from the TD direction is 0. 3 / μm ² or less, and the deviation angle between adjacent crystal grains is 30 ° or more, and the length per unit area of the crystal grain boundary is 0.8 μm / μm ² or less. Therefore, the Young's modulus in the TD direction is low, the yield strength in the TD direction is high, the fatigue resistance is excellent, and it is suitable for applications such as electric / electronic devices and automotive parts. This copper alloy plate material of the present invention has properties particularly suitable for lead frames, connectors, terminal materials, etc. for automobiles, automobile terminals, other terminal materials, relays, switches, sockets, etc. . Moreover, according to the manufacturing method of this invention, the said copper alloy board | plate material can be manufactured suitably.

FIG. 1 is an explanatory diagram schematically showing a multiphase material having a second phase Ω with respect to the mother phase M, respectively. In the multiphase material shown as Type A in FIG. 1A, the shape of the second phase Ω with respect to the parent phase M is a plate shape perpendicular to the stress axis indicated by the up and down arrows in the figure. Show the case. On the other hand, the multiphase material shown as Type B in FIG. 1B is a continuous fiber in which the shape of the second phase Ω is parallel to the stress axis indicated by the up and down arrows in the figure with respect to the matrix M. Is shown. FIG. 2 is an explanatory view schematically showing a state in which the crystal grains are controlled so that the crystal grains are aligned in a direction (TD) perpendicular to the rolling direction (RD). FIG. 2A shows a random state before the orientation control of crystal grains, and FIG. 2B shows a state in which the orientations of crystal grains are aligned. FIG. 3 is an explanatory view schematically showing the leaf spring fatigue test apparatus used in the examples. FIG. 4 is an explanatory view schematically showing the stress relaxation resistance test apparatus used in the examples.

  A preferred embodiment of the copper alloy sheet material of the present invention will be described in detail. The “plate material” in the present invention includes “strip material”.

[Metal structure with controlled orientation of flat grains with aspect ratio of 0.3 or less]
In order to lower the Young's modulus of the copper alloy sheet material in the TD direction (Transverse Direction. In this document, the vertical direction of rolling, or simply referred to as TD), the present inventors investigated in detail the correlation between the Young's modulus control and the structure. . As a result, when the structure is observed from the direction of the plate ND, that is, when the rolled surface is observed and analyzed, the orientation of the relatively flat crystal grains having an aspect ratio of 0.3 or less is controlled and the density of the crystal grains is controlled. It was found that the Young's modulus in the TD direction can be controlled to be low by controlling the value low. Specifically, while controlling the density of the flat grains arranged so that the major axis of the crystal grains of the parent phase is oriented in the TD direction, the length per unit area of the grain boundaries having a large grain boundary deviation angle of 30 ° or more. It was found that the Young's modulus in the TD direction can be controlled to be low by controlling the value small. Here, the arrangement of the major axis of crystal grains in the TD direction means that crystal grains having an aspect ratio of 0.3 or less as defined in the present invention are within ± 30 ° from the TD direction. (For example, FIG. 2B).

In the copper alloy sheet of the present invention, the metal structure is a crystal grain having an aspect ratio of 0.3 or less, and the density of the crystal grain facing within ± 30 ° from TD is 0.030 in the analysis on the rolling surface. pieces / [mu] m and ² or less, and the length per unit area of the deviation angle grain boundaries between adjacent crystal grains is 30 ° or more grain boundaries 0.8 [mu] m / [mu] m ² or less. Hereinafter, in this document, the crystal grains having an aspect ratio of 0.3 or less are also referred to as flat crystal grains or flat grains. Further, the “crystal grain boundary in which the deviation angle between adjacent crystal grains is 30 ° or more” is also referred to as “a crystal grain boundary having a large grain boundary deviation angle”. According to the present invention, the density of such flat grains is appropriately reduced, and the length per unit area of the crystal grain boundary having a large grain boundary deviation angle is appropriately shortened and obtained by controlling each. As a characteristic of the copper alloy sheet, a value with a low Young's modulus in the rolling vertical direction (TD direction), for example, 125 GPa or less is shown.

As for the metal structure of the copper alloy sheet material of the present invention, the density of the flat particles is preferably 0.030 particles / μm ² or less, and more preferably 0.025 particles / μm ² or less. Also, the metal structure of the copper alloy sheet of the present invention, the length of the grain boundary misalignment angle is large grain boundaries is 0.8 [mu] m / [mu] m ² or less as the length per unit area (1 [mu] m ²⁾ Is more preferable, and 0.7 μm / μm ² or less is more preferable. Furthermore, in the metal structure of the copper alloy sheet of the present invention, the average area of the flat particles is preferably 3.0 μm ² or less, and more preferably 2.5 μm ² or less. Such flat crystal grains are formed, for example, by appropriately performing each step of cold rolling 1 [step 2] and pre-annealing [step 3] after casting [step 1], and the orientation thereof. Can be controlled.

  In the present invention, the average area and grain size (major axis and minor axis) of crystal grains, and the length of crystal grain boundaries are determined by observing and analyzing by the EBSD method. Within a predetermined observation region, the longest particle diameter of each crystal grain of the base material is defined as a major axis a (μm), the shortest particle diameter thereof is defined as a minor axis b (μm), and the major axis a and minor axis b thereof. Each average value of is obtained. In the present invention, the aspect ratio means that each average value is obtained for the major axis a and the minor axis b that are straight lines, and the ratio of the minor axis / major axis obtained from each average value, that is, the value of the ratio b / a. Say.

[Average crystal grain size (average value of major axis and minor axis)]
In the present invention, the average crystal grain size of the base material is not particularly limited, but is usually 10 to 60 μm. Here, the average crystal grain size is an average value of the major axis a (μm). The average value of the minor axis b (μm) is not particularly limited, but is usually 5 to 40 μm. In the present invention, the major axis a is longer than the minor axis b.

[Relationship between flat grain orientation and Young's modulus] (From Non-Patent Document 1)
FIG. 1 schematically shows a multiphase material containing continuous fibers. In the multiphase material shown as Type A in FIG. 1A, the shape of the second phase Ω with respect to the parent phase M is a plate shape perpendicular to the stress axis indicated by the up and down arrows in the figure. Show the case. On the other hand, the multiphase material shown as Type B in FIG. 1B is a continuous fiber in which the shape of the second phase Ω is parallel to the stress axis indicated by the up and down arrows in the figure with respect to the matrix M. Is shown.

In an elementary analysis under the assumption of equal strain conditions, if the Young's modulus of the parent phase M is E _M and the Young's modulus of the second phase Ω is E _Ω , the stresses in the parent phase M and the strengthening phase Ω are both external. of each considered equivalent stress sigma ⁰ Aiuchi elastic strain epsilon _M and epsilon _Omega (elongation strain stress axis direction), respectively ε _M = σ ⁰ / _{E M} and ^{_{ε Ω = σ 0 / E Ω}} ··· (1)
Estimate. This is also called Reuss approximation. The Young's modulus EA _(R) of the plate-like laminated material (multiphase material) (Type A, FIG. 1 (A)) under this Reuss approximation is expressed as follows, where the volume fraction of the second phase Ω is V _f :
E _{A (R)} = σ ⁰ / {V _f ε _Ω + (1−V _f ) ε _M } = 1 / [(V _f / E _Ω ) + {(1−V _f ) / E _M }]・ (2)
It becomes.

On the other hand, in an elementary analysis under the assumption of an equal strain condition, it is considered that the elastic elongation strains in the stress axis direction in the matrix phase M and the reinforcement phase Ω both have the same value ε _u for the fiber reinforcement. This elastic strain ε _u is the stress σ _M and σ _Ω in each phase σ _M = E _M ε _u and σ _Ω = E _Ω ε _u (3)
Give as. Here, the stress distribution condition σ ⁰ = V _f σ _Ω + (1−V _f ) σ _M (4)
, The Young's modulus EB _(v) of the fiber reinforcing material (double phase material) (Type B, FIG. 1 (B)) under equal strain conditions is
E _{B (v)} = σ ⁰ / ε _u = V _{f EΩ} + (1−V _f ) E _M (5)
It is given in the form of a mixing rule of Young's modulus. This equal strain condition is also called a Voigt approximation.

From the above estimation, the relationship between E _{A (R)} and E _{B (v) in} the above (2) and (5) is E _{B (v)} > E _{A (R)} (6)
It becomes. From this, it was found that EB _(v) (Type B, FIG. 1 (B)) has a higher Young's modulus than EA _(R) (Type A, FIG. 1 (A)).

  Therefore, in the present invention, based on such knowledge, an attempt is made to control the orientation so as to reduce the state of the type B, that is, the crystal grains shown in FIG. That is, according to the present invention, Type B, that is, the structure shown in FIG. While controlling the orientation and reducing the density of grains having a predetermined low aspect ratio and controlling the length per unit area of the crystal grain boundary having a large deviation angle, it is obtained. The Young's modulus of the obtained copper alloy sheet is reduced.

[EBSD method]
The EBSD method is used for the observation and analysis of the above-described flat grains and crystal grain boundaries in the present invention. EBSD is an abbreviation for Electron BackScatter Diffraction, and is a crystal orientation analysis technique using reflected electron Kikuchi line diffraction that occurs when a sample is irradiated with an electron beam in a scanning electron microscope (SEM). In the present invention, the EBSD method is used to analyze not the crystal orientation but the average area and shape (aspect ratio) of crystal grains. In the EBSD measurement in the present invention, a 100 μm × 200 μm sample area containing 200 or more crystal grains is scanned in 0.1 μm steps, and the average area and shape of crystal grains and the length of crystal grain boundaries are analyzed. The measurement area and the scanning step may be determined according to the size of the crystal grains of the sample. In the present invention, they are 100 × 200 μm and 0.1 μm. For analysis of crystal grains after measurement, analysis software OIM Analysis (trade name) manufactured by TSL is used.

  The information obtained in the analysis of crystal grains by the EBSD method includes information up to a depth of several tens of nanometers in which the electron beam penetrates into the sample, but is sufficiently small with respect to the measured width. In it, it described as an average area of a crystal grain. Moreover, since the average area of crystal grains differs in the plate thickness direction, it is preferable to take an average for any number of points in the plate thickness direction.

  In the present invention, the properties of each crystal grain such as the aspect ratio and area are obtained by analysis using the EBSD method on the rolled surface. Here, the analysis on the rolling surface refers to observing and analyzing the rolling surface of the plate material from the plate thickness direction (Normal Direction; ND). According to the present invention, the orientation of the crystal grains is controlled so that the crystal grains are aligned in the rolling vertical direction (TD) perpendicular to the rolling direction (RD). This is shown in FIG. In the figure, the rolling surface is shown parallel to the paper surface. FIG. 2A shows a random state before the crystal grain orientation control. By subjecting this to predetermined heat treatment and processing, the crystal grains are aligned as shown in FIG.

FIG. 2B shows a typical example in which all the crystal grains are aligned within ± 30 ° from the rolling vertical direction (TD) perpendicular to the rolling direction (RD). The state of being aligned in parallel with TD is schematically shown. Parallel to TD means that the deviation of the orientation of the crystal grain is 0 ° with respect to TD.
Here, the deviation of the orientation of the crystal grains relative to the TD means how many times the orientation of the crystal grains is deviated from the TD when a straight line passing through the major axis of each crystal grain is taken as the orientation of the crystal.
In the present invention, the deviation of the crystal grain direction from TD is set within ± 30 °.

[Necessary additive elements]
It shows about content of the essential addition element to the copper alloy of this invention, and its effect | action.

(Ni)
Ni is an element that is contained together with Si, which will be described later, and that contributes to improving the strength of the copper alloy sheet material by forming a Ni ₂ Si phase precipitated by aging precipitation heat treatment. The Ni content is 1.0 to 5.0% by mass, preferably 1.5 to 4.7% by mass, and more preferably 2.0 to 4.5% by mass.
By setting the Ni content in the above range, the Ni ₂ Si phase can be appropriately formed, and the tensile strength of the copper alloy sheet can be increased. Also, the conductivity is high. Moreover, hot rolling workability is also favorable.

(Si)
Si is contained together with the Ni and forms a Ni ₂ Si phase precipitated by an aging precipitation heat treatment, thereby contributing to an improvement in the strength of the copper alloy sheet. Content of Si is 0.1-2.0 mass%, Preferably it is 0.2-1.8 mass%, More preferably, it is 0.6-1.5 mass%. The balance between conductivity and strength is best when the Si content is stoichiometrically Ni / Si = 4.2. Therefore, the Si content is preferably such that Ni / Si is in the range of 2.5 to 7.5, and more preferably 3.0 to 6.5.
By setting the Si content in the above range, the tensile strength of the copper alloy sheet can be increased. In this case, excess Si does not dissolve in the copper matrix and the electrical conductivity of the copper alloy sheet is not lowered. Moreover, the castability at the time of casting, and the hot and cold rolling workability are also good, and no casting cracks or rolling cracks occur.

[Sub-additive elements]
Next, the content of the auxiliary additive element in the copper alloy of the present invention and its action will be described. Preferable secondary additive elements include B, Mg, P, Cr, Mn, Fe, Co, Zn, Zr, Ag, and Sn. If these elements are contained in a total amount of 0.1 to 3.0 % by mass, the various characteristics described below can be improved without causing the adverse effect of lowering the conductivity. The copper alloy sheet material of the present invention may be added and contained. As a content for fully utilizing the effect of addition and not lowering the conductivity, it is preferable to contain at least one of these sub-added elements in a total amount of 0.1 to 3.0% by mass, 0 .3-1.5 mass% is further more preferable, and it is more preferable that it is 0.5-1.0 mass%. The effects of adding each element are shown below.

(Mg, Sn, Zn)
Mg, Sn, and Zn improve the stress relaxation resistance by adding and containing them. The stress relaxation resistance is further improved by the synergistic effect when each of them is added together than when they are added alone. In addition, the solder embrittlement is remarkably improved.

(Mn, Ag, B, P)
When Mn, Ag, B, and P are added and contained, the hot workability is improved and the strength is improved.

(Cr, Zr, Fe)
Cr, Zr, and Fe precipitate finely as a compound or a simple substance, and contribute to precipitation hardening. Moreover, it precipitates with the magnitude | size of 50-500 nm as a compound, and there exists an effect which makes a crystal grain size fine by suppressing grain growth, and makes bending workability favorable.

(Co)
Co forms precipitates of Co ₂ Si intermetallic compounds together with Si in the alloy and contributes to strength improvement by precipitation strengthening.

[Method for producing copper alloy sheet]
Next, preferable production conditions for the copper alloy sheet of the present invention will be described.

First, a conventional method for producing a precipitation-type copper alloy will be described.
In the conventional manufacturing method, a copper alloy material is melted and cast [Step 1-1] to obtain an ingot, which is subjected to a homogenization heat treatment [Step 1-2], and hot-rolled [Step 1-3], Water cooling [Step 1-4], chamfering [Step 1-5] and cold rolling [Step 1-6] to remove oxide scale are performed in this order to form a thin plate, and an intermediate solution is formed in a temperature range of 700 to 1000 ° C. After the heat treatment [Step 1-7] is performed to re-dissolve the solute atoms, the required strength (however, the low Young's modulus is obtained by the aging precipitation heat treatment [Step 1-8] and the finish cold rolling [Step 1-9]. Is not satisfied).

In contrast, in one embodiment of the method for producing a copper alloy sheet according to the present invention, a copper alloy material giving a predetermined alloy composition is melted and cast [Step 1], and then cold-rolled at a processing rate of 10% or less. 1 [Step 2], and after performing pre-annealing [Step 3] at 300 to 700 ° C. for 1 minute to 5 hours, then performing a homogenization heat treatment [Step 4] at 700 ° C. or higher for 5 minutes to 20 hours. Fine flat particles are formed in the tissue. Thereafter, hot rolling [Step 5] is performed to obtain a predetermined thickness, and then water quenching [Step 6] is performed, whereby flat grains grow in the structure to have a desired particle size. Then, chamfering [Step 7] is performed to remove oxide scale. Thereafter, cold rolling 2 [Step 8] is performed at a processing rate of 50% or more. Thereafter, an intermediate solution heat treatment (also referred to as intermediate annealing) [Step 9] is performed at a rate of temperature increase of 5 to 15 ° C./second, a holding temperature of 300 to 700 ° C., and a holding time of 1 second to 10 hours. By performing the cold rolling 3 [step 10] at a processing rate of, a new nucleus of crystal grains is generated in the already formed flat grains, which are partially recrystallized and dispersed at a constant density. At the same time, while the flat grains are oriented in the TD direction, the density of the high-angle grain boundaries in which the deviation angle of the grain boundaries between adjacent crystal grains is 30 ° or more is maintained. Thereafter, solution heat treatment [Step 11], aging precipitation heat treatment [Step 12], pickling to remove the oxide film on the surface [Step 13], and finish cold rolling [Step 14] are performed in this order. May be subjected to strain relief annealing (also referred to as low temperature annealing) [Step 15].
Further, in terms of controlling the formation of the flat grains and the orientation, the equiaxed in the copper alloy is obtained by two processes of cold rolling 1 [process 2] and pre-annealing [process 3] after casting [process 1]. It is considered that flat grain nuclei are formed in each crystal and columnar crystal.
In the present invention, it is preferable to perform all the steps from [Step 1] to [Step 15] in this order.

However, if necessary, cold rolling 1 [Step 2] and preliminary annealing [Step 3] may be repeated as appropriate (preferably 1 to 5 times) under the above-mentioned conditions.
If necessary, intermediate annealing [Step 9] and cold rolling 3 [Step 10] may be repeated as appropriate (preferably 1 to 5 times) under the above-mentioned conditions.
Further, the low temperature annealing [Step 15] may be omitted.
Further, after the solution heat treatment [Step 11], cold rolling 4 [Step 11 ′] may be performed. This cold rolling 4 [step 11 ′] can be performed, for example, under the same conditions as the cold rolling 3 [step 10].

Below, the preferable embodiment which set the conditions of each process in detail is described.
At least Ni is contained in an amount of 1.0 to 5.0% by mass and Si is contained in an amount of 0.1 to 2.0% by mass, and other sub-addition elements are blended as necessary so that the other elements are appropriately contained. An alloy material composed of unavoidable impurities is melted in a high-frequency melting furnace and casted [step 1] to obtain an ingot. The casting condition in the casting [Step 1] is preferably a cooling rate of 0.1 to 100 ° C./second. For this ingot, for example, using a large cold rolling mill, cold rolling 1 [step 2] is performed so that the total processing rate becomes 10% or less. This cold rolling 1 [step 2] may be performed in a plurality of rolling passes (preferably 1 to 10 times), but is always cold rolled once so that the (total) rolling rate exceeds 0%. Apply.

  Next, pre-annealing at a holding temperature of 300 to 700 ° C. for a holding time of 1 minute to 5 hours [Step 3] and reheated to hold at a holding temperature of 700 ° C. to 1100 ° C. for 5 minutes to 20 hours [Step] 4] After that, in hot rolling [Step 5], it is processed to a predetermined plate thickness. Note that the final temperature of the hot rolling [Step 5] is 400 ° C., and thereafter water cooling [Step 6] is performed, and chamfering [Step 7] is performed to remove oxidized scale on the rolled surface.

  Next, cold rolling 2 [Step 8] is performed at a processing rate of 50% or more and 99% or less, and the intermediate rate is 5 to 15 ° C./second, the holding temperature is 300 to 700 ° C., and the holding time is 1 second to 10 hours. Annealing [Step 9] is performed. Thereafter, cold rolling 3 [Step 10] is performed at a processing rate of 10 to 99%, and a solution heat treatment [Step 11] is performed at an ultimate temperature of 700 to 1020 ° C. and a holding time of 1 second to 60 seconds, The added element is dissolved again. In this solution heat treatment [Step 11], the rate of temperature rise to the ultimate temperature and the rate of cooling are both 100 ° C./second or more.

  Next, for precipitation strengthening, an aging precipitation heat treatment [Step 12] is performed at a holding temperature of 300 to 600 ° C. and a holding time of 10 minutes to 20 hours. The surface of the plate material after this aging precipitation heat treatment is pickled [step 13]. Thereafter, it is subjected to finish rolling [Step 14] at a rolling rate of 8 to 80% to adjust to a desired plate thickness and strength. Next, low temperature annealing is performed at a holding temperature of 300 to 600 ° C. and a holding time of 1 second to 60 seconds [Step 15] to obtain a target copper alloy sheet. After low-temperature annealing [Step 15], a slit [Step 16] may be performed in order to adjust the sheet width (strip width) of the final product.

In the present embodiment, the cold rolling 1 [Step 2] is a rolling process with a total processing rate of 10% or less, and is a process for breaking a coarse cast structure and segregation into a uniform structure. Here, if the rolling rate is too low, sufficient processing strain does not enter the ingot, and a coarse cast structure remains.
Next, in the pre-annealing [Step 3] at 300 to 700 ° C. for 1 minute to 5 hours, the processing strain introduced in the cold rolling 1 [Step 2] is released, and the nuclei of flat crystal grains are suppressed.
In the hot rolling [Step 5], processing for refining crystal grains by dynamic recrystallization is performed in a temperature range from a homogenization heat treatment temperature (700 ° C. to 1100 ° C.) to 800 ° C.
In cold rolling 2 [Step 8], processing is performed until a predetermined plate thickness is obtained.
In the subsequent intermediate annealing [Step 9], the crystal grains refined in the hot rolling [Step 5] and the structure to which the uneven strain is applied are partially recrystallized. Further, in the intermediate annealing [Step 9], the angle between adjacent crystal grains is 30 ° or more while reducing the nuclei of the flat grains by partially releasing the processing strain introduced in the cold rolling 2 [Step 8]. This is a precise heat treatment that maintains the density of high-angle grain boundaries.
In the solution heat treatment [step 11], the additive element is dissolved. At this time, if the ultimate temperature is too high, flat crystal grains grow and the target structure cannot be obtained. Therefore, the ultimate temperature is precisely controlled.

  The following are examples of more preferable conditions for each step after the above-described melting / casting [Step 1].

Cold rolling 1 [Process 2] is preferably 8% or less, more preferably 6% or less.
In the preliminary annealing [Step 3], the holding temperature is preferably 350 to 650 ° C, more preferably 400 to 600 ° C. The holding time is preferably 5 minutes to 4 hours, more preferably 10 minutes to 3 hours.
In the hot rolling [Step 5], rolling of several to several tens of passes is preferably performed at 1010 ° C. or lower, more preferably 1000 ° C. or lower.
In the cold rolling 2 [Step 8], rolling of preferably 55% or more, more preferably 60% or more is performed.

In the intermediate annealing [Step 9], the holding temperature is preferably 350 to 650 ° C, more preferably 400 to 600 ° C. The holding time is preferably 1 minute to 8 hours, more preferably 10 minutes to 5 hours.
In the solution heat treatment [step 11], the ultimate temperature is preferably 750 to 1000 ° C, more preferably 800 to 980 ° C. The holding time is preferably 3 seconds to 50 seconds, more preferably 6 seconds to 40 seconds.
In the aging precipitation heat treatment [Step 12], the holding temperature is preferably 350 to 600 ° C, more preferably 400 to 600 ° C. The holding time is preferably 30 minutes to 15 hours, more preferably 1 hour to 10 hours.
In order to remove the oxide scale on the surface of the material after the aging precipitation heat treatment [Step 12], pickling [Step 13] is performed.

  Moreover, when the shape after each rolling is not favorable, for example, correction by a tension leveler or the like may be introduced as necessary. However, if the shape of the plate after rolling is good, this straightening step can be omitted.

Here, the processing rate (or rolling rate or rolling processing rate) is a value defined by the following equation.
Processing rate (%) = {(t ₁ −t ₂ ) / t ₁ } × 100
In the formula, t ₁ represents the thickness before rolling, and t ₂ represents the thickness after rolling.

[Copper alloy sheet thickness, etc.]
The thickness of the copper alloy sheet of the present invention is not particularly limited, but is usually 0.05 to 0.5 mm.
The plate width of the copper alloy sheet of the present invention is not particularly limited, but is usually 10 to 750 mm. Further, as the strip material, the strip width is not particularly limited, but is usually 1.0 to 300 mm.

[Characteristics of copper alloy sheet]
By satisfy | filling the said content, the characteristic requested | required of the copper alloy board | plate material for connectors, for example can be satisfied. In the present invention, the copper alloy sheet preferably has the following characteristics. Detailed measurement conditions for each characteristic are as described in the following examples unless otherwise specified.

-It is preferable that the Young's modulus of a TD direction is 125 GPa or less. More preferably, it is 123 GPa or less. More preferably, it is 120 GPa or less.
-It is preferable that the deflection coefficient of a TD direction is 115 GPa or less. More preferably, it is 113 GPa or less. More preferably, it is 110 GPa or less.
-It is preferable that the 0.2% yield strength of TD direction is 600 Mpa or more. More preferably, it is 750 MPa or more, More preferably, it is 800 MPa or more.
· Fatigue properties, load stress 500MPa into plate material, it is preferred not to break at repetition count 10 ⁶ times conditions.
-It is preferable that electrical conductivity is 20% IACS or more. More preferably, it is 25% or more.
-As a stress relaxation-resistant characteristic, it is preferable that the stress relaxation rate (SR) after 1000-hour holding | maintenance at 150 degreeC is 20% or less. More preferably, it is 15% or less.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

(Examples 1 to 16, Comparative Examples 1 to 21)
About Examples 1 to 16, various auxiliary additive elements are blended with the main raw material Cu and the essential additive elements Ni and Si as necessary so as to have the compositions shown in Table 1, and the balance consists of Cu and inevitable impurities. An alloy material (alloy material) was obtained. Each alloy raw material was melted in a high-frequency melting furnace, and casted at a cooling rate of 0.1 to 100 ° C./second [Step 1] to obtain an ingot. Each ingot was subjected to cold rolling 1 [Step 2] at a total processing rate of 10% or less, and pre-annealed [Step 3] at a holding temperature of 300 to 700 ° C. and a holding time of 1 minute to 5 hours. Next, the material was reheated and subjected to a homogenization heat treatment [Step 4] at a holding temperature of 700 to 1100 ° C. for 5 minutes to 20 hours, and hot rolled at a temperature of 1020 ° C. or less (Step 5). The end temperature of the hot rolling [Step 5] was 400 ° C. Then, after water quenching [Step 6] and subsequently chamfering [Step 7] to remove oxide scale, cold rolling 2 [Step 8] was performed at a processing rate of 50% to 99%. . This face-cut workpiece is subjected to intermediate annealing in a large annealing furnace (for example, a BEL furnace) at a heating rate of 5 to 15 ° C./second, a holding temperature of 300 to 700 ° C., and a holding time of 1 second to 10 hours [step 9]. Thereafter, cold rolling 3 [Step 10] was performed at a processing rate of 10 to 99%. Thereafter, solution heat treatment [Step 11] is performed at an ultimate temperature of 700 to 1020 ° C. and a holding time of 1 to 60 seconds, and then an aging precipitation heat treatment [Step 12] at an ultimate temperature of 300 to 600 ° C. and a holding time of 10 minutes to 20 hours. Went. Then, in order to remove the oxide film on the surface, pickling [Step 13], finish cold rolling [Step 14] with a processing rate of 8 to 80%, and finally holding temperature 300 to 600 ° C. and holding time. Each sample material was subjected to low-temperature annealing [Step 15] for 1 second to 60 seconds.

  After each heat treatment and rolling, acid cleaning and surface polishing were performed according to the state of oxidation and roughness of the material surface, and correction with a tension leveler was performed according to the shape. In addition, the processing temperature in the hot rolling [Step 5] was measured with a radiation thermometer installed on the entry side and the exit side of the rolling mill.

  Separately from this, with respect to Comparative Examples 1 to 21 having the compositions shown in Table 1, each test material was obtained in the same manner as in the above Example. However, Comparative Example 1 to Comparative Example 21 differ from the manufacturing conditions in the above example in the following points.

In Comparative Examples 1 and 4 to 6, the total working rate in the cold working is too large and the cold rolling 1 [Step 2] is out of the specified range, and the holding temperature is too high to perform pre-annealing [Step 3]. ] Was also outside the prescribed range.
In Comparative Example 2, the total working rate in the cold working is too large, and the cold rolling 1 [Step 2] is outside the specified range, the holding temperature is too low, and the holding time is too short. Pre-annealing [Step 3] was also outside the specified range.
In Comparative Examples 3 and 13, the total working rate in the cold working was too large, and the cold rolling 1 [Step 2] was outside the specified range.
In Comparative Example 7, cold rolling 1 [Step 2] was not performed.
In Comparative Examples 8 to 11, neither cold rolling 1 [Step 2] nor pre-annealing [Step 3] was performed.
In Comparative Example 12, the total processing rate in the cold working is too large and the cold rolling 1 [Step 2] is outside the specified range, and the holding temperature is too low and the pre-annealing [Step 3] is also specified. It was out of range.
In Comparative Example 14, the preliminary annealing [Step 3] was not performed.

In Comparative Example 15, the total content of the auxiliary additive elements was too large.
In Comparative Examples 16 to 21, each or both of Ni and Si contained too much or too little content.

  The following property investigation was conducted on the test materials of the examples and comparative examples according to the present invention. Here, the final thickness of the test material was 0.08 mm.

a. Density and average area of flat grains having an aspect ratio of 0.3 or less In the EBSD measurement on the rolling surface of each specimen, measurement was performed in the range of 100 μm × 200 μm under the condition of a scan step of 0.1 μm. In analysis of the measurement results, crystal grains (flat grains) having an aspect ratio of 0.3 or less were extracted from all the crystal grains in the measurement range. Crystal grains having a major axis oriented within ± 30 ° with respect to the TD direction were further extracted from the flat grains. The density and average crystal grain area were calculated for the extracted flat grains.

b. Length per unit area of crystal grain boundary where the deviation angle between adjacent crystal grains is 30 ° or more The length of each crystal grain boundary was measured by the EBSD measurement. In the analysis of the measurement results, the length per unit area of the crystal grain boundary where the deviation angle between adjacent crystal grains is 30 ° or more was determined. In Tables 2-1 to 2-2, “length per unit area of grain boundaries of ≧ 30 ° [μm / μm ² ]” is shown.

c. The Young's modulus test piece in the TD direction was obtained by collecting a strip-shaped test piece having a width of 20 mm and a length of 200 mm from the vertical direction of rolling of each specimen (direction perpendicular to the rolling direction (RD) (TD)). A stress was applied in the length direction (that is, TD) by a tensile tester to determine a proportional constant between strain and stress. The strain amount of 80% of the yield amount when yielding is set as the maximum displacement amount, a displacement obtained by dividing the displacement amount into 10 is given, and the proportional constant of strain and stress is determined from the measured values at the 10 points, and the Young's modulus in the TD direction As sought.

d. Deflection coefficient in the TD direction The test piece was processed by punching with a press so that the width (0.25 mm) and the length (1.5 mm) were perpendicular to the rolling direction (TD) of each specimen. The front and back surfaces of the test piece were measured 10 times each with a cantilever beam, and the deflection coefficient E [GPa] calculated by the following equation was shown as the average value of the measurement 10 times for the front and back surfaces.
E = 4a / b × (L / t) ³
In the formula, a: slope of displacement f and stress w, b: width of specimen, L: distance between fixed end and load point, t: thickness of specimen. Here, as for the inclination a, the inclination (tangent) was obtained for an elastic region in which the displacement f and the stress w are in a proportional relationship.

e. Strength in TD direction [YS]
In the measurement of the deflection coefficient, the yield strength [MPa] was calculated from the indentation amount (displacement) up to the elastic limit of each test piece to obtain the strength, that is, the yield strength in the TD direction.
Yield strength [MPa] YS = {(3E / 2) × t × (f _max / L) × 1000} / L
In the equation, E is the deflection coefficient, t is the plate thickness, L is the distance between the fixed end and the load point, and f _{max is} the displacement (indentation depth) up to the elastic limit.

f. Fatigue resistance Fatigue resistance is based on JCBA T308; 2001 (Fatigue property test method for copper and copper alloy sheet strips), and the direction parallel to the rolling direction (that is, RD) from the samples of the examples and comparative examples. Specimens were cut out from the direction perpendicular to the rolling direction (ie, TD), and measurement was performed on each of them. FIG. 3 is an explanatory diagram showing the state in which the test piece is swung upward in the figure (planar spring fatigue test). 1 is a test piece, 2 is a knife edge, 3 is a fixture. The width of the test piece is 10 mm ± 0.2 mm, and the fixing torque of the test piece is 2 N · m at the bottom and 3 N · m at the top. The load stress value (σ) of the test piece was obtained by the following formula (a).
A repeated test was performed at a single amplitude of 2.0 mm by swinging under a load stress of 500 MPa, and the number of repetitions until the material broke was obtained.
The case where the number of repetitions until rupture was 10 ⁶ times or more for each specimen cut in the rolling parallel direction (RD) and the rolling vertical direction (TD) was “good”, and the rolling parallel direction and the rolling vertical direction. The case where any one or all of the test materials cut out in (1) were less than 10 ⁶ times was defined as “bad”.
σ = (3 × E × t × δ) / (2 × l ² ) (a)
In the formula, σ: maximum bending stress (N / mm ² ), E: the deflection coefficient (N / mm ² ), t: thickness of the test piece (mm), δ: deflection amount (mm), l: test piece Set length (mm).

g. Conductivity [EC]
The specific resistance was measured by a four-terminal method in a constant temperature bath maintained at 20 ° C. (± 0.5 ° C.) to calculate the conductivity (% IACS). In addition, the distance between terminals was 100 mm.

h. Stress relaxation rate [SR]
In accordance with the former Japan Electronic Materials Industry Association Standard (EMAS-3003), the measurement was performed under the conditions of 150 ° C. × 1000 hours as shown below. An initial stress of 80% of the proof stress was applied by the cantilever method.
4A and 4B are explanatory diagrams of a stress relaxation resistance test method. FIG. 4A shows a state before heat treatment, and FIG. 4B shows a state after heat treatment. As shown in FIG. 4A, the position of the test piece 11 when an initial stress of 80% of the proof stress is applied to the test piece 11 held in a cantilever manner on the test stand 14 is a distance of δ ₀ from the reference. is there. This was held for 1000 hours in a thermostat at 0.99 ° C., the position of the test piece 12 after removal of the load is the distance from the reference H _t as shown in Figure 4 (b). Reference numeral 13 denotes a test piece when no stress is applied, and its position is a distance H ₁ from the reference. From this relationship, the stress relaxation rate (%) was calculated as (H _t −H ₁ ) / δ ₀ × 100.

  About each test material of these Examples according to the present invention and comparative examples, the composition is shown in Table 1, the part of the manufacturing conditions, the obtained metal structure and properties are shown in Table 2-1 to Table 2-2, Each is shown.

  As shown in Table 1 and Table 2-1, in Examples 1 to 16, the alloy composition is within the prescribed range of the present invention, and the manufacturing conditions for the manufacturing are the manufacturing method of the present invention. The cold rolling 1 [Step 2] is rolled at a total rolling ratio of 10% or less, and the pre-annealing [Step 3] is a heat treatment at 300 to 700 ° C. for 1 minute to 5 hours. Went.

As shown in Table 2-1, Examples 1 to 16 were good in each characteristic. That is, the density of flat crystal grains whose major axis is within ± 30 ° with respect to the TD direction and whose aspect ratio is 0.3 or less is 0.030 particles / μm ² or less, and adjacent crystal grains When the length per unit area (1 μm ² ) of the grain boundary with a deviation angle of 30 ° or more is 0.8 μm / μm ² or less, the Young's modulus in the TD direction, the yield strength, the deflection coefficient, and the fatigue resistance The characteristics, conductivity, and stress relaxation resistance (stress relaxation rate) were both good.
Further, when the metal structure had an average area of the flat crystal grains of 3.0 μm ² or less, even better characteristics were exhibited.

  Therefore, the copper alloy plate material of the present invention is suitable for use in connectors for automobiles and other switches, terminal materials, relays, sockets, etc. Can be offered as.

On the other hand, in Comparative Examples 1 to 21 shown in Table 1 and Table 2-2, any one or more of the alloy composition, metal structure, and manufacturing method defined in the present invention were not satisfied.
As a result, as shown in Table 2-2, at least one of the characteristics of the samples of all the comparative examples was inferior.

That is, Comparative Example 1 has the same composition as Example 2, and the alloy composition satisfies the provisions of the present invention. However, in the manufacturing method, neither cold rolling 1 [Step 2] nor pre-annealing [Step 3] deviated from the conditions defined in the present invention. In Comparative Example 1, the control of the flat grains in the structure is insufficient, and the density of the flat grains in the structure and the length of the grain boundaries where the deviation angle between adjacent grain boundaries is 30 ° or more (the above-mentioned grains Since all of the grain boundary lengths with large boundary deviation angles were not sufficiently controlled and too large, the Young's modulus in the TD direction and the deflection coefficient were inferior. Comparative Example 1 was also inferior in stress relaxation resistance.
Comparative Example 2 has the same composition as Examples 1 and 3, and the alloy composition satisfies the provisions of the present invention. However, in the manufacturing method, neither cold rolling 1 [Step 2] nor pre-annealing [Step 3] deviated from the conditions defined in the present invention. In Comparative Example 2, the control of the flat grains in the structure is insufficient, and the density of the flat grains in the structure and the length of the crystal grain boundary where the deviation angle of the grain boundary is large are insufficient and large. Therefore, the Young's modulus in the TD direction and the deflection coefficient were inferior. Comparative Example 2 was also inferior in stress relaxation resistance.

In Comparative Examples 3 and 13, the alloy composition satisfies the provisions of the present invention. However, the manufacturing method was outside the conditions prescribed in the present invention by cold rolling 1 [step 2]. In Comparative Examples 3 and 13, since the control of the flat particles in the tissue was insufficient and the density of the flat particles in the tissue was insufficient and too large, the Young's modulus and the deflection coefficient in the TD direction were inferior. It was. Comparative Example 13 was also inferior in stress relaxation resistance. In Comparative Example 3, the length of the crystal grain boundary having a large grain boundary shift angle was too large due to insufficient control.
In Comparative Examples 4 to 6, the alloy composition satisfies the provisions of the present invention. However, in the manufacturing method, neither cold rolling 1 [Step 2] nor pre-annealing [Step 3] deviated from the conditions defined in the present invention. In each of Comparative Examples 4 to 6, the control of the flat grains in the structure is insufficient, and the density of the flat grains in the structure and the length of the crystal grain boundary where the deviation angle of the grain boundary is large are controlled. Since it was insufficient and too large, the Young's modulus in the TD direction and the deflection coefficient were inferior. Comparative Examples 4 to 5 were inferior in yield strength in the TD direction. Comparative Examples 5 and 6 were also inferior in stress relaxation resistance.
Comparative Example 7 has the same composition as Example 4, and the alloy composition satisfies the provisions of the present invention. However, the manufacturing method did not perform cold rolling 1 [step 2]. In Comparative Example 7, the control of the flat grains in the structure is insufficient, and the density of the flat grains in the structure and the length of the crystal grain boundary where the deviation angle of the grain boundary is large are insufficient and large. As a result, the Young's modulus in the TD direction, the deflection coefficient, and the fatigue resistance were inferior.

In Comparative Examples 8 to 10, the alloy composition satisfies the provisions of the present invention. However, the manufacturing method did not perform either cold rolling 1 [Step 2] or pre-annealing [Step 3]. In each of Comparative Examples 8 to 10, the control of the flat grains in the structure is insufficient, and the density of the flat grains in the structure and the length of the crystal grain boundary where the deviation angle of the grain boundary is large are controlled. Since it was insufficient and too large, the Young's modulus in the TD direction and the deflection coefficient were inferior. Comparative Example 8 was also inferior in stress relaxation resistance. Comparative Example 10 was also inferior in fatigue resistance.
Comparative Example 11 has the same composition as Example 5, and the alloy composition satisfies the provisions of the present invention. However, the manufacturing method did not perform either cold rolling 1 [Step 2] or pre-annealing [Step 3]. In Comparative Example 11, the control of the flat grains in the structure is insufficient, and the density of the flat grains in the structure and the length of the crystal grain boundary where the deviation angle of the grain boundary is large are insufficient and large. As a result, the Young's modulus in the TD direction, the deflection coefficient, and the fatigue resistance were inferior. Comparative Example 11 was also inferior in stress relaxation resistance.

In Comparative Example 12, the alloy composition satisfies the provisions of the present invention. However, in the manufacturing method, neither cold rolling 1 [Step 2] nor pre-annealing [Step 3] deviated from the conditions defined in the present invention. In Comparative Example 12, the control of the flat grains in the structure is insufficient, and the density of the flat grains in the structure and the length of the crystal grain boundary where the deviation angle of the grain boundary is large are insufficient and large. As a result, the Young's modulus in the TD direction, the deflection coefficient, and the fatigue resistance were inferior.
In Comparative Example 14, the alloy composition satisfies the provisions of the present invention. However, the manufacturing method did not perform pre-annealing [Step 3]. In Comparative Example 14, since the control of flat grains in the structure was insufficient and the control of the length of the crystal grain boundary with a large grain boundary shift angle was insufficient and too large, the Young's modulus in the TD direction, the deflection coefficient The fatigue resistance was inferior. Comparative Example 14 was also inferior in conductivity.

In Comparative Example 15, the cold rolling 1 [Step 2], the pre-annealing [Step 3] and the structure satisfy the provisions of the present invention, but the total content of the secondary additive elements is too large, and the alloy composition is the present invention. The regulation of the example was not satisfied and the conductivity was inferior.
In Comparative Examples 16 to 21, the manufacturing method including cold rolling 1 [Step 2] and pre-annealing [Step 3] satisfies the provisions of the present invention, but the content of either or both of Ni and Si is Too much or too little alloy composition does not satisfy the provisions of the present invention example, and the density of flat grains in the obtained structure is too high to satisfy the provisions of the present invention, and TD yield strength and fatigue resistance characteristics One or more of the conductivity and stress relaxation resistance properties were inferior.

In particular, in Comparative Example 13, the density of flat grains having an aspect ratio of 0.3 or less oriented within 30 ° in the ± TD direction is a value exceeding 0.03 particles / μm ^2. The length per unit area of the crystal grain boundary having a deviation angle of 30 ° or more was 0.8 μm / μm ² or less, but the obtained Young's modulus in the TD direction was 128 GPa. In Comparative Example 14, the density of flat grains having an aspect ratio of 0.3 or less that face within ± TD direction of 30 ° is 0.03 particles / μm ² or less. Although the length per unit area of the crystal grain boundary having an angle of 30 ° or more exceeded 0.8 μm, the obtained Young's modulus in the TD direction was 127 GPa. In these comparative examples 13 and 14, although a decrease in Young's modulus was observed, the density of the flat grains and the length of the crystal grain boundary with a deviation angle of 30 ° or more were all within the limits of the present invention. In contrast, the desired low Young's modulus in the TD direction, 125 GPa or less, could not be achieved.
Therefore, by making the structure in which the density of the flat grains in the structure and the length of the crystal grain boundary where the deviation angle between adjacent crystal grain boundaries is 30 ° or more are appropriately controlled, the Young's modulus in the TD direction, It can be seen that desired characteristics such as fatigue characteristics can be satisfied.

DESCRIPTION OF SYMBOLS 1 Test piece 2 Knife edge 3 Fixing tool 11 Test piece (The state hold | maintained by the cantilever)
12 Test piece (state after unloading)
13 Specimens (without stress)
14 Test stand

Claims (5)

Ni is 1.0 to 5.0 mass%, Si is 0.1 to 2.0 mass%, B is 0.10 mass% or less, Mg is 1.80 mass% or less, and P is 0.05 mass%. Hereinafter, Cr is 0.50 mass% or less, Mn is 0.16 mass% or less, Fe is 0.05 mass% or less, Co is 0.05 mass% or less, Zn is 0.51 mass% or less, and Zr is 0 .10% by mass or less, Ag is 0.05% by mass or less, and Sn is contained in a total of 0.1 to 3.0% by mass selected from the group consisting of 0.50% by mass or less, and the balance is copper. And a copper alloy sheet made of inevitable impurities,
In the analysis on the rolling surface, the crystal grains having an aspect ratio represented by the ratio of the minor axis / major axis of the crystal grains of 0.3 or less and oriented within ± 30 ° from the TD direction Density of 0.030 pieces / μm ² or less,
And the length per unit area of the crystal grain boundary whose deviation angle | corner between adjacent crystal grains is 30 degrees or more is 0.8 micrometer / micrometer < ² > or less, The copper alloy board | plate material characterized by the above-mentioned . The Young's modulus in the TD direction measured by a tensile test is 125 GPa or less, the deflection coefficient measured in the deflection test is 115 GPa or less, and the yield strength in the TD direction is measured by a tensile test. 2. The copper according to claim 1, which has a stress relaxation rate (SR) of 20% or less after holding at 150 ° C. for 1000 hours as stress relaxation resistance. Alloy plate material. 3. The copper alloy sheet according to claim 1, wherein the fatigue resistance characteristic by a leaf spring fatigue test is a load stress of 500 MPa or more and a repetition count of 10 ⁶ times or more. Ni is 1.0 to 5.0 mass%, Si is 0.1 to 2.0 mass%, B is 0.10 mass% or less, Mg is 1.80 mass% or less, and P is 0.05 mass%. Hereinafter, Cr is 0.50 mass% or less, Mn is 0.16 mass% or less, Fe is 0.05 mass% or less, Co is 0.05 mass% or less, Zn is 0.51 mass% or less, and Zr is 0 .10% by mass or less, Ag is 0.05% by mass or less, and Sn is contained in a total of 0.1 to 3.0% by mass selected from the group consisting of 0.50% by mass or less, and the balance is copper. And a method for producing a copper alloy plate material made of inevitable impurities, the copper alloy material comprising an alloy component composition that gives the copper alloy plate material,
Casting [process 1],
Cold rolling 1 with a processing rate of 10% or less [Step 2],
Pre-annealing at a holding temperature of 300 to 700 ° C. and a holding time of 1 minute to 5 hours [Step 3],
Homogenization heat treatment at a holding temperature of 700 ° C. or higher for 5 minutes to 20 hours [Step 4],
Hot rolling [step 5],
Water quenching [Step 6],
Chamfering [process 7],
Cold rolling 2 with a processing rate of 50% or more [Step 8],
Intermediate solution heat treatment [Step 9] with a temperature rising rate of 5 to 15 ° C./second, a holding temperature of 300 to 700 ° C., and a holding time of 1 second to 10 hours,
Cold rolling 3 [Process 10] with a processing rate of 10 to 99%,
Solution heat treatment [step 11] having an ultimate temperature of 700 to 1020 ° C. and a holding time of 1 second to 60 seconds,
Aging precipitation heat treatment [Step 12] with a holding temperature of 300 to 600 ° C. and a holding time of 10 minutes to 20 hours,
Pickling [Step 13] and finish cold rolling with a rolling rate of 8 to 80% [Step 14]
Each method of these is performed in this order, The method of manufacturing the copper alloy board | plate material of any one of Claims 1-3 characterized by the above-mentioned . 5. The method for producing a copper alloy sheet according to claim 4 , wherein after the finish cold rolling [Step 14], strain relief annealing [Step 15] is performed at a holding temperature of 300 to 600 ° C. and a holding time of 1 second to 60 seconds.

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