JP2007314847A - Copper alloy having high strength, high electroconductivity and superior bend formability, and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copper alloy which has all of high strength, high electroconductivity and superior bend formability. <P>SOLUTION: The copper alloy having all of the high strength, high electroconductivity and superior bend formability includes particular amounts of Ni, Si and P respectively so as to balance the strength and the electroconductivity; and has a structure which makes a reliable number density of precipitations with a particular size of 50 to 200 nm exist therein, further makes P-containing precipitates exist therein by controlling an average atom density of P contained in the precipitates with the size of the above range into a fixed range, and has fine crystal grains with an average size of 10 μm or smaller, produced by a pinning effect of restraining a crystalline grain growth by the P-containing precipitates. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a Corson-based copper alloy having high strength, high conductivity, and excellent bending workability, for example, semiconductor parts such as home appliances and lead frames for semiconductor devices, and electrical / electronic parts such as printed wiring boards. The present invention relates to a copper alloy suitable as a copper alloy sheet used for materials, switch parts, bus bars, mechanical parts such as terminals and connectors, and industrial equipment, and a method for producing the same.

  With the demand for downsizing and weight reduction of electronic devices, downsizing and weight reduction of electric / electronic parts are progressing. And since the miniaturization and weight reduction of this electric / electronic component are miniaturization and weight reduction of the terminal component, the plate thickness and width of the copper alloy material used for these also become small. Copper alloy sheets as thin as 0.1 to 0.15 mm are also being used.

  As a result, copper alloy materials used for these electric / electronic parts are required to have higher tensile strength. For example, high strength copper alloy plates of 80 Mpa or more are required for automobile connectors and the like.

  In addition, the tendency of the electric and electronic parts to become thinner and narrower reduces the cross-sectional area of the conductive portion of the copper alloy material. In order to compensate for the decrease in conductivity due to the reduction in the cross-sectional area, the copper alloy material itself is required to have a good conductivity of 40% I A C S or higher.

  Furthermore, the copper alloy plates used for these connectors, terminals, switches, relays, lead frames, etc. are required to have severe bending workability such as 90 ° bending after notching as well as the high strength and high conductivity. A lot is happening.

  Conventionally, 4 2 alloy (Fe-4 2 mass% Ni alloy) is known as a high-strength copper alloy material. This 4 2 alloy has a tensile strength of about 5 80 MPa, has little anisotropy, and has good bending workability. However, this 4 2 alloy cannot meet the demand for higher strength of 800 MPa or more. In addition, 4 2 alloy contains a large amount of Ni, and therefore has a problem of high price.

For this reason, the Corson alloy (Cu-Ni-Si alloy) which is excellent in the above-mentioned various characteristics and is inexpensive has come to be used for electric / electronic parts. This Corson alloy is an alloy in which the solid solubility limit of nickel silicide compound (Ni ₂ Si) to copper changes remarkably with temperature. It is a precipitation hardening type alloy that hardens by quenching and tempering, and has high heat resistance and high temperature strength. It is good and has been widely used for various conductive springs and high tensile strength cables.

  However, also in this Corson alloy, when the strength of the copper alloy material is improved, the conductivity and the bending workability are lowered. That is, in a high-strength Corson alloy, it is a very difficult problem to achieve good conductivity and bending workability, and further improvement in strength, conductivity and bending workability is required.

  Conventionally, measures for improving the strength, conductivity and bending workability of the Corson alloy have been proposed. For example, according to Patent Document 1, in addition to Ni and Si, the amount of Sn, Zn, Fe, P, Mg, Pb, etc. is specified, and in addition to conductivity, the solder peel resistance of the bent portion, the heat resistant creep characteristics, Strength and punching workability are improved while maintaining migration resistance and hot workability.

  According to Patent Document 2, in addition to Ni and Si, the Mg amount and the number per unit area of precipitates and inclusions present in the alloy having a particle size of 10 μm or more are defined, and the conductivity, strength and High temperature strength is improved.

  According to Patent Document 3, Mg is contained in addition to Ni and Si, and at the same time, the content of S 2 is limited to improve suitable strength, conductivity, bending workability, stress relaxation characteristics, and plating adhesion. .

  According to Patent Document 4, the amount of Fe is limited to 0.1% or less, and strength, conductivity, bending workability, and the like are improved.

  According to Patent Document 5, the size of inclusions is 10 μm or less and the number of inclusions having a size of 5 to 10 μm is limited to improve strength, conductivity, bending workability, etching property, and plating property. I am letting.

According to Patent Document 6, the dispersion state of Ni ₂ Si precipitates is controlled to improve the strength, conductivity, and bending workability.

According to Patent Document 7, the wear resistance is improved by defining the extending shape of the crystal grains of the surface texture of the copper plate.
Japanese Patent Laid-Open No. 9-209061 (full text) JP-A-8-225869 (full text) JP 2002-180161 A (full text) JP 2001-207229 A (full text) JP 2001-49369 A (full text) Japanese Patent Laying-Open No. 2005-89843 (full text) JP-A-5-279825 (full text)

  However, Patent Document 1 only defines the content of each component of the Corson alloy, and sufficient strength cannot be obtained by controlling only the component composition, and in fact, sufficient strength is not obtained.

  Patent Document 2 pays attention to the structure of the Corson alloy and regulates the size and number of the existing precipitates and inclusions, but does not go further into the structure, and also defines the solution treatment process. As a result, sufficient strength is not obtained.

  Patent Document 3 is not practical because the electrical conductivity is low and does not meet the requirement (29 to 33% IACS in the examples), and there is a concern about an increase in manufacturing cost by reducing S to a specified amount.

  As in Patent Document 4, sufficient conductivity, strength and bendability cannot be obtained simply by limiting the Fe content to 0.1% or less.

  Patent Document 5 pays attention to the structure of the Corson alloy and regulates the size and number of inclusions present, but does not go into the structure any more, and the solution process is not sufficiently controlled. And sufficient strength is not obtained.

Patent Document 6 pays attention to the structure of the Corson alloy, sets the average particle diameter of nickel silicide precipitates (Ni ₂ Si) observed by a transmission electron microscope at a magnification of 1 million times to 3 to 10 nm, and the interval. Is controlled to 25 nm or less, and the dispersion state of the precipitate is controlled. However, basically, the conductivity is not sufficiently high because the contents of Ni and Si are too large.

  Although Patent Document 7 defines the stretched shape of the crystal grains of the copper plate surface structure, sufficient strength cannot be obtained only by the shape of the crystal grains, the solution process is not sufficiently controlled, and the electrical conductivity is sufficient. not high.

  The present invention has been made to solve such problems, and provides a Corson copper alloy having high strength, high electrical conductivity, and excellent bending workability, and a method for producing the same. is there.

In order to achieve this object, the gist of the copper alloy having high strength, high electrical conductivity, and excellent bending workability according to the present invention is mass%, Ni: 0.4 to 4.0%, Si: 0.05. -1.0%, P: 0.005 to 0.5%, each of which is a copper alloy composed of the remaining copper and unavoidable impurities, and a field emission type transmission electron having a magnification of 30000 times of this copper alloy structure The number density of precipitates having a size of 50 to 200 nm, measured by a microscope and an energy dispersive analyzer, is 0.2 to 7.0 / μm ² on average, and P contained in precipitates having a size within this range The average atomic concentration is 0.1 to 50 at%, and n is the number of crystal grains measured by the crystal orientation analysis method in which a backscattered electron diffraction image system is mounted on a field emission scanning electron microscope. When the particle size is x, (Σx) / n The average crystal grain size represented is to be at 10μm or less.

  In order to achieve this object, the summary of the copper alloy production method of the present invention having high strength, high electrical conductivity, and excellent bending workability is to produce a copper alloy plate according to the above summary or a preferred embodiment described later. In the method of obtaining a copper alloy sheet by a process including copper alloy casting, hot rolling, cold rolling, solution treatment, cold rolling, age hardening treatment, and strain relief annealing, 400 ° C. in the solution treatment. Up to an average temperature increase rate from 400 ° C. to a solution treatment temperature of 100 ° C./s or more, a solution treatment temperature of 700 ° C. or more and less than 900 ° C. The average cooling rate after the solution treatment is set to 50 ° C./s or more.

  In order to achieve the above object, the copper alloy excellent in high strength and bending workability of the present invention was further measured by the field emission type transmission electron microscope and energy dispersive analyzer of the copper alloy structure, 50 ~ It is preferable that the atomic ratio P / Si of P and Si contained in the precipitate having a size of 200 nm is 0.01 to 10 on average.

  The copper alloy excellent in high strength and bending workability of the present invention is further in mass%, and one or more of Cr, Ti, Fe, Mg, Co, and Zr are added in a total amount of 0.01 to 3.0. % May be contained. Moreover, you may contain Zn: 0.005-3.0% by the mass%. Moreover, you may contain Sn: 0.01-5.0% by the mass%.

  The present invention improves the bending workability of a copper alloy by refining the average crystal grain size in the Corson-based copper alloy structure to 10 μm or less. And this crystal grain refinement in the structure is a P-containing precipitate such as Ni-Si-P, Fe-P, Fe-Ni-P, Ni-Si-Fe-P (hereinafter also referred to as phosphide or phosphorus compound). ), Which is achieved by the pinning effect of suppressing crystal grain growth.

The present inventors have found that the pinning effect of suppressing the crystal grain growth of the P-containing precipitate is significantly larger than the pinning effect of a normal Ni ₂ Si-based precipitate not containing P. At the same time, it was also found that the magnitude of this pinning effect depends on the P content (atomic concentration) in the P-containing precipitate.

In other words, in the conventional Corson-type copper alloy structure, it was practically difficult to make the average crystal grain size finer to 10 μm or less because the ordinary Ni ₂ Si-based precipitate containing no P is used alone. This is probably because the pinning effect has a big limit.

Here, even if P is contained as an alloy component, not all precipitates present in the copper alloy structure become P-containing precipitates. That is, in an actual copper alloy structure, in addition to P-containing precipitates, other precipitates such as Ni ₂ Si that do not contain P are mixed. In other words, a P-containing precipitate having a large pinning effect for suppressing crystal grain growth and a precipitate such as another Ni ₂ Si-based material that does not contain P and has a small pinning effect for suppressing crystal grain growth. .

  For this reason, the pinning effect of actual crystal grain growth suppression depends on the amount of P-containing precipitates in the copper alloy structure. In other words, in order to refine the average crystal grain size of the copper alloy structure to 10 μm or less, it is necessary that a certain amount or more of P-containing precipitates exist in the copper alloy structure.

  In this regard, in the present invention, the amount of P-containing precipitates present in the copper alloy structure is not directly defined, but P in all precipitates of the specific size (50 to 200 nm) present in the copper alloy structure. The amount of P-containing precipitates is controlled by the atomic concentration. It is inefficient and inaccurate to pick up and analyze only P-containing precipitates from P-containing precipitates mixed in the copper alloy structure and other precipitates not containing P. Because.

  Therefore, in the present invention, the atomic concentration of P is measured for all precipitates of these specific sizes (total precipitates regardless of whether or not they contain P), and the average atomic concentration of P in the precipitates is measured. To control the amount of P-containing precipitates in the copper alloy structure. As a premise, in the present invention, the number density of all precipitates (compounds) of the specific size is guaranteed (defined).

  As a result, in the present invention, the pinning effect of suppressing the crystal grain growth is exerted, the average crystal grain size in the Corson-based copper alloy structure is refined to 10 μm or less, and the bending workability of the copper alloy is improved.

  The guarantee of the number density of precipitates (compounds) of these specific sizes and the control of the average atomic concentration of P in the precipitates are based on the control of the content of the present invention such as P and the solution treatment. This can be achieved by controlling the rate of temperature rise and the cooling rate after solution treatment. If the average atomic concentration of P contained in the precipitate is not controlled (control of the amount of P-containing precipitate), it is difficult to reduce the average crystal grain size in the Corson-based copper alloy structure to 10 μm or less.

In addition, in the present invention, in order to keep the electrical conductivity high, the contents of Ni and Si, which are basic alloy components, are controlled to be relatively low. Then, the aforementioned P-containing precipitates and other precipitates including Ni ₂ Si are finely precipitated to improve the strength, and the strength is increased even if the Ni and Si contents are controlled to be relatively low.

  Thus, the present invention obtains a copper alloy having a high balance of high strength, high conductivity, and excellent bending workability.

(Copper alloy component composition)
First, the chemical component composition in the Corson alloy of the present invention for satisfying the required strength and electrical conductivity and further high bending workability and stress relaxation resistance will be described below for various applications.

In the present invention, in order to achieve high strength, high electrical conductivity, and high bending workability, Ni: 0.4 to 4.0%, Si: 0.05 to 1.0%, P : 0.005 to 0.5% each, and a basic composition comprising a copper alloy composed of the remaining copper and inevitable impurities. This composition is an important precondition from the component composition side to refine the crystal grains of the copper alloy structure and to control the average atomic concentration of P contained in the precipitate (Ni ₂ Si). In addition, all the% display described in description of each following element is the mass%.

  In addition to this basic composition, one or more of Cr, Ti, Fe, Mg, Co, and Zr may be contained in a total of 0.01 to 3.0%. Moreover, you may contain Zn: 0.005-3.0%. Moreover, you may contain Sn: 0.01-5.0%.

Ni: 0.4-4.0%
Ni has the effect of securing the strength and conductivity of the copper alloy by crystallizing or precipitating a compound with Si (Ni ₂ Si or the like). It also forms compounds with P. If the Ni content is too low, less than 0.4%, the crystal / precipitate generation amount is insufficient, so that the desired strength cannot be obtained and the crystal grains of the copper alloy structure become coarse. Moreover, the ratio of the crystallized substance which is easy to segregate becomes high, and the dispersion | variation in the characteristic of a final product becomes large. On the other hand, if the Ni content exceeds 4.0% and the conductivity is too low, in addition to the decrease in conductivity, the number density of precipitates becomes too high and the bending workability decreases. Therefore, the Ni content is in the range of 0.4 to 4.0%.

Si: 0.05-1.0%
Si crystallizes and precipitates a compound with Ni (Ni ₂ Si) to improve the strength and conductivity of the copper alloy. It also forms compounds with P. If the Si content is too low, less than 0.05%, the formation of crystals / precipitates is insufficient, so that the desired strength cannot be obtained and the crystal grains become coarse. Moreover, the ratio of the crystallized substance which is easy to segregate becomes high, and the dispersion | variation in the characteristic of a final product becomes large. On the other hand, if the Si content is more than 1.0%, the number of precipitates increases too much, and bending workability deteriorates, and at the same time, the atomic ratio P / Si of P and Si contained in the precipitates is low. Too much. Therefore, the Si content is in the range of 0.05 to 1.0%.

P: 0.005-0.5%
P is an important element for generating a P-containing precipitate and controlling the atomic concentration of P in the P-containing precipitate within the specific range described above. By forming P-containing precipitates (phosphides and phosphorus compounds), strength and electrical conductivity are improved, and crystal grains are refined by the formation of phosphides and bending workability is improved. However, among these effects, the bending workability improving effect is exhibited particularly by controlling the atomic concentration of P in the P-containing precipitate within the specific range described above.

  If the P content is too low, less than 0.005%, these functions and effects are not effectively exhibited. On the other hand, if the content of P exceeds 0.5%, the precipitate becomes coarse, the bending workability is impaired, and the atomic concentration of P contained in the precipitate becomes too high. Therefore, the P content is in the range of 0.005 to 0.5%.

  Here, the P-containing precipitate referred to in the present invention is a P-containing precipitate of Ni—Si—P in the basic composition of Ni—Si—P. When Fe, Mg, or the like is contained therein, together with or instead of the P-containing precipitates of Ni—Si—P, (Fe, Mg) —P, (Fe, Mg) —Ni—P, Ni—Si— P-containing precipitates such as (Fe, Mg) -P are generated. In addition, when Cr, Ti, Co, Zr, or the like is contained, a P-containing precipitate is formed in which these Fe and Mg parts are partially or completely substituted.

Cr, Ti, Fe, Mg, Co, Zr: 0.01 to 3.0% in total
As described above, these elements form phosphides, thereby improving the strength and electrical conductivity, and are effective in refining crystal grains. In order to exert these effects, one or more of Cr, Ti, Fe, Mg, Co, and Zr are selectively contained in a total of 0.01% or more. However, if the total content (total amount) of these elements exceeds 3.0%, the precipitate becomes coarse, the bending workability is impaired, and the atomic concentration of P contained in the precipitate becomes too low. Therefore, the content of Cr, Ti, Fe, Mg, Co, and Zr in the case where they are selectively contained is in the range of 0.01 to 3.0% in total (total amount).

Zn: 0.005 to 3.0%
Zn is an element effective for improving the heat-resistant peelability of Sn plating and solder used for joining electronic components and suppressing thermal peeling. When such an effect is exhibited effectively, 0.005% or more is selectively contained. However, if the content exceeds 3.0%, the wet Sn spreadability of the molten Sn or solder is deteriorated. On the other hand, if the content is increased, the electrical conductivity is greatly reduced. Accordingly, Zn is selectively contained in consideration of the effect of improving the heat-resistant peelability and the effect of decreasing the conductivity, and the Zn content in that case is in the range of 0.005 to 3.0%, preferably 0.00. The range is 005 to 1.5%.

Sn: 0.01-5.0%
Sn dissolves in the copper alloy and contributes to strength improvement. In order to effectively exhibit such an effect, the content is selectively 0.01% or more. However, if the content exceeds 5.0%, the effect is saturated, and if the content is increased, the conductivity is greatly reduced. Accordingly, Sn is selectively contained in consideration of the strength improving effect and the conductivity lowering effect, and the Sn content in that case is in the range of 0.01 to 5.0%, preferably 0.01 to The range is 1.0%.

Other element content:
The other elements are basically impurities and are preferably as small as possible. For example, impurity elements such as Al, Be, V, Nb, Mo, and W tend to generate coarse crystals / precipitates, which not only deteriorates the bending workability but also easily lowers the conductivity. Therefore, it is preferable that these elements have a total content of 0.5% or less as much as possible. In addition, elements such as B, C, Na, S, Ca, As, Se, Cd, In, Sb, Bi, and MM (Mischi metal) contained in trace amounts in the copper alloy are likely to cause a decrease in conductivity. Therefore, it is desirable to keep the total amount of these contents as small as 0.1% or less. However, in order to reduce these elements, manufacturing costs such as the use of metal and refining tend to increase, and in order to suppress the increase in manufacturing costs, the total amount of these elements up to the above-mentioned upper limit. Inclusion is allowed.

(Copper alloy structure)
In the present invention, on the premise of the above Cu-Ni-Si-P alloy composition, the structure of this copper alloy is designed, the average crystal grain size is refined to 10 μm or less, and the bending workability of the copper alloy is improved. Improve.

  This structure design is achieved by controlling the average atomic concentration of P contained in precipitates existing in the copper alloy structure (controlling the amount of P-containing precipitates). Unless control of the average atomic concentration of P contained in this precipitate is performed, an appropriate amount of P-containing precipitate having a large pinning effect for suppressing crystal grain growth cannot be secured in the copper alloy structure. As a result, it is difficult to reduce the average crystal grain size in the copper alloy structure to 10 μm or less.

(Number density of precipitates)
However, as this premise, it is necessary to guarantee the number density of precipitates present in the copper alloy structure. If the number density of precipitates present in the copper alloy structure is too small or too large, even if the average atomic concentration of P contained in these precipitates or the average atomic concentration of P and Si is controlled, the bendability is improved. Of course, this may occur when the above cannot be fully demonstrated. Therefore, in the present invention, in order to guarantee the effect of refining the crystal grain size due to the precipitates, the number density of the precipitates having a specific size is set within a certain range.

That is, the number density of precipitates having a size of 50 to 200 nm as measured by the field emission transmission electron microscope and energy dispersive analyzer of the copper alloy structure is 0.2 to 7.0 / μm ^2. And Regardless of whether or not the precipitate of a specific size specified here contains P, only the size (maximum diameter) of each precipitate is used as a selection criterion.

If the number density of these precipitates is less than 0.2 / μm ² , the amount of precipitates is too small. For this reason, even if the average atomic concentration of P or P and Si contained in this precipitate is controlled, the effect of refining the crystal grain size cannot be sufficiently exhibited, the crystal grains become coarse, and the bending workability decreases. there is a possibility.

On the other hand, when the number density of the precipitates is larger than 7.0 / μm ² , the precipitates are excessive, and the formation of shear bands is promoted during bending, and the bending workability is lowered. Accordingly, the number density of precipitates having a size of 50 to 200 nm is set to a range of 0.2 to 7.0 / μm ² , preferably 0.5 to 5.0 / μm ² .

(Method for measuring the number density of precipitates)
The method for measuring the number density of precipitates is a pre-stage for measuring the average atomic concentration of P contained in the precipitates, which will be described later. Specifically, a sample is collected from the manufactured final copper alloy (such as a plate), and a thin film sample for TEM observation is prepared by electrolytic polishing. Then, a bright field image is obtained from this sample, for example, by Hitachi: HF-2200 field emission transmission electron microscope (FE-TEM) at a magnification of 30000 times. This bright-field image is printed and developed, and the diameter and number of precipitates are measured from the photograph, and the precipitate having a size in which the maximum diameter of each precipitate is in the range of 50 to 200 nm is specified. From this measurement, the number density (number / μm ² ) of precipitates having a size in the range of 50 to 200 nm can be calculated.

(Average atomic concentration of P contained in the precipitate)
In the present invention, after guaranteeing the number density of precipitates, in order to refine the average crystal grain size in the copper alloy structure to 10 μm or less, the field emission type transmission electron microscope and the energy dispersion type of the copper alloy structure have a magnification of 30000 times. The average atomic concentration of P contained in a precipitate such as nickel silicide having a size of 50 to 200 nm measured by an analyzer is controlled in the range of 0.1 to 50 at%.

  As described above, in the present invention, the amount of the P-containing precipitates present in the copper alloy structure is not directly defined, but in the total precipitates of the specific size (50 to 200 nm) present in the copper alloy structure. The amount of P-containing precipitates is controlled by the average atomic concentration of P. Therefore, in the present invention, the atomic concentration of P is measured for all the precipitates of these specific sizes (precipitates regardless of whether or not they contain P), and the average atomic concentration of P in these precipitates is measured. The amount of P-containing precipitates in the copper alloy structure is controlled.

  When the average atomic concentration of P contained in the precipitate is too low and less than 0.1 at%, the crystal grains of the copper alloy structure become coarse and bending workability is deteriorated. On the other hand, if the average atomic concentration of P contained in the precipitate is too high and exceeds 50 at%, the amount of solid solution elements other than P in the copper alloy structure increases so that the conductivity decreases. Therefore, the average atomic concentration of P contained in the precipitate is in the range of 0.1 to 50 at%, preferably in the range of 0.5 to 40 at%.

(Atom ratio of P and Si contained in the precipitate)
In the present invention, in order to guarantee the refinement of the crystal grain size of the copper alloy, the precipitation of 50 to 200 nm in size measured by the field emission transmission electron microscope and the energy dispersive analyzer of the copper alloy structure. It is preferable that the atomic ratio P / Si of P and Si contained in the product is 0.01 to 10 on average.

  When the atomic ratio P / Si between P and Si contained in the precipitate is smaller than 0.01 on average, the crystal grains are coarsened, and the possibility that the bending workability is lowered increases. On the other hand, if the atomic ratio P / Si of P and Si contained in the precipitate is larger than 10 on average, the amount of solute Si is excessively increased, and the possibility that the conductivity is lowered is increased. Therefore, the atomic ratio P / Si between P and Si contained in the precipitate is, on average, preferably 0.01 to 10, more preferably 0.10 to 5.0.

(Measuring method of average atomic concentration of P contained in precipitate)
For each precipitate of the same bright field image (the same observation image) by a field emission type transmission electron microscope having a magnification of 30000 times, the number density of the precipitates was measured. The component quantitative analysis of each precipitate is performed by EDX). The beam diameter for this analysis is 5 nm or less. This analysis was performed only on each precipitate (total precipitate) having a size with a maximum diameter of 50 to 200 nm (not performed on precipitates of other sizes), and The atomic concentration (at%) of P and Si in the precipitate (total precipitate) is measured. Then, the average atomic concentration of P and Si contained in the precipitate in the bright field image is calculated.

(Method for measuring the number ratio of P and Si contained in the precipitate)
From the measurement of the average atomic concentration of P and Si contained in the precipitate (in the precipitate), the average atomic ratio P / Si of P and Si contained in the precipitate having a size in the range of 50 to 200 nm. Can also be calculated.

  In order to improve the reproducibility and accuracy of these measurements or calculations, the number of measurement samples collected from the copper alloy is 10 from any 10 locations, and the average atomic concentration of P and Si contained in the precipitate, P Each numerical value such as the atomic number ratio P / Si between Si and Si, and the number density of precipitates is the average of these ten.

(Average crystal grain size)
In the present invention, the crystal grain size of the copper alloy structure refined by controlling the precipitates of the copper alloy structure defines the average crystal grain size of the copper alloy structure as a measure for substantially improving the bending workability. . That is, when the number of crystal grains measured by a crystal orientation analysis method in which a backscattered electron diffraction image system is mounted on a field emission scanning electron microscope with a magnification of 350 times is n, and each measured crystal grain size is x, The average crystal grain size represented by (Σx) / n is 10 μm or less.

  If the average crystal grain size is larger than 10 μm, the bending workability that the present invention intends to obtain cannot be obtained. Therefore, the average crystal grain size is 10 μm or less, preferably 7 μm or less.

(Average crystal grain size measurement method)
In the present invention, these average crystal grain size measurement methods are installed in a field emission scanning electron microscope (FESEM) with a backscattered electron diffraction image (EBSP: Electron Back Scattering (Scattered) Pattern) system. The crystal orientation analysis method is defined because the measurement method is highly accurate because of its high resolution.

  The EBSP method projects an EBSP on a screen by irradiating a sample set in a FESEM column with an electron beam. This is taken with a high-sensitivity camera and captured as an image on a computer. In the computer, the orientation of the crystal is determined by analyzing this image and comparing it with a pattern obtained by simulation using a known crystal system. The calculated crystal orientation is recorded as a three-dimensional Euler angle together with position coordinates (x, y) and the like. Since this process is automatically performed for all measurement points, tens of thousands to hundreds of thousands of crystal orientation data are obtained at the end of measurement.

  As described above, the EBSP method has a wider field of view than the X-ray diffraction method or the electron diffraction method using a transmission electron microscope. There is an advantage that information on the standard deviation of particle diameter or orientation analysis can be obtained within a few hours. In addition, since the measurement is performed by scanning a specified region at an arbitrary fixed interval instead of measurement for each crystal grain, there is also an advantage that each of the above-described information on the numerous measurement points covering the entire measurement region can be obtained. is there. Details of the crystal orientation analysis method in which the EBSP system is mounted on these FESEMs are described in detail in Kobe Steel Engineering Reports / Vol.52 No.2 (Sep.2002) P66-70 and the like.

  Using the crystal orientation analysis method in which the EBSP system is mounted on these FESEMs, in the present invention, the texture of the surface portion of the product copper alloy in the plate thickness direction is measured, and the average crystal grain size is measured.

  Here, in the case of a normal copper alloy plate, the Cube orientation, Goss orientation, Brass orientation (hereinafter also referred to as B orientation), Copper orientation (hereinafter also referred to as Cu orientation), S orientation, etc. as shown below. A texture composed of many orientation factors called is formed, and there are crystal planes corresponding to them. These facts are described in, for example, edited by Shinichi Nagashima, “Aggregate” (published by Maruzen Co., Ltd.) and “Light Metal”, Vol. 43, 1993, P285-293, published by the Japan Institute of Light Metals.

  The formation of these textures differs depending on the processing and heat treatment methods even in the case of the same crystal system. In the case of a texture of a plate material by rolling, it is expressed by a rolling surface and a rolling direction, the rolling surface is expressed by {ABC}, and the rolling direction is expressed by <DEF> (ABCDEF indicates an integer). Based on this expression, each direction is expressed as follows.

Cube orientation {001} <100>
Goss direction {011} <100>
Rotated-Goss orientation {011} <011>
Brass direction (B direction) {011} <211>
Copper orientation (Cu orientation) {112} <111>
(Or D direction {4 4 11} <11 11 8>
S orientation {123} <634>
B / G direction {011} <511>
B / S orientation {168} <211>
P direction {011} <111>

  In the present invention, basically, deviations of orientation within ± 15 ° from these crystal planes belong to the same crystal plane (orientation factor). Further, a boundary between crystal grains in which the orientation difference between adjacent crystal grains is 5 ° or more is defined as a crystal grain boundary.

  In addition, in the present invention, the number of crystal grains measured by the crystal orientation analysis method is n, and the measured crystal grains are irradiated with an electron beam at a pitch of 0.5 μm to a measurement area of 300 × 300 μm. When the diameter is x, the average crystal grain size is represented as (Σx) / n.

(Production conditions)
Next, preferable manufacturing conditions for making the structure of the copper alloy the structure defined in the present invention will be described below. The copper alloy of the present invention is basically a copper alloy plate, and strips obtained by slitting the strip in the width direction and those obtained by coiling these strips are included in the scope of the copper alloy of the present invention.

  Also in the present invention, as with a general manufacturing process, casting of a copper alloy melt adjusted to a specific component composition, ingot chamfering, soaking, hot rolling, cold rolling, and solution treatment (recrystallization annealing) ), Age (hardening) treatment (precipitation annealing), strain relief annealing, etc., the final (product) plate is obtained. However, even in the above manufacturing process, it is possible to obtain the structure, strength / high conductivity and bending workability defined in the present invention by carrying out a combination of preferable manufacturing conditions described below.

  First, the end temperature of hot rolling is preferably 550 to 850 ° C. When hot rolling is performed at a temperature lower than 550 ° C., recrystallization is incomplete, resulting in a non-uniform structure, and bending workability is deteriorated. When the end temperature of hot rolling is higher than 850 ° C., the crystal grains become coarse and bending workability deteriorates. It is preferable to perform water cooling after this hot rolling.

  Next, it is preferable that the cold rolling rate in the cold rolling after the hot rolling and before the solution treatment (recrystallization annealing) is 70 to 98%. If the cold rolling rate is lower than 70%, there are too few sites to be recrystallized nuclei, which inevitably becomes larger than the average crystal grain size to be obtained by the present invention, and the bending workability may be deteriorated. is there. On the other hand, if the cold rolling rate is higher than 98%, the variation in crystal grain size becomes large, so that the crystal grains become non-uniform and the bending workability that the present invention intends to obtain may deteriorate.

(Solution treatment)
The solution treatment is an important step in order to refine the crystal grain size and improve the bending workability of the copper alloy by controlling the precipitate of the copper alloy structure in the present invention. In particular, the control of the rate of temperature rise at the start of the solution treatment and the cooling rate from the solution treatment temperature after the solution treatment is important for the control of precipitates in the copper alloy structure.

  In this regard, in the present invention, the average temperature increase rate up to 400 ° C. in the solution treatment is in the range of 5 to 100 ° C./h, the average temperature increase rate from 400 ° C. to the solution treatment temperature is 100 ° C./s or more, The heat treatment temperature is set to 700 ° C. or higher and lower than 900 ° C., and the average cooling rate after the solution heat treatment is set to 50 ° C./s or higher.

In the temperature raising and cooling processes in the solution treatment step, first, precipitation of nickel silicide precipitates (Ni ₂ Si) or the like occurs in a relatively low temperature region from room temperature to about 600 ° C. or less, and high temperature of about 600 ° C. or more. In these regions, these precipitates are dissolved again. In addition, the recrystallization temperature range of the copper alloy of the present invention is about 500 to 700 ° C., and the crystal grain size of the copper alloy is greatly influenced by the dispersion state of precipitates during the recrystallization.

  The average rate of temperature rise from the start of solution heat-up to 400 ° C. is relatively small, and is 5 to 100 ° C./h. However, if the average heating rate is less than 5 ° C./h, the deposited precipitate becomes coarse, the average crystal grain size becomes large, and the bending workability decreases. On the other hand, if the average rate of temperature increase is greater than 100 ° C./h, the amount of precipitates produced decreases. For this reason, the number density of precipitates is insufficient, the average crystal grain size is increased, and bending workability is lowered.

  Next, the average rate of temperature increase from 400 ° C. to the solution temperature is relatively increased to 100 ° C./s or more. When the rate of temperature increase is less than 100 ° C./s and less than 100 ° C./s, the growth of recrystallized grains is promoted, the average crystal grain size is increased, and bending workability is lowered.

  Solution treatment temperature shall be 700 degreeC or more and less than 900 degreeC. When the solution treatment temperature is lower than 700 ° C., the solution treatment becomes insufficient, and not only the high strength desired by the present invention is obtained but also the bendability is lowered. On the other hand, when the solution treatment temperature is 900 ° C. or higher and higher than 900 ° C., the number density of the precipitates becomes too small, and the atomic concentration of P contained in the precipitates becomes too low. Processability and high conductivity cannot be obtained.

  The average cooling rate after the solution treatment is 50 ° C./s or more. When the cooling rate is less than 50 ° C./s, the growth of crystal grains is promoted, and becomes larger than the average crystal grain size to be obtained by the present invention, and the bending workability is lowered.

(Process after solution treatment)
After this solution treatment (after recrystallization annealing), precipitation annealing (intermediate annealing, secondary annealing) is performed at a temperature in the range of about 300 to 450 ° C. to form fine precipitates, and the strength of the copper alloy sheet The conductivity may be improved (recovered). Moreover, you may perform the last cold rolling in 10 to 30% of range after these annealing. In addition, you may perform the intermediate annealing for recovering electrical conductivity before the final cold rolling and after the solution treatment.

  By carrying out by appropriately combining these manufacturing conditions described above, it is possible to obtain a copper alloy excellent in high strength, high conductivity and bending workability that satisfies the above requirements of the present invention. Since the copper alloy of the present invention thus obtained has high strength, high electrical conductivity and excellent bending workability, it can be used widely and effectively for home appliances, semiconductor parts, industrial equipment, and automotive electric electronic parts.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. Of course, it is possible to implement them, and both are included in the technical scope of the present invention.

  Examples of the present invention will be described below. By changing the Cu alloy composition and manufacturing method, in particular the solution treatment conditions, variously changing the P average atomic concentration in the precipitate in the Cu alloy structure, etc., changing the average crystal grain size of the obtained Cu alloy thin plate, Properties such as strength, conductivity and bendability were evaluated.

  Specifically, copper alloys having the chemical composition shown in the following Tables 1 and 2 were melted under a charcoal coating in the atmosphere in a kryptor furnace, cast into a cast iron book mold, and had a thickness of 50 mm and a width of 75 mm. An ingot with a length of 180 mm was obtained. Then, after chamfering the surface of the ingot, it was hot-rolled at a temperature of 950 ° C. until the thickness became 20 mm, and quenched into water from the hot rolling end temperature of 750 ° C. or higher. Next, after removing the oxide scale, primary cold rolling was performed to obtain a plate having a thickness of 0.25 mm.

  Subsequently, using a salt bath furnace, as shown in Tables 2 and 3, solution treatment was performed by changing the temperature raising and cooling conditions in various ways. The plate holding time at the solution temperature was commonly 30 seconds. Next, cold rolled sheets each having a thickness of 0.20 mm were obtained by finish cold rolling. This cold-rolled sheet was subjected to an artificial age hardening treatment at 450 ° C. for 4 hours to obtain a final copper alloy sheet.

  For each of the copper alloy plates thus produced, in each example, using a sample cut out from the final copper alloy plate, the structure investigation and the strength (0.2% proof stress) measurement by tensile test, conductivity Measurement, bending test and evaluation were carried out. These results are shown in Tables 3 and 4.

  Here, in each of the copper alloys shown in Tables 1 and 2, the remaining composition excluding the element amount described is Cu, and other elements other than those described in Tables 1 and 2 are Al, Be, V, Nb, Mo, The total amount of impurity elements such as W was 0.5% or less. In addition, elements such as B 2, C 2, Na, S 2, Ca, As, Se, Cd, In, Sb, Bi, and MM (Mischmetal) were 0.1% or less in total. In addition, "-" shown in each element content of Tables 1 and 2 indicates that it is below the detection limit.

These copper alloy sample structures were examined by examining the average atomic concentration (at%) of P contained in precipitates having a size of 50 to 200 nm and the average number of atoms of P and Si contained in precipitates having a size of 50 to 200 nm. The ratio P / Si, and the average number density (pieces / μm ² ) of precipitates having a size of 50 to 200 nm were measured by the methods described above.

  In addition, when the number of crystal grains of the copper alloy sample structure is n and each measured crystal grain size is x, the average crystal grain size (μm) represented by (Σx) / n is the above-described field emission. Measured by crystal orientation analysis with backscattered electron diffraction image system mounted on scanning electron microscope. Specifically, the surface of the rolled surface of the product copper alloy was mechanically polished, and further subjected to electrolytic polishing after buffing to prepare a sample whose surface was adjusted. Thereafter, crystal orientation measurement and crystal grain size measurement by EBSP were performed using FESEM (JEOL JSM 5410) manufactured by JEOL Ltd. The measurement area was an area of 300 μm × 300 μm, and the measurement step interval was 0.5 μm. As the EBSP measurement / analysis system, EBSP: manufactured by TSL (OIM) was used.

(Tensile test)
The tensile test was performed using a JIS No. 13 B test piece in which the longitudinal direction of the test piece was the rolling direction, at a room temperature, a test speed of 10.0 mm / min, and GL = 50 mm using a 5882 type Instron universal testing machine. The 0.2% yield strength (MPa) was measured. Three test pieces under the same conditions were tested, and the average value thereof was adopted.

(Conductivity measurement)
The electrical conductivity is measured by measuring the electrical resistance with a double-bridge resistance measurement device by processing a strip-shaped test piece of width 10 mm x length 300 mm by milling with the longitudinal direction of the test piece as the rolling direction. Calculated by the method. Three test pieces under the same conditions were tested, and the average value thereof was adopted.

(Evaluation test for bending workability)
The bending test of the copper alloy sheet sample was performed according to the Japan Copper and Brass Association technical standard. The plate material is cut to a width of 10 mm and a length of 30 mm, and a Good Way (bending axis is perpendicular to the rolling direction) is bent at a bending radius of 0.15 mm with a load of 1000 kgf, and the presence or absence of cracks in the bent portion is 50 times optical. Visual observation was performed with a microscope. At this time, the case where there was no crack was evaluated as ○, and the case where the crack occurred was evaluated as ×. If it is excellent in this bending test, it can be said that it is excellent also in severe bending workability such as 90 ° bending after contact bending or notching.

  As is apparent from Tables 1 and 3, Invention Examples 1 to 18, which are copper alloys within the composition of the present invention, are subjected to solution treatment within a preferable range of conditions to obtain product copper alloy sheets.

For this reason, the structures of Invention Examples 1 to 18 have an average number density of precipitates having a size of 50 to 200 nm according to each measurement method in the range of 0.2 to 7.0 / μm ^2. The average atomic concentration of P contained in the precipitate is in the range of 0.1 to 50 at%, and the average crystal grain size is 10 μm or less. The atomic ratio P / Si between P and Si contained in the precipitate having a size of 50 to 200 nm is 0.01 to 10 on average.

  As a result, Invention Examples 1 to 18 have high strength and high conductivity of 0.2% proof stress of 800 MPa or more, conductivity of 40% IACS or more, and excellent bending workability.

  In contrast, the copper alloys of Comparative Examples 19 to 27 and 33 to 35 are out of the scope of the present invention in the component composition. For this reason, although the solution treatment (manufacturing method) is performed within a preferable range of conditions, the bending workability is commonly inferior, and the strength and conductivity are low.

  The copper alloy of Comparative Example 19 does not contain P. For this reason, the average atomic concentration of P contained in the precipitate is 0, and the average crystal grain size is larger than 10 μm. For this reason, strength is low with bending workability.

  In the copper alloy of Comparative Example 20, the Ni content is out of the upper limit. For this reason, electrical conductivity is remarkably low with bending workability.

  In the copper alloy of Comparative Example 21, the Ni content deviates slightly from the lower limit. For this reason, although the average atomic concentration of P contained in the precipitate having a size of 50 to 200 nm is 4 at%, the average crystal grain size is coarsened exceeding 10 μm. As a result, the strength is extremely low along with the bending workability.

  In the copper alloy of Comparative Example 22, the Si content deviates from the upper limit. For this reason, although the average atomic concentration of P contained in the precipitate having a size of 50 to 200 nm is 1.5 at%, the average crystal grain size is coarsened exceeding 10 μm. As a result, the electrical conductivity is remarkably low as well as bending workability.

  In the copper alloy of Comparative Example 23, the Si content is off the lower limit. For this reason, the number density of the precipitates having a size of 50 to 200 nm is too small, and the average crystal grain size becomes coarser than 10 μm even though the average atomic concentration of P contained in this size precipitate is 20 at%. ing. As a result, strength and conductivity are extremely low as well as bending workability.

  In the copper alloy of Comparative Example 24, the P content deviates from the upper limit. For this reason, electrical conductivity is remarkably low with bending workability.

  In the copper alloy of Comparative Example 25, the average atomic concentration of P contained in the precipitate having a size of 50 to 200 nm is too small, and the Fe content is not higher than the upper limit of 3.0%. For this reason, the average crystal grain size is coarsened exceeding 10 μm. As a result, the electrical conductivity is remarkably low as well as bending workability.

  In the copper alloy of Comparative Example 26, the average atomic concentration of P contained in the precipitate having a size of 50 to 200 nm is too small, and the contents of Cr and Co are outside the upper limit of 3.0%. For this reason, the average crystal grain size is coarsened exceeding 10 μm. As a result, strength and conductivity are extremely low as well as bending workability.

  Moreover, although the composition of the copper alloys of Comparative Examples 27 to 35 is within the range of the present invention, the solution treatment conditions (manufacturing method) are out of the preferable condition range. As a result, bending workability is inferior in common, and strength and conductivity are also low.

  In Comparative Example 27, the average temperature increase rate up to 400 ° C. in the solution treatment is too small. For this reason, although the average atomic concentration of P contained in the precipitate having a size of 50 to 200 nm is 3.7 at% and the average crystal grain size is 6 μm, the bending strength and the strength are extremely low.

  In Comparative Example 28, the average heating rate up to 400 ° C. in the solution treatment is too large. For this reason, the number density of precipitates is insufficient, the average crystal grain size becomes large, and the bending workability is low.

  In Comparative Example 29, the average rate of temperature increase from 400 ° C. to the solution temperature is too small. For this reason, an average crystal grain size becomes large and bending workability is low.

  In Comparative Example 30, the solution treatment temperature is too low. For this reason, solutionization becomes insufficient, strength is low, and bendability is low.

  In Comparative Example 31, the solution treatment temperature is too high. For this reason, the number density of precipitates having a size of 50 to 200 nm is too small, the average atomic concentration of P contained in the precipitates of this size is as small as 0.2 at%, and the average crystal grain size is coarsened exceeding 10 μm. . As a result, bending workability and electrical conductivity are low.

  In Comparative Example 32, the average cooling rate after the solution treatment is too small. For this reason, the number density of precipitates having a size of 50 to 200 nm and the average atomic concentration of P contained therein are within the range, but the growth of crystal grains is promoted, the average crystal grain size is large, and the bending workability is low. . Also, the strength is low.

  The copper alloys of Comparative Examples 33 and 35 do not contain P. Moreover, the content of Cr and Co deviates from the upper limit of 3.0%. Furthermore, the solution treatment temperature is too high, and the number density of precipitates having a size of 50 to 200 nm is too small. For this reason, the average crystal grain size becomes larger than 10 μm and the bending workability is low. Also, the conductivity is remarkably low.

  In Comparative Example 34, although the number density of precipitates having a size of 50 to 200 nm is too small and the average atomic concentration of P contained in this size precipitate is within the range, the average crystal grain size exceeds 10 μm. It has become coarse. As a result, bending workability and strength are low.

  From the above results, the component composition and structure of the copper alloy sheet of the present invention for further improving the bending workability after increasing the strength and conductivity, and further preferable manufacturing conditions for obtaining the structure The significance is supported.

  As described above, according to the present invention, it is possible to provide a copper alloy that has excellent bending workability as well as high strength and high electrical conductivity. As a result, for electrical and electronic parts that have been reduced in size and weight, in addition to semiconductor device lead frames, lead frames, connectors, terminals, switches, relays, etc. have high strength and high conductivity, and severe bending workability. It can be applied to the required use.

Claims (6)

In mass%, Ni: 0.4 to 4.0%, Si: 0.05 to 1.0%, P: 0.005 to 0.5%, respectively, and the balance copper and inevitable impurities The number density of precipitates having a size of 50 to 200 nm as measured by a field emission transmission electron microscope having a magnification of 30000 times and an energy dispersive analyzer of the copper alloy structure is 0.2 to 7.7 on average. 0 pieces / [mu] m ^2, the average atom concentration of P contained in the precipitate size in this range with a 0.1~50at%, equipped with a backscattered electron diffraction image system field emission scanning electron microscope The average crystal grain size represented by (Σx) / n is 10 μm or less, where n is the number of crystal grains measured by the crystal orientation analysis method and x is the measured crystal grain size. High strength, high conductivity and bending workability Excellent copper alloy.   On average, the atomic ratio P / Si of P and Si contained in the precipitate having a size of 50 to 200 nm, measured by the field emission transmission electron microscope and the energy dispersive analyzer, of the copper alloy structure is 0. The copper alloy according to claim 1, which is 0.01 to 10.   The copper alloy further contains 0.01 to 3.0% in total of one or more of Cr, Ti, Fe, Mg, Co, and Zr by mass%. Copper alloy.   The copper alloy according to any one of claims 1 to 3, wherein the copper alloy further contains Zn: 0.005 to 3.0% by mass.   The copper alloy plate according to any one of claims 1 to 4, wherein the copper alloy plate further contains Sn: 0.01 to 5.0% by mass.   A method for producing a copper alloy plate according to any one of claims 1 to 5, wherein the casting, hot rolling, cold rolling, solution treatment, cold rolling, age hardening treatment, and strain relief annealing of the copper alloy are performed. In obtaining a copper alloy sheet by the process of including, the average temperature increase rate from 400 degreeC to solution treatment temperature is 100 degreeC / s in the range of 5-100 degreeC / h in the average temperature increase rate to 400 degreeC in solution treatment. As described above, the solution treatment temperature is set to 700 ° C. or more and less than 900 ° C., and the average cooling rate after the solution treatment is set to 50 ° C./s or more. Excellent in high strength, high conductivity and bending workability A method for producing copper alloy.