JP6301618B2 - Copper alloy material and method for producing the same - Google Patents

Description

  The present invention relates to a copper alloy material having a strength and conductivity suitable for applications such as terminals, connectors, switches, relays, lead frames, and the like, and having good pretreatment properties for plating and plating, and a method for producing the same. Is.

  With the recent miniaturization and higher performance of electrical and electronic equipment, materials such as connectors used in such equipment have been required to have stricter characteristics, and have high strength and high electrical conductivity. The development of copper alloy materials is progressing.

  In conventional connectors, CDA alloy beryllium copper (JIS-C1720 alloy) has been used when high strength characteristics are required. However, in recent years, there is a concern about the use of metal beryllium from the viewpoint of the toxicity of metal beryllium. It has spread. For this reason, contact materials for connectors and the like have been strongly desired to have materials having characteristics equivalent to those of beryllium copper, inexpensive, and highly safe. Therefore, as an alloy system having higher conductivity than such beryllium copper, a Cu—Ni—Si alloy (Corson alloy) has been developed in recent years.

Cu-Ni-Si alloys improve strength and electrical conductivity by uniformly dispersing finely intermetallic compounds containing Ni and Si (Ni ₂ Si, etc.) into the copper alloy matrix at a nanometer size. Can be made. Cu-Ni-Si alloy by increasing the amount of Ni and Si and increasing the amount of dispersion of the compound containing Ni and Si, because the shorter the distance between the particles of the compound, the higher the strength characteristics can be obtained. The strength is further increased.

  On the other hand, copper alloys used for electronic devices are usually plated with precious metals and the like, and pickling is performed as a base treatment. However, in Cu—Ni—Si based alloys, Ni and Si are used during pickling. May oxidize and remain on the surface as a smut. If the smut remains on the surface of the Cu-Ni-Si-based alloy, it causes plating abnormalities (plating peeling, plating hump, etc.), so such smut is removed from the surface of the Cu-Ni-Si-based alloy as much as possible. There is a need to.

  However, as described above, in a Cu-Ni-Si alloy, if the amount of the compound containing Ni and Si is increased in accordance with the demand for high strength and high conductivity, smut is generated during pickling. Since the amount tends to increase, there is a problem in that the smut remains without being removed and causes plating abnormality. Particularly in applications of electronic devices, there is a possibility that corrosion resistance after plating of noble metals such as Au cannot be sufficiently obtained due to poor plating.

As a technique for reducing the remaining amount of smut in the Cu—Ni—Si based alloy material, for example, Patent Document 1 discloses that the Ni ₂ Si precipitate particle size is limited to 10 nm or less, and the content of Ni and Si. It is disclosed that the smut remaining at the time of pickling is suppressed by limiting the thickness.

Further, Patent Document 2 discloses a copper alloy for electronic materials in which etching properties and the like are improved by making coarse inclusions of 5 to 10 μm less than 50 pieces / mm ² in a rolling parallel cross section.

Japanese Patent No. 3056394 Japanese Patent No. 3383615

However, it is essential for the copper alloy described in Patent Document 1 to contain a high concentration of Zn, and in particular, the grain size of the Ni ₂ Si precipitate must be controlled within a range of 10 nm or less. Thus, the smut cannot be removed effectively. In addition, in order to obtain high strength and high conductivity, it is more difficult to remove smut when it is necessary to further improve the amount of fine precipitates produced by containing high concentrations of Ni and Si. There is a problem.
Moreover, since the copper alloy described in Patent Document 2 may be present if the number of coarse inclusions of 5 to 10 μm is less than 50 pieces / mm ² , the existence of such coarse inclusions Is not preferable from the viewpoint of removing smut. In addition, in order to obtain high strength and high conductivity, when it is necessary to further improve the amount of fine precipitates containing high concentrations of Ni and Si, it is difficult to remove smut. is there.
For this reason, the techniques of Patent Documents 1 and 2 both control the size and amount of a compound containing Ni and Si for removing smut, but higher strength and higher conductivity are required. In recent copper alloys, a composition containing high concentrations of Ni and Si, and to develop a technology that can easily remove smuts by washing even in situations where smuts are more likely to occur than conventional copper alloys. Was needed.

  The present invention is a copper alloy material having high strength and high electrical conductivity in view of the above-mentioned problems of the prior art, and further having a low residual rate of smut and excellent corrosion resistance after Au plating. And it aims at providing the manufacturing method.

  As a result of intensive studies to solve the above problems, the present inventors have determined that the major axis of the precipitate (compound) containing Ni and Si is α nm, in a copper alloy material containing a specific amount of Ni and Si. When the minor axis is β nm, the minor axis β is more than 2 nm and less than 10 nm, and the ratio of the major axis α to the minor axis β of the precipitate, that is, the aspect ratio is optimized to maintain high strength and high conductivity characteristics. However, the present inventors have found that a copper alloy material having improved smut cleaning properties and excellent corrosion resistance after Au plating and a method for producing the same can be provided. The present invention has been completed based on this finding.

That is, the gist configuration of the present invention is as follows.
(1) Ni: 2.0 to 6.0 mass%, Si: 0.3 to 2.0 mass%, Cr: 0 to 1.0 mass%, Mg: 0 to 1.0 mass%, Sn: 0 -0.8 mass% and Zn: a copper alloy material containing 0-0.8 mass%, the balance consisting of Cu and inevitable impurities,
When the major axis of the precipitate containing Ni and Si is α nm and the minor axis is β nm, the minor axis β is more than 2 nm and less than 10 nm,
The copper alloy material, wherein the ratio α / β of the major axis to the minor axis of the precipitate is less than 5.

  (2) Cr: The copper alloy material according to (1) above, containing 0.05 to 1.0% by mass.

  (3) The alloy material includes at least one selected from the group consisting of Mg: 0.05 to 1.0 mass%, Sn: 0.05 to 0.8 mass%, and Zn: 0.05 to 0.8 mass%. The copper alloy material according to (1) or (2) above, wherein the total amount of seed components is 0.05 to 2.6% by mass.

  (4) The copper alloy material according to (1), (2) or (3) above, wherein the remaining area ratio of the surface smut is less than 3%.

(5) A method for producing a copper alloy material having at least melting, casting, homogenizing heat treatment, hot working, cold working, solution treatment, aging heat treatment, and finish cold working in this order,
In the homogenization heat treatment, the first stage is performed at a temperature of 1000 ° C. or more and 1055 ° C. or less for 30 minutes or more and 1 hour or less, and subsequently, the second stage is cooled to 800 ° C. or more and less than 1000 ° C.,
The hot working is continuously performed after the homogenization treatment, and is finished at a temperature of 600 ° C. or higher.
The solution treatment is performed in a range of 800 ° C. to 1000 ° C., 5 seconds to 300 seconds,
The aging heat treatment is performed without performing cold working after the solution treatment, and is heated from room temperature to 200 ° C. at a temperature increase rate of 0.3 ° C./min to less than 4 ° C./min. A temperature raising stage, and a second temperature raising stage for heating from 200 ° C. to the holding temperature at a temperature rising rate of 2 ° C./min to 4 ° C./min and higher than the temperature rising rate in the first temperature rising stage; The temperature is raised in the two-stage heating stage of the above, and subsequently held at a temperature of 400 ° C. or more and 500 ° C. or less for 0.5 hour or more and 6 hours or less. The manufacturing method of the copper alloy material characterized by cooling with.

According to the present invention, in a copper alloy material containing relatively high concentrations of Ni and Si, when the major axis of the precipitate (compound) containing Ni and Si is α nm and the minor axis is β nm, the minor axis β By maintaining the ratio of the major axis α to the minor axis β of the precipitate (compound), that is, the aspect ratio, by maintaining and improving the high strength and high conductivity characteristics, the smut cleaning property is maintained. In addition, it has become possible to provide a copper alloy material having excellent corrosion resistance after Au plating.
Further, according to the present invention, the temperature at which Ni and Si are dissolved during the solution treatment, and the temperature rising temperature from room temperature to 200 ° C. and the temperature rising temperature from 200 ° C. to the holding temperature during the aging heat treatment, continue. By maintaining the holding temperature and holding time, and the cooling rate at the subsequent holding temperature to 200 ° C., the smut cleaning performance is improved while maintaining the above-described high strength and high conductivity characteristics. In addition, it has become possible to provide a method for producing a copper alloy material having excellent corrosion resistance after Au plating.

  Next, a typical Cu—Ni—Si based copper alloy material according to the present invention will be described below. In addition, embodiment shown below has illustrated only typical embodiment used in order to demonstrate this invention concretely, and can take various embodiment in the scope of this invention. In addition, the copper alloy material of the present invention is formed by rolling, and is particularly called “plate material” when formed into a plate or strip, and “bar material” when formed into a rod or wire. Or “wire”.

(Alloy components)
First, the alloy elements used for the copper alloy material of the present invention will be described. Cu-Ni-Si-based copper alloys are aging precipitation that improves strength and electrical conductivity by uniformly dispersing and precipitating Ni and Si-containing compounds (mainly Ni ₂ Si compounds) on the copper matrix in the nanometer order. Type alloy.

  In the present invention, the content of Ni (nickel) is 2.0 to 6.0 mass%, and the content of Si (silicon) is 0.3 to 2.0 mass%. If the content of any element of Ni or Si is less than the lower limit, the strength improvement due to aging precipitation is insufficient. On the other hand, if the content of any element exceeds the upper limit, crystals formed during casting The formation of exudates increases, resulting in an increase in undissolved compounds and a significant increase in the amount of smut generated. Therefore, the Ni content is particularly preferably 3.5% by mass or more and the Si content is 0.4% by mass or more from the point of strength improvement, and the Ni content is particularly preferable from the viewpoint of manufacturability. The amount is preferably 5.0% by mass or less, and the Si content is preferably 1.8% by mass or less.

  Next, the content range of each element in the case of containing chromium (Cr), magnesium (Mg), tin (Sn), and zinc (Zn) will be described. If necessary, these elements are Cr: 0.05 to 1.0% by mass, Mg: 0.05 to 1.0% by mass, Sn: 0.05 to 0.8% by mass, and Zn: 0. At least 1 sort (s) chosen from the group of 05-0.8 mass% can be contained.

  Cr forms silicides in the form of binary system of Cr-Si and multi-system of Ni-Cr-Si, and suppresses the movement of grain boundaries during solution treatment to make the parent phase crystal grain size finer. This contributes to suppression of grain boundary reaction type precipitation. If the amount of Cr added is less than 0.05% by mass, the effects of grain boundary migration and grain boundary reaction type precipitation suppression cannot be obtained, while Cr exceeding 1.0% by mass may be added. , It does not contribute to strength, grain boundary migration and grain boundary reaction type precipitation control, and the number of coarse particles increases, resulting in poor strength and plating properties. Therefore, the content of Cr is preferably 0.05 to 1.0% by mass, and Cr is preferably limited to a total amount of less than 2.0% by mass in combination with additive elements other than Ni and Si. .

  Mg exists in a form that dissolves in the matrix phase, and suppresses the formation of grain boundary reaction type precipitation and has an effect of improving stress relaxation characteristics. If the amount of Mg added is less than 0.05% by mass, the improvement effect cannot be expected. On the other hand, if Mg is added in an amount exceeding 1.0% by mass, the conductivity is significantly lowered. Therefore, the content of Mg is preferably 0.05 to 1.0% by mass, and Mg is preferably limited to a total amount of less than 2.0% by mass in combination with additive elements other than Ni and Si. .

  Sn exists in a solid solution form in the matrix phase, and suppresses the formation of grain boundary reaction type precipitation and improves the stress relaxation characteristics. If the addition amount of Sn is less than 0.05% by mass, the improvement effect is weak. On the other hand, if Sn is added in excess of 0.8% by mass, the electrical conductivity is lowered, and particularly hot workability is remarkably reduced. I will let you. Therefore, the Sn content is preferably 0.05 to 0.8% by mass, but Sn may not be added as long as the stress relaxation characteristics can be sufficiently satisfied with a Ni—Si compound. In addition, Sn is preferably limited to a total amount of less than 2.0% by mass together with additive elements other than Ni and Si.

  Zn exists in the form of a solid solution in the matrix phase, and has the effect of enhancing the hot workability and improving the plating adhesion while promoting the grain boundary reaction type precipitation. When the addition amount of Zn is less than 0.05% by mass, the improvement effect is weak. On the other hand, when Zn is added in excess of 0.8% by mass, the conductivity is lowered, and grain boundary reaction type precipitation is promoted. Strength will fall. Therefore, the Zn content is preferably 0.05 to 0.8% by mass, but it may not be added if the plating adhesion can be sufficiently secured by controlling the precipitates. In addition, Zn is preferably limited to a total amount of less than 2.0% by mass together with additive elements other than Ni and Si.

  When Mg, Sn, Zn is contained, one or more elements selected from the group of Mg, Sn, Zn can be contained in a total amount of 0.05 to 2.6% by mass, and Mg, Sn, Zn Based on the above-mentioned characteristics obtained by the addition of, it can be added to the copper alloy of the present invention in a prescribed addition amount as necessary.

(Organizational form)
Next, the favorable structure | tissue form of the copper alloy in this invention is demonstrated. In the smut to be removed in the present invention, Si contained mainly in the alloy component is oxidized and adsorbed at the time of pickling to remain on the surface of the copper alloy material. When the volume fraction of the precipitate containing Ni and Si is increased, the amount of smut formed increases, but the present inventors controlled the shape of the precipitate as described above, and subsequently washed the smut. I found that the sex is very different. That is, among the precipitates (compounds) in the copper alloy, the ratio α / β (aspect ratio) of the major axis αnm to the minor axis βnm of the deposit is controlled to be less than 5 (α / β <5). That is, the smut detergency can be improved by controlling the shape of the precipitate. When α / β is 5 or more, the oxide is not exposed on the surface of the copper alloy material but is partially buried in the base material, and as a result, the smut is poorly cleaned. Therefore, the ratio α / β of the major axis αnm to the minor axis βnm of the precipitate needs to satisfy less than 5 (α / β <5), and is preferably in the range of 1 or more and 4 or less. Note that the closer the value of α / β is to 1, the closer the precipitate is to a spherical shape.

  Since the particle size of the precipitate containing Ni and Si can affect the strength, it is necessary to control it within a certain range. The relationship between the strength of the material and the precipitate is generally explained by the Orowan mechanism or the cutting mechanism, and it is said that the dominant mechanism differs depending on the size of the particle size. Also in the present invention, when the particle diameter of the precipitate containing Ni and Si is too large, strengthening by the Orowan mechanism becomes dominant, and the strength decreases as the particle diameter increases. Moreover, when the particle diameter of the precipitate containing Ni and Si is too small, strengthening by the cutting mechanism becomes dominant, and the strength decreases as the particle diameter decreases. Therefore, the minor axis β of the precipitate containing Ni and Si needs to be 2 nm <β <10 nm. The major axis α of the precipitate containing Ni and Si is 2 nm <α <50 nm.

  In Cu-Ni-Si based copper alloy materials, the undissolved deposits called smuts remain on the surface in the pickling process before plating, causing plating defects. It needs to be as low as possible. The residual amount of smut can be measured by a general measurement method. For example, after degreasing and cleaning the manufactured alloy material, it is immersed in a pickling solution containing sulfuric acid and hydrogen peroxide solution for a predetermined time, and subsequently By ultrasonic cleaning, the amount of smut remaining on the surface of the alloy material can be measured. If the remaining area ratio of the smut is 3% or more, as described above, defective plating due to the occurrence of the smut increases, so the remaining area ratio of the smut is preferably less than 3%.

(Production method)
Next, the manufacturing method of the copper alloy material of this invention is demonstrated. The copper alloy material of the present invention can be manufactured by a manufacturing method having, for example, melting, casting, homogenizing treatment, hot working, cold working, solution treatment, aging heat treatment, and finish cold working in this order. It is. Note that chamfering may be performed after hot working. After the finish cold working, low temperature annealing for tempering may be performed. In each process, for example, by performing the following control, it is possible to manufacture a copper alloy material having good characteristics while achieving the above-described structure form.

  Melting and casting can be performed by known methods. The above-described copper alloy having the components of the copper alloy material of the present invention is melted and cast. When segregation of components occurs in casting, the Ni and Si concentrations locally increase and decrease, causing fluctuations in strength, uneven generation of smut, and the like. Although it is desirable to remove such segregation as much as possible by controlling the cooling system in the solidification process or the like, the degree of influence can be reduced by carrying out the homogenization described below.

  The homogenization process is performed in two steps. First, in the first stage, holding is performed at a temperature of 1000 ° C. to 1055 ° C. for 30 minutes to 1 hour. Thereafter, in the second stage, cooling is performed once to a temperature of 800 ° C. or higher and lower than 1000 ° C. The holding is not particularly necessary because it may be cooled to less than 1000 ° C. However, the holding is performed in less than 30 minutes. It is preferably within 10 minutes, particularly preferably within 3 minutes. In addition, the 1st stage and 2nd stage of a homogenization process, and the subsequent hot processing are implemented continuously. By holding the material at a temperature of 1000 ° C. or more and 1055 ° C. or less in the first stage of the homogenization heat treatment, segregation is further relaxed and the subsequent control of the compound containing Ni and Si can be performed effectively. When the temperature of the first stage exceeds 1055 ° C., melting starts from the grain boundary, and segregation is promoted. If the temperature is lower than 1000 ° C., the temperature is low and proper homogenization cannot be performed. In addition, the reason for cooling to 800 ° C. or higher and 1000 ° C. or lower in the second stage of the homogenizing heat treatment is to stably perform the subsequent hot working. When the temperature in the second stage of the homogenization heat treatment is below 800 ° C., coarse precipitated particles remain, and the precipitated particles remain without being erased even during the solution treatment, which causes a decrease in strength.

  Hot working begins immediately after the second stage of the homogenization heat treatment. The hot working starts hot working between 800 ° C. and 1000 ° C. and ends at a temperature of 600 ° C. or higher. In the case of producing a plate / strip product, the hot working is preferably hot rolling, but may be a method such as hot extrusion or hot forging. When the hot working is performed at a temperature lower than 600 ° C., the precipitated particles remain and affect the solution treatment and the aging heat treatment. As a result, the shape of the precipitate containing Ni and Si is changed to the aspect ratio described above. It becomes difficult to control within the range. This hot working is performed at a working rate of 70 to 99%.

  Subsequently, the thickness is adjusted by cold working such as rolling. In this cold working, cold working is usually performed at a working rate of 50 to 99%.

  In solution treatment after cold working, it is better to dissolve Ni and Si as much as possible. This is because if Ni or Si-based compounds remain after the solution treatment, the shape of Ni and Si precipitates cannot be controlled within the above-mentioned aspect ratio range. Also, in the solution treatment process, recrystallization of the parent phase and coarsening of the parent phase crystal grains proceed, but even if some of the parent phase crystal grains are coarsened, it is better to prioritize solid solution to improve smut cleaning properties. It is good from the viewpoint. From such a point, the solution treatment is performed in the temperature range of 800 ° C. or higher and 1000 ° C. or lower and the processing time is 5 seconds or longer and 300 seconds or shorter. It is preferable to select in the range where the average crystal grain size of the matrix is 10 to 30 μm. After the solution treatment, the solution is cooled to room temperature at a cooling rate of 50 ° C./second or more by forced air cooling, water cooling, or the like to maintain solid solution of Ni and Si.

  It is desirable that the aging heat treatment is performed after the solution treatment without performing cold working. If dislocations due to strain remain in the material before aging, compounds containing Ni and Si are likely to be coarsened by precipitation on the dislocations, and the shape of precipitates containing Ni and Si This is because it cannot be controlled. In the present invention, the shape of the precipitate containing Ni and Si, that is, the aspect ratio can be controlled within the range of α / β <5 by managing the conditions of the aging heat treatment. Specifically, it is achieved by strictly controlling the temperature rising rate, holding temperature and holding time, and cooling rate in the aging heat treatment during the manufacturing process of the copper alloy material.

  The temperature increase rate needs to be adjusted by two temperature increase steps, and the temperature increase rate from room temperature to 200 ° C. is adjusted as the first temperature increase step. In the first temperature raising step, if the temperature raising rate is less than 0.3 ° C./min, it takes too much time from an industrial point of view. On the other hand, if the temperature raising rate is 4 ° C./min or more, it is uniform. Temperature accelerating rate from room temperature to 200 ° C. is 0.3 ° C./min or more and less than 4 ° C./min, preferably 0.5 ° C./min or more and 2 ° C./min or less. is there. Conventionally, it was thought that the temperature range from room temperature to 200 ° C. did not particularly affect the precipitation phenomenon, so it was unexpected that controlling this temperature range would promote uniform nucleation. It was. Subsequently, as the second temperature raising step, the temperature raising rate from 200 ° C. to the holding temperature is adjusted. Even in the second temperature raising step, if the temperature rising rate is less than 2 ° C./min, it takes too much time from an industrial point of view. On the other hand, if the temperature rising rate exceeds 4 ° C./min, it is uniform. Since no nucleation is promoted, the rate of temperature increase from 200 ° C. to the holding temperature is 2 ° C./min to 4 ° C./min, preferably 2.3 ° C./min to 4 ° C./min. . At that time, it is important that the temperature increase rate in the second stage temperature increase process is faster than the temperature increase rate in the first stage temperature increase process. The speed is set to a speed that is faster than the temperature increase rate in the first stage temperature increase process, thereby promoting uniform nucleation.

  Holding temperature and holding time affect the strength of the copper alloy material. If the holding temperature is too low, the compound containing Ni and Si does not grow sufficiently and sufficient strength cannot be obtained. On the other hand, if the holding temperature is too high, the compound grows too much to decrease the strength and increase the smut amount. Therefore, the holding temperature is preferably in the range of 400 ° C. or more and 500 ° C. or less. Also. Similarly, when the holding time is less than 0.5 hours, the strength is insufficient. When the holding time exceeds 6 hours, the amount of smut increases. Therefore, the holding time may be 0.5 hours or more and 6 hours or less. preferable.

  The cooling rate after reaching and holding also affects the strength of the copper alloy material. If the cooling rate is too slow, sufficient strength cannot be obtained. On the other hand, if the cooling rate is too fast, a high temperature portion and a low temperature portion with a temperature difference are easily formed in the copper alloy material, and thermal stress is generated. Cheap. Therefore, the cooling rate from the holding temperature to 200 ° C. is preferably 3 ° C./min or more and 30 ° C./min or less.

  After aging heat treatment, finish cold working can be applied to adjust the strength. The processing rate of the finish cold working can be usually performed at 5 to 50%, and considering the bending workability, the processing rate is preferably 30% or less.

  After finish cold working, strength adjustment and ductility recovery are performed by low-temperature annealing. It is preferable to carry out at a temperature of 300 ° C. or higher and 550 ° C. or lower in a relatively short time of about 5 seconds to 10 minutes.

  In addition, the place mentioned above only showed the example of embodiment of this invention, and can be changed in a claim.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1 / Comparative Example 1
As shown in Table 1 below, copper alloys having the composition defined in the present invention (Examples 1-1 to 1-15) and copper alloys outside the composition defined in the present invention (Comparative Examples 1-1 to 1) As shown in −8), a predetermined raw material was melted in a melting furnace, held at 1300 ° C. for 5 minutes, and cast into a mold to obtain an ingot. Each ingot is homogenized and kept at a temperature of 1025 ° C. for 1 hour in the first stage treatment, then once cooled to a temperature of 960 ° C. in the second stage treatment, and continuously heated without any holding time. It used for hot rolling and produced the hot-rolled board with a plate thickness of 12 mm. These hot rollings were finished at 600 ° C. or higher, and were quickly cooled with water. Further, both sides of each sample that could be hot-rolled were chamfered 1 mm each to obtain a plate thickness of 10 mm, and then cold-rolled to a plate thickness of 0.235 mm.

  In the subsequent solution treatment, Examples 1-1 and 1-2 were held at 830 ° C. for 15 seconds, and then cooled at a cooling rate of 100 ° C./second or more. In Examples 1-3 to 1-5, after holding at 850 ° C. for 15 seconds, cooling was performed at a cooling rate of 100 ° C./second or more. Examples 1-6, 1-7, and 1-11 to 1-15 were held at 880 ° C. for 15 seconds, and then cooled at a cooling rate of 100 ° C./second or more. In Example 1-8, after holding at 930 ° C. for 15 seconds, cooling was performed at a cooling rate of 100 ° C./second or more. Inventive Example 1-9 was held at 940 ° C. for 15 seconds and then cooled at a cooling rate of 100 ° C./second or more. Inventive Example 1-10 was held at 950 ° C. for 15 seconds and then cooled at a cooling rate of 100 ° C./second or more.

  In Comparative Example 1-1, after holding at 800 ° C. for 15 seconds, cooling was performed at a cooling rate of 100 ° C./second or more. In Comparative Example 1-3, after holding at 820 ° C. for 15 seconds, cooling was performed at a cooling rate of 100 ° C./second or more. In Comparative Examples 1-4 and 1-7, after holding at 880 ° C. for 15 seconds, cooling was performed at a cooling rate of 100 ° C./second or more.

  About each sample after solution treatment, the temperature rising rate from room temperature to 200 ° C is 1.2 ° C / min, the temperature rising rate from 200 ° C to holding temperature is 2.3 ° C / min, the holding temperature is 475 ° C, The holding time was 2 hours, and the cooling rate from after holding to 200 ° C. was controlled under the condition of 8 ° C./min, and aging heat treatment was performed. After the aging heat treatment, it was finished to a thickness of 0.2 mm corresponding to a rolling rate of 15% by cold working and subjected to low temperature annealing at 450 ° C. for 30 seconds.

  The following evaluation was performed on each sample obtained in the above process.

a. Strength characteristics:
The test piece of JIS Z2201-13B cut out from the rolling parallel direction was measured for 0.2% proof stress on three pieces according to JIS Z2241, and the average value was shown. The measured value was rounded off to the nearest whole number. As a standard for high strength characteristics, the 0.2% proof stress is desirably 600 MPa or more.

b. conductivity:
The specific resistance was measured by a four-terminal method in a constant temperature bath maintained at 20 ° C. (± 0.5 ° C.), and the conductivity (% IACS) was calculated. The distance between terminals was 100 mm. In this example , the conductivity (% IACS) was set to 29 or higher, higher than that of beryllium copper , as a standard for high conductivity characteristics.

c. Evaluation of precipitated particles:
The evaluation of the precipitated particles was performed by TEM observation. The Ni ₂ Si compound is observed by dark field observation using the diffraction point of the Ni ₂ Si compound, specifically, the diffraction point of the precipitate at 1/2 (022) when viewed from the parent phase, and by image analysis, The major axis αnm and minor axis βnm of the precipitated particles were calculated for each particle, α / β was calculated, and the average value was calculated. The average value of the minor axis β nm was also calculated. Ten observation fields were observed at 1.5 million magnification.

d. Evaluation of smut cleanability:
A sample whose surface was adjusted by applying # 2400 buff to the surface of the sample in a degreasing solution containing 60 g / L of a cleaner 160S (manufactured by Meltex Co.) at a liquid temperature of 60 ° C. and a current density of 2.5 A / dm ² . And cathodic electrolysis for 30 seconds. Thereafter, acid dissolution was performed for 5 minutes with a solution of H ₂ SO ₄ 60 ml / L + H ₂ O ₂ 35 ml / L + 1-propanol 10 ml / L, and ultrasonic cleaning was immediately performed in water for 1 minute. Thereafter, observation is carried out with a stereomicroscope, and the area where the smut remains is expressed as a percentage of the observed area, defined as the residual ratio. 3% or more were judged as “x” as defective.

e. Evaluation of corrosion resistance after Au plating:
A sample whose surface was adjusted by applying # 2400 buff to the surface of the sample in a degreasing solution containing 60 g / L of a cleaner 160S (manufactured by Meltex Co.) at a liquid temperature of 60 ° C. and a current density of 2.5 A / dm ² . And cathodic electrolysis for 30 seconds. Subsequently, the pickling treatment was performed by immersing in a pickling solution containing 100 g / L of sulfuric acid at room temperature for 30 seconds. After ultrasonic cleaning for 1 minute, Ni plating was applied as an undercoat of 1.0 μm, and Au plating was applied by 0.2 μm. Thereafter, a salt spray test was carried out for 24 hours under the conditions of 5% NaCl and 35 ° C., and “×” indicates that pitting corrosion was observed in the appearance after the test, and “◯” indicates that the pitting corrosion was not observed. It was judged.

  In Examples 1-1 to 1-15 in Table 1, since the alloy composition was specified and the value of α / β satisfied α / β <5, 0.2% proof stress and smut cleaning properties were obtained. In addition, a copper alloy material having excellent corrosion resistance after Au plating could be obtained. On the other hand, in Comparative Example 1-1, the amount of Ni was lower than the specified amount, so the 0.2% proof stress was small. In Comparative Example 1-3, the amount of Si was lower than the specified amount, so 0 As a result, a copper alloy material having high strength characteristics could not be obtained. Further, in Comparative Example 1-4, the amount of Si exceeded the specified amount, and the value of α / β was also out of the specified range. Therefore, the obtained copper alloy material was inferior in smut cleaning properties and corrosion resistance after Au plating. It was. Moreover, in Comparative Example 1-7, since the amount of Zn exceeded the specified value, the conductivity was small, and a copper alloy material having high conductivity characteristics could not be obtained. In addition, since Comparative Examples 1-2, 1-5, 1-6, and 1-8 contained Ni, Mg, Sn, or Cr elements in excess of the content specified in the present invention, Cracking occurred during hot rolling, and subsequent evaluation was impossible.

Example 2 / Comparative Example 2
In Table 2, the influence of the structure in the present invention, that is, the aspect ratio of the precipitate containing Ni and Si was compared by fixing Ni, Si and other additive elements contained in the alloy.

  As shown in Table 2 below, the copper alloy (Examples 2-1 to 2-13) having the composition defined in the present invention, and the composition defined in the present invention, which contains Ni and Si. The predetermined raw material was melted in a melting furnace so as to be a copper alloy (Comparative Examples 2-1 to 2-12) whose aspect ratio is outside the scope of the present invention, and then held at 1300 ° C. for 5 minutes to form a mold. An ingot was obtained by casting. Each ingot is homogenized and kept at a temperature of 1025 ° C. for 1 hour in the first stage treatment, then once cooled to a temperature of 960 ° C. in the second stage treatment, and continuously heated without any holding time. It used for hot rolling and produced the hot-rolled board with a plate thickness of 12 mm. At this time, regarding Comparative Example 2-4, after holding at 1025 ° C. for 1 hour, it was subjected to hot rolling as it was without cooling. Therefore, cracks occurred during hot rolling, and evaluation after the next step was performed. It was impossible. These hot rollings were finished at 600 ° C. or higher, and were quickly cooled with water. At this time, for Comparative Example 2-5, the hot rolling was completed at 500 ° C., and then water cooling was performed promptly. Both sides of the sample that could be hot-rolled were each 1 mm chamfered to a plate thickness of 10 mm, and then cold-rolled to a plate thickness of 0.235 mm.

  Each sample of Examples 2-1 to 2-13, Comparative Examples 2-1 to 2-3, and Comparative Examples 2-5 to 2-12 was held for 15 seconds at the solution temperature described in Table 3 below. Then, cooling was performed at a cooling rate of 100 ° C./second or more. Further, aging heat treatment was carried out under the aging conditions shown in Table 3 for each sample after the solution treatment. At this time, with respect to Comparative Example 2-3, as cold working, rolling corresponding to 5% was added before the aging heat treatment, and the aging heat treatment was performed after setting the plate thickness to 0.223 mm. After the aging heat treatment, it was finished to a thickness of 0.2 mm corresponding to a rolling rate of 15% by cold working and subjected to low temperature annealing at 450 ° C. for 30 seconds.

  Each sample obtained in the above process was evaluated in the same manner as in Example 1.

  As shown in Tables 2 and 3, in Examples 2-1 to 2-13, the aspect ratio of the precipitates containing the structure defined in the present invention, that is, Ni and Si, is Since it was within the range, it was possible to obtain a copper alloy material having excellent smut cleaning properties and good corrosion resistance after Au plating while maintaining high strength and high conductivity characteristics. On the other hand, in Comparative Examples 2-1 to 2-12, the aspect ratio of the precipitates containing the structure defined in the present invention, that is, Ni and Si was a value outside the range of the present invention. Corrosion resistance after plating was inferior. Therefore, it was not possible to obtain a copper alloy material having excellent smut cleaning properties and good corrosion resistance after Au plating while maintaining high strength and high conductivity characteristics.

According to the present invention, in a copper alloy material containing relatively high concentrations of Ni and Si, when the major axis of the precipitate (compound) containing Ni and Si is α nm and the minor axis is β nm, the minor axis β By making the ratio of the major axis α to the minor axis β of the precipitate (compound), that is, the aspect ratio appropriate, the smut cleaning property is improved while maintaining high strength and high conductivity characteristics. In addition, it has become possible to provide a copper alloy material having excellent corrosion resistance after Au plating.
Further, according to the present invention, the temperature at which Ni and Si are dissolved during the solution treatment, and the temperature rising temperature from room temperature to 200 ° C. and the temperature rising temperature from 200 ° C. to the holding temperature during the aging heat treatment, continue. By maintaining the holding temperature and holding time, and the cooling rate at the subsequent holding temperature to 200 ° C., the smut cleaning performance is improved while maintaining the above-described high strength and high conductivity characteristics. In addition, it has become possible to provide a method for producing a copper alloy material having excellent corrosion resistance after Au plating.

Claims (4)

Ni: 2.0-6.0 mass%, Si: 0.3-2.0 mass%, Cr: 0-1.0 mass%, Mg: 0-1.0 mass%, Sn: 0-0. A copper alloy material containing 8% by mass and Zn: 0 to 0.8% by mass with the balance being Cu and inevitable impurities,
When the major axis of the precipitate containing Ni and Si is α nm and the minor axis is β nm, the average value of the major axis α is more than 2 nm and less than 50 nm, and the average value of the minor axis β is more than 2 nm and less than 10 nm,
The copper alloy material, wherein the average value of the ratio α / β of the major axis to the minor axis of the precipitate is less than 5.   The copper alloy material according to claim 1, wherein Cr: 0.05 to 1.0% by mass is contained.   The alloy material includes at least one component selected from the group consisting of Mg: 0.05 to 1.0 mass%, Sn: 0.05 to 0.8 mass%, and Zn: 0.05 to 0.8 mass%. The copper alloy material according to claim 1 or 2, characterized by containing 0.05 to 2.6 mass% in total.   The copper alloy material according to any one of claims 1 to 3, wherein the remaining area ratio of the surface smut is less than 3%.