TWI381397B - Cu-Ni-Si-Co based copper alloy for electronic materials and its manufacturing method - Google Patents

Description

Cu-Ni-Si-Co copper alloy for electronic materials and manufacturing method thereof

The present invention relates to a precipitation hardening type copper alloy, and more particularly to a Cu-Ni-Si-Co based copper alloy suitable for use in various electronic machine parts.

For copper alloys for electronic materials used in various electronic equipment parts such as connectors, switches, relays, pins, terminals, lead frames, etc., it is required to have both high strength and high electrical conductivity (or thermal conductivity). Basic characteristics. In recent years, the high-integration, miniaturization, and thinning of electronic components have been rapidly progressing, and accordingly, the level of demand for copper alloys used in electronic component parts is gradually increasing.

From the viewpoint of high strength and high electrical conductivity, the use amount of the precipitation hardening type copper alloy is increasing in place of the solid solution strengthening type copper alloy represented by phosphor bronze, brass, or the like which is a copper alloy for electronic materials. In the precipitation hardening type copper alloy, by subjecting the solution-treated supersaturated solid solution to aging treatment, the fine precipitates are uniformly dispersed, and the strength of the alloy is increased while the amount of solid solution elements in the copper is increased. Reduced and improved conductivity. Therefore, a material excellent in mechanical properties such as strength and elasticity and excellent in electrical conductivity and thermal conductivity can be obtained.

Among the precipitation-hardened copper alloys, the Cu-Ni-Si-based copper alloy, which is generally called a Carson-based alloy, has a high copper alloy which is excellent in electrical conductivity, strength, and bending workability, and is widely used in the industry. One of the alloys developed. The copper alloy is obtained by precipitating fine Ni-Si-based intermetallic compound particles to Copper matrix to increase strength and electrical conductivity.

Attempts have been made to further improve its properties by adding Co to the Carson alloy.

In the same manner as in Ni, Co forms a compound with Si to improve the mechanical strength, and when the aging treatment is performed on the Cu-Co-Si system, the mechanical strength thereof is obtained. The conductivity is only slightly better than that of the Cu-Ni-Si alloy. It is also revealed that a Cu-Co-Si system or a Cu-Ni-Co-Si system may be selected if the cost permits. Further, it is also disclosed that the alloy is produced by recrystallization at 700 to 920 ° C after cold working, and secondly, cold working at 25% or less, and aging treatment at 420 to 550 ° C, and further cold working of 25% or less. And low temperature annealing method (patent application scope 10).

Japanese Laid-Open Patent Publication No. 2005-532477 (Patent Document 2) discloses a hot copper alloy comprising nickel: 1% to 2.5%, cobalt: 0.5 to 2.0%, lanthanum: 0.5% to 1.5%, and The remainder of the composition of copper and unavoidable impurities, the total content of nickel and cobalt is 1.7% to 4.3%, and the ratio of (Ni + Co) / Si is 2:1 to 7:1, and the hot copper alloy has more than Conductivity of 40% IACS. In combination with cobalt and ruthenium, in order to limit particle growth and improve softening resistance, a telluride effective for age hardening is formed. It is also disclosed that the alloy is manufactured by performing hot working at 850 ° C to 1000 ° C → performing solution treatment at 800 ° C to 1000 ° C → performing first aging annealing at a temperature of 350 ° C to 600 ° C for 30 minutes to 30 hours. → Performing a cold working to reduce the cross-sectional area by 10% to 50% → performing a second aging annealing at a temperature lower than the first aging annealing temperature (Patent No. 25, 26 items).

In the specification of the International Publication No. 2006/101172 (Patent Document 3), it is disclosed that, in the solution treatment, if the cooling rate after heating is intentionally increased, the effect of improving the strength of the Cu-Ni-Si alloy can be further exerted. The cooling rate is set to be about 10 ° C or more per second, and cooling is highly effective (paragraph 0028).

Japanese Laid-Open Patent Publication No. Hei 9-20943 discloses a method for producing a Cu-Ni-Si-Co alloy as follows: after hot rolling, a cold rolling of 85% or more is carried out, and it is carried out at 450 to 480 ° C for 5 to 30 minutes. After the annealing, cold rolling of 30% or less is carried out, and aging treatment is carried out at 450 to 500 ° C for 30 to 120 minutes (the fifth patent application).

[Patent Document 1] Japanese Patent Laid-Open No. Hei 11-222641

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2005-532477

[Patent Document 3] International Publication No. 2006/101172

[Patent Document 4] Japanese Patent Laid-Open No. 9-20943

As described above, it is known that the strength and conductivity are improved by the addition of Co to the Cu-Ni-Si-based alloy. However, the conventional Cu-Ni-Si-Co-based alloy has a problem that even if it is the same material, it depends on the measurement site. Mechanical properties such as strength, stress relaxation characteristics, and bending thickness are also likely to be deviated.

Therefore, one of the problems of the present invention is to provide a Cu-Ni-Si-Co alloy which has better mechanical and electrical properties and uniform mechanical properties. A copper alloy for electronic materials. Further, another object of the present invention is to provide a method for producing the above Cu-Ni-Si-Co alloy.

First, the present inventors have found that the size of crystal grains of the Cu-Ni-Si-Co alloy to date has a large variation, and large particles and small particles are mixed, and the unevenness of the crystal grain size has been ascertained. The deviation of mechanical properties is related. In the Cu-Ni-Si-Co alloy, since Co is added, it is necessary to carry out a solution treatment at a temperature higher than that of a usual Cu-Ni-Si alloy, and in addition, the recrystallized grains are easily coarsened. On the other hand, the second phase particles such as crystals or precipitates precipitated in the previous stage of the solution treatment step become obstacles and hinder the growth of the crystal grains. Therefore, the Cu-Ni-Si-Co alloy tends to have a large variation in recrystallized grains as compared with a conventional Cu-Ni-Si alloy.

Therefore, the inventors of the present invention conducted intensive studies on the method of reducing the variation of the recrystallized grains, and obtained the following findings: in the preceding stage of the solution treatment step, the fine second phase particles are preliminarily precipitated at equal intervals as much as possible. In the copper matrix phase, even if the solution treatment is carried out at a relatively high temperature, the crystal grains do not become too large due to the pinning effect of the second phase particles, and the pinning effect uniformly acts. Throughout the copper matrix phase, the size of the growing recrystallized grains can also be uniformized. Further, as a result, it is known that a Cu-Ni-Si-Co alloy having a small variation in mechanical properties can be obtained.

One aspect of the present invention completed in view of the above findings is a copper alloy for an electronic material containing Ni: 1.0 to 2.5% by mass, Co: 0.5 to 2.5% by mass, and Si: 0.3 to 1.2% by mass, the remainder being Cu and an unavoidable impurity are used. The average crystal grain size of the copper alloy for electronic material is 15 to 30 μm, and the average value of the difference between the maximum crystal grain size and the minimum crystal grain size of 0.5 mm ² per observation field is 10 μm or less.

In a specific embodiment, the copper alloy of the present invention further contains a maximum of 0.5% by mass of Cr.

In another specific embodiment, the copper alloy of the present invention further comprises one or more selected from the group consisting of Mg, Mn, Ag, and P in a total amount of 0.5% by mass in total.

In still another specific embodiment, the copper alloy of the present invention further comprises one or two selected from the group consisting of Sn and Zn in a total amount of 2.0% by mass in total.

In another specific embodiment, the copper alloy of the present invention further comprises one or more selected from the group consisting of As, Sb, Be, B, Ti, Zr, Al, and Fe in a total amount of 2.0% by mass in total.

In another aspect, the present invention is a method for producing a copper alloy, comprising the steps of: step 1, performing melt casting on an ingot having a desired composition; and step 2, at 950 ° C to 1050 ° C After heating for 1 hour, hot rolling is performed, the temperature at the end of hot rolling is 850 ° C or higher, and the average cooling rate from 850 ° C to 400 ° C is 15 ° C / s or more for cooling; Step 3, processing The degree is more than 85% cold rolling; step 4, aging treatment at 350~500 °C for 1~24 hours; step 5, solid solution treatment at 950 °C ~ 1050 °C, the material temperature is lowered from 850 °C to 400 The average cooling rate of °C is set to 15 °C / s or more Cooling is carried out; step 6, optional cold rolling; step 7, aging treatment; and step 8, optional cold rolling.

In still another aspect, the present invention is a copper-clad product comprising the above copper alloy.

In still another aspect, the present invention is an electronic machine component including the above copper alloy.

According to the present invention, the crystal grain size can be made uniform within an appropriate range, so that a Cu-Ni-Si-Co alloy having uniform mechanical properties can be obtained.

Ni, Co and Si addition amount

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

When the amounts of addition of Ni, Co, and Si are respectively Ni: less than 1.0% by mass, Co: less than 0.5% by mass, and Si: less than 0.3% by mass, the desired strength cannot be obtained. Conversely, if Ni: exceeds 2.5 mass%, Co: more than 2.5% by mass, and Si: more than 1.2% by mass, although high strength can be achieved, but the electrical conductivity is remarkably lowered, and the hot workability is deteriorated. Therefore, the addition amounts of Ni, Co, and Si are Ni: 1.0 to 2.5% by mass, Co: 0.5 to 2.5% by mass, and Si: 0.3 to 1.2% by mass. The addition amount of Ni, Co, and Si is preferably Ni: 1.5 to 2.0% by mass, Co: 0.5 to 2.0% by mass, and Si: 0.5 to 1.0% by mass.

Cr addition amount

Cr is preferentially precipitated to the crystal grain boundary during the cooling process during melt casting, so that the grain boundary can be strengthened, and cracks are less likely to occur during hot working, thereby suppressing a decrease in yield. In other words, Cr which is precipitated at the grain boundary during the melt casting is re-solid-solved by a solution treatment or the like, and when it is precipitated in the subsequent aging, a precipitated particle of a bcc structure containing Cr as a main component or a compound with Si is generated. In the conventional Cu-Ni-Si alloy, the amount of Si added does not contribute to the precipitation of Si, which inhibits the increase in conductivity in a state of being dissolved in the matrix phase, but is added as a deuteration. The Cr of the material forming element further precipitates the telluride, and 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, coarse second phase particles are easily formed, which may impair product characteristics. Therefore, in the Cu-Ni-Si-Co alloy of the present invention, 0.5% by mass of Cr can be added at the maximum. However, if it is less than 0.03 mass%, the effect is small, so it is preferably added in an amount of 0.03 to 0.5% by mass, more preferably 0.09 to 0.3% by mass.

Addition amount of Mg, Mn, Ag and P

When a small amount of Mg, Mn, Ag, and P is added, product characteristics such as strength and stress relaxation characteristics are improved without impairing electrical conductivity. The effect of addition is mainly achieved by solid-solving the Mg, Mn, Ag, and P in the matrix phase, but further effects can be exerted by including the Mg, Mn, Ag, and P in the second phase particles. However, if the total concentration of Mg, Mn, Ag, and P exceeds 0.5%, the property improving effect is saturated, and the manufacturability is impaired. Therefore, in the Cu-Ni-Si-Co alloy of the present invention, one or two or more selected from the group consisting of Mg, Mn, Ag, and P may be added in a total amount of 0.5% by mass. However, if it is less than 0.01% by mass, the effect is small, so it is preferable to add 0.01 to 0.5% by mass in total, and more preferably 0.04 to 0.2% by mass in total.

Addition amount of Sn and Zn

When a small amount of Sn and Zn are added, product properties such as strength, stress relaxation characteristics, and plating properties are improved without impairing the electrical conductivity. The effect of addition is mainly exerted by dissolving the above Sn and Zn in the matrix phase. However, when the total of Sn and Zn exceeds 2.0% by mass, the property improving effect is saturated and the manufacturability is impaired. Therefore, in the Cu-Ni-Si-Co alloy of the present invention, a total of 2.0% by mass or less of one or two selected from the group consisting of Sn and Zn can be added. However, if it is less than 0.05% by mass, the effect is small, so it is preferable to add 0.05 to 2.0% by mass in total, and more preferably 0.5 to 1.0% by mass in total.

As, Sb, Be, B, Ti, Zr, Al, and Fe

For As, Sb, Be, B, Ti, Zr, Al, and Fe, the amount of addition is adjusted according to the required product characteristics, thereby improving products such as conductivity, strength, stress relaxation characteristics, and plating properties. characteristic. The effect of addition is mainly achieved by dissolving the above As, Sb, Be, B, Ti, Zr, Al, and Fe in the matrix phase, but the second phase particles may contain the above-mentioned As, Sb, and Be, B, Ti, Zr, Al, and Fe, or the formation of a second phase particle of a new composition exerts a further effect. However, if the total of these elements exceeds 2.0% by mass, the property improving effect will be saturated and the manufacturability will be impaired. Therefore, in the Cu-Ni-Si-Co alloy of the present invention, a total of 2.0% by mass or more of one or more selected from the group consisting of As, Sb, Be, B, Ti, Zr, Al, and Fe may be added. . However, if it is less than 0.001% by mass, the effect is small because This is preferably 0.001 to 2.0% by mass in total, and more preferably 0.05 to 1.0% by mass in total.

When the total amount of Mg, Mn, Ag, P, Sn, Zn, As, Sb, Be, B, Ti, Zr, Al, and Fe added exceeds 3.0%, the manufacturability is liable to be impaired, so that the total amount of these is preferable. It is 2.0% by mass or less, more preferably 1.5% by mass or less.

Crystal grain size

The crystal grains have an effect on the strength, and the intensity is proportional to the -1/2 power of the crystal grain size, that is, the Hall-Petch equation generally holds. Further, the coarse crystal grains deteriorate the bending workability and become a cause of surface roughness during bending. Therefore, as for the copper alloy, in general, the fineness of the crystal grains can improve the strength, which is preferable. Specifically, it is preferably 30 μm or less, and more preferably 23 μm or less.

On the other hand, since the Cu-Ni-Si-Co alloy of the present invention is a precipitation strengthening type alloy, it is necessary to pay attention to the precipitation state of the second phase particles. The second phase particles which are precipitated into the crystal grains during the aging treatment contribute to the improvement of the strength, but the second phase particles which are precipitated to the crystal grain boundaries hardly contribute to the improvement of the strength. Therefore, in order to increase the strength, it is preferred to precipitate the second phase particles into the crystal grains. When the crystal grain size is small, the grain boundary area is increased, so that the second phase particles are preferentially precipitated to the grain boundary during the aging treatment. In order to precipitate the second phase particles into the crystal grains, the crystal grains must have a certain size. Specifically, it is preferably 15 μm or more, and more preferably 18 μm or more.

In the present invention, the average crystal grain size is controlled in the range of 15 to 30 μm. The average crystal grain size is preferably from 18 to 23 μm. Average crystal grain size By controlling such a range, the two effects of the strength improving effect by the grain size finening and the strength improving effect by precipitation hardening can be obtained in a balanced manner. Moreover, if it is the crystal grain size of this range, the outstanding bending workability and stress relaxation characteristic can be acquired.

In the present invention, the crystal grain size refers to the diameter of the smallest circle surrounding each crystal grain when the cross section parallel to the thickness direction of the rolling direction is observed by a microscope, and the average crystal grain size means the average of the crystal grain sizes. value.

In the present invention, the average value of the difference between the maximum crystal grain size and the minimum crystal grain size per observation field of 0.5 mm ² is 10 μm or less, preferably 7 μm or less. The average value of the difference is preferably 0 μm, but it is practically difficult to achieve, so the actual minimum value of the lower limit is set to 3 μm, and typically 3 to 7 μm. Here, the maximum crystal grain size refers to the largest crystal grain size observed in an observation field of 0.5 mm ² ; the so-called minimum crystal grain size refers to the smallest crystal grain observed in the same field of view. path. In the present invention, the difference between the maximum crystal grain size and the minimum crystal grain size is obtained in the observation field at a plurality of points, and the average value of the differences is taken as the average value of the difference between the maximum crystal grain size and the minimum crystal grain size.

The difference between the maximum crystal grain size and the minimum crystal grain size is small, which means that the crystal grain size is uniform, and the deviation of the mechanical properties of each measurement site in the same material is reduced. As a result, the quality stability of the copper-clad product or the electronic machine part obtained by processing the copper alloy of the present invention is improved.

Production method

In the general process of the Caston copper alloy, the atmospheric melting furnace is used first. The raw materials of electrolytic copper, Ni, Si, Co, and the like are melted to obtain a melt of a desired composition. The melt is then cast into an ingot. Thereafter, hot rolling is performed, and cold rolling and heat treatment are repeated to form a strip or foil having a desired thickness and characteristics. The heat treatment includes solution treatment and aging treatment. In the solution treatment, heating is performed at a high temperature of about 700 to 1000 ° C to dissolve the second phase particles in the Cu matrix and recrystallize the Cu matrix. Hot rolling is also used as a solution treatment. In the aging treatment, the temperature is heated in a temperature range of about 350 to about 550 ° C for 1 hour or more, and the second phase particles which have been solid-solved in the solution treatment are precipitated as fine particles of the nanometer order. In this aging treatment, the strength and electrical conductivity will increase. In order to obtain higher strength, cold calendering is sometimes performed before the aging treatment and/or after the aging treatment. Further, in the case where cold rolling is performed after the aging treatment, stress relief annealing (low temperature annealing) is performed after cold rolling.

At the intervals of the above steps, grinding, polishing, and shot blast pickling for removing rust scale on the surface are appropriately performed.

The copper alloy of the present invention is basically also subjected to the above-described process, but in order to control the deviation of the average crystal grain size and the crystal grain size within the range specified in the present invention, as described above, it is important that the solid solution treatment step is preceded by The fine second phase particles are preliminarily precipitated into the copper matrix phase at equal intervals and in the same manner. In order to obtain the copper alloy of the present invention, it is particularly necessary to pay attention to the following viewpoints for production.

First, coarse crystals are inevitably produced during the solidification process during casting, and coarse precipitates are inevitably generated during the cooling process during casting. Therefore, in the subsequent steps, the crystals must be crystallized. Solid solution In the mother phase. When the temperature is 950 ° C to 1050 ° C for 1 hour or more and then hot rolling, and the temperature at the end of hot rolling is 850 ° C or higher, even if Co is added and Cr is added, the above The crystals can also be dissolved in the parent phase. Temperature conditions above 950 ° C are higher than those of other Carson-based alloys. If the holding temperature before hot rolling is less than 950 ° C, the solid solution may be insufficient, and if it exceeds 1050 ° C, the material may be melted. Further, when the temperature at the end of the hot rolling is less than 850 ° C, the elements which have been solid-solved are precipitated again, so that it is difficult to obtain high strength. Therefore, in order to obtain high strength, it is preferred to terminate the hot rolling at 850 ° C and rapidly cool it.

At this time, if the cooling rate is slow, the Si-based compound containing Co or Cr will be precipitated again. When the heat treatment (aging treatment) for increasing the strength is carried out by using such a composition, the precipitate which precipitated during the cooling process is the core and grows into a coarse precipitate which does not contribute to the improvement of strength, so that high strength cannot be obtained. Therefore, it is necessary to increase the cooling rate as much as possible, specifically, 15 ° C / s or more. However, since the precipitation of the second phase particles is remarkable at a temperature of up to about 400 ° C, the cooling rate at a temperature of less than 400 ° C is not a problem. Therefore, in the present invention, the average cooling rate of the material temperature from 850 ° C to 400 ° C is 15 ° C / s or more, preferably 20 ° C / s or more, and is cooled. The so-called "average cooling rate from 850 ° C to 400 ° C" refers to the measurement of the cooling time of the material temperature from 850 ° C to 650 ° C, and by "(850-400) ( ° C) / cooling The value (°C/s) calculated from time (s).

As a method of speeding up cooling, water cooling is most effective. However, the cooling rate varies depending on the temperature of the water used for water cooling, so the water temperature can be used Management to further accelerate cooling. If the water temperature is 25 ° C or more, the required cooling rate may not be obtained, and therefore it is preferably kept at 25 ° C or lower. If the material is placed in a tank for water storage and water-cooled, the temperature of the water will rise and easily become 25 ° C or higher. Therefore, it is preferred to spray in a mist (shower or mist) to fix it. The water temperature (below 25 ° C) cools the material or allows the constant low temperature water to flow in the water tank to prevent the water temperature from rising. Further, by adding a water-cooling nozzle or increasing the amount of water per unit time, the cooling rate can also be increased.

Cold rolling is performed after hot rolling. In order to uniformly precipitate the precipitate, the cold rolling is performed to increase the distortion at the deposition position, and it is preferable to carry out cold rolling at a rolling reduction ratio of 85% or more, and more preferably to perform cold rolling at a rolling reduction ratio of 95% or more. Calendering. If the solution treatment is carried out shortly after hot rolling without cold rolling, the precipitates are not uniformly deposited. The combination of hot rolling and subsequent cold rolling can also be suitably repeated.

The first aging treatment is performed after cold rolling. If the second phase particles remain before the step is carried out, when the step is carried out, the second phase particles will further grow, so that the second phase particles initially precipitated in this step have a difference in particle size, but In the present invention, since the second phase particles are substantially eliminated in the step of the preceding stage, the fine second phase particles can be uniformly precipitated in a uniform size.

However, if the aging temperature of the first aging treatment is too low, the amount of precipitation of the second phase particles which bring the pinning effect is reduced, and only the pinning effect by the solution treatment can be partially obtained, and thus the crystal grains are The size becomes uneven. On the other hand, if the aging temperature is too high, the second phase particles become coarse. Further, since the second phase particles are unevenly precipitated, the particle size of the second phase particles becomes uneven. Further, the longer the aging time, the more the second phase particles grow, and it is necessary to set an appropriate aging time.

The first aging treatment is performed at 350 to 500 ° C for 1 to 24 hours, preferably at a temperature of 350 ° C or higher and less than 400 ° C for the first aging treatment for 12 to 24 hours, at 400 ° C or higher and less than 450 ° C. The temperature is subjected to the first aging treatment for 6 to 12 hours, and the first aging treatment is performed at a temperature of 450 ° C or higher and less than 500 ° C for 3 to 6 hours, whereby the fine second phase particles can be uniformly deposited to In the mother phase. In the case of such a composition, the growth of the recrystallized grains generated in the solution treatment in the next step can be similarly pinned, and the composition of the whole grains having a small variation in crystal grain size can be obtained.

The solution treatment is carried out after the first aging treatment. Here, while the second phase particles are solid-solved, fine and uniform recrystallized grains are grown. Therefore, the solution temperature must be set to 950 ° C to 1050 ° C. Here, the recrystallized grains are first grown, and thereafter, since the second phase particles precipitated in the first aging treatment are solid-solved, the growth of the recrystallized grains can be controlled by the pinning effect. However, since the pinning effect disappears after solid solution of the second phase particles, if the solution treatment is continuously performed for a long period of time, the recrystallized grains become large. Therefore, the time for the appropriate solution treatment is 60 seconds to 300 seconds, preferably 120 to 180 seconds at a temperature of 950 ° C or more and less than 1000 ° C; and 1000 ° C or more and less than 1050 ° C. The temperature is 30 seconds to 180 seconds, preferably 60 seconds to 120 seconds.

Even in the cooling process after solution treatment, in order to avoid precipitation of the second phase particles, the average temperature of the material temperature decreases from 850 ° C to 400 ° C However, the speed should be 15 ° C / s or more, preferably 20 ° C / s or more.

A second aging treatment is performed after the solution treatment. The condition of the second aging treatment may be a condition that is practically used for the fineness of the precipitate, but care must be taken to set the temperature and time so that the precipitate does not coarsen. One of the conditions for aging treatment is as follows: a temperature range of 350 to 550 ° C for 1 to 24 hours, more preferably a temperature range of 400 to 500 ° C for 1 to 24 hours. Furthermore, the cooling rate after the aging treatment hardly affects the size of the precipitate. In the case of the second aging treatment, the precipitation position is increased, and the precipitation position is used to promote age hardening, thereby achieving strength improvement. In the case of the second aging treatment, the precipitate is used to promote work hardening, thereby achieving strength improvement. Cold rolling may also be performed before and/or after the second aging treatment.

The Cu-Ni-Si-Co alloy of the present invention can be processed into various copper-exposed products, for example, can be processed into plates, strips, tubes, rods and wires, and in addition, the Cu-Ni-Si-Co-based copper alloy of the present invention can be processed. Used for electronic components such as lead frames, connectors, pins, terminals, relays, switches, and foils for secondary batteries.

[Examples]

In the following, the embodiments and the comparative examples of the present invention are shown, but the present invention is not intended to limit the present invention.

In a high-frequency melting furnace, a copper alloy having the composition shown in Table 1 (Example) and Table 2 (Comparative Example) was melted at 1300 ° C, and cast into an ingot having a thickness of 30 mm. Next, after heating the ingot to 1000 ° C, it is hot rolled until the thickness is 10 mm, and the rising temperature (hot rolling) The temperature at the end was set to 900 °C. After the completion of the hot rolling, the average cooling rate when the material temperature was lowered from 850 ° C to 400 ° C was set to 18 ° C / s, and water-cooling was carried out, followed by being placed in the air for cooling. Next, surface cutting was performed to remove the scale of the surface to a thickness of 9 mm, and then a plate having a thickness of 0.15 mm was formed by cold rolling. Then, after performing the first aging treatment for 3 to 12 hours at various aging temperatures, the solution treatment is carried out at various solid solution temperatures for 120 seconds, and immediately after the material temperature is lowered from 850 ° C to 400 ° C, the average cooling is performed. The temperature was set to 18 ° C / s and water-cooled, and then placed in the air for cooling. Next, cold rolling was carried out until the thickness was 0.10 mm, and the second aging treatment was carried out at 450 ° C for 3 hours in an inert atmosphere, and finally cold rolling was performed until the thickness was 0.08 mm, thereby producing a test piece.

Hereinafter, various characteristics of each test piece obtained in the above manner were evaluated.

(1) Average crystal grain size

The crystal grain size is such that the observation surface is a cross section parallel to the thickness direction of the rolling direction, the sample is embedded in the resin, and the observation surface is mirror-polished by mechanical polishing, and then mixed with water of 100 parts by volume. In a solution of 10 parts by volume of 36% hydrochloric acid, the dissolved iron is 5% by weight of the solution. The sample was immersed in the solution prepared in the above manner for 10 seconds to cause a metal composition to appear. Next, the metal composition was magnified 100 times by an optical microscope, and an observation field of 0.5 mm ² was taken as a photograph, and the diameter of all the smallest circles surrounding each crystal grain was determined, and the average value was calculated for each observation field, and 15 points were obtained. The average value of the visual field was observed as the average crystal grain size.

(2) The average of the difference between the maximum crystal grain size and the minimum crystal grain size

Regarding the crystal grain size measured at the time of obtaining the average crystal grain size, the difference between the maximum value and the minimum value was obtained for each field of view, and the average value of the observation fields at 15 points was taken as the maximum crystal grain size - the smallest crystal grain size. The average of the difference in diameter.

(3) Intensity

Regarding the strength, a tensile test in the parallel direction of rolling was performed, and an endurance of 0.2% (YS: MPa) was measured. The deviation of the strength of the measurement site is the difference between the maximum intensity and the minimum intensity at 30, and the average intensity is the average of the 30 points.

(4) Conductivity

The conductivity (EC: % IACS) was determined by measurement of the volume resistivity of the double bridge. The deviation of the conductivity of the measurement site was the difference between the maximum intensity and the minimum intensity at 30, and the average conductivity was the average of the 30 points.

(5) Stress relaxation characteristics

As for the stress relaxation characteristics, as shown in Fig. 1, the test piece having a thickness of 10 mm × 100 mm and a thickness of t = 0.08 mm is used, and the gauge length is 25 mm, and the load stress at the height y ₀ is 0.2%. The height is determined by 80%, and the bending stress is applied. The permanent deformation amount (height) y shown in Fig. 2 after heating at 150 ° C for 1000 hours is measured to calculate the stress relaxation rate {[1-(yy ₁ )]. (mm) / (y _{0 -} y ₁ ) (mm)] × 100 (%)}. Furthermore, y ₁ is the initial warpage height before the load stress. The deviation of the stress relaxation rate at the measurement site was the difference between the maximum strength and the minimum strength at 30 points, and the average stress relaxation rate was the average of the 30 points.

(6) Bending workability

The bending workability is evaluated by the surface roughness of the bent portion. The W bending test of the Badway (the bending axis and the rolling direction are the same direction) was carried out in accordance with JIS H 3130, and the surface of the curved portion was analyzed by a conjugated focal laser microscope to obtain Ra (μm) defined in JIS B 0601. The deviation of the bending thickness of the measurement portion is the difference between the maximum Ra and the minimum Ra at 30 points, and the average bending thickness is the average value of Ra at the 30 points.

The alloy of No. 1 to 34 is an embodiment of the present invention, and has strength and electrical conductivity suitable for an electronic material, and variations in characteristics are also small.

The alloys of No. 35 to 37 and 46 to 48 were not subjected to the first aging treatment, and when the solution treatment was performed, the crystal grain size became coarse, and the strength and the bending workability were deteriorated.

Regarding the alloys of No. 38, 39, 42, 44, 49, and 50, since the aging temperature of the first aging treatment is too low and the second phase particles are small, the crystal grain size becomes coarse and the strength is increased during the solution treatment. And the bending workability is deteriorated. Moreover, the variation in crystal grain size increases. As a result, the variation in characteristics becomes large.

Regarding the alloys of Nos. 40, 41, 43, 45, and 51 to 54, since the aging temperature of the first aging treatment is too high, the second phase particles are unevenly grown, and thus the crystal grain size is uneven. As a result, the variation in characteristics becomes large.

Regarding No. 55 and 56, since the amount of addition of Co is too large, strength and electrical conductivity are deteriorated.

No. 57-60 was not subjected to the first aging treatment, and the solid solution temperature was low. The second phase particles are not sufficiently solid-dissolved, and the crystal grains are too small, so that the strength and stress relaxation characteristics are deteriorated.

L‧‧‧ gauge length

T‧‧‧thickness

Y‧‧‧ permanent deformation (height)

y ₀ ‧‧‧height

Figure 1 is an explanatory diagram of the stress relaxation test method.

Fig. 2 is an explanatory diagram of the amount of permanent deformation of the stress relaxation test method.

Claims (4)

A copper alloy for electronic materials, comprising: Ni: 1.0 to 2.5% by mass, Co: 0.5 to 2.5% by mass, Si: 0.3 to 1.2% by mass, Cr: 0 to 0.5% by mass, selected from Mg, Mn, Ag, and 1 or more of P: 0 to 0.5% by mass in total, one or two selected from the group consisting of Sn and Zn: 0 to 2.0% by mass in total, selected from As, Sb, Be, B, Ti, Zr One or more of Al and Fe: 0 to 2.0% by mass in total, and the remainder consists of Cu and unavoidable impurities; the average crystal grain size is 15 to 30 μm, and the maximum per field of observation is 0.5 mm ² The average value of the difference between the crystal grain size and the minimum crystal grain size is 10 μm or less. A method for producing a copper alloy for manufacturing a copper alloy for an electronic material according to the first aspect of the patent application, comprising the steps of: step 1, performing melt casting on an ingot having a desired composition; and step 2; After heating at 950 ° C to 1050 ° C for 1 hour, hot rolling is performed, and the temperature at the end of hot rolling is 850 ° C or higher, and the average cooling rate from 850 ° C to 400 ° C is 15 ° C / s or more for cooling. Step 3: performing cold rolling with a processing degree of 85% or more; step 4, performing aging treatment at 350 to 500 ° C for 1 to 24 hours; and step 5, performing solid solution treatment at 950 ° C to 1050 ° C for material temperature Cooling is performed by setting the average cooling rate from 850 ° C to 400 ° C to 15 ° C / s or more; step 6, performing random cold rolling; step 7, performing aging treatment; In step 8, random cold rolling is performed. A copper-strength product obtained by processing a copper alloy for an electronic material of the first application of the patent scope into a plate, a strip, a tube, a rod or a wire. An electronic machine part having the copper alloy for electronic materials of claim 1 of the patent application.