WO2002053790A1

WO2002053790A1 - High strength copper alloy excellent in bendability and method for producing the same and terminal and connector using the same

Info

Publication number: WO2002053790A1
Application number: PCT/JP2001/011483
Authority: WO
Inventors: Kazuhiko Fukamachi; Masato Shigyo
Original assignee: Nippon Mining & Metals Co., Ltd.
Priority date: 2000-12-28
Filing date: 2001-12-26
Publication date: 2002-07-11
Also published as: CN1250756C; US20030188814A1; US20080210353A1; JPWO2002053790A1; KR20030057561A; CN1476486A; KR100535737B1; JP4177104B2; TW526272B

Abstract

A high strength copper alloy excellent in bendability which has been finally cold rolled, has a difference between a tensile strength and a 0.2% proof stress of 80 Mpa or less, and has been subjected to such a control of structure that it exhibits a mean grain size (mGS) of 5 νm after the anneal at 425°C for 10,000 sec and a standard deviation of said mean grain size (σGS) of 1/3 X mGS or less; a method for producing the copper alloy which comprises subjecting a copper alloy to a cold rolling at a working ratio of 45 % or more, subjecting the resultant product to a final annealing to provide an alloy having a mean grain size (mGS) of 3νm and a standard deviation of said mean grain size (σGS) of 2 νm or less, and then subjecting the annealed product to a final cold rolling at a working ratio of 10 to 45 %. The above copper ally has been found as a result of an investigation for providing a high strength material having excellent bendability in a general copper alloy, particularly phosphor bronze, which involves adjusting the conditions for the cold rolling and annealing of phosphor bronze, searching the relationship between various properties after final rolling and has lead to stable accomplishment of the improvement of the properties which is considered to be due to the combined effect of grain boundary reinforcement and dislocation reinforcement.

Description

Description High-strength copper alloy with excellent bending workability, method for producing the same, and terminals and connectors using the same

(Technical field to which the invention belongs)

The present invention relates to a high-strength copper alloy excellent in bending workability, particularly high-strength phosphor bronze used for electronic components such as terminals and connectors, and a method for producing the same, and to a terminal-to-connector using them. .

(Conventional technology)

Phosphor bronze strips such as C5210 and C 5191 (according to JISH 3110 and JISH 3130 ') and copper alloy materials such as C 2600 (according to JISH 3100) have excellent workability and mechanical strength, and are therefore electronic components. Widely used in terminal-connector applications.

In recent years, the progress of lighter, thinner and shorter electronic components has been more remarkable than before, and accordingly, copper alloy strips for electronic components have been required to have a thinner material. However, when the material becomes thin, the strength of the material itself is required to maintain the contact pressure of the connector. On the other hand, in order to miniaturize electronic components, in order to fulfill its function in a small space, bending is performed with a small bending radius, and high bending workability is required. Therefore, contradictory properties such as high strength and good bending workability are required for the material.

Along with this, high-strength copper alloys such as beryllium copper and titanium copper, and Corson alloy (Cu-Ni-Si) -based and chromium copper-based (Cu-Cr) , Cu—Cr—Zr, Cu—Cr—Sn). However, these high-strength copper alloys, which are relatively new as copper alloys for electronic components, do not yet have general versatility, so they are not suitable for market supply and demand and distribution. For example, there is a problem that it is not widely used in a market where priority is placed on standard. Also, these high-strength copper alloys are not preferable because they are more expensive than conventional copper alloys such as phosphor bronze.

From these viewpoints, general copper alloys such as brass and phosphor bronze, which have been said to have relatively high mechanical strength among conventional copper alloys, require further improvements in strength and workability. Was. As for workability, good bendability is particularly required. This is because with the progress of high-density packaging of mobile phones, digital cameras, video cameras, etc., severe bending of metal parts such as terminals, connectors, and lead frames of electronic components is also performed.

Generally, in order to increase the strength of a metal, a method such as solid solution strengthening> precipitation strengthening, grain boundary strengthening, dislocation strengthening, and the like, which are combined with each other, have been attempted. Phosphor bronze, whose component composition range is standardized, is a solid solution strengthened copper alloy. In order to further improve its strength, tempering such as cold rolling and annealing is performed from the viewpoint of grain boundary strengthening and dislocation strengthening. Although it is intended to achieve higher strength, the current situation is that it has lagged the recent demand for rapid progress in making electronic components lighter, thinner and shorter.

(Problems to be solved by the invention)

In view of such a current situation, an object of the present invention is to develop a technology that combines high strength and bending workability of a solid solution strengthened copper alloy, particularly a versatile phosphor bronze.

(Means for solving the problem)

If solid-solution strengthened copper alloys, especially general-purpose phosphor bronze, are strengthened by grain boundary strengthening and dislocation strengthening, that is, heat treatment and rolling, grain boundaries cannot be revealed in the final product. In other words, when the metal strip is deformed by cold working, the difference in local deformation inside the crystal grain becomes remarkable with the progress, and various deformation bands such as a shear band and a micro band appear. Due to these deformation zones, the grain boundaries formed by recrystallization before cold working become discontinuous, and their cross sections are etched and observed with an optical microscope. The crystal structure becomes unclear even if it is observed. Even when the degree of cold working is about 20%, when observing the structure with a transmission electron microscope image, it is observed that a part of the recrystallized grain boundary before cold working remains, but it is already covered with the cell structure. Therefore, the crystal grain size cannot be specified accurately. This was a major obstacle to improving the properties of cold rolled materials.

The present inventors adjusted the cold rolling and annealing conditions of phosphor bronze and investigated the correlation between the characteristic values after final rolling, and found that the combined effect of grain boundary strengthening and dislocation strengthening was We succeeded in obtaining stable improvements. The present invention provides a high strength copper alloy with excellent bendability, which can be defined by the following properties:

(1) A final cold-rolled copper alloy in which the difference between the tensile strength and the 0.2% proof stress is within 8 OMPa, the copper alloy being annealed at 425 ° C for 100 000 seconds. The average crystal grain size (mG S) after the bending is 5 μιη or less and the standard deviation (a GS) of the average crystal grain size is 1 Z 3 X m GS or less. Excellent high-strength copper alloy,

(2) Sn: l ~: L lma ss%, P: 0.03 ~ 0.35mass ⁰ / o, composed of the balance Cu and unavoidable impurities, and represented by TS _Sn (MPa) A copper alloy having a strength of TS _Sn > 500 + 15 XSn ( _Sn : tin concentration (mass%)), and the copper alloy is annealed at 425 ° C for 100 000 seconds. (1) characterized in that the average crystal grain size (mG S) after the process is 5 / Xm or less and the standard deviation (a GS) of the average crystal grain size is 1Z3 XmGS or less. High-strength copper alloy with excellent bending workability

(3) Sn: l ~: L lma ss%, P: 0.03 ~ 0.35ma ss%, consisting of residual Cu and unavoidable impurities, after annealing at 425 ° C for 100 000 seconds The average grain size (mGS (μτϊΐ)) of mGS is less than mGS.2.7 X exp (0.043 6 XS n

(Sn: tin concentration (mass%)), characterized in that it is a high-strength copper alloy excellent in bending workability according to (1) or (2),

(4) Copper alloy is Sn: l ~ l lma ss ^o / _o , P: 0.03 ~ 0.35ma ss%, and Fe, Ni, Mg, Si, Zn, Cr , Ti, Zr, Nb, Al, Ag , Be, Ca, Y, Mn, and one or more of In: Phosphor bronze consisting of 0.05 to 2.0 mass% in total, with the balance being Cu and unavoidable impurities. A high-strength copper alloy excellent in bending workability according to (1) to (3),

(5) Copper alloy is Sn: l ~ l lma ss ^o / _o , P: 0.03 ~ 0.35ma ss%, and Fe, Ni, Mg ヽ Si, Zn, Cr, TiZr , Nb, Al, Ag, Be, Ca, Y, Mn, and one or more of In: 0.05 to 2. Oma ss% in total, the balance Cu and phosphorus consisting of unavoidable impurities a bronze, present in a section 0. 1 mu m or more in the diameter of the particles composed mainly of precipitates or crystallized substances forces one alloy element taken parallel to relative rolling direction 100 / mm ² or more A high-strength copper alloy excellent in bending workability according to any one of (1) to (3), characterized in that:

The present invention also provides a method for producing a high-strength copper alloy having excellent bending workability based on the following conditions:

(6) After cold rolling at a workability of 45% or more, final annealing is performed to reduce the average grain size (mGS) to 3 m or less and the standard deviation (aGS) of the crystal grain size to 2 m or less. A method for producing a high-strength copper alloy with excellent bending workability, characterized by subjecting to final cold rolling of 10 to 45%,

(7) After cold rolling at a working ratio of 45% or more, final annealing is performed to reduce the average grain size (mGS) to 2 m or less and the standard deviation of the grain size (aGS) to the following values. A method for producing a high-strength copper alloy with excellent bending workability, characterized by performing a final cold rolling of 70%.

(8) TS is the tensile strength after the final cold rolling with a work ratio of X (%). The cold-rolled material (MP a), tensile strength TS _a (MP _a) is TS _a rather TS. (1) The method for producing a high-strength copper alloy excellent in bending workability according to (6) to (7), wherein the strain relief annealing is performed until the value becomes X.

The above methods (6) to (8) can be applied as the above-mentioned methods (1) to (5) for producing a copper alloy. The present invention further provides a method for producing a high-strength copper alloy having excellent bending workability based on the following conditions:

(9) After cold rolling at a workability of 45% or more, final annealing and average grain size (mGS) (3) or less and the standard deviation (aGS) of the crystal grain size is 2 μπι or less, followed by final cold rolling at a workability of 10 to 45%. A method for producing a high-strength copper alloy with excellent bending workability,

(10) After cold rolling at a workability of 45% or more, final annealing is performed to reduce the average grain size (mGS) to 2 μm or less and the standard deviation (σ GS) of the grain size to 1 μm or less. The method for producing a high-strength copper alloy excellent in bending workability according to any one of (1) to (5), wherein final cold rolling is performed at a workability of 20 to 70%.

(11) In connection with (9) to (10), the tensile strength after final cold rolling with a workability of X (%) is TS. (MP a) cold tensile strength rolled material TS _a (MP a) of TS _a <TS ₀ - until X is characterized by applying strain琅焼blunt (1) to serial mounting (5) For producing high-strength copper alloys with excellent bending workability.

The present invention also provides

(1 2) A terminal-connector using a high-strength copper alloy excellent in bending workability according to (1) to (5).

(Embodiment of the invention)

Hereinafter, the reasons for limiting each element constituting the present invention will be described for each claimed invention (also referred to as the present invention).

(Invention of a high-strength copper alloy excellent in bending workability according to claim 1)

The invention of claim 1 is directed to a copper alloy having a strength characteristic in which a difference between a tensile strength and a 0.2% proof stress is within 8 OMPa, wherein the copper alloy has an average crystallinity after an annealing test at 425 ° C for 10,000 seconds. It defines that the particle size (mGS) is 5μπι or less, and the standard deviation ( _ff GS) of the crystal particle size is 1/3 mGS or less.

In the present invention, the crystal grain size is measured by a cutting method according to JISH0501. Specifically, the number of crystal grains completely cut by a line segment of a predetermined length is counted, and the average value of the cut lengths is used as the crystal grain size.The standard deviation, which is an index of the variation, is It is not the standard deviation but the standard deviation of the grain size. The copper alloy of the present invention is basically cold rolled at a workability of 45% or more, and finally annealed to have an average grain size (mGS) of 3 ιη or less and a standard deviation (GS) of the grain size of 2 / m or less, followed by final cold rolling at a work ratio of 10 to 45% or the average grain size (mGS) is 2πι or less and the standard deviation (σ GS) of the grain size is 1 μm The product was manufactured by performing the following cold rolling at a working ratio of 20 to 70%. As mentioned above, if grain boundary strengthening and dislocation strengthening, ie, heat treatment and rolling, are used to increase the strength, grain boundaries cannot be revealed in the final product. In other words, when the metal strip is deformed by cold working, the difference in local deformation inside the crystal grains becomes remarkable with the progress, and various deformation bands such as a shear band and a microphone opening band appear. Due to these deformation bands, the grain boundaries formed by recrystallization before cold working become discontinuous, and the crystal structure becomes unclear even when the cross section is etched and observed with an optical microscope. Even when the degree of cold working is about 20%, when observing the structure with a transmission electron microscope image, it is observed that a part of the recrystallized grain boundary before cold working remains, but it has already been observed in the cell structure. It is covered and the crystal grain size cannot be determined accurately. That is, it was extremely difficult to accurately quantify the crystal grain size.

In the present invention, it has been found that the recrystallization behavior after cold working is correlated with the properties of copper alloy having both bending workability and strength. This correlation is useful for material identification. That is, the present invention relates to a copper alloy having a strength characteristic in which the difference between the tensile strength and the 0.2% proof stress is within 8 OMPa, the average crystal grain size when annealed at 425 ° C for 10,000 seconds.

An object of the present invention is to provide a copper alloy having excellent bendability due to crystal grain characteristics having an (mGS) of 5 / xm or less and a standard deviation ( _ff GS) of its crystal grain size of 1 / 3mGS or less.

Generally, when performing cold working after annealing, the difference between the tensile strength and 0.2% proof stress decreases as the degree of cold working increases, but at the same time, ductility decreases and bending occurs. Cracking easily occurs during processing. However, the present invention has found that by adjusting the final annealing conditions before the final rolling and the cold working conditions before the final rolling, the reduction of the total 14 can be reduced. The difference between the tensile strength and the 0.2% proof stress is within 80 MPa. A remarkable effect can be expected in a high-strength copper alloy having the following characteristics.

Even if the copper alloy of the present invention is annealed at 425 ° C for 10,000 seconds, which is a condition under which the conventional copper alloy grows with a large crystal grain size, the average crystal grain size is maintained at 5 jum or less. Is also defined by the unique property of After final annealing, reduce the average grain size (mGS) to 3 μπι or less and the standard deviation of the grain size (and GS) to 2 / m or less, and then perform final cold rolling at a workability of 10 to 45% or The product is produced by setting the average grain size (mGS) to 2 μm or less and the standard deviation GS) of the crystal grain size to 1 μm or less, and then performing final cold rolling at a workability of 20 to 70%. In addition, the copper alloy of the present invention has an ultrafine crystal structure in which a grain boundary cannot appear in the final product, but such a fine crystal structure is subjected to calcination at 425 ° C for 10,000 seconds. However, it has the unique property that crystals do not grow and the average grain size is maintained at 5 μιη or less, and by using this property, it is distinguished from other copper alloys to define the copper alloy of the present invention. You can do it.

This product of copper alloys has low ductility reduction due to final cold working, and has both high strength and excellent bending workability when the products are manufactured.

More preferably, if the average crystal grain size after annealing at 425 ° C. for 1.0000 seconds is 3 μm or less, the relationship between tensile strength and bending workability is further improved.

However, even if the average grain size (mGS) is 5 im or less, the effect is low if the grain size varies. As will be described later, the production method must be strictly controlled to achieve a uniform microstructure. The allowable range of the variation must be less than l / 3mGS, expressed as the standard deviation of the crystal grain size. This is because when the standard deviation ((JGS)) exceeds 1/3 mGS, the effect of improving bending workability is small.

(Invention of a high-strength copper alloy excellent in bending workability according to claim 2)

The present invention limits the copper alloy to phosphor bronze, which has a high tensile strength. Of the copper alloys, phosphor bronze to which tin is added as a solid solution strengthening element has a work hardening characteristic that differs depending on the tin concentration.Therefore, in the case of phosphor bronze, the range in which the present invention is particularly effective as a high-strength material is considered. The experimentally determined relationship between tin concentration and tensile strength As a clerk,

The tensile strength is shown as TS _Sn (MPa)> 500 + 15 XSn (tin mass% concentration). The more satisfying this relationship, the more effective the components described in claim 1 will be. That is, when the degree of cold working is low, the ductility decreases little, and even if the crystal grain size is not controlled, good bending workability is obtained, and the influence of manufacturing conditions before final annealing is reduced.

(Invention of a high-strength copper alloy excellent in bending workability according to claim 3)

In the present invention, similarly, the copper alloy is limited to phosphor bronze, and the average grain size (mGS: μχη) after annealing at 425 ° C. for 1000 seconds and the tin concentration (S n: ma ss%) are determined. The relationship is mG S <2.7 X exp (0.04 3 6 XS n)

It is specified. In the case of phosphor bronze, the grain growth behavior of recrystallized grains shows a tendency peculiar to phosphor bronze. That is, the average recrystallized grain size in the final annealing is mGS

It is preferable to adjust the crystal grains so as to satisfy (0.043 6 X Sn). This standard covers the processing conditions, properties (strength and bending workability) and 425 ° CX 10000 for phosphor bronze containing 1 to 11%, especially 2% to 10% tin. This is an empirical formula that correlates the crystal grain size after heat treatment for a second. If the mGS is above the specified value, the effect of grain refinement is low, and high strength cannot be achieved unless the degree of rolling is increased, and the ductility of the high-strength material is greatly reduced. The performance is not improved.

Basically, the relationship between crystal grain size and strength (proof stress) is a force mainly due to the effect of grain refinement described by the generally known formula of Ha11-P etch After recrystallization. It has been found that the subsequent work hardening ability itself is increased by the crystal grain size.

In consideration of the practical use of phosphor bronze, this feature enables high strength to be achieved by low work rolling. Although the lower limit is not specified, if the average crystal grain size (mGS) after final annealing is reduced to less than 0.4 μηι, the ductility reduced by cold rolling before final annealing cannot be fully recovered. Since the final cold rolling further reduces ductility, desirably, mGS should be 0.4 / zm or more. preferable.

(Invention of high-strength copper alloy excellent in bending workability of claim 4)

The present invention relates to the above identified copper alloys, especially phosphor bronze, for the Fe, Ni, Mg, Si and Zn groups and for the Cr, Ti, Zr, Nb, Al, Ag, Be , Ca, Y, Mn, and In are added in a total of 0.05 to 2. Omass%.

First, the addition of Fe, Ni, Mg, Si, and Zn will be described.

The addition of trace amounts of Fe, Ni, Mg, and Si to the copper alloy is phosphor bronze means that these elements and P, etc., form intermetallic compounds and disperse in the matrix. In the inventions of the items 1 to 3, the present invention is to improve the characteristics of the bronze manufactured mainly by grain boundary strengthening and solid solution strengthening. When intermetallic compounds such as Fe-P are precipitated and dispersed in these combinations, the strength of the alloy itself is enhanced by the precipitation strengthening function, and the effect of pinning the crystal grain boundaries by residual particles of precipitates or crystallized substances This makes it difficult for crystal grains to grow and facilitates grain refinement. For that purpose, 0.05 ma s s% is necessary, and if it exceeds 2. O mas s s%, it is harmful rather than electrical conductivity.

In addition, Zn is an element that suppresses the thermal delamination of tin and solder when added to a copper alloy.Especially, when Zn is added at about 0.5 ss% or more, its effect is exhibited, but when it exceeds 0.5 ss%, The improvement effect saturates and the electrical conductivity decreases.

As described above, Fe, Ni, Mg, Si, and Zn are additive elements that enhance the strength of phosphor bronze or improve the heat-peelability of tin and soldering, and it is recommended to add them. You. The amount of addition is determined in consideration of bending workability and electrical conductivity, and the total amount is 0.05 to 2. Omass%. The reason is that if the total amount is less than 0.05 mass ° / o, the strength does not improve, and there is no effect of improving the heat-peeling resistance of the plating, and if it exceeds 2.0 mass%, the bending workability deteriorates and the electrical conductivity Is also reduced. The decrease in electrical conductivity is particularly significant for low-tin high-conductivity phosphor bronze with a tin concentration of about 1 to 4 mass%. However, for the above-mentioned reason, Zn may be set to 0.1 to 0.5mass%. desirable.

Next, a description will be given of the addition of other elements Cr, Ti, Zr, Nb, Al, Ag, Be, Ca, Y, Mn, and In.

These elements are elements that strengthen the copper alloy by solid solution strengthening and precipitation strengthening, and, as in the case of Fe, Ni, Mg, Si, and Zn, do not deteriorate the bending workability, and the total amount is 1. Addition of Omass% or less enables higher strength.

F e, Ni, Mg, Si, Zn, and one of Cr, Ti, Zr, Nb, A1, Ag, Be, Ca, Y, Mn, and In By adding two or more kinds in a total of 0.05 to 2. Omass ° / ₀ , the strength is improved. The above-listed additional elements are representative elements that can be used from an economical point of view, and even if they are other elements, they do not degrade the properties such as conductivity of the copper alloy. In addition, a copper alloy mainly containing, as an auxiliary component, an element that strengthens solid solution also belongs to the scope of the present invention.

(Invention of a high-strength copper alloy excellent in bending workability according to claim 5)

The present invention, in the invention of claim 4, further defines the distribution of precipitates and crystals of the alloy element.

This is to find the optimum state specific to phosphor bronze for the purpose of refining the above crystal grains. That is, it is estimated to be closely related to the phosphorus grain boundary energy, etc. bronze, 0. 1 μιη least 10 Myupaiiota less diameter of the particles is, if it is 100 / mm ² or more in cross-section observation, the grain refining The effect is remarkable. The particles are coarse precipitates and are crystallized, but the effect of grain refinement is recognized regardless of the component composition of the precipitates and crystals.

It is thought that the particles that actually contribute to the nucleation of crystal grains and the pinning effect of grain boundaries in grain refinement include those with smaller diameters, but are observed at the level of a scanning electron microscope. As far as possible, an excellent crystal grain refinement effect is observed in the state of the cross-sectional structure of the particle distribution described above. In other words, the substitute properties of grain refinement and Then, the distribution of the precipitates and crystals is specified.

(Invention of a method for producing a high-strength copper alloy excellent in bending workability according to claim 6)

The present invention relates to a method for producing a high-strength copper alloy having excellent bending workability. More specifically, in copper alloys manufactured by repeating cold rolling and annealing, the final cold rolling, the final annealing before that, and the excellent bending workability that defines the previous cold rolling process It relates to a method for producing a high-strength copper alloy '.

These inventions also basically aim at the effect of crystal grain refinement after final annealing and before final rolling. T The material thickness before cold rolling. X = (t _0-1 ) t, where t is the material thickness after cold rolling. X 100 (%) Defined degree of cold rolling before final annealing X is set to 45% or more.If it is less than 45%, even after adjusting the heat treatment conditions for final annealing, after final annealing, This is a force that makes it difficult for the crystal grain size to be reduced.

The reason why the average crystal grain size after annealing was 3 πι or less and the standard deviation, which is the variation of the grain size, was 2 μm or less was that the heating temperature profile during annealing was strictly controlled and uniform. This is because it is necessary to have a fine crystal grain structure.

Here, for fine recrystallized grains, strictly speaking, the crystal grain size is not normally distributed, but if the average crystal grain size (mGS) is 3 / χΐη and its standard deviation (aGS) is 2 / zm, It means that 99% or more of the crystal grain size is less than mGS + 3σGS, that is, 9 μιη or less.

Furthermore, it is often undesirable that crystal grains having a diameter of 8 μm or more are mixed in the recrystallized structure, and for that purpose, the standard deviation of the crystal grain diameter is desirably 1.5 μm or less.

The effect of the degree of cold rolling before final annealing on the recrystallized structure after final annealing is such that as the degree of work is increased, the grain size of the recrystallized structure after annealing tends to decrease, but at the same time, nucleation and subsequent Secondary recrystallization behavior greatly varies, and the particles tend to be mixed.

In particular, the tendency is strong in a copper alloy having a pure copper type recrystallized structure having a high copper concentration. Conversely, 30m ass ° /. With brass containing Zn or phosphor bronze containing 411 3% or more of 311 as described above, recrystallized grains after relatively strong working are easily sized. In consideration of these, it is necessary to optimize the annealing conditions, that is, the temperature, time, and temperature profile for each alloy system, to obtain the recrystallized structure.

If the average crystal grain size is out of the specified range of 3 μm or less and its standard deviation of 2 μm or less, high work hardening ability in final cold rolling cannot be obtained.

Final cold working with a workability of 10 to 45% with an average crystal grain size of 3 μm or less and a standard deviation of 2 m or less results in a copper alloy with high strength and excellent bending workability. .

At a work ratio of less than 10%, even a conventional copper alloy having an average crystal grain size after final annealing of about 1 O / zm has good bending workability and a small effect of grain refinement. On the other hand, when the working ratio exceeds 45%, the bending property is reduced, and the range of use as a metal member such as a contact to be bent is narrowed.

(Invention of a method for producing a high-strength copper alloy excellent in bending workability according to claim 7)

In the present invention, the standard deviation of the crystal grain size is preferably 2; χπι or less, but the average crystal grain size is 2 μm or less, and the standard deviation is 1 μm or less. If the variation in crystal grain size is reduced, the workability of final cold rolling is further increased due to the effect of uniform and fine grain size, and even if it is set to 20 to 70%, bending workability is not deteriorated. A high strength copper alloy is obtained.

(Invention of a method for producing a high-strength copper alloy excellent in bending workability according to claim 8)

The present invention is to perform strain relief annealing after final rolling on the above-mentioned copper alloy, and to specify the amount of decrease in tensile strength in the strain relief annealing. . (MP a), the tensile strength after stress relief annealing as _{TS a (MP a), TS} a rather TS. X (the final cold rolling work ratio (%)).

Phosphor bronze, nickel silver, etc. may be subjected to strain relief annealing. Unlike recrystallization annealing performed before final rolling, strain relief annealing is intended to restore ductility (workability) after cold working and to improve spring properties, for example. For example, phosphor bronze for springs (C5 210: commonly used in JISH 310).

This strain relief annealing is necessary after the final rolling by tension annealing line etc. Can be applied according to

The copper alloy according to the present invention has higher strength and superior bending workability even after strain relief annealing than alloys manufactured by conventional techniques.

Furthermore, it is effective to perform strain relief annealing according to the final working degree in order to minimize the decrease in ductility, especially when cold rolling annealed material with a small crystal grain size.

. Especially bending improve workability, the final cold rolling degree and X%, tensile strength: for cold rolled material (TS. MP a), tensile after stress relief annealing strength TS _a (MP a) is TS _a <TS. Perform strain relief annealing under the condition of (1) X. For example, in the case of a cold-rolled material that has been hardened to 700 MPa at a final working ratio of 30%, this material is subjected to strain relief annealing, and subjected to strain relief annealing to less than 67 OMPa. Can be obtained.

(Inventions of the method for producing a high-strength copper alloy according to claims 1 to 5, which are excellent in bending workability in claims 9, 10, and 11)

The production methods of claims 6 to 8 are applicable to the production method of high-strength copper alloys, particularly, phosphor bronze described in claims 1 to 5. The description is as described above.

(Claim 12 Terminal 'connector invention)

As described above, Hinaaki provides a high-strength copper alloy excellent in bending workability and a method of manufacturing the same for solid-solution strengthened copper alloys, particularly phosphor bronze-based copper alloys, and has a small and excellent bending property. Applicable to terminals-connectors that require high strength and high strength.

Further, even if plating is applied to the contact of the terminal and the connector before or after the processing, the strength and bending workability are hardly deteriorated, and the effect of the present invention is exhibited.

(Example)

Next, the effects of the present invention will be described with reference to various phosphor bronze examples.

(1) Example 1 (Example relating to the inventions according to claims 1 to 3)

Phosphor bronze with the composition shown in Table 1 was coated with charcoal in the air, dissolved, An agglomerate with a size of mm ^w X 4 Omm ¹ X 15 Omm ¹ was prepared.

The lump was homogenized and annealed at 700 in a 75% N ₂ + 25% H ₂ atmosphere at 700 for 1 hour, and the tin segregation layer on the surface was polished with a grinder and removed.

Thereafter, cold rolling and recrystallization annealing are repeated a plurality of times as necessary, and in particular, the cold rolling degree before the final annealing, the final recrystallization annealing, and the final cold rolling degree are adjusted. A plate having a thickness of mm was obtained.

Table 1 shows the characteristics.

(Test method)

Tensile strength (TS: MPa) and 0.2% resistance (YS: MPa) were determined by taking a 13B test piece (JISZ 2201) in parallel with the rolling direction and performing a tensile test (JISZ 2241). .

The crystal grain size is calculated by the cutting method (JISH 0501), by counting the number of crystal grains completely cut by a line segment of a predetermined length, taking the average of the cut lengths as the crystal grain size, and the standard deviation of the crystal grain size ( aGS) is the standard deviation of the grain size. That is, the cross-sectional structure in the direction perpendicular to the rolling direction was magnified 4000 times with a scanning electron microscope image (SEM image), and the number of intersections between the line and the grain boundary was 50 in the line segment with a length of 50. Is the crystal grain size, and the average of each grain size obtained by measuring 10 line segments is the average grain size (mGS) in this application, and the standard deviation of each grain size is The standard deviation (crGS) in this application was used.

For bending '14 (rZt), a test piece with dimensions of 10 mm ^w x 100 mm ¹ was sampled at right angles to the rolling direction, and a W bending test (JISH 3110) was performed at various bending radii. The minimum bending radius ratio (r (bending radius) / t (specimen thickness)) that can provide a good appearance with a rating of C rank or higher and that does not cause cracks or rough skin, based on the technical standard J BTA T 307: 1999. Determined (Evaluation criteria are rank A: no wrinkle, rank B: wrinkle small, rank C: large wrinkle, rank D: small crack, rank E: large crack and 5 ranks. Rank A, B, Which is evaluated as C). The bending axis in the W bending test is parallel to the rolling direction. Roto

Table 1 shows Inventive Example 18 and Comparative Examples I to ₄ which are conventional materials, and Examples _A to _E in which the parameters were further changed for the purpose of explaining the effect of the present invention (ratio: comparative example, small: book) (Indicating invention)) is shown separately for convenience.

Comparative examples 14 are examples of conventional materials, and when these examples and the present invention examples I to _D were subjected to fefeT, they had the same composition and the same strength, but the present invention examples 1 to ₄ and _D _It can be seen that _r zt is small and the bending force tri property is improved. Example D of the present invention is an example in which TS-YS is large in the scope of claim 1. (This is an example for the purpose of clarifying the definition of S-YS≤80. Indicates that the bending workability has been improved.)

Inventive Examples 5 to 8 are examples in which the crystal grain size is further reduced in Inventive Examples 1 to 4, but according to the tin concentration in accordance with mGS, 2.7 XeXp (0.0436 XSn). By adjusting the crystal grain size, the strength is improved, the shear force and rZt are equal or smaller, and the bending process is good.

In Comparative Example A, the mGS satisfies Claim 1, but 03 does not satisfy Claim 1. Therefore, the bending workability is lower than that of Invention Example 2.

Comparative Example B is an example in which mGS and _ff GS satisfy claim 1, but TS-YS does not satisfy claim 1. Although the crystal grains after annealing are fine, the strength is low due to the large TS-YS, and the strength and bending workability are the same as those of conventional material C, and no improvement is observed.

Comparative Example C is an example for the purpose of comparison with Comparative Example B.

Comparative example E is an example for the purpose of comparison with inventive example D.

(2) Example 2 (Example of verification of the invention according to claims 4 and 5)

A test piece was prepared in the same manner as in Example 1 with a composition to which iron, nickel, and the like were added based on the component of phosphor bronze.

Meanwhile, the dispersion state of the precipitates and crystallized substances of the compound composed of the types of the added elements was adjusted under the conditions of the homogenization annealing of the lump.

The recrystallization sintering was adjusted while adjusting the crystal grains and observing the coarse precipitates, the residual state of the crystallized substances, and the growth of the precipitates.

The precipitates and crystals were analyzed for the number of particles in a cross section with a diameter of 0.1 μm or more using an energy dispersive analyzer of a field emission scanning electron microscope (FESEM) and observed.Table 2 shows the results. is there.

From the comparison with the present invention C u- S n-P-based alloy Table 1, C u- S _n - by the addition of other elements to P-based alloy trace, CxGS decreases, the further the crystal grain size It can be seen that the miniaturization can be stably performed, and further, by dispersing the particles composed of these elements, the strength is further improved and the bendability is excellent.

r T i Z r Nb Al A _g B e Ca Y Mn, and In A similar effect was also confirmed for the alloys having a small thickness. These examples are also shown in Table 2 as A to H (book: present invention, ratio: comparative example).

'Comparative Example H is an example in which the sum of the sub-components exceeds 2.Omass%, and has poor bending workability.

(3) Example 3 (Examples of Verification of Inventions According to Claims 6, 7, 9, and 10) The compositions of Examples 17 to 20 of the present invention correspond to Tables 1 to 4 in Example 1. Comparative Examples 5 to 8 are examples of conventional materials. Examples A to F (ratio: comparative example, present: present the present invention) in which the parameters are further changed for the purpose of explaining the effect of the present surprise are separately classified for convenience. The test method was in accordance with Example 1. Table 3 shows the results.

O

Comparative Example 58 is an example of a conventional material, in which the degree of cold rolling before final annealing and the average crystal grain size in final annealing deviate from the present invention, but Examples _{17 to} 20 of the present invention are comparative examples. Example _{58 Higher} strength, lower _r / _{t and} better bending workability than the conventional material of Example 8. The present invention Example A, the crystal grain size after recrystallization annealing of the present invention Example丄₉ _2. And 6, but satisfy the claim 6 is an example not satisfying the claim _7, the crystal grain size fine Example 丄 Nine is slightly stronger.

Example B of the present invention is an example in which the final cold work degree satisfies claim 6 but does not satisfy claim 7, and the workability is low, that is, the strength is low V, and the bending workability is good.

In Comparative Example C, the cold rolling workability before recrystallization was low, so the mGS was reduced by recrystallization annealing.However, a fine and uniform structure was not obtained, and the variation (aGS) increased. As a result, the bending workability is poor as compared with Example A of the present invention.

Comparative Example D is an example in which the workability of rolling and mGS satisfy claims 6 and 7, but the temperature history during recrystallization firing is poor and σ GS is not satisfied. Is bad.

Comparative Example Ε is an example in which the final cold rolling degree is low, but the strength is almost the same as that of the conventional material of Comparative Example F, and since the strength is low, no improvement effect is recognized.

Comparative example F is a conventional material example as described above (TS is about the same as Ε and rZt is the same).

(4) Example 4 (Study on the effect of strain relief annealing in claims 8 and 11)

In Table 4, 21 to 28 of the examples of the present invention correspond to the above examples of the present invention No. 2, 3, 4, 7, 8, 15, 16, and 20, respectively, as described above, and comparative examples (conventional materials). Nos. 9 to 12 correspond to Comparative Examples Nos. 3, 4, 7, and 8 described above. Comparative Examples A and B are for the purpose of showing a case where TS lowered by strain relief annealing is small, and correspond to Examples 16 and 20 of the present invention.

These test pieces were subjected to strain relief annealing under various final cold rolling reduction conditions to evaluate their properties. The amount of decrease in tensile strength (TS) due to strain relief annealing is also shown.

Dimension

Invention Example No. 21 is a material having a tin concentration of 6.2 mass%, a tensile strength ( _TS ) of 570 MPa, and a bending or raw ( _r / t) of 0.

Inventive Examples Nos. 22, 24, 26, Comparative Examples Nos. 9 and 11, which are conventional materials, are tin-rich / gears of 8.0 to 8.2 mass%. is _(TS) is _{6 5 2~7 6} 0MP a, while bending workability {chi / t) is _{0 _to 2.0,} Comparative example The tensile strength (TS) was 650 ~ 6981 ^? & And the r / t force was 1.5 ~ 2.5, indicating that the present invention has high strength and good bending workability.

In addition, the inventive examples Nos. 23, 25, 27, and 28 and the comparative examples No. 10 and 12 are materials having a tin concentration of 10.0 to 10.2 mass%, but the tensile strength (TS) of the inventive examples was Whereas, while the bending workability (r / t) is 1.5 to 3.0, the tensile strength (TS) force is 06 to 762 MPa and the r / t force is S3. 0 indicates that the present invention has high strength and good bending workability.

In Comparative Examples A and B, the tensile strength (TS) is 841 to 886 MPa, but since the TS reduced by strain relief annealing is small, the bending workability (r / t) is 3.0 to 3.5. And not much improved.

As described above, the material of the present invention subjected to the strain relief annealing can clearly achieve higher strength and improved bending workability than the conventional material of the comparative example. In other words, if the strength is the same, the bendability is significantly improved, and if the bendability is the same, the strength is greatly increased.

(The invention's effect)

According to the present invention example, the copper alloy, particularly the phosphor bronze alloy, can be strengthened without deteriorating the bending workability, and the characteristics required for the copper alloy for terminals and connectors for electronic components can be improved. .

Also, in the high-tin phosphor bronze (Cu-10mass Sn-P: CDA52400) field of high-strength copper alloy, which is an exclusive market for beryllium copper and other materials that could not be entered because of its poor bending workability. It is now possible to enter the market.

Claims

The scope of the claims

1. A final cold-rolled copper alloy in which the difference between the tensile strength and the 0.2% proof stress is within 8 OMPa, and the average grain size of the copper alloy after annealing at 425 ° C for 10,000 seconds. A high-strength copper alloy excellent in bending workability, characterized in that the diameter (mGS) is 5 _μm or less and the standard deviation (aGS) of the average crystal grain size is 1 / 3XmGS or less.

2. Sn: l ~: L lma ss%, P: 0.03 ~ 0.35mass%, the balance consists of Cu and unavoidable impurities, and the tensile strength expressed by TS _Sn (MPa) is TS _Sn > 500+ 15 XSn (Sn: tin concentration (ma ss%)) copper alloy with an average crystal grain size (mG S) of 5 EQ after annealing for 10,000 seconds at 425 ° C. 2. The high-strength copper alloy excellent in bending workability according to claim 1, characterized in that the standard deviation (GS) of the average crystal grain size is 1 / 3XmGS or less.

3. Sn: l ~: L lma ss%, P: 0.03 ~ 0.35mass%, the balance consisting of Cu and unavoidable impurities, average grain size after annealing at 425 ° C for 10,000 seconds The diameter (mG S (μm)) is mG S <2.7 X exp (0.0436 XS n

(Sn: tin concentration (mass%)). The high-strength copper alloy according to claim 1, wherein the high-strength copper alloy has excellent bending properties.

4. Copper alloy is Sn: l ~ l lma ss%, P: 0.03 ~ 0.35ma ss%, and Fe, Ni, Mg, Si, Zn, Cr, Ti, Zr, Nb , Al, Ag, Be, Ca, Y, Mn, and one or more of In: phosphoric bronze consisting of 0.05 to 2.0 mass% in total, balance of Cu and unavoidable impurities The high-strength copper alloy excellent in bending workability according to any one of claims 1 to 3, characterized in that:

5. Copper alloy is Sn: l ~ l lma ss%, P: 0.03 ~ 0.35ma ss%, and Fe, Ni, Mg, Si, Zn, Cr, Ti, Zr, One or more of Nb, Al, Ag, Be, Ca, Y, Mn, and In: 0.05 to 2. Oma ss% in total Phosphor bronze consisting of residual Cu and unavoidable impurities Yes, or The particles are characterized in that at least 100 particles / ram ² are present in a cross section cut in parallel to the rolling direction, with particles having a diameter of 0.1 m or more, which are mainly composed of precipitates or crystallized elements of alloying elements. Item 4. A high-strength copper alloy excellent in bending workability according to items 1 to 3.

6. After cold rolling at a working ratio of 45% or more, final annealing is performed to reduce the average grain size (mGS) to 3 μm or less and the standard deviation GS of the grain size to 2 / zm or less. A method for producing a high-strength copper alloy having excellent bending properties, comprising subjecting a final cold rolling to 10 to 45%.

7. After cold rolling at a working ratio of 45% or more, final annealing is performed to reduce the average grain size (mGS) to 2 / zm or less and the standard deviation GS of the grain size to Ιμπι or less, A method for producing a high-strength copper alloy with excellent bending workability, characterized by performing a final cold rolling of -70%.

8. TS is the tensile strength after final cold rolling with a work ratio of X (%). The cold-rolled material (MP a), tensile strength TS _a (MP _a) is TS _a <TS. 8. The method for producing a high-strength copper alloy excellent in bending workability according to claim 6, wherein a strain relief annealing is performed until the value reaches X.

9. After cold rolling at a working ratio of 45% or more, final annealing is performed to reduce the average grain size (mGS) to 3 m or less and the standard deviation (σ GS) of the grain size to 2 μππ or less. 6. The method for producing a high-strength copper alloy excellent in bending workability according to claim 1, wherein final cold rolling is performed at a degree of 10 to 45%.

10. After cold rolling at a workability of 45% or more, final annealing is performed to reduce the average crystal grain size (mGS) to 2 or less and the standard deviation of the crystal grain size (aGS) to a value below. 6. The method for producing a high-strength copper alloy excellent in bending workability according to claim 1, wherein the final cold rolling is performed. .

11. After cold rolling at a workability of 45% or more, final annealing is performed. (A) The average grain size (mGS) is set to 3 μπι or less and the standard deviation (aGS) of the crystal grain size is set to 2 μπι or less. Perform final cold rolling at a working ratio of 10 to 45%, or (mouth) the average grain size (m GS) to 2 μπι or less and the standard deviation GS of the grain size to the following. 70% final cold rolling is performed, and then the maximum The tensile strength after final cold rolling is TS. The cold rolled material (MP a), tensile strength TS _a (MP _a) is TS _a <TS ₀ - according to claims 1 to 5, characterized by applying stress relief annealing until the X bending A method for producing high-strength copper alloys with excellent workability.

12. A terminal / connector using a high-strength copper alloy excellent in bending workability according to claim 1 to 5.