CN111500893A

CN111500893A - Ultrahigh-strength copper alloy plate strip and manufacturing method thereof

Info

Publication number: CN111500893A
Application number: CN202010526602.6A
Authority: CN
Inventors: 高维林; 屠晓梅
Original assignee: Tongling High Copper Technology Co ltd
Current assignee: Gao Weilin; Tu Xiaomei
Priority date: 2020-06-10
Filing date: 2020-06-10
Publication date: 2020-08-07

Abstract

The invention provides an ultrahigh strength copper alloy sheet strip, which comprises 2.2-3.2 wt% of Ni, 0.8-1.8 wt% of Co, 0.6-1.25 wt% of Si, 0.5-1.5 wt% of Sn, 0.05-0.20 wt% of Mg and the balance of Cu and unavoidable impurities, wherein the copper alloy sheet strip has the composition proportion relationship meeting the following formulas (1) and (2): 4 ≦ ({ Ni } + { Co })/{ Si } ≦ 5 … … (1) { Mg }/{ Sn } > 0.1 … … (2), wherein { Ni }, { Co }, { Si }, { Mg } and { Sn } respectively represent the wt% of Ni, Co, Si, Mg and Sn in the copper alloy sheet. The copper alloy sheet strip has an ultra-high strength of 900MPa or more in tensile strength, an electric conductivity of 30% IACS or more, and good bending workability for practical use.

Description

Ultrahigh-strength copper alloy plate strip and manufacturing method thereof

Technical Field

The present invention relates to an ultrahigh strength copper alloy sheet strip having a high requirement for material strength, such as a spring plate, in electronic parts such as a connector, a relay, a switch, etc., and a method for producing the same. The ultrahigh-strength copper alloy plate strip has ultrahigh strength and good conductivity and bending processability.

Background

In use, materials for electric and electronic parts such as connectors, relays, switches, etc., require a sufficient contact pressure between the parts in order to ensure the flow of electric current, and thus, copper alloy materials are required to have a sufficiently high strength. Meanwhile, in order to suppress heat generation at the time of energization, the material is required to have good electrical conductivity. Further, since electronic parts are generally formed by bending, the material is required to have good bending workability.

The thickness of the ultrahigh-strength copper alloy sheet strip which is most widely used in electronic components at present is 0.15 to 0.30mm, and in recent years, with the densification, miniaturization and weight reduction of electronic components, the ultrahigh-strength copper alloy sheet strip used is required to be thinner, for example, the thickness is required to be 0.10mm or less and 0.08 to 0.06mm, so that the material is required to have higher strength. Meanwhile, as electronic components have more flexible functions, their shapes become more and more complex, and the requirements for the bending workability of materials are also becoming higher and higher.

Currently, the highest strength copper alloy is known as beryllium copper (Cu — Be) alloy (e.g., C1720, tensile strength up to 1000MPa or more), and electrical conductivity up to 20% IACS. However, in recent years, due to the increased awareness of environmental protection, the application of beryllium copper alloys containing toxic Be elements has been restricted by many regulations (such as RoSH in the european union), and the substitution of beryllium copper has become a trend in the industry.

Secondly, the titanium copper (Cu-Ti) alloy has the tensile strength of 900-950 MPa, and is the most favorable alloy for replacing beryllium copper at present. But the conductivity of the alloy is only about 10-15% IACS, and the alloy needs vacuum dissolution casting, so that the manufacturing cost is high, the production efficiency is low, and the production and application of the alloy are limited.

And a Cu-Ni-Si alloy (so-called Corson alloy), for example, the most representative C7025 has a tensile strength of 720 to 760MPa, and C7035 developed by adding Co has a tensile strength of 800 to 850MPa, and has a good electric conductivity of about 45% IACS, and is a commercial copper alloy having the most excellent overall characteristics at present.

Finally, the alloy is the most used tin-phosphor bronze (Cu-Sn-P) alloy, the strength is higher (the tensile strength of C5210 containing 8% of Sn can reach more than 700MPa, and the tensile strength of C5240 containing 10% of Sn can reach more than 750 MPa), but the electric conductivity is lower (10-15% IACS).

The present invention has been made in view of the actual market demand and the current situation that the conventional copper alloy cannot satisfy the electric conductivity of the tensile strength of 900MPa or more and 30% IACS or more and the good bending workability that can be put into practical use.

Disclosure of Invention

The inventors of the present invention have found, based on detailed research and study, that a copper alloy sheet or strip having high strength and excellent bending workability can be obtained by adding an appropriate amount of Sn and Mg to a Cu-Ni-Co-Si alloy and by optimizing the composition and making reasonable manufacturing process conditions, thereby effectively preventing the problem of cracking during hot rolling. The present invention has been completed based on these findings.

The invention provides an ultrahigh-strength copper alloy plate strip, which comprises 2.2-3.2 wt% of Ni, 0.8-1.8 wt% of Co, 0.6-1.2 wt% of Si, 0.0.5-1.5 wt% of Sn, 0.05-0.20 wt% of Mg and the balance of Cu and unavoidable impurities, wherein the copper alloy plate has the composition proportion relation satisfying the following formulas (1) and (2)

4≤({Ni}+{Co})/{Si}≤5……(1)

{Mg}/{Sn}≧0.1……(2)

Wherein { Ni }, { Co }, { Si }, { Mg } and { Sn } represent the weight percentages of Ni, Co, Si, Mg and Sn, respectively, in the copper alloy sheet. The ultrahigh-strength copper alloy sheet strip has ultrahigh strength of tensile strength of 900MPa or more, electric conductivity of 30% IACS or more, and good bending workability for practical use.

Further, the ultra-high strength copper alloy sheet strip contains one or more elements selected from the group consisting of Zn, Fe, Cr, P, Zr, Ti and Mn in a total amount of 2.0 wt% or less.

It is particularly preferable that the average grain diameter of the above copper alloy sheet is5 to 15 μm. The average crystal grain diameter can be measured by a line-cutting method in JISH0501 by observing the surface (rolling surface) of a sample under a microscope after polishing and etching.

The copper alloy sheet material has a tensile strength of 900MPa or more, an electrical conductivity of 30% IACS or more, and a ratio R/t of a minimum bending radius R representing bending workability to a sheet thickness t of 2.0 or less.

The tensile strength was measured by cutting a sample from each plate material in the rolling direction (L D) and measuring the tensile strength by the method specified in JIS Z2241, the electric conductivity was measured by the method specified in JIS H0505, the bending workability was measured by bending the sample (10 mm in width) taken in the rolling direction (L D) and the sample taken in the direction perpendicular to the rolling direction (TD) in the longitudinal direction by the 90 DEG W bending method specified in JIS H3110, and the value of the ratio R/t of the minimum bending radius R to the plate thickness t at which no crack occurred was obtained was evaluated by

The invention also provides a manufacturing method of the copper alloy sheet material, which comprises the following steps of sequentially carrying out the following steps on the copper alloy with the composition: the ingot cast by the semi-continuous casting method comprises the steps of hot rolling after heating for 3-5 hours between 900 and 950 ℃, intermediate annealing after cold rolling to the temperature range of 1.0-3.0mm of plate thickness and 550 and 650 ℃, cold rolling, solution treatment at the temperature of above 950 ℃, aging treatment between 400 and 500 ℃, final cold rolling with the rolling rate of 15-35% (when the strength is specially required, the final rolling rate of above 35 percent can be selected), and low-temperature annealing at the temperature of 550 ℃ of 150.

In the solution treatment, it is preferable to perform the solution treatment at a temperature of 950 ℃ or higher by setting the speed of passing the sheet material so that the average crystal grain size after the solution treatment is5 to 15 μm. The final cold rolling is preferably followed by a low temperature anneal of 150-550 ℃.

According to the invention, the copper alloy plate strip has high strength of more than 900MPa, electric conductivity of more than 30% IACS and good bending processability with R/t less than 2.0, and is difficult to obtain copper alloy plate strips with excellent comprehensive characteristics according to the existing manufacturing technology. If the requirement on bending workability is not high in use, the tensile strength can reach more than 1000 MPa. Therefore, the present invention has been made to meet the anticipated demand for miniaturization and densification of electronic components in the future.

Description of the preferred embodiments

Composition of

Ni (nickel) and Si (silicon) improve the strength and conductivity of the material in the form of precipitation from a supersaturated solid solution. If the Ni content is less than 2.2 wt%, it is difficult to effectively achieve the strength target of the present invention. However, if the Ni content exceeds 3.2 wt%, the addition of Co as described below will result in a solid solution temperature of more than 1000 ℃ for complete solid solution of the alloying elements, and thus, the industrial production cannot be realized; if the alloying element is not completely dissolved or nearly completely dissolved, coarse precipitates tend to remain, and the strength and bending workability cannot be achieved. Therefore, the Ni content must be controlled to 3.2 wt% or less, preferably 3.0 wt% or less.

Co (cobalt) also forms Co with Si₂Si precipitates, which are more effective than Ni in improving strength and conductivity₂Si is more preferable. Therefore, from the viewpoint of improving the alloy characteristics, the higher the amount of Co added, the better. However, since the solid solubility of Co in the Cu matrix is relatively low, excessive addition is meaningless. If the content of Co is less than 0.8 wt%, it is difficult to effectively achieve the strength target of the present invention. However, if the Ni content exceeds 1.8 wt%, the solid solubility limit of Ni in Cu is approached or exceeded (about 2.0 wt%), and therefore, the Co content must be controlled to 1.8 wt% or less, preferably 1.5 wt% or less.

Si (silicon) is formed when Ni and Co are added together with (Ni, Co)₂Precipitates mainly composed of Si, wherein the ratio of the sum of the atomic numbers of Ni and Co to the atomic number of Si is 2: 1. Therefore, the ratio of the contents of Ni, Co and Si is preferably as close as possible to the content of the precipitates (Ni, Co)₂Atomic ratio of Si. When the content of the elements in the present invention is expressed in wt%, this ratio is 4.2: 1. after the aging treatment, Ni, Co, and Si are not always present as precipitates but are present in the Cu matrix as solid solutions to a greater or lesser extent. Since Si is more reduced in conductivity than Ni and Co when both are present as a solid solution, the content ratio of Ni, Co and Si is close to the ratio in the precipitates as much as possible, and is slightly biased toward the side where Ni and Co are excessive, that is,

the range of (Ni + Co)/Si is controlled to be 4.0 to 5.0 (i.e., formula (1)), preferably 4.2 to 4.8.

4≤({Ni}+{Co})/{Si}≤5……(1)

The Si content is controlled to be 0.6-1.25 wt% in accordance with the Ni and Co content range and the formula (1).

Sn (tin) has a very strong solid solution strengthening effect, and at the same time, it reduces electrical conductivity and easily causes a problem of cracking of a material during hot rolling. To achieve the strength object of the present invention, the Sn content is 0.5 wt% or more. However, if the Sn content exceeds 1.5 wt%, hot rolling cracks are easily caused. Accordingly, the content of Sn should be between 0.5 and 1.5 wt%, preferably between 0.6 and 1.0 wt%.

Mg (magnesium) is generally considered to be added to improve the stress relaxation resistance and remove S (sulfur). In the invention, Mg is found to effectively alleviate the segregation of Sn, thereby inhibiting the cracking of the plate material in hot rolling. To fully exert these effects, the Mg content is 0.05 wt% or more. However, Mg is an element which is easily oxidized, and if the Mg content exceeds 0.20 wt%, it is likely to cause oxide formation in the ingot, and various defects such as slag inclusion and peeling of the plate material in the subsequent step are caused. Therefore, the Mg content is controlled to 0.20 wt% or less.

In order to fully exhibit the effect of Mg in suppressing Sn segregation, the content of Mg is increased as the content of Sn increases, i.e., satisfies the following formula (2). { Mg }/{ Sn } > 0.1 … … (2)

As the other elements, Zn, Fe, Cr, Co, B, P, Zr, Ti and Mn may be contained as the case may be. For example, Zn (zinc) has improved weldability and castability; fe, Cr, B, P, Zr and Ti have the functions of refining the cast crystal grains and slowing down Sn segregation; when one or more elements selected from Zn, Fe, Cr, B, P, Zr, Ti and MnV are contained, the total content is preferably 0.01 wt% or more in order to sufficiently exhibit the above-described various actions. However, when the content of each element is too large, the hot workability or cold workability is likely to be lowered, and the raw material cost is likely to be increased. Therefore, the total content of these elements is preferably controlled to 2.0 wt% or less, more preferably 1.0 wt% or less.

Second, average grain diameter

The smaller the average crystal grain diameter is, the more dispersed the strain is during bending deformation, which is more advantageous for improving the bending workability; however, the crystal grains of the final material are formed by recrystallization during the solution treatment, and if the crystal grains are too small, the solution of the alloying elements is insufficient,

the strength after aging is easily low. According to the results of the detailed investigation by the present inventors, if the final average crystal grain size is5 μm or more and 15 μm or less, the above-mentioned objects of the present invention required for bending workability and strength can be satisfied at the same time. The average grain diameter is more preferably controlled to be between 8 and 12 μm. The final average crystal grain diameter almost completely depends on the state after the solution treatment, and the average crystal grain diameter can be controlled by the solution treatment conditions described below.

Third, characteristics

At present, the most commonly used copper alloy strips for parts (USB, charger, various electronic connectors, and the like) such as smart phones and computers are Cu-Ni-Si alloy (tensile strength 680-760MPa, conductivity 40-45% IACS) represented by C7025 and tin-phosphor bronze (tensile strength 600-700MPa, conductivity 10-15% IACS) represented by C5210, and the thickness of the used copper alloy strips is generally 0.15-0.25 mm. In order to meet the demand for miniaturization and densification of electric and electronic parts, there is an increasing demand for copper alloy sheet strips having a thickness of 0.10mm or less, and the tensile strength of copper alloys corresponding thereto is required to be 900MPa or more, preferably 950MPa or more, as with beryllium copper and titanium copper. Meanwhile, as the material becomes thinner, the electrified cross-sectional area is reduced, and the requirement on the conductivity is correspondingly improved, and the requirement is preferably more than 30% IACS (higher than 20-25% IACS of beryllium copper, 10-15% IACS of titanium copper and the like).

Meanwhile, if the directions parallel and perpendicular to the rolling direction on the sheet surface are referred to as L D and TD, respectively, it is required that the bending workability in the L D and TD directions satisfy, and the ratio R/t of the minimum bending radius R and the sheet thickness t, at which no crack occurs at the 90 DEG W bending, is generally 2.0 or less, the L D bending workability mentioned here means that the sample is cut out with the longitudinal direction of the sample parallel to the rolling direction, and the bending axis at the bending is the TD direction, and similarly, the TD bending workability means that the sample is cut out with the longitudinal direction of the sample perpendicular to the rolling direction, and the bending axis at the bending is the L D direction.

Fourth, the manufacturing method

The copper alloy sheet material of the present invention described above can be produced, for example, by the following general process flow. Namely: melting/casting, hot rolling, cold rolling, solution treatment, aging treatment, final cold rolling and low-temperature annealing.

However, as will be described below, control of several of these process conditions is important. In addition, although not mentioned above, optional milling (sharpening) may be performed after hot rolling, optional pickling may be performed after heat treatment,

grinding or degreasing, stretch bending straightening and the like. The respective processes are further explained below.

1. [ melting casting ]

A general vertical semi-continuous casting method of copper alloy may be used. In order to prevent oxidation of Si, Mg, etc., charcoal may be added to the melting furnace and the launder, and nitrogen gas may be introduced.

2. [ Hot Rolling ]

The ingot is hot rolled after being heated at 950 ℃ for 3-5 hours. Generally, a copper alloy containing Sn is likely to crack during hot rolling. According to the content and proportion of Sn and Mg specified by the invention, the process is carried out according to the common hot rolling process of the copper alloy, and hot rolling cracking does not occur.

3. [ Cold Rolling ]

Then, cold rolling is performed to a thickness of 1.0 to 3.0 mm. The copper alloy plate strip has high strength, and cold rolling edge cracking is easily caused when the rolling rate in the stage is too high. The plate is rolled to the thickness of 1.0-3.0mm, so that edge cracking can be avoided.

4. [ intermediate annealing ]

Annealing treatment is carried out for 3-5 hours in the temperature range of 550-650 ℃. Can soften the sheet and is beneficial to further cold rolling. If the temperature is too high, the sheet is too softened, and the storage in the subsequent cold rolling is not enough, so that the grain size control in the subsequent solution treatment is not facilitated; if the temperature is too low, the temperature enters the aging temperature range of 400-500 ℃, and the plate becomes harder and is not beneficial to the subsequent cold rolling.

5. [ Cold Rolling ]

Then, cold rolling is performed to a predetermined thickness. The set thickness is set according to the final product thickness and the final rolling reduction.

6. [ solution treatment ]

Solution treatment generally solutionizes solute elements and recrystallizes the material. Because of the large amount of Co, the solution treatment temperature should be above 950 ℃ to achieve the basic solid solution of the alloy elements. Too low a temperature results in insufficient solid solution amount of solute elements and incomplete recrystallization. The upper limit of the furnace temperature of a common copper alloy air cushion furnace is about 850 ℃, and the solution treatment of the alloy of the invention can not be satisfied. A high-temperature continuous annealing furnace widely used for steel materials is required, and the furnace temperature is 950 ℃ or higher, preferably about 1000 ℃. Since the melting point of the alloy of the present invention is between 1060-1050 ℃, it is noted that the actual temperature of the strip during solution treatment preferably does not exceed 1030 ℃.

The treatment time and the final temperature at the time of the solution treatment are set so that the average grain size of recrystallized grains (twin boundaries are not defined as grain boundaries) is5 to 15 μm, preferably 8 to 12 μm. The average crystal grain size is too small and the solid solution is insufficient, whereas too large an average crystal grain size tends to cause roughness of the surface of the bent portion and to deteriorate the bending workability. The recrystallized grain size varies depending on the cold rolling reduction before the solution treatment and the chemical composition. The relationship between temperature and time and the average crystal grain diameter can be grasped by preliminary experiments. Specifically, the appropriate solution treatment conditions for the copper alloy within the composition range specified in the present invention are within a temperature range of 950-.

7. [ aging treatment ]

Then, aging treatment is carried out. The aging treatment is carried out under conditions favorable for improving the conductivity and strength of the alloy. The aging treatment temperature is too high, and the overaging is easy to occur (namely, the strength is low); on the contrary, the temperature is too low, and the required time is too long. Specifically, it is desirable that the aging treatment temperature is preferably between 400 ℃ and 500 ℃, more preferably between 420 ℃ and 480 ℃. Good results are obtained with ageing times in the range of approximately 3 to 6 hours.

8. [ Final Cold Rolling ]

In order to further improve the strength of the material, final cold rolling with a rolling reduction of 15-35% is performed after the aging treatment. The strength extremely rapidly increases with an increase in the rolling rate, and the bending workability decreases. The present inventors have found, through a detailed study, that the strength and bending workability which are the effects of the present invention can be achieved if the rolling reduction is controlled to be 15 to 35%.

For applications where bending is not required or bending properties are not required, such as various male terminals for connectors and flat-blanked press-formed parts, the final cold rolling may be performed after aging at a reduction of 35% or more. The tensile strength can reach 1000MPa on the premise of not damaging the conductivity.

The final thickness of the copper alloy of the present invention may be in the range of 0.05 to 0.5mm, preferably 0.06 to 0.15 mm.

9. [ Low temperature annealing ]

After the final cold rolling, the vacancy and the dislocation at the slip surface can be reduced through low-temperature annealing, and the stress relaxation resistance is improved. And simultaneously, the residual stress in the plate can be reduced and eliminated, and the bending processability is improved without obviously reducing the strength. In addition, the conductivity can be improved. The heating temperature in the low-temperature annealing is preferably set within 150-550 ℃. If the temperature is set too high, softening of the sheet is easily caused. Conversely, if the temperature is set too low, the desired effect is not achieved. The holding time is preferably 5 seconds or more, and a good effect can be obtained by low-temperature annealing within 1 hour in general.

Fifth, example

Ingots having the compositions shown in table 1 were cast by a vertical type continuous casting machine. With some comparative exceptions, the ingot was hot rolled after cutting off the head and tail, heating to 950 and holding for 4 hours. And removing the oxide film on the surface by milling the surface after hot rolling. Then cold rolling is carried out, the thickness of the rolled plate is 2.5mm, intermediate annealing is carried out for 5 hours in a bell jar furnace at the temperature of 600 ℃, then the plate is re-rolled to the required thickness, and solution treatment is carried out by a high-temperature continuous annealing furnace. The annealing temperature is adjusted within a temperature range of 950-1000 ℃ and a time range of 30 seconds-3 minutes according to the alloy components, so that the average grain diameter (twin boundaries are not regarded as grain boundaries) after the solution treatment is 5-15 mu m. Followed by aging. The ageing treatment is carried out at a temperature of 450 ℃ by adjusting the ageing time to maximize the hardness. The optimum solution treatment conditions and aging time for the alloy composition are known from prior experiments. And (3) carrying out final cold rolling with the rolling rate of 10-30% on the material sample after the aging treatment, and carrying out low-temperature annealing for 3 minutes in a heating furnace at 400 ℃ after the cold rolling. The middle is subjected to the procedures of acid washing, degreasing, stretch bending, edge shearing and the like as required. And finally, evaluating the characteristics of the obtained plate. The thickness of the test pieces was set to 0.08 mm. The main production conditions of each sample are shown in table 2.

[ Table 1 ]:

note: the lower line represents the outside of the range specified by the present invention

The characteristics of the obtained sample were evaluated as follows. Namely: electrical conductivity, tensile strength and bending workability.

[ conductivity ]: measured according to the method defined in JIS H0505.

Tensile Strength L D tensile Strength specimens (JIS specimen No. 5) were cut from the respective materials and subjected to JIS Z2241

Measured by a prescribed method.

[ bending workability ] A plate-like specimen (10 mm in width) cut out in the longitudinal direction of L D and TD, respectively, was bent by the 90 DEG W-type bending method defined in JIS H3110, the surface and cross-section of the specimen after bending were observed at 100X with an optical microscope, the minimum bending radius R at which no crack occurred was obtained, the value of the ratio R/t between the minimum bending radius R and the plate thickness t was used as an evaluation of bending workability, and the smaller the value of R/t, the better the bending workability.

The results of the characteristic evaluation are shown in table 2.

[ Table 2 ] As follows:

note: with lower line indicating outside the specified scope of the invention

As can be seen from Table 2, all the invention examples have the composition requirements and manufacturing process conditions of the invention, the hot rolling does not crack, the electrical conductivity is 30% IACS or more, the tensile strength is high at 900MPa or more (the tensile strength is 1000MPa or more regardless of the bending workability), and the excellent bending workability is L D and R/t in TD direction is less than 2.0.

In contrast, comparative examples Nos. 21 to 25 are examples in which good characteristics were not obtained because the contents or ratios of Ni, Co and Si were out of the ranges specified in the present invention. The Ni and Co contents of No.21 were too low, and as a result, the strength was lowered because of the formation of too few precipitates. The Ni and Co contents of Nos. 22 and 23 were too high, no proper solution treatment condition was found, no complete recrystallization was found, and a mixed grain structure was produced, resulting in strength and bending workability. No.24 and 25 are examples in which the (Ni + Co)/Si ratio is too large or too small, resulting in deterioration of conductivity and strength.

Comparative examples Nos. 26 to 27 are examples in which the contents of Sn and Mg or the Mg/Sn ratio were out of the range specified in the present invention, and no good characteristics or hot rolling cracks were obtained. The Sn content in No.26 was too high, and hot rolling cracking could not be suppressed even by adding a proper amount of Mg. The content of Mg in No. 27is too low, which results in too low Mg/Sn ratio, and the occurrence of hot rolling cracks cannot be suppressed even if the content of Sn is in compliance.

Claims

1. An ultra-high strength copper alloy sheet strip comprising 2.2 to 3.2 wt% of Ni, 0.8 to 1.8 wt% of Co, 0.6 to 1.25 wt% of Si, 0.5 to 1.5 wt% of Sn, 0.05 to 0.20 wt% of Mg, and the balance Cu and unavoidable impurities, the copper alloy sheet having a composition ratio satisfying the following formulae (1) and (2):

4≤({Ni}+{Co})/{Si}≤5……(1)

{Mg}/{Sn}≧0.1……(2)

wherein { Ni }, { Si }, { Mg } and { Sn } represent the weight percentages of Ni, Si, Mg and Sn, respectively, in the copper alloy sheet.

2. The ultra-high strength copper alloy sheet strip according to claim 1, which comprises 2.2 to 3.0 wt% of Ni, 0.8 to 1.5 wt% of Co, 0.6 to 1.2 wt% of Si, 0.6 to 1.0 wt% of Sn, 0.05 to 0.20 wt% of Mg, and the balance Cu and unavoidable impurities, and which has a composition ratio satisfying the following formulae (1) and (2):

4.2≤({Ni}+{Co})/{Si}≤4.8……(1)

{Mg}/{Sn}≧0.1……(2)。

3. the copper alloy sheet according to claim 1 or 2, further comprising one or more elements selected from the group consisting of Zn, Fe, Cr, B, P, Zr, Ti and Mn, and a total amount thereof is 2.0 wt% or less.

4. A copper alloy sheet according to claim 3, characterized in that the total amount of one or more elements of Zn, Fe, Cr, B, P, Zr, Ti and Mn is 0.01-1.0 wt%.

5. The ultra-high strength copper alloy sheet strip according to claim 1 or 2, characterized in that it has an average grain diameter of 5-15 μm.

6. The ultra-high strength copper alloy sheet strip according to claim 5, having an average grain diameter of 8-12 μm.

7. The ultra-high strength copper alloy sheet or strip according to claim 1 or 2, wherein the copper alloy sheet or strip has a tensile strength of 900MPa or more, an electrical conductivity of 30% IACS or more, and a ratio R/t of a minimum bending radius R to a sheet thickness t of 2.0 or less.

8. A method of manufacturing an ultra-high strength copper alloy sheet strip according to any one of claims 1 to 7, comprising the sequential steps of: melting casting, heating and hot rolling at 950 ℃, cold rolling to the thickness of 1.0-3.0mm, intermediate annealing in the temperature range of 550-650 ℃, cold rolling, solution treatment in the temperature range of 950-1030 ℃, aging treatment in the temperature range of 400-500 ℃, aging treatment time of 3-6 hours, and low-temperature annealing at 150-550 ℃ after final cold rolling and final cold rolling.

9. The method for manufacturing an ultra-high strength copper alloy sheet strip as defined in claim 8, wherein in the solution treatment step, the average grain size of the recrystallized grains after the solution treatment is 5-15 μm by adjusting the holding time within the temperature range of 900-950 ℃.

10. The method for producing an ultra-high strength copper alloy sheet strip according to claim 8, wherein a final cold rolling reduction in the final cold rolling is 15 to 35%.