WO2015182776A1

WO2015182776A1 - Copper alloy sheet, connector comprising copper alloy sheet, and method for producing copper alloy sheet

Info

Publication number: WO2015182776A1
Application number: PCT/JP2015/065688
Authority: WO
Inventors: 岳己磯松; 樋口　優
Original assignee: 古河電気工業株式会社
Priority date: 2014-05-30
Filing date: 2015-05-29
Publication date: 2015-12-03
Also published as: JPWO2015182776A1; CN106460099B; CN106460099A; KR20170012282A; KR101935987B1; JP5972484B2

Abstract

　Provided is a copper alloy sheet having a composition containing 1.0 to 6.0 mass% Ni, and 0.2 to 2.0 mass% Si, further containing a total of 0 to 3.000 mass% of at least one type of element selected from the group comprising B, Mg, P, Cr, Mn, Fe, Co, Zn, Zr, Ag and Sn, with the remainder comprising copper and unavoidable impurities, wherein: the strain hardening exponent, n_RD, in the rolling direction, RD, is 0.010 to 0.150; and the ratio, n_RD/n_TD, between n_RD and the strain hardening component, n_TD, in the transverse direction, TD, is 0.500 to 1.500. On the surface parallel to the rolled surface of the copper alloy sheet at a depth D, the average value, Sa, of the area ratio, S(D), of crystal grains in which the angle of deviation from cube orientation {001}<100> is within 15° is 5.0 to 30.0%. Thus, the copper alloy sheet has: excellent bendability; excellent strength; a low deflection coefficient as a spring property after bending work; and little specificity for each of the properties of bendability, strength and deflection coefficient in the rolling direction and transverse direction.

Description

Copper alloy sheet, connector made of copper alloy sheet, and method for producing copper alloy sheet

The present invention relates to a copper alloy sheet and a manufacturing method thereof. In particular, it has excellent bending workability and strength, as well as spring characteristics after bending, and is a copper alloy plate material applied to lead frames, connectors, terminal materials, relays, switches, sockets, etc. for automotive parts and electrical / electronic devices. And a manufacturing method thereof.

Characteristic items required for copper alloy sheets used in automotive parts and lead frames, connectors, terminal materials, relays, switches, sockets, etc. for electric components, electrical conductivity, yield strength, There are tensile strength and bending workability. In recent years, the required characteristics have been increased with the reduction in size, weight, functionality, high-density mounting, and use environment of electric / electronic devices. In particular, since a demand for thinning a copper or copper alloy plate material used for in-vehicle components or electrical / electronic equipment components, the required strength level is becoming higher.

Also, a low deflection coefficient is required as one of the characteristic items required for copper alloy materials used for electrical / electronic equipment and automotive parts applications. In recent years, with the progress of miniaturization of connectors and in-vehicle components, the dimensional accuracy of terminals and the tolerance of press work have become severe. By reducing the deflection coefficient of the material, the influence of the dimensional variation on the contact pressure of the contact portion can be reduced, so that the design becomes easy.

In addition, the stress applied during the assembly and operation of in-vehicle components and electrical / electronic equipment is applied to the materials used for connectors, terminals, lead frames, relays, switches, and other components that make up in-vehicle components and electrical / electronic components. High strength that can withstand is required.

Conventionally, as materials for electrical and electronic devices, copper-based materials such as phosphor bronze, red brass and brass have been widely used as materials for electric and electronic devices. These 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. In this method, the electrical conductivity is insufficient, and a high strength is obtained by applying cold working at a high rolling rate, so that bending workability and stress relaxation resistance are insufficient.

There is a precipitation strengthening method in which a fine second phase is precipitated in the material as a strengthening method of the copper alloy. This strengthening method has the advantage of improving the conductivity at the same time in addition to increasing the strength, and is therefore performed in many alloy systems. However, with the recent miniaturization of electrical and electronic equipment and on-vehicle components for automobiles, copper alloys are designed to bend with a smaller radius to a higher-strength material and have excellent bending workability. There is a strong demand for copper alloy sheets. Furthermore, it is not preferable that there is a difference in characteristics between the rolling parallel direction (RD, rolling direction) and the rolling vertical direction (TD, width direction) even for a plate material having high strength, high spring property and good bending workability. It is important to show good characteristics even in the direction of. In particular, when it is used as a microminiature terminal, it is important that fine processing is applied to the pin type with a narrow width, and here, it is important to show good characteristics in both the rolling parallel direction and the rolling vertical direction. In a conventional Cu—Ni—Si based copper alloy, in order to obtain high strength, a large work hardening was obtained by increasing the rolling rate. However, this method deteriorates bending workability as described above, and it is difficult to achieve both high strength and good bending workability.

In recent years, terminals and connectors for electrical and electronic equipment, in-vehicle terminals, etc. have been bent with a smaller radius than ever and processed into more complex shapes as the entire module has become smaller and the density of electrical components has increased. Has been. Whether the bending axis is perpendicular to the rolling direction (GW bending) or parallel (BW bending), complicated processing with a small bending radius is included, and the spring characteristics (contact pressure, deflection amount) after processing are uniform. (As designed) Conventionally, when a Corson alloy (Cu—Ni—Si alloy) plate material is processed and used as a contact portion of a terminal, it is processed only in a specific direction (GW or BW). However, recently, since it is processed into a complicated shape as described above, the design is such that a number of GW and BW bends can be made at one terminal. In this case, a conventional material having anisotropy in bending, strength, and work hardening index is cracked by either GW or BW bending and cannot be used as a terminal or a connector. In addition, if there is anisotropy, the spring characteristics after processing also vary depending on the bending direction, and cannot be used as terminals or connectors.

Conventionally, several proposals have been made to solve the demand for improvement in bending workability by controlling the work hardening index and crystal orientation. For example, Patent Document 1 controls the tensile strength, yield strength, uniform elongation, total elongation, and work hardening index in both the rolling parallel direction (LD) and the rolling vertical direction (TD) in a Cu—Ni—Si alloy. It has been proposed to improve the bending workability of GW and BW. Patent Document 2 proposes that bending workability is improved by controlling the crystal orientation and work hardening index of a Cu—Ni—Si alloy. Patent Document 3 proposes that both strength and bending workability can be achieved by controlling the Cube orientation area ratio to 10% or more.

JP 2010-031379 A JP 2013-047360 A JP 2011-1117034 A

In the invention described in Patent Document 1, by controlling the mechanical characteristics in the rolling parallel direction and the rolling vertical direction, excellent characteristics in which strength and bending workability are balanced are obtained. However, there is no description about control of crystal orientation and crystal grain size. In the invention described in Patent Document 2, both strength and bending workability are achieved by controlling the crystal orientation and the work hardening index. However, the anisotropy in the rolling parallel direction and the rolling vertical direction is not controlled, and each crystal orientation is controlled, but there is no description about the distribution in the plate thickness direction. In Patent Document 3, bending workability is improved by accumulating the Cube orientation area ratio. However, the work hardening index is not controlled, and the anisotropy in both the rolling parallel direction and the rolling vertical direction is not controlled.

In view of the problems of the prior art as described above, the present invention has excellent bending workability and excellent strength, and has a low deflection coefficient as a spring characteristic after bending, and these bending workability and strength. High quality that can perform complicated processing such as both GW bending and BW bending on one member with little anisotropy in the rolling parallel direction and rolling vertical direction of each characteristic of the deflection coefficient It is an object of the present invention to provide a copper alloy plate material suitable for connectors and terminal materials, relays, switches, sockets, and the like for lead frames, connectors, terminal materials, etc. for automobiles, etc.

The present inventors have repeatedly studied copper alloy sheets suitable for electric / electronic parts applications and automotive parts applications, which have greatly improved bending workability and strength in Cu—Ni—Si alloy copper alloy sheets. As a result of intensive studies, it was found that there is a correlation between work hardening index, bending workability and strength and their anisotropy. Further, it has been found that both the bending and strength anisotropy can be reduced by appropriately controlling the relationship between the work hardening indices of the plate material in the rolling parallel direction and the rolling vertical direction. Furthermore, when it examined, it discovered that bending workability and its anisotropy could be improved by controlling a texture appropriately about bending workability and its anisotropy. The present invention has been completed based on these findings.

That is, according to the present invention, the following means are provided.
(1) Contains 1.0 to 6.0% by mass of Ni and 0.2 to 2.0% by mass of Si, and contains B, Mg, P, Cr, Mn, Fe, Co, Zn, Zr, Ag and Sn A copper alloy sheet material containing a total of at least one selected from the group consisting of 0.000 to 3.000 mass%, with the balance being composed of copper and inevitable impurities (provided that B, Mg, P above) , Cr, Mn, Fe, Co, Zn, Zr, Ag, and Sn are optional additional components that may contain one or more of them, or none of them.
The work hardening index n _{RD in the} rolling parallel direction (RD) is 0.010 to 0.150,
The ratio _n RD _{/ n TD} and work hardening coefficient _{n TD} of the direction parallel to the rolling direction of the work hardening coefficient _{n RD} to the rolling direction perpendicular (TD) is from 0.500 to 1.500,
The thickness of the copper alloy sheet is t, the depth in the thickness direction from the rolled surface of the copper alloy sheet is D, and the surface parallel to the rolled surface at the depth D of the copper alloy sheet is Cube. When the area ratio of crystal grains whose deviation angle from the orientation {001} <100> is within 15 ° is S (D), the average value Sa of S (D) in the plate thickness direction is 5.0 to 30.0. %, A copper alloy sheet.
(2) Contains at least 0.005 to 3.000 mass% in total of at least one selected from the group consisting of B, Mg, P, Cr, Mn, Fe, Co, Zn, Zr, Ag, and Sn. The copper alloy sheet material according to the item).
(3) About the crystal grain of a base material, ratio a / b of the average particle diameter a of a rolling parallel direction and the average particle diameter b of a rolling perpendicular direction is 0.8 or more, It describes in (1) or (2) term Copper alloy sheet material.
(4) The deflection coefficient in the rolling parallel direction and the rolling vertical direction are both 140 GPa or less, and the ratio E _TD / E _RD between the deflection coefficient (E _RD ) in the rolling parallel direction and the deflection coefficient (E _TD ) in the rolling vertical direction is The copper-based alloy sheet according to any one of (1) to (3), which is 1.05 or less.
(5) A connector comprising the copper alloy sheet according to any one of (1) to (4).
(6) A method for producing a copper alloy sheet according to any one of (1) to (4),
Melting / casting process, ingot rolling process, homogenizing heat treatment process, hot rolling process, rapid cooling process, cold rolling 1 process, slit / trimming process, cold rolling 2 process, intermediate solution treatment process, rapid cooling process, aging We perform each process of heat treatment process in this order,
In the ingot rolling process, the rolling process per pass is performed at least once at a processing rate of 1.0% or more,
In the cold rolling 1 step, an average rolling pressure per pass is 50 N / mm ² or more, and the total processing rate is 30% or more,
In the two cold rolling processes, the average rolling pressure per pass is 50 N / mm ² or more, and the total processing rate is 50% or more,
In the intermediate solution treatment step, a solution treatment is performed in a high temperature range of an ultimate temperature of 600 to 1100 ° C. at a temperature increase rate of 5 ° C./sec or more.
(7) The method for producing a copper alloy sheet according to (6), wherein the pickling / polishing step, the cold rolling step 3 and the final annealing step are performed in this order after the aging heat treatment step.
The above and other features and advantages of the present invention will become more apparent from the following description, with reference where appropriate to the accompanying drawings.

The copper alloy sheet of the present invention is excellent in bending workability, exhibits excellent strength, and has little anisotropy in the rolling parallel direction and the vertical direction of rolling in the respective characteristics of bending workability and strength. Therefore, the copper alloy sheet material of the present invention has properties particularly suitable for relays, switches, sockets, etc. in addition to connectors and terminal materials for automotive in-vehicle parts, such as lead frames, connectors, and terminal materials for electrical and electronic equipment. It is a copper alloy sheet material.
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 showing the relationship between the copper alloy sheet 1 of the present invention, the rolling direction RD, the rolling vertical direction (width direction) TD, and the rolling surface normal direction (sheet thickness direction) ND. The main surface of the copper alloy sheet 1 is referred to as a rolled surface 2. FIG. 2 is an explanatory diagram showing a surface 3 parallel to the surface of the rolled surface at a depth D less than the plate thickness t of the copper alloy sheet material.

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

In the present invention, by properly controlling the work hardening index in the rolling parallel direction and the rolling vertical direction of the plate material, it is possible to improve the bending workability while increasing the strength.
In general, due to plastic deformation to a metal material, strain accumulates in a metal structure (crystal), work hardening occurs, and material strength (proof strength, tensile strength) increases. Here, the greater the work hardening index of a metal material, the greater the increase in strength due to work hardening of that material. On the other hand, the smaller the work hardening index of the metal material, the smaller the work hardening amount in plastic deformation such as bending or pressing, and the less the influence of the work. That is, when the deformation amount is the same, a material having a large work hardening index can be easily strengthened.

In this respect, for example, in the bending process for terminals and connectors, the amount of plastic deformation is larger in the vicinity of the apex portion of the bending than in other portions. For this reason, when a material having a relatively high work hardening index is subjected to bending, the work hardening amount is increased and the strength is easily increased. Generally, when the material becomes stronger, the bending workability tends to deteriorate. For this reason, if the strength is increased locally on the bent surface of the terminal or the connector, a crack is generated starting from the location where the strength is increased. Therefore, in order to obtain good bending workability, it is necessary to control the work hardening index to a certain value or less. In particular, in recent electrical and electronic equipment connectors and in-vehicle component connectors, as described above, both GW bending in which the bending axis is perpendicular to the rolling direction and BW bending in which the bending axis is parallel to the rolling direction are included. Since it may have a complicated shape, it is desirable to appropriately control both the work hardening indexes in both the rolling parallel direction and the rolling vertical direction of the plate material.

In addition, in the present invention, in addition to controlling the work hardening index, the texture state of the copper alloy sheet is also controlled. Specifically, the plate thickness of the copper alloy plate material is t, the depth in the plate thickness direction from the rolled surface surface of the copper alloy plate material is D, and in a plane parallel to the rolled surface surface at the depth D of the copper alloy plate material, When the area ratio of crystal grains whose deviation angle from the Cube orientation {001} <100> is within 15 ° is S (D), the average value Sa of S (D) in the plate thickness direction is 5.0-30. By setting the content to 0.0%, bending workability is improved while maintaining material strength, and the anisotropy is also reduced. In this way, by controlling the work hardening index and the texture, the deflection coefficient is excellent as a spring characteristic after bending.

[Alloy composition]
First, the composition of the copper alloy constituting the plate material of the present invention will be described.

(Essential additive element)
The contents of the essential addition elements Ni and Si to the copper alloy constituting the plate material of the present invention and the action thereof will be shown.

(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 1.00 to 6.00 mass%, preferably 1.20 to 5.80 mass%, more preferably 1.50 to 5.50 mass%. By setting the Ni content in the above range, the Ni ₂ Si phase can be appropriately formed, and the mechanical strength (tensile strength and 0.2% yield 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. The Si content is 0.20 to 2.00% by mass, preferably 0.25 to 1.90% by mass, and more preferably 0.50 to 1.70% by mass. The balance between conductivity and strength is best when the Si content is stoichiometrically Ni / Si = 4.2. Therefore, the content of Si is preferably such that Ni / Si is in the range of 2.50 to 7.00, more preferably 3.00 to 6.50. 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 crack or rolling crack occurs.

(Sub-added element)
Next, the types of sub-addition elements in the copper alloy constituting the plate material of the present invention and the effect of addition will be described. Preferred secondary additive elements include B, Mg, P, Cr, Mn, Fe, Co, Zn, Zr, Ag, and Sn. The total amount of these elements is preferably 3.000% by mass or less because no adverse effect of decreasing the electrical conductivity occurs. In order to fully utilize the additive effect and not lower the electrical conductivity, the total amount is preferably 0.005 to 3.000% by mass, more preferably 0.010 to 2.800% by mass, It is particularly preferable that the content be 0.030 to 2.500% by mass. The effect of adding each element is shown below.

(Mg, Sn, Zn)
Addition of Mg, Sn and Zn improves the stress relaxation resistance. The stress relaxation resistance is further improved by the synergistic effect when added together than when they are added. In addition, the solder embrittlement is remarkably improved. The content of each of Mg, Sn, and Zn is preferably 0.00 to 2.00% by mass, more preferably 0.10 to 1.80% by mass.

(Mn, Ag, B, P)
When Mn, Ag, B, and P are added, the hot workability is improved and the strength is improved. The contents of Mn, Ag, B, and P are each preferably 0.00 to 1.00% by mass, and more preferably 0.050 to 0.70% by mass.

(Cr, Zr, Fe, Co)
Cr, Zr, Fe, and Co are finely precipitated as a compound or simple substance, and contribute to precipitation hardening. Further, it precipitates as a compound with a size of 50 to 500 nm, and has an effect of making the crystal grain size fine by suppressing grain growth, thereby improving the bending workability. The content of each of Cr, Zr, Fe, and Co is preferably 0.00 to 1.50 mass%, more preferably 0.10 to 1.30 mass%.

[Work hardening index]
The copper alloy sheet of the present invention, the work hardening coefficient _{n RD} of the direction parallel to the rolling direction of the plate material, 0.01 to 0.15, preferably 0.01 to 0.10 or less, more preferably 0.01 or more 0. It is 08 or less, more preferably 0.01 or more and 0.06 or less.
The work hardening index n _{TD in the} vertical direction of rolling of the plate material is preferably 0.01 or more and 0.15 or less, more preferably 0.01 or more and 0.10 or less, and still more preferably 0.01 or more and 0.08 or less. Particularly preferably, it is 0.01 or more and 0.06 or less.
The ratio n _RD / n _TD of the work hardening index n _{RD in} the rolling parallel direction to the work hardening index n _{TD in} the rolling vertical direction is 0.50 to 1.50, preferably 0.70 to 1.40, more preferably. Is 0.75 to 1.35, more preferably 0.80 to 1.30. By controlling to the above work hardening index, the Cube azimuth area ratio can be easily controlled.

The reason for setting the work hardening index within this range is that the work hardening index tends to be relatively small and good workability can be obtained by controlling the work hardening index to a certain level or less. It is.

[Organization]
In the copper alloy sheet of the present invention, the thickness of the copper alloy sheet is t, the depth in the sheet thickness direction from the rolled surface of the copper alloy sheet is D, and the surface of the copper alloy sheet is parallel to the rolled surface at the depth D. In the plane, when the area ratio of crystal grains whose deviation angle from the Cube orientation {001} <100> is within 15 ° is S (D), the average value Sa of S (D) in the plate thickness direction is 5.0. % Or more and 30.0% or less. For analysis of the Cube orientation, crystal orientation analysis in EBSD measurement is used. In addition, the area ratio of the crystal grains whose deviation angle from the Cube orientation {001} <100> is within 15 ° (including 0 °) means the area ratio of the Cube orientation. This means the ratio of the area of the crystal grain region whose deviation angle from the Cube orientation is 15 ° or less in the total area of the surface when the surface is observed from the plate thickness direction.

FIG. 1 is a diagram showing the relationship between the copper alloy sheet 1 of the present invention, the rolling direction RD, the rolling vertical direction (width direction) TD, and the rolling surface normal direction (sheet thickness direction) ND. The main surface of the copper alloy sheet is referred to as a rolling surface 2. FIG. 2 shows a surface 3 parallel to the surface of the rolled surface at a depth D of the copper alloy sheet.

A copper alloy sheet is usually manufactured by repeating rolling and has a texture associated with the rolling direction and the like. This texture is expressed using RD, TD, and ND perpendicular to each other as reference axes. The crystal grains of Cube orientation {001} <100> in the present invention are the crystal of copper (plane-extended cubic lattice) in the crystal grains, the {001} plane of the crystal is perpendicular to ND, and the crystal The <100> direction is a state parallel to the RD.

The copper alloy sheet material of the present invention has an area ratio S (D) in the sheet thickness direction with respect to the area ratio S (D) of crystal grains having a Cube orientation in the plane 3 parallel to the surface of the rolled surface at a depth D from the surface. ) Is an average value Sa of 5.0 to 30.0%. That is, for the surface 3 parallel to the surface of the rolled surface at the depth D in FIG. 2, the area ratio of the Cube orientation of this surface is S (D), and the average value of this S (D) is Sa. The value of the depth D takes a value from 0 to t. Therefore, if the concept of Sa is expressed as a mathematical expression, it is expressed as follows.

However, it is physically difficult to calculate Sa by measuring the area ratio S (D) of the Cube orientation on all the surfaces from the copper alloy plate material surface (D = 0) to the back surface (D = t). Therefore, in the present invention, S (D1), S (D2),... At five or more depths D1, D2,... Are measured, and the average value thereof is calculated as Sa. In particular, the depth D is preferably 5 types: D = 1 / 20t, 1 / 4t, 1 / 2t, 3 / 4t, 19 / 20t. In the thickness direction, it is preferable to select a plurality of depths D with respect to the center of the thickness (D = 1 / 2t).

Hereinafter, the average value Sa of the area ratio is also referred to as “the average value of the area ratio of the Cube orientation in the plate thickness direction”. The average value of the area ratio of the Cube orientation in the plate thickness direction is preferably 8.0% or more and 30.0% or less. Bending workability can be improved by controlling Sa to 5.0% or more. This is thought to be because the generation of shear bands that occur during bending can be suppressed. Similarly, on the back surface in the plate thickness direction at the time of bending, the occurrence of a shear band accompanying compression deformation can be suppressed by setting the Cube orientation area ratio to 5.0% or more. Further, by controlling the Cube azimuth area ratio in the vicinity of the center of the plate thickness to 5.0% or more, it is possible to suppress the development of cracks accompanying deformation as in the case of the front and back surfaces. Therefore, each value of the area ratio S (D) of the crystal grains having the Cube orientation in the plane 3 parallel to the rolling surface at the depth D is also preferably 5.0% or more and 30.0% or less. .

(Evaluation of texture distribution in the thickness direction)
The area ratio of the Cube-oriented crystal grains in the copper alloy is measured by changing the polishing amount in order to investigate the distribution in the plate thickness direction. In order to observe the structure from the thickness direction, one side of the test piece is masked and only the opposite side is electropolished. At this time, polishing is performed while paying attention to the fact that the surface of the test piece has a mirror finish. Actually, it became possible to grasp the structure by fine adjustment of the polishing amount by electrolytic polishing here, and it was found that detailed analysis can be performed by EBSD analysis. The prepared test piece is measured by scanning an area of 300 μm × 300 μm in 0.1 μm steps by orientation analysis by EBSD, and measuring the area ratio of Cube-oriented crystal grains.

(EBSD method)
The EBSD method is used for the analysis of the crystal orientation in the present invention. The EBSD method 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). A sample area of 300 μm × 300 μm containing 200 or more crystal grains is scanned in 0.1 μm steps, and the crystal orientation of each crystal grain is analyzed. The measurement area and scan step are set to 300 × 300 μm and 0.1 μm from the size of the crystal grains of the sample. The area ratio of each orientation is obtained by calculating the area of a crystal grain having a normal line of the crystal grain within a range of ± 15 ° from the ideal orientation of the Cube orientation {001} <100>, and with respect to the total measurement area of the obtained area. It can be calculated as a percentage. The information obtained in the azimuth analysis by EBSD includes azimuth information up to a depth of several tens of nanometers at which the electron beam penetrates into the sample. It is described as area ratio. In addition, OIM Analysis (product name) is used for the analysis of the EBSD measurement result.

[Method for producing copper alloy sheet]
First, a conventional method for producing a precipitation-type copper alloy will be described.
The conventional method for producing a precipitation-type copper alloy is to melt and cast a copper alloy material [Step 1] to obtain an ingot, which is subjected to homogenization heat treatment [Step 3], hot rolling [Step 4], Water cooling [Step 5], chamfering [Step 6], and cold rolling [Step 7] are performed in this order to form a thin plate, and an intermediate solution treatment [Step 10], aging precipitation heat treatment [Step] in a temperature range of 700 to 1000 ° C. 11] and finish cold rolling [Step 13] satisfy the required strength. Further, final annealing [step 14] for removing strain may be performed after finish cold rolling [step 13]. Furthermore, an oxide film removal step (pickling and polishing [step 12]) may be inserted between the aging precipitation heat treatment [step 11] and the finish cold rolling [step 13]. In this series of steps, the texture of the material is roughly determined by recrystallization that occurs during the intermediate solution treatment, and finally determined by the orientation rotation that occurs during finish cold rolling.

On the other hand, in the method of the present invention, through the manufacturing process different from the conventional method, the average value Sa of the Cube orientation area ratio in the plate thickness direction and the work hardening index in both the rolling parallel direction and the rolling vertical direction The copper alloy sheet material is controlled.
Specifically, in the present invention, melting / casting [step 1], ingot rolling [step 2], homogenization heat treatment [step 3], hot rolling [step 4], water cooling [step 5], face milling [Step 6], cold rolling 1 [step 7], slit trimming [step 8], cold rolling 2 [step 9], intermediate solution treatment [step 10], water cooling [step 10-2], aging precipitation Heat treatment [Step 11], pickling / polishing [Step 12], cold rolling 3 [Step 13], and final annealing [Step 14] are performed in this order. If the plate material having desired properties is obtained, the pickling / polishing [Step 12], cold rolling 3 [Step 13], and final annealing [Step 14] may be omitted.

Among these, in melting and casting [Step 1], a predetermined additive element is added to obtain an ingot. The cooling rate during casting is usually 0.1 to 100 ° C./second.
Next, in the ingot rolling [Step 2], a constant cold rolling is applied to the ingot, so that it is partially recrystallized in the vicinity of the grain boundary during the homogenization heat treatment. This contributes to the formation of equiaxed crystal grains in recrystallization. The rolling processing rate per pass in the ingot rolling [Step 2] is 1.0% or more (preferably 5.0% or less), and the number of passes is 1 or more.

Next, a homogenization heat treatment [step 3] is performed so that the ultimate temperature is 800 ° C. or higher and 1100 ° C. or lower and the holding time is 5 minutes to 20 hours. Thereafter, hot rolling [Step 4] is performed by a plurality of passes up to a predetermined plate thickness in a processing temperature range of 1100 ° C. or lower (preferably 800 ° C. or higher), and immediately after the hot rolling is completed by water cooling [Step 5]. Cool (rapid cooling, so-called quenching). Then, in order to remove the oxide film on the surface of the hot-rolled material, face milling [Step 6] is performed, and then cold rolling 1 [Step 7] is performed.
In cold rolling 1 [Step 7], cold rolling is performed in several to several tens of passes so that the total rolling ratio is 30% or more (preferably 60% or less). In order to grow certain Cube-oriented crystal grains during recrystallization and to control the work hardening index, the average rolling pressure during rolling per rolling pass is controlled to 50 N / mm ² or more.

Next, in order to adjust the shape of the material end during cold rolling, slit [Step 8] is performed and unnecessary ends are removed by trimming.
Thereafter, in cold rolling 2 [step 9], cold rolling is performed in several to several tens of passes so that the total rolling ratio is 50% or more (preferably 80% or less). Also here, in order to grow the Cube-oriented crystal grains during recrystallization and to control the work hardening index, the average rolling pressure during rolling per rolling pass is controlled to 50 N / mm ² or more.
Thereafter, in the intermediate solution treatment [Step 10], the solute raw element is solid-solubilized at a temperature increase rate of 5.0 ° C./sec or more and an ultimate temperature of 600 to 1100 ° C. (About 5 hours), Cube orientation crystal grains are formed as the grains grow. In the cold rolling 1 and the cold rolling 2 before the intermediate solution treatment [Step 10], a processed structure was once formed. The following description will be made by recrystallization in the intermediate solution treatment [Step 10]. Equiaxial crystal grains can be obtained. When the ultimate temperature and time are satisfied, water cooling [step 10-2] for rapid cooling (so-called quenching) is performed.

Thereafter, the required strength is satisfied by an aging precipitation heat treatment [Step 11] at a holding temperature of 400 to 700 ° C. and a holding time of 5 min to 10 h.
Thereafter, pickling and polishing [Step 12] are performed to remove the oxide film on the surface of the plate material, if necessary. Thereafter, if necessary, final finish rolling is performed in cold rolling 3 [step 13]. In order to maintain the equiaxed grains formed in the intermediate solution treatment [Step 10], even when the cold rolling 3 [Step 13] is performed, the rolling process rate is as low as 1.0% or more. The upper limit of the rolling rate in the cold rolling 3 [Step 13] is preferably 40% or less.
Thereafter, if necessary, the internal strain of the plate material is removed in the final annealing (temper annealing) that is maintained at 200 to 700 ° C. for 1 minute to 5 hours [Step 14]. This final annealing is also called strain relief annealing.

Below, the preferable conditions of each process are demonstrated in detail.
In the ingot rolling [Step 2], cold rolling is applied to the ingot to cause nucleation near the grain boundary during reheating in the next step of homogenization heat treatment, and further in the subsequent intermediate solution treatment. In crystals, it contributes to the formation of equiaxed crystal grains. Here, the cold rolling processing rate per pass is 1.0% or more, and the number of passes is one or more times. Preferably, the cold rolling process rate per pass is 2.0% or more and the number of passes is 3 times or more, more preferably the cold rolling process rate per pass is 3.0% or more and the number of passes is 5 times or more.

In the cold rolling 1 [Step 7], in order to control the Cube orientation area ratio and the work hardening index during recrystallization in the subsequent intermediate solution treatment [Step 10], the total processing rate is set to 30% or more. Rolling of several tens of passes is performed, and the average rolling pressure per pass is controlled to 50 N / mm ² or more. Preferably, the average rolling pressure is at 60N / mm ² or more, more preferably 70N / mm ² or more.
In cold rolling 2 [step 9], in the same manner as in cold rolling 1 [step 7], the Cube orientation area ratio and work hardening index during recrystallization in the subsequent intermediate solution treatment [step 10] are controlled. Rolling of several to several tens of passes is performed so that the processing rate becomes 50%, and the average rolling pressure per pass is controlled to 50 N / mm ² or more. Preferably, the average rolling pressure is at 60N / mm ² or more, more preferably 70N / mm ² or more.

In the subsequent intermediate solution treatment [Step 10], the average particle size (dimension) a in the rolling parallel direction is obtained by recrystallization in a high temperature region at a temperature increase rate of 5 ° C./sec or more and an ultimate temperature of 600 to 1100 ° C. Equiaxial crystal grains having a vertical average grain diameter b ratio a / b of 0.8 or more are obtained. The large number of equiaxed crystal grains reduces the anisotropy of the work hardening index. Preferably, the grain size ratio a / b of the crystal grains is 0.85 or more, more preferably a / b is 0.9 or more (preferably 1.1 or less). Since the processing rate of the cold rolling 3 after the intermediate solution treatment is small, the crystal grain size of the base material of the copper alloy sheet of the present invention is rolled within the range of the conditions of the cold rolling 3 [Step 13]. However, a / b is 0.8 or more.

Here, the processing rate (or cross-sectional reduction rate in rolling) is a value defined by the following equation.
Processing rate (%) = {(t1-t2) / t1} × 100
In the formula, t1 represents the thickness before rolling, and t2 represents the thickness after rolling.

[Thickness of plate material]
The thickness of the copper alloy sheet of the present invention is not particularly limited, but is preferably 0.04 to 0.50 mm, and more preferably 0.05 to 0.45 mm.

[Characteristics of copper alloy sheet]
The copper alloy sheet of the present invention can satisfy the characteristics required for a copper alloy sheet for connectors, for example. The copper alloy sheet of the present invention preferably has the following characteristics.

In the 180 ° U bending test where the bending workability is R / t = 1.0 expressed by the bending radius R and the sheet thickness t, the bending axis is perpendicular to the rolling direction (GW bending) and parallel (BW bending). In any case, it is preferable that no cracks are generated on the surface after bending. In addition, when a specimen having a narrow width of 1.0 mm or less is similarly subjected to 180 ° U bending where R / t = 1.0, the surface is also subjected to either GW bending or BW bending. It is more preferable to have bending workability that does not cause cracks.

-The tensile strength (TS) of the plate material is 650 MPa or more for both the tensile strength (TS-RD) in the rolling parallel direction (RD) and the tensile strength (TS-TD) in the vertical direction (TD) of the plate material. preferable. The ratio TS-RD / TS-TD is preferably 1.10 or less, more preferably 1.08 or less. Although there is no restriction | limiting in particular in the upper limit of tensile strength, For example, it is 1020 Mpa or less.

-The 0.2% yield strength (YS) of the plate material is 600 MPa or more in both the 0.2% yield strength (YS-RD) in the rolling parallel direction and the 0.2% yield strength (YS-TD) in the vertical direction of the plate. Preferably there is. Further, the ratio YS-RD / YS-TD is preferably 1.10 or less, more preferably 1.08 or less. Although there is no restriction | limiting in particular in the upper limit of 0.2% yield strength, For example, it is 1000 Mpa or less.

-The deflection coefficient (E) after 180 ° bending is preferably 140 GPa or less for both the deflection coefficient (E-RD) in the rolling parallel direction and the deflection coefficient (E-TD) in the rolling vertical direction of the plate material. Further, the ratio E-RD / E-TD is preferably 1.05 or less, more preferably 1.03 or less. Although there is no restriction | limiting in particular in the upper limit of this deflection coefficient, For example, it is 140 GPa or less.

-It is preferable that electrical conductivity is 20.0% ICAS or more. Here, “% IACS” represents the electrical conductivity when the resistivity 1.7241 × 10−8 Ωm of universal standard copper (International Annealed Copper Standard) is 100% IACS. Although there is no restriction | limiting in particular in the upper limit of electrical conductivity, For example, it is 50% IACS or less.
Unless otherwise specified, detailed measurement conditions for each characteristic are as described in the examples.

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 and Comparative Examples 1 to 14)
For each of the examples and comparative examples, the respective amounts of Ni and Si shown in Table 1 and, if necessary, secondary additive elements and the like are contained, and the alloy material consisting of Cu and inevitable impurities is melted in a high-frequency melting furnace. This was cooled at a cooling rate of 0.1 ° C./second to 100 ° C./second and casted [Step 1] to obtain an ingot.

This ingot was subjected to ingot rolling [step 2] for cold rolling at a processing rate of 1.0% or more and the number of passes once or more. Thereafter, the ingot was subjected to a homogenization heat treatment [step 3] at 800 ° C. to 1100 ° C. for 5 minutes to 20 hours. Thereafter, hot rolling [Step 4] as hot working was performed at 800 ° C. or higher and 1100 ° C. or lower, and further, water quenching cooling [Step 5] was performed to obtain a hot rolled sheet. Next, the surface of the hot-rolled sheet was chamfered [Step 6] to remove the oxide film. Thereafter, in cold rolling 1 [Step 7], rolling was performed in several to several tens of passes so that the total processing rate was 30% or more. At this time, the average rolling pressure per pass was 50 N / mm ² or more. Next, both ends of the rolled material were slit [step 8]. Thereafter, in cold rolling 2 [Step 9], rolling was performed in several to several tens of passes so that the total processing rate was 50% or more, and the average rolling pressure per pass was 50 N / mm ² or more. Thereafter, in the intermediate solution treatment [Step 10], a heat treatment was performed by holding at a temperature rising rate of 5 ° C./sec or more and an ultimate temperature of 600 to 1100 ° C. for 1 second to 5 hours, and then rapidly cooling [Step 10-2]. . Here, by recrystallization in a high temperature region, a ratio of the dimension a in the rolling parallel direction to the dimension b in the rolling vertical direction, a / b was 0.8 or more, and equiaxed crystal grains were obtained. Thereafter, the required strength was satisfied by an aging precipitation heat treatment [Step 11] at a holding temperature of 400 to 700 ° C. and a holding time of 5 min to 10 h. Thereafter, in order to remove the oxide film on the surface of the plate material, pickling and polishing [Step 12] were performed. Then, the final finish rolling was performed by cold rolling 3 [process 13]. In cold rolling 3 [step 13], in order to maintain the equiaxed grains formed in the intermediate solution treatment [step 10], the rolling was performed at a rolling reduction rate as low as 1.0% or more. Specifically, the rolling rate in cold rolling 3 [step 13] was set to 1.0 to 40.0%. Thereafter, strain in the plate material was removed by final annealing [Step 14] in which the temperature was maintained at 200 to 700 ° C. for 1 minute to 5 hours.

As shown in Table 2, the production conditions of each Example and Comparative Example were changed from the above conditions and shown in the column of “Process X” (X is the number of the process).
As described above, a copper alloy plate having a final plate thickness (t) of 0.15 mm was obtained.

The following characteristic survey was conducted for each specimen.

(A) Work hardening index [n value]
About the test material of each Example and a comparative example, the work hardening index | exponent was measured with the inclination of the plastic deformation area | region of a stress-strain curve by the tension test of a JIS5 test piece. In addition, the tensile test was measured based on JISZ2241. The evaluation criteria were that the work hardening index (n _RD ) in the rolling parallel direction passed 0.010 to 0.150, and the work hardening index (n _TD ) in the rolling vertical direction passed 0.010 to 0.150. The ratio n _RD / n _TD between the work hardening index (n _RD ) in the parallel direction and the work hardening index (n _TD ) in the vertical direction of the rolling is 0.500 to 1.500. Passed.

(B) Cube orientation area ratio With respect to the test materials of the examples and comparative examples, the crystal orientation was measured by the EBSD method under the conditions of a measurement area of 300 μm × 300 μm and a scan step of 0.1 μm. In the analysis, the EBSD measurement result of 300 μm × 300 μm was divided into 25 blocks, and the area ratio of the crystal grains having the Cube orientation of each block was confirmed as follows. The electron beam was generated from thermionic electrons from the W filament of the scanning electron microscope. As a measuring device of the EBSD method, OIM5.0 (product name) manufactured by TSL Solutions Co., Ltd. was used, and OIM Analysis was used for analysis.
Further, in the polishing before the EBSD measurement, the target part tissue was exposed by electrolytic polishing in order to observe the structure. As the parts exposed by polishing, five locations of depths D = 1 / 20t, 1 / 4t, 1 / 2t, 3 / 4t, 19 / 20t with respect to the plate thickness t were observed by EBSD. . The occupancy (that is, the area ratio) of the Cube-oriented crystal grains with respect to the measurement visual field was determined at all five locations. And the average value Sa of these five area ratios was calculated | required, and this was shown as "average value (%) of the thickness direction of Cube azimuth | direction area ratio" in the table | surface.

(C) 180 degree U bending test About the test material of each Example and a comparative example, the perpendicular | vertical rolling direction test piece punched with the press so that it may become width 0.25mm and length 1.5mm perpendicularly to a rolling direction, A rolled parallel direction test piece punched out by a press so as to have a width of 0.25 mm and a length of 1.5 mm parallel to the rolling direction was subjected to the test. GW (Good Way) obtained by bending W so that the bending axis is perpendicular to the rolling direction with respect to the rolling parallel direction test piece, and so that the bending axis is parallel to the rolling direction with respect to the rolling vertical direction test piece. BW (Bad Way) is W bent to 90 ° W in accordance with Japan Copper and Brass Association Technical Standard JCBA-T307 (2007), then 180 ° contact without attaching inner radius with compression tester Bending was performed. The bent surface was observed with a 100 × scanning electron microscope to investigate the presence of cracks. Those with no cracks were represented as “A” as “good”, and those with cracks were represented as “D” as “bad”. When generated, the cracks had a maximum width of 30 μm to 100 μm and a maximum depth of 10 μm or more.

(D) Tensile strength [TS]
About the test material of each Example and a comparative example, the rolling vertical direction test piece punched by the press so that it may become width 0.25mm and length 1.5mm perpendicularly to a rolling direction is used for a tension test, and a rolling vertical direction Tensile strength (TS-TD) was determined. Separately, a rolling parallel direction test piece punched out by a press so as to have a width of 0.25 mm and a length of 1.5 mm parallel to the rolling direction was subjected to a tensile test to obtain a rolling parallel direction tensile strength (TS-RD). . The tensile strength was measured based on JIS Z 2241.
The anisotropy of tensile strength between the rolling parallel direction and the rolling vertical direction was confirmed. A TS of 600 MPa or more was accepted and a TS of less than 600 MPa was rejected.

(E) Conductivity [EC]
The specific resistance was measured by a four-terminal method in a thermostat kept at 20 ° C. (± 0.5 ° C.) to calculate the conductivity. In addition, the distance between terminals was 100 mm. An EC of 20% IACS or higher was accepted, and a TS of less than 20% IACS was rejected.

(F) Deflection coefficient [E]
According to Japan Copper and Brass Association Technical Standard JCBA T312, the specimens of the examples and comparative examples were punched by a press so that the width was 0.25 mm and the length was 1.5 mm perpendicular to the rolling direction. From the test piece, the deflection coefficient (E _TD ) in the rolling vertical direction was determined. Separately, a rolling parallel direction deflection coefficient (E _RD ) was determined from a rolled parallel direction test piece punched out by a press so as to have a width of 0.25 mm and a length of 1.5 mm parallel to the rolling parallel direction. Sampling was taken from five locations in the width direction of the coil, and the average value of the measurement results was taken.
Each of the 180 ° U-bending test pieces was fixed to a jig, and the test pieces were pushed in 10 times, and the average value of displacement (pushing depth) f and stress w was obtained.
The deflection coefficient E (GPa) is expressed by the following formula (1).
E = 4a / b × (L / t) 3 (1)
a is the displacement (indentation depth) f and the slope of the stress w, b is the width of the specimen, L is the distance between the fixed end and the load point, and t is the thickness of the specimen. The fixed end at L was the apex of the bend.
The anisotropy of the deflection coefficient between the rolling parallel direction and the rolling vertical direction was confirmed. E passed 110 GPa or more, and E was rejected when less than 110 GPa.

(G) 0.2% yield strength [YS]
About the test material of each Example and Comparative Example, 0.2% proof stress in the vertical direction of rolling from a vertical test piece of a punch that was punched by a press so that the width was 0.25 mm perpendicular to the rolling direction and the length was 1.5 mm. (YS-TD) was determined. Separately, 0.2% proof stress (YS-RD) in the rolling parallel direction was determined from a rolling parallel direction test piece punched out by a press so that the width was 0.25 mm and the length was 1.5 mm parallel to the rolling direction.
In the measurement of the deflection coefficient, 0.2% proof stress Y (MPa) was calculated from the following formula (2) from the amount of displacement (displacement) up to the elastic limit of each test piece.
Y = {(3E / 2) × t × (f / L) × 1000} / L (2)
E is the deflection coefficient, t is the plate thickness, L is the distance between the fixed end and the load point, and f is the displacement.
Anisotropy of 0.2% proof stress in the rolling parallel direction and the rolling vertical direction was confirmed. A YS of 600 MPa or more was accepted and a YS of less than 600 MPa was rejected.

From the results shown in Table 2, it can be seen that the samples of the respective examples according to the present invention had good bending workability, tensile strength, 0.2% proof stress, electrical conductivity, and deflection coefficient. In bending workability, no crack occurred at the top of the bending in the 180 ° U bending test. In particular, all of bending workability, tensile strength, 0.2% proof stress, electrical conductivity, and deflection coefficient had small anisotropy in the rolling parallel direction and the rolling vertical direction.
Therefore, the copper alloy sheet material of the present invention is suitable as a copper alloy sheet material suitable for connectors, terminal materials, relays, switches, sockets, etc. for automobiles, such as lead frames, connectors, and terminal materials for electric and electronic devices. is there.

On the other hand, from the results shown in Table 2, it can be seen that the samples of the respective comparative examples were inferior in any of the characteristics.
Comparative Examples 1 to 7 are test examples manufactured outside the manufacturing conditions defined in the present invention. In each of Comparative Examples 1 to 7, both the work hardening index and the average value Sa of the Cube orientation area ratio were outside the range specified in the present invention. Comparative Examples 2 to 7 are inferior in bending workability. In Comparative Examples 1 to 7, all of tensile strength, 0.2% proof stress, conductivity, and deflection coefficient are anisotropic in the rolling parallel direction and the vertical direction of rolling. It was greatly inferior.
Comparative Examples 8 to 14 are test examples that deviate from the alloy composition defined in the present invention. In each of Comparative Examples 8 to 14, the average value Sa of the Cube orientation area ratio was outside the range specified in the present invention. In Comparative Examples 8 to 14, the bending workability, tensile strength, 0.2% proof stress, electrical conductivity, and deflection coefficient were inferior in at least one or more including the anisotropy in the rolling parallel direction and the rolling vertical direction. .

While this invention has been described in conjunction with its embodiments, we do not intend to limit our invention in any detail of the description unless otherwise specified and are contrary to the spirit and scope of the invention as set forth in the appended claims. I think it should be interpreted widely.

This application claims priority based on Japanese Patent Application No. 2014-112974 filed in Japan on May 30, 2014, which is hereby incorporated herein by reference. Capture as part.

DESCRIPTION OF SYMBOLS 1 Copper alloy board | plate material 2 Rolling surface 3 A surface parallel to the rolling surface surface in the depth D of the copper alloy board | plate material (1) less than board thickness t

Claims

A group containing 1.0 to 6.0% by mass of Ni and 0.2 to 2.0% by mass of Si, and consisting of B, Mg, P, Cr, Mn, Fe, Co, Zn, Zr, Ag and Sn A copper alloy sheet having a total composition of at least one selected from the group consisting of 0.000 to 3.000% by mass, the balance being composed of copper and inevitable impurities (wherein B, Mg, P, Cr, Mn, Fe, Co, Zn, Zr, Ag, and Sn are optional additional components that may contain one or more of them, or none of them.
The work hardening index (n RD ) in the rolling parallel direction is 0.010 to 0.150,
The ratio n RD / n TD between the work hardening index (n RD ) in the rolling parallel direction and the work hardening index (n TD ) in the rolling vertical direction is 0.500 to 1.500,
The thickness of the copper alloy sheet is t, the depth in the thickness direction from the rolled surface of the copper alloy sheet is D, and the surface parallel to the rolled surface at the depth D of the copper alloy sheet is Cube. When the area ratio of crystal grains whose deviation angle from the orientation {001} <100> is within 15 ° is S (D), the average value Sa of S (D) in the plate thickness direction is 5.0 to 30.0. %, A copper alloy sheet.
The total content of at least one selected from the group consisting of B, Mg, P, Cr, Mn, Fe, Co, Zn, Zr, Ag and Sn is 0.005 to 3.000% by mass. Copper alloy sheet material.
The copper alloy sheet according to claim 1 or 2, wherein the ratio of a / b between the average grain size a in the rolling parallel direction and the average grain size b in the rolling vertical direction is 0.8 or more for the crystal grains of the base material.
The deflection coefficient in the rolling parallel direction and the rolling vertical direction are both 140 GPa or less, and the ratio E-TD / E-RD between the deflection coefficient E-RD in the rolling parallel direction and the deflection coefficient E-TD in the rolling vertical direction is 1.05. The copper alloy sheet according to any one of claims 1 to 3, wherein:
A connector comprising the copper alloy sheet according to any one of claims 1 to 4.
A method for producing a copper alloy sheet according to any one of claims 1 to 4,
Melting / casting process, ingot rolling process, homogenizing heat treatment process, hot rolling process, rapid cooling process, cold rolling 1 process, slit / trimming process, cold rolling 2 process, intermediate solution treatment process, rapid cooling process, aging We perform each process of heat treatment process in this order,
In the ingot rolling process, the rolling process per pass is performed at least once at a processing rate of 1.0% or more,
In the cold rolling 1 step, an average rolling pressure per pass is 50 N / mm 2 or more, and the total processing rate is 30% or more,
In the two cold rolling processes, the average rolling pressure per pass is 50 N / mm 2 or more, and the total processing rate is 50% or more,
In the intermediate solution treatment step, a solution treatment is performed in a high temperature range of an ultimate temperature of 600 to 1100 ° C. at a temperature increase rate of 5 ° C./sec or more.
The method for producing a copper alloy sheet according to claim 6, wherein the pickling / polishing step, the cold rolling step 3 and the final annealing step are performed in this order after the aging heat treatment step.