TWI626323B - Copper alloys for electronic materials - Google Patents

Abstract

The invention provides a copper alloy for electronic materials, which has a suitable 0.2% drop strength and electrical conductivity and is used for electronic materials to improve dimensional stability during stamping. The copper alloy for electronic materials of the present invention contains 0.5 to 3.0% by mass of Co, 0.1 to 1.0% by mass of Si, and the balance is composed of Cu and unavoidable impurities. The 0.2% rolling strength in the parallel rolling direction is 500 MPa or more. The electrical conductivity is 60% IACS or more, the average crystal grain size in the rolled parallel section is 10 μm or less, the X-ray diffraction integrated intensity I {200} from the {200} crystal plane on the surface, X-ray diffraction integrated intensity I {220}, X-ray diffraction integrated intensity I {311} from {311} crystal plane, satisfying (I {220} + I {311}) / I {200} 5.0 relationship.

Description

Copper alloys for electronic materials

The present invention relates to a precipitation-hardening copper alloy system Cu-Co-Si suitable for various electronic components, and particularly to a technique for improving dimensional stability during stamping.

As for copper alloys for electronic materials used in various electronic components such as connectors, switches, relays, pins, wiring, and lead frames, basic characteristics require high strength and high electrical conductivity (or thermal conductivity). Therefore, in recent years, with the rapid development of high integration, miniaturization, and thinning of electronic components, the requirements for copper alloys used in electronic device components have been further upgraded.

From the standpoint of high strength and high conductivity, as a copper alloy for electronic materials, solid solution-strengthened copper alloys typified by phosphor bronze and brass have been used in the past. gradually increase. In precipitation hardening copper alloys, by aging treatment of the super-saturated solid solution treated with solid solution, the fine precipitates are uniformly dispersed, the strength of the alloy is improved, and the amount of solid solution elements in copper is reduced and conductive Sexual improvement. Therefore, a material having excellent mechanical properties such as elasticity and good electrical and thermal conductivity can be obtained.

Among precipitation-hardening copper alloys, Cu-Ni-Si based alloys, commonly known as Corson alloys, are representative copper alloys with high electrical conductivity, strength, and bendability. They are actively developed in the industry. An alloy. In this copper alloy, fine Ni-Si-based intermetallic compound particles are precipitated in a copper matrix, and strength and electrical conductivity can be improved.

In order to achieve the purpose of further improving characteristics, a Cu-Co-Si-based alloy in which Co is added to the above-mentioned Corson alloy or Ni is replaced by Co is proposed.

Compared with Cu-Ni-Si-based alloys, Cu-Co-Si-based alloys generally have a higher solid solution temperature, making it difficult to miniaturize crystal grains after solution treatment. In response, Patent Documents 1 to 3 and the like describe a technique for controlling crystal grains by using a Cu-Co-Si based alloy.

Specifically, Patent Document 1 describes that the crystal grains are made finer by focusing on improving the bendability and improving the degeneration of mechanical properties, and performing aging treatment before the solution treatment. Further, Patent Document 2 discloses that the average crystal grains are controlled by adjusting the end temperature of hot rolling or the finishing degree of intermediate rolling passes to improve the plating properties. Further, Patent Document 3 describes that the bendability is improved by controlling the crystal orientation of the cube orientation.

Generally, the above-mentioned Cu-Co-Si based alloy is produced by melting and casting an ingot, followed by hot rolling, first cold rolling, solution treatment, aging treatment, and final cold rolling in this order.

[Xizhi technical literature]

Patent Document 1: Japanese Patent Publication No. 2012-72470.

Patent Document 2: Japanese Patent Publication No. 2011-252216.

Patent Document 3: Japanese Patent Publication No. 2013-32564.

However, with the miniaturization and thinness of electronic components in recent years, for example, the interval (ie, the pitch) between the pins adjacent to each other, which is arranged in the built-in connector, is extremely narrow, and the thickness is getting more and more thin.

In order to manufacture such a small-sized connector, if the Cu-Co-Si based alloy in the prior art is subjected to a stamping process, the pitch may vary greatly during the stamping process. Move left and right to deform. That is, with the control of the crystal grain size in the prior art, the dimensional stability of the punching process cannot be significantly improved. This deterioration in product size will result in a significant reduction in the step-down ratio in the assembly process.

In addition, even if the material of the connector with a long spring length in the narrow pitch, which is representative of the floating connector, is often used a Corson alloy with excellent strength and electrical conductivity characteristics. Under this situation, it is urgently desired to obtain This is an effective countermeasure against the problem that the dimensions of the pins are unstable when punching as described above.

The present invention aims to solve the above-mentioned problems, and an object thereof is to provide a copper alloy for electronic materials which has an appropriate 0.2% drop strength and electrical conductivity for electronic materials and can improve dimensional stability when stamped into a connector shape or the like.

After intensive discussions by the inventors, the following insights were obtained. X-rays derived from each of the {200} crystal plane, {220} crystal plane, and {311} crystal plane measured by X-ray diffraction while controlling the crystal orientation of Cu-Co-Si based alloy The diffraction integral intensity satisfies a predetermined relationship, and thereby the size of the pin of the connector terminal during press processing can be stabilized. Therefore, between the first cold rolling and the aging treatment in the conventional manufacturing process, the solution treatment is performed twice under the predetermined conditions, and then the intermediate rolling is performed under the predetermined conditions between the solution treatments. As described above, the crystal grains can be made finer and the crystal orientation can be controlled.

Based on the above findings, the copper alloy for electronic materials of the present invention contains 0.5 to 3.0% by mass of Co, 0.1 to 1.0% by mass of Si, and the balance is composed of Cu and unavoidable impurities, and 0.2% of rolling is reduced in the parallel direction. The strength is 500 MPa or more, the conductivity is 60% LACS or more, the average crystal grain size in the rolled parallel section is 10 μm or less, the X-ray diffraction integrated intensity I {200} from the {200} crystal plane on the surface, and the { 220} X-ray diffraction integrated intensity of crystal plane I {220}, X-ray diffraction integrated intensity of {311} crystal plane I {311}, satisfying (I {220} + I {311}) / I {200} 5.0 relationship.

In the copper alloy for electronic materials of the present invention, it is preferable that the difference of 0.2% yield strength obtained by subtracting the 0.2% yield strength in the rolling right-angle direction from the 0.2% yield strength in the rolling parallel direction is 50 MPa or less.

The copper alloy for electronic materials of the present invention preferably has an X-ray diffraction integrated intensity I {200} on the surface from the {200} crystal plane and an X-ray diffraction integrated intensity I ₀ {200} of pure copper standard powder, which satisfies I {200} / I ₀ {200} 1.0 relationship.

The copper alloy for electronic materials of the present invention can further contain Cr in an amount of 0.5% by mass or less.

Furthermore, the copper alloy for electronic materials of the present invention can also contain 2.0% by mass or less of Ni.

In addition, the copper alloy for electronic materials of the present invention can further contain Zn and Sn of 1.0% by mass or less, Mg, P, Ca, and Mn of 0.2% by mass or less, respectively, and is selected from the group consisting of Zn, Sn, Mg, P, and Ca. And the total content of one or more of Mn is 2.0% by mass or less.

According to the copper alloy for electronic materials of the present invention, the X-ray diffraction integrated intensity I {200} on the surface from the {200} crystal plane, the X-ray diffraction integrated intensity I {220} from the {220} crystal plane, and the {311 Integral intensity of X-ray diffraction of crystal plane I {311}, satisfying (I {220} + I {311}) / I {200} The relationship of 5.0 can effectively improve the dimensional accuracy after punching. This makes it possible to increase the step-down ratio when manufacturing electronic materials.

FIG. 1 is a schematic view schematically showing a fracture surface and a shear surface formed on a press fracture surface by using the pressability evaluation in the example.

Hereinafter, embodiments of the present invention will be described in detail.

The copper alloy for electronic materials according to one embodiment of the present invention contains 0.5 to 3.0% by mass of Co, 0.1 to 1.0% by mass of Si, and the balance is composed of Cu and unavoidable impurities, and is 0.2% in the rolling parallel direction. The yield strength is 500 MPa or more, the conductivity is 60% IACS or more, the average crystal grain size obtained in the rolling parallel section is 10 μm or less, and the integrated intensity of the X-ray diffraction from the {200} crystal plane on the surface I {200} , X-ray diffraction integrated intensity I {220} from {220} crystal plane, X-ray diffraction integrated intensity I {311} from {311} crystal plane, satisfying (I {220} + I {311}) / I { 200} 5.0 relationship.

[Addition amount of Co and Si]

Co and Si are formed by performing an appropriate heat treatment to form an intermetallic compound, which can increase the strength without lowering the conductivity.

With regard to the amounts of Co and Si added, if Co is less than 0.5% by mass and Si is less than 0.1% by mass, desired strength cannot be obtained. In addition, when Co exceeds 3.0% by mass and Si exceeds 1.0% by mass, Although high strength can be achieved, the electrical conductivity is significantly reduced, and the hot workability is also deteriorated. Therefore, the amounts of Co and Si added are set such that Co: 0.5 to 3.0% by mass and Si: 0.1 to 1.0% by mass.

For the Cu-Co-Si system, it is desired that the strength be higher than that of the Cu-Ni-Si system. Therefore, the Co concentration is preferably high, preferably 1.0% by mass or more, and more preferably 1.5% by mass or more. The addition amounts of Co and Si are preferably Co: 1.0 to 2.5% by mass, Si: 0.3 to 0.8% by mass, more preferably Co: 1.5 to 2.0% by mass, and Si: 0.4 to 0.6% by mass.

[Cr added amount]

Cr precipitates preferentially to the grain boundaries during the cooling process during melting and casting, so it can strengthen the grain boundaries, make it difficult to crack during hot working, and control the yield ratio. That is, Cr precipitated at the grain boundary during melt casting is re-dissolved by solid solution treatment or the like, and then aging treatment generates precipitated particles of bcc structure containing Cr as a main component or a compound with Si. Of the amount of Si added to ordinary Cu-Ni-Si-based alloys, Si, which does not contribute to aging precipitation, remains in a solid solution state and controls the increase in conductivity, and the silicide-forming element Cr is added. Precipitation of silicide can reduce the amount of solid solution Si, and can increase the conductivity without damaging the strength. However, if the excessive Cr concentration exceeds 0.5% by mass, a coarse second phase example is likely to be formed, and product characteristics are impaired. Therefore, in the present invention, Cr can be added at a maximum of 0.5% by mass. However, since the effect is small when it is less than 0.03% by mass, it is preferable to add 0.03 to 0.5% by mass, and more preferably 0.09 to 0.3% by mass.

[Addition amount of Sn and Zn]

Even in Sn and Zn, product characteristics such as strength, stress relaxation characteristics, and plating properties can be improved without impairing the electrical conductivity by a small amount of addition. The effect of addition is exerted mainly by solid solution to the mother phase. However, when the respective concentrations of Sn and Zn exceed 1.0% by mass, the characteristic improvement effect is saturated, and productivity is impaired. Therefore, in the present invention, Sn and Zn can be added up to 1.0% by mass, respectively. However, when the total amount of Sn and Zn is less than 0.05% by mass, the effect is reduced. Therefore, the total amount of Sn and Zn is preferably 0.05 to 2.0% by mass, and more preferably 0.5 to 1.0% by mass.

[Addition of Mg, P, Ca and Mn]

By adding a small amount of Mg, P, Ca, and Mn, product characteristics such as strength and stress relaxation characteristics can be improved without impairing conductivity. The effect of addition is mainly achieved by solid solution in the mother phase, but further effects can be exhibited because it is contained in the particles of the second phase. However, when the respective concentrations of Mg, P, Ca, and Mn exceed 0.5% by mass, the characteristic improvement effect is saturated, and productivity is impaired. Therefore, in the present invention, Mg, P, Ca, and Mn can be added up to 0.5% by mass, respectively. However, when the total amount of Mg, P, Ca, and Mn is less than 0.01 mass%, the effect is low. Therefore, the total amount of Mg, P, Ca, and Mn is preferably 0.01 to 0.5 mass%, and more preferably 0.04 to 0.2 mass%.

When the above-mentioned Zn, Sn, Mg, P, Ca, and Mn are contained, at least one kind of substances selected from the above-mentioned Zn, Sn, Mg, P, Ca, and Mn is totaled to 2.0% by mass or less, and if the total amount exceeds 2.0% by mass, When the characteristic improvement effect is saturated, productivity also deteriorates.

[Added amount of Ni]

Ni can also improve product characteristics such as electrical conductivity, strength, stress relaxation characteristics, and plating properties by adjusting the amount of addition according to the required product characteristics. The effect of addition is mainly achieved by solid solution into the mother phase, but it is contained in the second phase particles (mainly Ni-Co-Si based or Ni-Si based precipitates), or it forms a second component with a new composition Phase particles, so that further effects can be exhibited. However, when the addition amount of Ni exceeds 2.0% by mass, the characteristic improvement effect is saturated, and productivity is impaired. Therefore, in the present invention, Ni can be added up to 2.0% by mass. However, since the effect is low when it is less than 0.001% by mass, it is preferably 0.001 to 2.0% by mass, and more preferably 0.05 to 1.0% by mass.

[0.2% drop intensity]

In order to meet the required characteristics of the specified electronic materials such as connectors, the 0.2% drop strength in the parallel rolling direction needs to be set to 500 MPa or more. The 0.2% drop strength in the rolling parallel direction is preferably in the range of 500 MPa to 950 MPa, and more preferably 600 MPa to 950 MPa.

The difference of 0.2% yield strength obtained by subtracting the 0.2% yield strength in the right-angle direction from the 0.2% yield strength in the rolling parallel direction is preferably 50 MPa or less. This can further greatly improve the dimensional stability at the time of pressing. In short, if the difference in 0.2% drop strength is too large, the pins of the connector are easily deformed up, down, left, and right during punching, which may cause a reduction in dimensional accuracy. From this viewpoint, a small difference of 0.2% in yield strength is preferable, and specifically, 30 MPa is preferable, and 20 MPa is more preferable.

The 0.2% drop strength was measured using a tensile tester based on the JIS Z2241 standard.

[Conductivity]

The conductivity is 60% IACS or more. Thereby, it can be effectively used as an electronic material. Electrical conductivity can be measured based on the JIS H0505 standard. The conductivity is preferably 65% IACS or more.

[Average crystal grain size]

Refinement of the crystal grain size not only obtains high strength, but also makes the crystal grain size in the rolling parallel section particularly fine, which is advantageous for improving the dimensional stability at the time of pressing. Therefore, the average grain size of the rolled parallel sections is 10 μm or less. When the average crystal grain size exceeds 10 μm, the punchability is deteriorated. From this viewpoint, the average crystal grain size is preferably 8 μm or less, and more preferably 6 μm or less.

On the other hand, the lower limit of the average crystal grain size is not particularly limited, and if it is adjusted to 2 μm or less, a part of the metal structure becomes non-recrystallized, and if the non-recrystallized portion remains, the punchability is deteriorated, so it is preferably 2 μm or more.

The average crystal grain size is measured based on the JIS H0501 (cutting method) standard.

[Integrated intensity of X-ray diffraction]

With regard to the copper alloy for electronic materials of the present invention, the X-ray diffraction integrated intensity I {200} from the {200} crystal plane and the {from 200} crystal plane on the surface (rolled surface) obtained by the X-ray diffraction method (XRD) The integrated X-ray diffraction intensity I {220} of the crystal plane 220 and the integrated X-ray diffraction intensity I {311} of the {311} crystal plane satisfy (I {220} + I {311}) / I {200} 5.0 relationship. This can improve dimensional stability after pressing. This is because the slip system of the material differs depending on the crystal orientation, and this has an effect on the formation of the cross section during the press working. But it is not limited to the above theory.

From the above reasons, it is known that (I {220} + I {311}) / I {200} is preferably 5.0 or more, and particularly preferably 6.0 or more. Although there is no particular upper limit, it is preferably less than 10.0.

Further, in the present invention, it is preferable that the X-ray diffraction integrated intensity I {200} on the surface from the {200} crystal plane and the X-ray diffraction integrated intensity I _{0 of the} pure copper standard powder satisfy I {200} / I ₀ {200} 1.0 relationship. This is because the higher the strength of I {200} / I ₀ {200}, the worse the punchability is. The {200} crystal plane is more easily deformed than other orientations, and the crystal grains including the {200} crystal plane are preferentially deformed during punching, so the stampability of the polycrystalline copper alloy is deteriorated.

On the other hand, if the ratio of I {200} / I ₀ {200} is too small, unrecrystallized residues remain in a part of the metal structure, which may deteriorate the stampability.

Therefore, the ratio of I {200} / I ₀ {200} is preferably 0.1 or more and 1.0 or less, and particularly preferably 0.2 or more and 0.7 or less.

The X-ray diffraction integrated intensity can be measured by using a predetermined X-ray diffraction device.

[Production method]

The Cu-Co-Si-based alloy as described above can be sequentially melted and cast a steel ingot step, a hot rolling step, a first cold rolling step, a first solution treatment step, a second cold rolling step, and a second solution treatment. Processes, aging treatment processes in which the material temperature is set to 450 ° C to 550 ° C, and final cold rolling processes are performed for manufacturing. After hot rolling, if necessary, planing can be performed.

Specifically, first, raw materials such as electrolytic copper, Co, and Si are melted using an atmospheric melting furnace or the like to obtain a desired combination of melts. This melt is then cast into a steel ingot. After that, hot rolling, first cold rolling, first solution treatment, second cold rolling, second solution treatment, aging treatment (for 2-20 hours at 450 to 550 ° C), and final cold rolling (workability 5) ~ 50%). After the final cold rolling, stress relief annealing is performed. Stress relief annealing can usually be performed in an inert gas atmosphere such as Ar for 5 to 300 seconds. After the second solution treatment, the final cold rolling and the aging treatment are sequentially performed, and the above steps can be interchanged.

Here, in the manufacturing method described above, it is most important to perform the first cold rolling, and then perform the first solid solution treatment, the second cold rolling, and the second solid solution treatment under predetermined conditions. In the prior art, the above-mentioned steps are not performed, but a solution treatment is performed after hot rolling, so that the crystal grains of the present invention cannot be obtained, and the dimensional stability after pressing cannot be significantly improved.

Hereinafter, the detailed description will be given focusing on each step of the first solution treatment, the second cold rolling, and the second solution treatment. In other processes, the conditions often used in the manufacturing process of Cu-Co-Si based alloys may be used.

In the first solution treatment, the material temperature was set to 900 to 1000 ° C. As a result, Co and Si promote the solid solution of Ni depending on the occasion, and the crystal grains after the second solution treatment are reduced to a predetermined size, and at the same time, the crystal orientation as described above can be controlled. When the temperature is lower than 900 ° C, the progress of the solid solution cannot be promoted, so that the crystal grains are coarsened. On the other hand, when the temperature is higher than 1000 ° C, the solid solution progresses too fast and it is difficult to control the crystal orientation.

Generally, the aggregate structure of a copper alloy is affected by the amount of solid solution and the precipitation state before the final solid solution, so the first solid solution is important. The first solution treatment can be performed for 15 to 300 seconds. If the time is too long, the balance between solid solution and precipitation becomes poor, it is difficult to control the aggregate structure, and if too short, the solid solution cannot proceed, and the crystal grains become coarse.

The purpose of the second cold rolling after the first solution treatment is to refine the crystal grains and control the crystal orientation. For the above purpose, the workability of the second cold rolling is set to 30 to 60%. When the degree of processing is less than 30%, coarsening of the crystal grains is caused. On the other hand, when the degree of processing exceeds 60%, the crystal orientation may fail to meet the above requirements.

In addition, from the viewpoint of improving the strength in the right-angle direction of rolling and improving the dimensional accuracy after pressing, it is preferable that the arithmetic average roughness Ra of the material surface after the second cold rolling is set to be less than 0.2 μm. That is, this is because, by controlling the arithmetic average roughness Ra of the material surface after the second cold rolling as described above, the 0.2% drop strength in the rolling direction in the finish rolling is improved, and the punchability is good. The surface roughness becomes rough, so the emissivity of the material changes. Although it does not appear in (I {220} + I {311}) / I {200}, the balance of the aggregate structure after the second solid solution is the most It is optimized, and the friction on the surface of the material increases during finish rolling, so the distortion imparted to the material increases. As a result, the 0.2% drop strength in the rolling direction is improved, and the stampability is improved.

The arithmetic mean roughness Ra is the roughness of the surface of the material after the second cold rolling obtained in accordance with JIS B0601 (2001). By achieving the surface roughness as described above, the rolled surface of the second cold rolling can be improved.

After the second cold rolling, a second solution treatment is performed. The second solution treatment can be performed at a material temperature of 850 ° C to 1000 ° C. If the temperature is lower than 850 ° C, the strength will decrease due to insufficient solid solution. Moreover, if it is higher than 1000 ° C, recrystallized grains are grown and crystal grains are enlarged.

The time of the second solution treatment can be set to 15 to 60 seconds. If the time of the second solution treatment is too long, the recrystallized grains grow, the crystal grains increase, and the punchability is deteriorated. When the recrystallization grain is too short, unrecrystallized residues remain in a part of the metal structure, which may result in poor punchability. .

In addition, when the temperature of the aging treatment is lower than 450 ° C, the conductivity is lowered, and when higher than 550 ° C, the strength is lowered. Therefore, 450 to 550 ° C is preferred. In addition, if the final cold rolling workability is too low, the required strength cannot be obtained, so it is set to 5% or more. On the other hand, although there is no preferable upper limit, it is generally set to 50% or less in order to prevent deterioration in bendability.

The Cu-Co-Si-based alloy of the present invention can be processed into various copper products, such as plates, bars, tubes, rods, and wires, and the Cu-Co-Si-based copper alloy can be used for lead frames, connectors, and pins. , Terminals, relays, switches, and other electronic components such as foil materials for secondary batteries. In particular, it is possible to obtain high dimensional accuracy at the time of pressing when manufacturing a connector.

[Example]

Next, a copper alloy for an electronic material according to the present invention will be produced, and the following description will be made in order to confirm its performance. However, the description herein is merely for the purpose of illustration, and is not intended to limit the present invention.

A high-frequency melting furnace was used to melt a copper alloy having a combination of the components shown in Table 1 at 1300 ° C, and cast a steel ingot having a thickness of 30 mm. Next, the steel ingot was heated at 1000 ° C for 2 hours. After that, hot rolling was performed so that the thickness of the sheet reached 10 mm, and the hot rolling completion temperature was set to 900 ° C. After the hot rolling is completed, the average cooling rate when the material temperature is lowered to 850 ° C to 400 ° C is set to 18 ° C / s, water cooling is performed, and then it is left to cool in the air. Then, since the surface was descaled, planing was performed to a thickness of 9 mm, and thereafter, a plate having a thickness of 0.15 mm was set by cold rolling. Then, under the conditions shown in Table 1, a first solution treatment, a second cold rolling, a second solution treatment, and an aging treatment were sequentially performed to produce a test piece.

For each test piece obtained by the above method, the following characteristics were evaluated. The results are shown in Table 2.

[strength]

For each test piece, a tensile test in each of the rolling parallel direction and the rolling orthogonal direction was performed based on JIS Z2241, and the 0.2% yield strength (YS: MPa) was measured, and the above 0.2% yield strength difference was calculated.

[Conductivity]

The electrical conductivity (EC:% IACS) was obtained by volume resistivity measurement using a double bridge based on JIS H0505.

[Average crystal grain size]

Regarding the average crystal grain size, a cross section parallel to the rolling direction was mirror-polished and then subjected to chemical etching, and was obtained by a cutting method (JIS H0501 standard).

[Crystal orientation]

For each test piece, an X-ray diffraction apparatus manufactured by Rigaku Co., Ltd. and RINT2500 was used to obtain the surface diffraction intensity curve under the following measurement conditions, and the {200} crystal plane, {220} crystal plane, and {311} crystal plane were measured. The respective integrated intensity I is calculated as (I {220} + I {311}) / I {200}. In addition, for the standard sample of pure copper powder, the integrated intensity I of the {200} crystal plane was also measured under the same measurement conditions, and I {200} / I ₀ {200} was calculated.

‧Target: Co bulb

‧Tube voltage: 30kV

‧ Tube current: 100mA

‧Scanning speed: 5 ° / min

‧Sampling width: 0.02 °

‧Measuring range (2θ): 5 ° ~ 150 °

[Stampability]

In a state of being disposed between a square-shaped punch having a side of 10 mm and a die having a clearance of 0.01 mm, the punch was moved toward the die at a speed of 0.1 mm / min to perform punching. Observe the punched section after punching with an optical microscope. As shown in Fig. 1, the width of the observed surface is set to Lo, the total length of the boundary between the sheared surface and the fractured surface is set to L, and L / Lo The punchability was evaluated. The total length L is calculated from the image of the observation surface using image analysis software. The width Lo of the observation surface is usually set to 5 mm or more, and the observation surface is a central portion in the width direction of the press section.

In Table 2, "◎" indicates (1 <L / Lo 1.1), "○" means (1.1 <L / Lo 1.3), "×" means (L / Lo> 1.3).

As shown in Tables 1 and 2, in any of Invention Examples 1 to 20, the first solution treatment, the second cold rolling, and the second solution treatment and the aging treatment were performed under predetermined conditions, and the rolling was performed in parallel. The 0.2% drop strength in the direction is 500 MPa or more, the electrical conductivity is 60% IACS or more, the average crystal grain size in the rolled parallel section is 10 μm or less, and (I {220} + I {311}) / I {200} 5.0. As a result, good pressability can be obtained.

In Comparative Examples 1 to 8, since the first solution treatment was not performed, the temperature of the first solution treatment was too high or too low, the workability of the second cold rolling was outside the predetermined range, and the surface after the second cold rolling The roughness Ra is small or the temperature of the second solution treatment is too low, so that the crystal grains are coarsened, or the crystal orientation does not satisfy the prescribed conditions, and the punchability is poor.

In Comparative Example 9, since the temperature of the second solution treatment was too high, the crystal grains became coarse and the stampability was poor. Comparative Example 10 had a low aging temperature and low conductivity. In Comparative Example 11, the 0.2% drop strength was low due to the high aging temperature. In Comparative Examples 12 and 13, since the amount of Co or Si added was large, the conductivity was low.

As can be seen from the above, the present invention is suitable for electronic materials and has 0.2% drop strength and electrical conductivity, and can improve dimensional stability when stamped into a connector shape or the like.

Claims (6)

A copper alloy for electronic materials, characterized in that it contains 0.5 to 3.0% by mass of Co and 0.1 to 1.0% by mass of Si. The balance is composed of Cu and unavoidable impurities. The 0.2% rolling strength in the parallel rolling direction is 500 MPa. Above, the conductivity is 60% IACS or more, and the average crystal grain size in the rolled parallel section is 10 μm or less; the X-ray diffraction integrated intensity I {200} from the {200} crystal plane on the surface, and the {220} crystal from the surface Integrated X-ray diffraction intensity I {220} of the plane, and integrated X-ray diffraction intensity I {311} of the {311} crystal plane, satisfying (I {220} + I {311}) / I {200} 5.0 relationship. The copper alloy for electronic materials according to item 1 of the scope of the patent application, wherein the difference between the 0.2% yield strength obtained by subtracting the 0.2% yield strength in the rolling direction from the 0.2% yield strength in the parallel rolling direction is less than 50 MPa. The copper alloy for electronic materials according to item 1 or item 2 of the patent application scope, wherein the X-ray diffraction integrated intensity I {200} on the surface from the {200} crystal plane and the X-ray diffraction integrated intensity of the pure copper standard powder I ₀ {200}, satisfying I {200} / I ₀ {200} 1.0 relationship. The copper alloy for electronic materials according to item 1 or item 2 of the patent application scope further contains Cr of 0.5% by mass or less. The copper alloy for electronic materials according to item 1 or item 2 of the scope of patent application, further containing 2.0% by mass or less of Ni. The copper alloy for electronic materials according to item 1 or item 2 of the scope of patent application, which further contains Zn and Sn of 1.0% by mass or less, and Mg, P, Ca, and Mn of 0.2% by mass or less, respectively. The total content of at least one or more elements selected from the group consisting of Zn, Sn, Mg, P, Ca, and Mn is 2.0% by mass or less.