TW201736615A - Copper foil for electronic material having suitable 0.2% yielding strength and conductivity and capable of enhancing dimensional stability during stamping processing - Google Patents

Abstract

The present invention provides a copper alloy for electronic material applied to the electronic material and having suitable 0.2% yielding strength and conductivity and capable of enhancing dimensional stability during stamping processing. The copper foil for electronic material contains 0.5~3.0 mass% of Co and 0.1~1.0 mass% of Si, with the remainder constituted by Cu and inevitable impurities, whose 0.2% yielding strength parallel to the rolling direction is above 500 MPa, conductivity is above 60% IACS, the average crystalline particle diameter on the rolling parallel cross section is below 10 <mu>m, while the X-ray diffraction integral strength I {200} coming from {200} crystalline surface, the X-ray diffraction integral strength I {220} coming from {220} crystalline surface, and the X-ray diffraction integral strength I {311} coming from {311} crystalline surface on the surface satisfy the relationship of (I{220}+I{311})/I{200} ≥ 5.0.

Description

Copper alloy for electronic materials

The present invention relates to a precipitation hardening type copper alloy system Cu-Co-Si suitable for use in various electronic parts, and in particular, a technique for improving dimensional stability during press working.

Copper alloys for electronic materials used in various electronic components such as connectors, switches, relays, pins, wiring, and lead frames are required to have high strength and high electrical conductivity (or thermal conductivity) as basic characteristics. As a result, in recent years, with the rapid integration of electronic components, miniaturization, and thinning, the demand for copper alloys used in electronic device components has been further upgraded.

From the viewpoint of high strength and high electrical conductivity, as a copper alloy for electronic materials, a solid solution-strengthened copper alloy typified by phosphor bronze or brass has been used in the past, and the use amount of the precipitation hardening type copper alloy is replaced by gradually increase. In the precipitation hardening type copper alloy, by subjecting the solution-treated supersaturated solid solution to aging treatment, the fine precipitates are uniformly dispersed, the strength of the alloy is improved, and the amount of solid solution elements in the copper is reduced, and the conductive material is electrically conductive. Sexual improvement. Therefore, it is possible to obtain a material which is excellent in mechanical properties such as elasticity and which is excellent in electrical conductivity and thermal conductivity.

Among the precipitation hardening type copper alloys, the Cu-Ni-Si alloy generally called the Corusson alloy is a representative copper alloy having high electrical conductivity, strength, and bending workability, and is currently actively developed in the industry. An alloy. In the copper alloy, fine Ni-Si-based intermetallic compound particles are precipitated in the copper matrix, and strength and electrical conductivity can be improved.

In order to further improve the characteristics, a Cu-Co-Si alloy in which Co is added to the above-mentioned Corusson alloy or Ni is replaced with Co is proposed.

Compared with the Cu-Ni-Si alloy, the Cu-Co-Si alloy generally has a high solid solution temperature, and it is difficult to refine the crystal grains after the solution treatment. On the other hand, Patent Documents 1 to 3 and the like describe a technique for controlling crystal grains using a Cu-Co-Si-based alloy.

Specifically, in Patent Document 1, attention is paid to improving the flexibility and improving the deterioration of mechanical properties, and performing aging treatment before the solution treatment to refine the crystal grains. Further, Patent Document 2 discloses that the average crystal grain is controlled by adjusting the end temperature of hot rolling or the finishing degree of the end rolling of the intermediate rolling to improve the plating property. Further, Patent Document 3 describes that the bending property is improved by controlling the crystal orientation of the Cube orientation.

In general, the Cu-Co-Si-based alloy is produced by sequentially melting a steel ingot and casting it, followed by hot rolling, first cold rolling, solution treatment, aging treatment, and final cold rolling.

[Practical Technical Literature]

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

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

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

However, with the recent miniaturization and thinning of electronic components, for example, the spacing between adjacent pins (ie, the pitch) or the width of the terminals arranged in the built-in connector is extremely narrow, and the thickness is also increasingly thin.

In order to manufacture such a small-sized connector as described above, if a Cu-Co-Si-based alloy as in the above-described prior art is subjected to press working, the pitch may vary greatly during the stamping, for example, the pin is moved up and down from the target size. Move the deformation left and right. That is to say, the dimensional stability of the press working cannot be remarkably improved by the control of the crystal grain size of the prior art. This product size degradation can result in a significant reduction in the rate of drop in the assembly process.

Moreover, even as a material of a connector having a long spring length in a narrow pitch represented by a floating connector, a Brookson alloy having excellent properties such as strength and electrical conductivity is often used, and in this state, it is eagerly desired. An effective countermeasure against the problem that the size of the lead is unstable when punching as described above.

The present invention has been made to solve the above problems, and an object thereof is to provide a copper alloy for an electronic material which has an appropriate 0.2% fall strength and electrical conductivity for an electronic material and can improve dimensional stability when it is press-formed into a connector shape or the like.

After intensive discussions by the inventors, the following insights were obtained. The crystal grain of the Cu-Co-Si alloy is refined while controlling the crystal orientation, and each X-ray from the {200} crystal plane, the {220} crystal plane, and the {311} crystal plane measured by the X-ray diffraction method is controlled. The diffraction integrated intensity satisfies a predetermined relationship, whereby the size of the lead of the connector terminal during press working 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 predetermined conditions, and further intermediate rolling is performed between the solution treatments under predetermined conditions. It is possible to refine the crystal grains and control the crystal orientation as described above.

Under 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 the rolling parallel direction is delayed. The strength 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 the X-ray diffraction integrated intensity I{200} from the {200} crystal plane on the surface is from { 220} X-ray diffraction integrated intensity I{220} of the crystal plane, X-ray diffraction integrated intensity I{311} from the {311} crystal plane, satisfying (I{220}+I{311})/I{200} The relationship of 5.0.

The copper alloy for electronic materials of the present invention preferably has a difference of 0.2% of the 0.2% drop strength obtained by subtracting the 0.2% drop strength in the direction perpendicular to the rolling direction from the 0.2% drop strength in the rolling parallel direction to 50 MPa or less.

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

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

Further, the copper alloy for an electronic material of the present invention can further contain 2.0% by mass or less of Ni.

Further, the copper alloy for an electronic material of the present invention may further contain 1.0% by mass or less of Zn and Sn, and each of 0.2% by mass or less of Mg, P, Ca, and Mn, and is selected from the group consisting of Zn, Sn, and Mg, respectively. The total content of one or more of P, Ca, and Mn is 2.0% by mass or less.

A copper alloy for an electronic material according to the present invention, an X-ray diffraction integrated intensity I{200} from a {200} crystal plane on the surface, an X-ray diffraction integrated intensity I{220} from a {220} crystal plane, from {311 } The X-ray diffraction integrated intensity I{311} of the crystal plane satisfies (I{220}+I{311})/I{200} With the 5.0 relationship, the dimensional accuracy after punching can be effectively improved. Thereby, the fall ratio at the time of manufacturing an electronic material can be improved.

Fig. 1 is a schematic view schematically showing a fracture surface and a shear surface formed on a press section by the evaluation of the punchability in the examples.

Embodiments of the present invention will be described in detail below.

A copper alloy for an electronic material according to an 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 0.2% in the parallel direction of rolling. The lodging strength is 500 MPa or more, the electrical conductivity is 60% IACS or more, the average crystal grain diameter obtained in the rolling parallel section is 10 μm or less, and the X-ray diffraction integrated intensity from the {200} crystal plane is 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} The relationship of 5.0.

[Co, Si addition amount]

Co and Si can form an intermetallic compound by performing appropriate heat treatment, and can achieve high strength without deteriorating the electrical conductivity.

When Co and Si are added in an amount of less than 0.5% by mass and Si is less than 0.1% by mass, the desired strength is not obtained, and when Co exceeds 3.0% by mass and Si exceeds 1.0 mass, Although the strength can be increased, the electrical conductivity is remarkably lowered, and the hot workability is deteriorated. Therefore, the addition amount of Co and Si is set to Co: 0.5 to 3.0% by mass, and Si: 0.1 to 1.0% by mass.

For the Cu-Co-Si system, the strength is desirably higher than that of the Cu-Ni-Si system. Therefore, the Co concentration is preferably a high concentration, preferably 1.0% by mass or more, and more preferably 1.5% by mass or more. The addition amount of Co and Si is 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.

[addition amount of Cr]

Cr preferentially precipitates to the grain boundary during the cooling process during melt casting, so that the grain boundary can be strengthened, cracking hardly occurs during hot working, and the yield ratio is controlled. In other words, Cr precipitated at the grain boundary during the melt casting is re-dissolved by a solution treatment or the like, and then a precipitated particle of bcc structure or a compound of Si having Cr as a main component is generated during the aging treatment. In the amount of Si added to the ordinary Cu-Ni-Si alloy, Si which does not act on the aging precipitation remains in a state of being solid-solubilized in the mother phase, and the increase in conductivity is controlled, and the telluride forming element Cr is added, and further When the telluride is precipitated, the amount of solid solution Si can be reduced, and the conductivity can be improved without impairing the strength. However, if the Cr concentration exceeds 0.5% by mass, it is easy to form a coarse second phase example, which impairs product characteristics. Therefore, in the present invention, at most 0.5% by mass of Cr can be added. However, since the effect is small when it is less than 0.03 mass%, it is preferable to add 0.03 to 0.5 mass%, more preferably 0.09 to 0.3 mass%.

[Addition amount of Sn and Zn]

Even in the case of Sn and Zn, the 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. It is mainly added by solid solution to the parent phase. However, if the respective concentrations of Sn and Zn exceed 1.0% by mass, the property improving effect is saturated and the productivity is impaired. Therefore, in the present invention, Sn and Zn can be added at most 1.0% by mass. However, when the total amount of Sn and Zn is less than 0.05% by mass, the effect is lowered. Therefore, the total amount of Sn and Zn is preferably 0.05 to 2.0% by mass, more preferably 0.5 to 1.0% by mass.

[Addition amount 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 the electrical conductivity. The effect of addition is mainly exhibited by solid solution to the mother phase, but it is contained in the second phase particles, so that further effects can be exhibited. However, when the respective concentrations of Mg, P, Ca, and Mn exceed 0.5% by mass, the property improving effect is saturated and the productivity is impaired. Therefore, in the present invention, Mg, P, Ca, and Mn can be added at most 0.5% by mass. However, when the total amount of Mg, P, Ca, and Mn is less than 0.01% by mass, the effect is low. Therefore, the total amount of Mg, P, Ca, and Mn is preferably 0.01 to 0.5% by mass, more preferably 0.04 to 0.2% by mass.

When the Zn, Sn, Mg, P, Ca, and Mn are contained, at least one or more selected from the group consisting of Zn, Sn, Mg, P, Ca, and Mn is 2.0% by mass or less, and if the total amount is more than 2.0% by mass, When the characteristic improvement effect is saturated, the productivity is also deteriorated.

[Addition amount of Ni]

In the case of Ni, it is also possible to improve the properties of the electrical conductivity, the strength, the stress relaxation property, and the plating property by adjusting the amount of addition according to the required product characteristics. The additive effect is mainly exerted by solid solution to the mother phase, but is contained in the second phase particles (mainly Ni-Co-Si-based or Ni-Si-based precipitates) or forms a new composition. The phase particles are able to exert further effects. However, if the amount of Ni added exceeds 2.0% by mass, the property improving effect is saturated and the productivity is impaired. Therefore, in the present invention, Ni can be added at most 2.0% by mass. However, when the amount is less than 0.001% by mass, the effect is low, so it is preferably 0.001 to 2.0% by mass, more preferably 0.05 to 1.0% by mass.

[0.2% fall strength]

In order to satisfy the characteristics required in a predetermined electronic material such as a connector, the 0.2% drop strength in the parallel direction of the rolling needs to be set to 500 MPa or more. The 0.2% relief strength in the parallel direction of the rolling is preferably in the range of 500 MPa to 950 MPa, more preferably 600 MPa to 950 MPa.

Further, the difference of 0.2% of the lodging strength obtained by subtracting the 0.2% of the rolling strength in the direction perpendicular to the rolling direction from the 0.2% relief strength in the rolling parallel direction is preferably 50 MPa or less. Thereby, the dimensional stability at the time of punching can be further greatly improved. In short, if the difference between the 0.2% drop strength is too large, the pins of the connector are easily deformed up and down and left and right when punching, which may cause dimensional accuracy to decrease. From this point of view, it is desirable that the difference of the 0.2% drop strength is small, specifically, preferably 30 MPa, more preferably 20 MPa.

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 used effectively as an electronic material. The conductivity can be measured based on the JIS H0505 standard. The preferred conductivity is above 65% IACS.

[Average crystal grain size]

By making the crystal grain size fine, in addition to obtaining high strength, in particular, the crystal grain size in the rolling parallel cross section is made fine, which is advantageous in improving the dimensional stability at the time of pressing. Therefore, the average grain size of the rolled parallel section is 10 μm or less. When the average crystal grain size exceeds 10 μm, the punchability deteriorates. From this point of view, the preferred average crystal grain size is 8 μm or less, 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 is not recrystallized, and if the non-recrystallized portion remains, the punchability is deteriorated, so that it is preferably 2 μm or more. .

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

[Integral intensity of X-ray diffraction]

In the copper alloy for electronic materials of the present invention, the X-ray diffraction integrated intensity I{200} from the {200} crystal plane in the surface (rolled surface) obtained by X-ray diffraction (XRD) is from { 220} X-ray diffraction integrated intensity I{220} of the crystal plane and X-ray diffraction integrated intensity I{311} from the {311} crystal plane satisfy (I{220}+I{311})/I{200} The relationship of 5.0. Thereby, dimensional stability after press can be improved. This is because the slip system of the material according to the crystal orientation is also different, which affects the formation of the cross section at the time of press working. But it is not limited to the above theory.

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

Further, in the present invention, the X-ray diffraction integrated intensity I{200} from the {200} crystal plane and the X-ray diffraction integrated intensity I ₀ {200} of the pure copper standard powder on the surface are preferably I{200}/I. ₀ {200} The relationship of 1.0. 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 at the time of punching, so that the punchability of the polycrystalline copper alloy is deteriorated.

On the other hand, if the ratio of I{200}/I ₀ {200} is too small, a part of the metal structure remains without recrystallization, which may cause deterioration of punchability.

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.

Further, the integrated intensity of X-ray diffraction can be measured by using a predetermined X-ray diffraction apparatus.

[Production method]

The Cu-Co-Si-based alloy as described above can be sequentially subjected to a step of melt-casting a steel ingot, a hot rolling step, a first cold rolling step, a first solution treatment step, a second cold rolling step, and a second solution treatment. The process is carried out by setting the material temperature to 450 ° C to 550 ° C for the aging treatment step of heating and the final cold rolling step. Moreover, after hot rolling, planing can be performed as needed.

Specifically, first, a raw material such as electrolytic copper, Co, or Si is melted using an atmospheric melting furnace or the like to obtain a desired combined melt. The melt is then cast into a steel ingot. Thereafter, hot rolling, first cold rolling, first solution treatment, second cold rolling, second solution treatment, aging treatment (2-20 hours at 450 to 550 ° C), and final cold rolling (processing degree 5) are performed. ~50%). Stress relief annealing is performed after the final cold rolling. Stress relief annealing can usually be carried out in an inert gas atmosphere at 250 to 600 ° C for 5 to 300 seconds. After the second solution treatment, final cold rolling and aging treatment are sequentially performed, and the above steps can be interchanged.

Here, in the above-described manufacturing method, it is most important to perform the first solution treatment, the second cold rolling, and the second solution treatment under predetermined conditions after the first cold rolling. In the prior art, the above-described steps are not carried out, but the solution treatment is carried out once after hot rolling, whereby the crystal grains described in the present invention cannot be obtained, and the dimensional stability after pressing cannot be remarkably improved.

Hereinafter, the respective steps of the first solution treatment, the second cold rolling, and the second solution treatment will be described in detail. Further, in other processes, conditions that are often employed in the production process of the Cu-Co-Si-based alloy may be employed.

In the first solution treatment, the material temperature is set to 900 to 1000 °C. Thereby, Co and Si promote the solid solution of Ni depending on the case, and the crystal grains after the second solution treatment are refined to a predetermined size, and the crystal orientation as described above can be controlled. When the temperature is less than 900 ° C, the solid solution is not promoted, and thus the crystal grains are coarsened. On the other hand, when the temperature exceeds 1000 ° C, the solid solution proceeds too quickly, and it is difficult to control the crystal orientation.

Generally, the aggregate structure of the copper alloy is affected by the amount of solid solution and the state of precipitation before the final solid solution, so the first solid solution is important. Moreover, the first solution treatment can be performed for 15 to 300 seconds. If the above time is too long, the balance between solid solution and precipitation is deteriorated, and the aggregate structure is difficult to control, and when it is too short, solid solution cannot be performed, and the crystal grains are coarsened.

The purpose of the second cold rolling after the first solution treatment is also to refine the crystal grains and control the crystal orientation. For the above purpose, the degree of processing of the second cold rolling is set to 30 to 60%. When the degree of processing is less than 30%, the crystal grains are coarsened. On the other hand, when the degree of processing exceeds 60%, the crystal orientation may not satisfy the above specification.

Further, from the viewpoint of improving the strength in the direction perpendicular to the rolling direction and improving the dimensional accuracy after the press, it is preferable that the arithmetic mean roughness Ra of the surface of the material after the second cold rolling is set to be less than 0.2 μm. That is, this is because the calculation of the surface of the material after the second cold rolling is controlled by the above The average roughness Ra is 0.2% of the rolling strength in the direction perpendicular to the rolling in the finish rolling, and the punching property is good. The roughness of the surface becomes rough, so the radiance of the material changes, although it does not appear in (I{220}+I{311})/I{200}, the equilibrium of the aggregated structure after the second solid solution is the most Since the friction of the surface of the material is increased during the finish rolling, the distortion of the imparting material is increased, whereby the 0.2% relief strength in the direction perpendicular to the rolling is improved, and the punchability is improved, but it is not limited to the above theory.

The above arithmetic mean roughness Ra is the roughness of the surface of the material after the second cold rolling obtained according to the JIS B0601 (2001) standard. Since the surface roughness as described above is achieved, 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 carried out by setting the material temperature to 850 ° C to 1000 ° C. If the above 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 to increase crystal grains.

The time of the second solution treatment can be set to 15 seconds to 60 seconds. If the time of the second solution treatment is too long, the recrystallized grain grows, the crystal grains increase, and the punchability deteriorates, and when it is too short, a part of the metal structure remains unrecrystallized, which may cause deterioration of punchability. .

Further, with respect to the temperature of the aging treatment, if the temperature is lower than 450 ° C, the electrical conductivity is lowered, and if it is higher than 550 ° C, the strength is lowered, so that it is preferably 450 to 550 ° C. Further, if the degree of processing of the final cold rolling is too low, the required strength cannot be obtained, so it is set at 5% or more. On the other hand, although there is no preferable upper limit, in order to prevent deterioration of the bendability, it is generally possible to set it to 50% or less.

The Cu-Co-Si alloy of the present invention can be processed into various copper products such as plates, strips, tubes, rods, and wires, and the above Cu-Co-Si based copper alloy can be used for lead frames, connectors, and leads. , electronic components such as terminals, relays, switches, and foil materials for secondary batteries. In particular, it is possible to obtain high dimensional accuracy when punching is performed when the connector is manufactured.

[Examples]

Next, the copper alloy for electronic materials of the present invention is tried to be produced, and the following description will be made to confirm the performance. However, the description herein is for illustrative purposes only and is not intended to limit the invention.

A copper alloy in which the components shown in Table 1 were combined was melted at 1300 ° C using a high-frequency melting furnace to cast a steel ingot having a thickness of 30 mm. Next, the steel ingot was heated at 1000 ° C for 2 hours, and then hot rolled to a thickness of 10 mm, and the hot rolling completion temperature was set to 900 ° C. After hot rolling The average cooling rate when the material temperature was lowered to 850 ° C to 400 ° C was set to 18 ° C / s, water cooling, and then placed in the air for cooling. Then, since the surface was descaled, planing was carried out to a thickness of 9 mm, and then a plate having a thickness of 0.15 mm was set by cold rolling. Thereafter, under the conditions shown in Table 1, the first solution treatment, the second cold rolling, the second solution treatment, and the aging treatment were sequentially performed to prepare test pieces.

The following characteristics were evaluated for each test piece obtained by the above method. 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 perpendicular direction was performed based on JIS Z2241, and 0.2% drop strength (YS: MPa) was measured, and the difference of the above 0.2% fall strength was calculated.

[Conductivity]

Regarding the conductivity (EC: % IACS), it was obtained by volume resistivity measurement by a double bridge based on JIS H0505.

[Average crystal grain size]

Regarding the average crystal grain size, the cross section parallel to the rolling direction was mirror-polished and then chemically etched, and 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 RINT 2500 was used, and the diffraction intensity curve of the surface was obtained by the following measurement conditions, and the {200} crystal plane, the {220} crystal plane, and the {311} crystal plane were measured. For each integral intensity I, (I{220}+I{311})/I{200} is calculated. In addition, regarding the pure copper powder standard sample, the integral intensity I of the {200} crystal plane was also measured under the same measurement conditions, and I{200}/I ₀ {200} was calculated.

‧Object: Co bulb

‧ Tube voltage: 30kV

‧ Tube current: 100mA

‧Scanning speed: 5°/min

‧Sampling width: 0.02°

‧Measurement range (2θ): 5°~150°

[punchability]

In a state in which a square-shaped punch having a side of 10 mm and a die having an interval of 0.01 mm were disposed, the press was displaced toward the die at a speed of 0.1 mm/min, and the press was performed. The punched cross section after punching was observed by an optical microscope. As shown in Fig. 1, the width of the observation surface was set to Lo, and the total length of the boundary portion between the sheared surface and the fracture surface was set to L by L/Lo. The stamping property was evaluated. The total length L is calculated from the image of the observation surface using the image analysis software. The width Lo of the observation surface is usually set to 5 mm or more, and the observation surface is the central portion in the width direction of the press section.

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

As shown in Tables 1 and 2, in any of Invention Examples 1 to 20, the first solid solution treatment, the second cold rolling, and the second solid solution treatment are performed under predetermined conditions, and the rolling is performed in parallel. The 0.2% drop strength of the direction is 500 MPa or more, the electric conductivity is 60% IACS or more, and the average crystal grain size in the rolling 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, the temperature at which the first solution treatment was not performed, the temperature of the first solution treatment was too high or too low, and the degree of processing 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 predetermined conditions, and the punchability is poor.

In Comparative Example 9, since the temperature of the second solution treatment was too high, the crystal grains were coarsened and the punchability was poor. Comparative Example 10 had a low aging temperature and a low electrical conductivity. Comparative Example 11 due to aging treatment temperature High, resulting in a low 0.2% drop strength. In Comparative Examples 12 and 13, since the addition amount of Co or Si was large, the electrical conductivity was low.

As described above, the present invention is applicable to an electronic material and has a 0.2% fall strength and electrical conductivity, and can improve dimensional stability when press working 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, and the balance is composed of Cu and unavoidable impurities; 0.2% of the rolling parallel direction is 500 MPa. The above, the 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, from {220} crystallizing The integrated X-ray diffraction intensity I{220}, the integrated X-ray diffraction intensity I{311} from the {311} crystal plane, satisfies (I{220}+I{311})/I{200} The relationship of 5.0. The copper alloy for electronic materials according to claim 1, wherein a difference of 0.2% of the 0.2% drop strength obtained by subtracting 0.2% of the rolling strength in the direction perpendicular to the rolling direction is 50 MPa or less. . The copper alloy for electronic materials according to claim 1 or 2, wherein the X-ray diffraction integrated intensity I{200} from the {200} crystal plane and the X-ray diffraction integrated intensity of the pure copper standard powder are obtained. I ₀ {200}, satisfying I{200}/I ₀ {200} The relationship of 1.0. The copper alloy for electronic materials according to the first or second aspect of the invention, which further contains 0.5% by mass or less of Cr. The copper alloy for electronic materials according to the first or second aspect of the invention, which further contains 2.0% by mass or less of Ni. The copper alloy for an electronic material according to the first or second aspect of the invention, which further contains 1.0% by mass or less of Zn and Sn, and contains 0.2% by mass or less of Mg, P, Ca and Mn, 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.