JPWO2009104615A1 - Copper alloy material - Google Patents

Abstract

Ni is included in 1.8 to 5.0 mass%, Si is included in 0.3 to 1.7 mass%, Ni / Si content ratio is 3.0 to 6.0, and S content Is a copper alloy material consisting of Cu and inevitable impurities, and satisfying the following formulas (1) to (4). 130 × C + 300 ≦ TS ≦ 130 × C + 650 (1) 0.001 ≦ d ≦ 0.020 (2) W ≦ 150 (3) 10 ≦ L ≦ 800 (4) (where TS is a rolling parallel of a copper alloy material) Tensile strength (MPa) in the direction (LD), C is the Ni content (mass%) of the copper alloy material, d is the average crystal grain size (mm) of the copper alloy material, W is the width of the precipitation-free zone (nm), L represents the average particle size (nm) of the compound on the grain boundary.)

Description

  The present invention relates to a copper alloy material.

  Conventionally, as materials for electrical / electronic devices, copper-based materials such as phosphor bronze, red brass, brass, etc., which are excellent in electrical conductivity and thermal conductivity, have been widely used as materials for electric / electronic devices. In recent years, there has been an increasing demand for miniaturization and weight reduction of electric / electronic devices and the accompanying high-density mounting, and various properties are also required for copper-based materials applied thereto. The main characteristics required of copper-based materials are mechanical properties, electrical conductivity, and bending formability to achieve product functions, and stress relaxation to obtain reliability during product use. Characteristics and fatigue properties are required. Conventionally, high strength alloys such as titanium copper and beryllium copper having good fatigue strength have been used for members that require reliability such as fatigue properties.

High-strength alloys such as titanium copper and beryllium copper are more expensive than copper alloys such as phosphor bronze, and in beryllium copper, metal beryllium is harmful to the human body. Alternative materials are desired.
In recent years, Cu—Ni—Si alloys (Corson alloys), which have relatively low manufacturing costs and are excellent in balance between strength and electrical conductivity, have attracted attention and have been used as copper alloys for connectors. The Cu—Ni—Si based alloy is a precipitation type alloy that forms and precipitates precipitates composed of Ni and Si, and has a very high ability to strengthen.

  In general, the fatigue characteristics are improved as the tensile strength is improved. However, in a Cu—Ni—Si based alloy, it is difficult to maintain bending workability as the tensile strength increases. Further, when a high processing rate is introduced into the material in order to obtain a tensile strength, there is a problem that the stress relaxation resistance is deteriorated. Therefore, development of a Cu-Ni-Si alloy that simultaneously satisfies good stress relaxation properties and fatigue properties to obtain strength and bending workability to achieve product functions and reliability during product use is required. It has been.

In the Corson alloy, Patent Documents 1-2 and the like have proposed high-strength copper alloys having improved strength, bending workability, strength, and fatigue properties. However, as described above, there is a demand for a copper alloy material having further improved proof stress, bending workability, stress relaxation resistance, and fatigue characteristics.
Japanese Patent No. 3520034 JP 2005-48262 A

  In view of the problems as described above, the object of the present invention is to provide terminals, connectors, and switches for electrical and electronic devices that have high strength, excellent bending workability and stress relaxation resistance, and excellent fatigue characteristics. It is to provide a copper alloy material suitable for a relay or the like.

The present inventors have studied copper alloy materials suitable for electric / electronic component applications, and formed a precipitate-free zone (PFZ) near the crystal grain boundary in the copper alloy during aging treatment. Precipitation zone is lower in strength than in the grains, so when processing or repeated stress is applied to copper alloy, deformation occurs preferentially and deteriorates bending workability and fatigue characteristics. It was found that it can be made harmless if it is narrowed. In addition, by controlling the particle size and crystal grain size of the compound existing on the grain boundary, copper has high strength, excellent bending workability and stress relaxation resistance, and excellent fatigue properties. The invention of the alloy material has been completed.
That is, the present invention
<1> Ni is included in 1.8 to 5.0 mass%, Si is included in 0.3 to 1.7 mass%, Ni / Si content ratio Ni / Si is 3.0 to 6.0, S A copper alloy material having a content of less than 0.005 mass%, the balance being Cu and inevitable impurities, and satisfying the following formulas (1) to (4):
130 × C + 300 ≦ TS ≦ 130 × C + 650 (1)
0.001 ≦ d ≦ 0.020 (2)
W ≦ 150 (3)
10 ≦ L ≦ 800 (4)
(Where TS is the tensile strength (MPa) of the copper alloy material in the rolling parallel direction (LD), C is the Ni content (mass%) of the copper alloy material, and d is the average crystal grain size (mm) of the copper alloy material. W represents the width (nm) of the precipitation-free zone (PFZ), L represents the particle diameter (nm) of the compound on the grain boundary),
<2> The copper alloy material according to <1>, further containing Mg in an amount of 0.01 to 0.20 mass%.
<3> The copper alloy material according to <1> or <2>, further containing 0.05 to 1.5 mass% of Sn,
<4> The copper alloy material according to any one of <1> to <3>, further containing 0.2 to 1.5 mass% of Zn, and
<5> Further, any one of the following (I) to (IV) is contained in a total of 0.005 to 2.0 mass%, and any one of <1> to <4> The copper alloy material according to item,
(I) 0.005-0.3 mass% of one or more selected from the group consisting of Sc, Y, Ti, Zr, Hf, V, Mo, and Ag,
(II) Mn is 0.01 to 0.5 mass%,
(III) Co is 0.05 to 2.0 mass%,
(IV) 0.005 to 1.0 mass% of Cr,
Is to provide.

  The Cu—Ni—Si based copper alloy material of the present invention is a copper alloy material having higher strength and superior bending properties, stress relaxation resistance and fatigue properties as compared with the prior art.

  The above and other features and advantages of the present invention will become more apparent from the following description, with reference where appropriate to the accompanying drawings.

FIG. 1 is a transmission electron micrograph of the vicinity of a crystal grain boundary including a precipitation-free zone as an example of the copper alloy material of the present invention. FIG. 2 is an explanatory diagram of how to determine the width W of the precipitation-free zone and the particle diameter L of the compound on the grain boundary defined in the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Grain boundary 2 Compound on grain boundary 3 Ni ₂ Si precipitate in crystal grain

  Preferred embodiments of the composition and alloy structure of the copper alloy material of the present invention will be described in detail below. In the present invention, the copper alloy material means a copper alloy processed into a specific shape such as a plate material, a strip material, or a foil by a rolling process.

When nickel (Ni) and silicon (Si) in a copper alloy are subjected to an aging treatment, a Ni ₂ Si phase is mainly formed to improve strength and conductivity. The Ni content is 1.8 to 5.0 mass%, preferably 2.0 to 4.8 mass%. The reason for specifying in this way is that if the content is less than 1.8 mass%, sufficient strength as a copper alloy for connector use cannot be obtained, and if it is more than 5.0 mass%, the strength is increased during casting or hot working. This is because the formation of a compound that does not contribute to the improvement occurs, and the strength corresponding to the content cannot be obtained, and the hot workability is deteriorated and adversely affects.

The content of Si is 0.3 to 1.7 mass%, preferably 0.35 to 1.6 mass%. The reason for specifying in this way is that when the Si amount is less than 0.3 mass%, the strength improvement by the aging treatment is insufficient and sufficient strength cannot be obtained, and the Si content is more than 1.7 mass%. When the amount is too large, the same problem as in the case where the amount of Ni is large is caused, and the conductivity is lowered.
Since Ni and Si mainly form a Ni ₂ Si phase, there is an optimum ratio of Ni and Si in order to improve the strength. The ratio of Ni (mass%) and Si (mass%) when the amount of Si formed the Ni ₂ Si phase, Ni / Si is 4.2, and Ni / Si is 3.0 to It is desirable to be in the range of 6.0, and it is more preferable to be in the range of 3.8 to 4.6.

  Although a trace amount of sulfur (S) is contained in the copper alloy, the hot workability is deteriorated at 0.005 mass% or more, so the content is specified to be less than 0.005 mass%. In particular, less than 0.002 mass% is preferable.

  The copper alloy preferably contains magnesium (Mg). The amount is 0.01-0.20 mass%. Mg greatly improves the stress relaxation properties, but adversely affects bending workability. For improvement of stress relaxation characteristics, the Mg content is preferably as large as 0.01 mass% or more, but if it exceeds 0.20 mass%, the bending workability does not satisfy the required characteristics. Preferably it is 0.05-0.15 mass%.

  The copper alloy preferably contains tin (Sn). The amount is 0.05 to 1.5 mass%. Sn interacts with Mg to improve the stress relaxation characteristics, but the effect is not as great as with Mg. If Sn is less than 0.05 mass%, the effect is not sufficiently exhibited, and if it exceeds 1.5 mass%, the conductivity is significantly lowered. Preferably it is 0.1-0.7 mass%.

  The copper alloy preferably contains zinc (Zn). The amount is 0.2 to 1.5 mass%. Zn slightly improves the bending workability. By containing Zn in an amount of 0.2 to 1.5 mass%, even if Mg is added up to a maximum of 0.20 mass%, bending workability at a level that does not cause a practical problem can be obtained. In addition, Zn improves the adhesion and migration characteristics of Sn plating and solder plating. If the amount of Zn is less than 0.2 mass%, the effect cannot be sufficiently obtained, and if it exceeds 1.5 mass%, the conductivity is lowered. Preferably it is 0.3-1.0 mass%.

The copper alloy may be any one of scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), molybdenum (Mo), and silver (Ag). Two or more kinds can be added in a total amount of 0.005 to 0.3 mass%. Sc, Y, Ti, Zr, Hf, V, and Mo have an effect of forming a compound with Ni or Si and suppressing the coarsening of the crystal grain size. The addition amount can be added in the above range which does not deteriorate the properties such as strength and conductivity.
Ag improves heat resistance and strength, and at the same time, prevents coarsening of crystal grains and improves bending workability. If the Ag amount is less than 0.005 mass%, the effect cannot be sufficiently obtained, and even if added over 0.3 mass%, there is no adverse effect on the characteristics, but the cost increases. From these viewpoints, the content of Ag is preferably within the above range.

Manganese (Mn) has an effect of improving hot workability, and it is effective to add 0.01 to 0.5 mass% so as not to deteriorate the conductivity.
Cobalt (Co), like Ni, forms a compound with Si and has the effect of improving the strength, so it is preferable to contain 0.05 to 2.0 mass% of Co. If the content is less than 0.05 mass%, the effect cannot be sufficiently obtained. If the content exceeds 2.0 mass%, crystallization / precipitates that do not contribute to the strength exist after the solution treatment, and bending workability deteriorates. .
Chromium (Cr) precipitates finely in copper and contributes to strength improvement, and forms a compound with Si or Ni and Si, and the group of Sc, Y, Ti, Zr, Hf, V, and Mo described above. Similarly, there is an effect of suppressing the coarsening of the crystal grain size. When it is added, if less than 0.005 mass%, the effect cannot be sufficiently obtained, and if it exceeds 1.0 mass%, bending workability deteriorates.

  When adding two or more of the above-mentioned Sc, Y, Ti, Zr, Hf, V, Mo, Ag, Mn, Co, and Cr, a total range of 0.005 to 2.0 mass% depending on the required characteristics Determined within.

In the present invention, the tensile strength TS in the rolling parallel direction (LD) of the copper alloy material having the above composition is defined. Since both hot rolling and cold rolling are performed in the same direction in the production process of the copper alloy material, the rolling directions are the same.
In applications such as terminals, connectors, and relays, the strength of the copper alloy material is necessary to maintain the spring property, but the bending workability deteriorates when the strength is significantly improved by processing or the like. Further, when the Ni and Si contents are increased in the Cu—Ni—Si based alloy, the strength is increased, but even if the Ni and Si contents described above are increased, the cost increases if they are increased unnecessarily. From this point of view, it has been clarified that Ni and Si contents suitable for each strength region exist within the above-described Ni and Si content ranges, and the formula (1) has been derived. At this time, the Si content has an optimum region for the ratio of Ni and Si content as described above, and can be defined by the Ni content C as a representative. When the tensile strength TS is too small, it means that the contents of Ni and Si are large with respect to the strength, which increases the cost. When the tensile strength TS is too large, it means that the strength is remarkably improved by processing or the like, and the bending workability is deteriorated.
130 × C + 300 ≦ TS ≦ 130 × C + 650 (1)
In the present invention, TS is obtained according to JIS Z 2241. TS is preferably (130 × C + 350) ≦ TS ≦ (130 × C + 600).

  In the present invention, the average crystal grain size d (mm) of the crystal grains of the base material of the copper alloy material is 0.001 ≦ d ≦ 0.020. The reason for prescribing the average crystal grain size d to be 0.001 mm or more and 0.020 mm or less is that when the average crystal grain size d is less than 0.001 mm, the recrystallized structure is mixed (a structure in which crystal grains having different sizes are mixed). When the average crystal grain size d exceeds 0.020 mm, stress concentration near the grain boundary is promoted at the time of bending, and no precipitation zone (PFZ) and This is because the bending workability deteriorates with the compound on the grain boundary. The crystal grain size d is a value measured based on JIS H 0501 (cutting method). The number of measurements for determining the crystal grain size d is 1000 or more. The average crystal grain size d (mm) is preferably 0.001 ≦ d ≦ 0.015.

The non-precipitation zone (PFZ) is a region that is formed near the grain boundary in the course of aging treatment and no precipitate is present. FIG. 1 is a transmission electron micrograph in the vicinity of a grain boundary including a precipitation-free zone of one example of the copper alloy material of the present invention. The non-precipitation zone (PFZ) is an area where no precipitate is present, and thus is relatively softer than in the crystal grains. Therefore, when deformation or repetitive stress is applied to the copper alloy material, the deformation progresses preferentially, and becomes a starting point of cracking and a starting point of fatigue failure due to accumulation of dislocations. Therefore, the weakness of the copper alloy structure is reduced when the PFZ width W is narrow. As a result of detailed examination, it has been found that if the width W (nm) of the precipitation-free zone is W ≦ 150 (150 nm or less), the bending workability and fatigue characteristics are not greatly affected.
In the present invention, the PFZ width W is obtained by photographing a transmission electron micrograph at 50,000 magnifications in two fields around the grain boundary of a copper alloy plate with the (100) plane of the beam incident direction, and at five locations per field of view. The PFZ width is measured and set to the average value of a total of 10 locations. W is preferably 0 to 100 nm.

The compound on the crystal grain boundary is mainly an intermetallic compound, and is harder than in the crystal grain and the non-precipitated zone. When deformation or repeated stress is applied to a copper alloy material, a difference in strength occurs between the hard compound and the surrounding structure, dislocations tend to accumulate in the copper alloy structure near the compound, and become the starting point of cracking and the starting point of fatigue failure . Therefore, the smaller the compound on the grain boundary, the less the brittleness of the copper alloy structure. In the present invention, the average particle diameter L (nm) of the compound on the grain boundary is 10 ≦ L ≦ 800. If the average particle diameter L of the compound is 800 nm or less, the bending workability and the deterioration of fatigue characteristics are not greatly affected. The average particle diameter L of the compound is preferably 500 nm or less. However, the compound existing at the crystal grain boundary has an effect of suppressing the movement of the crystal grain and keeping the crystal grain size fine. Therefore, the particle diameter L is 10 nm or more, preferably 30 nm or more.
In the present invention, the average particle diameter L of the compound on the grain boundary is obtained by taking a transmission electron micrograph at 50000 magnifications at five fields with the grain boundary of the copper alloy material aligned with the (100) plane of the beam. The major axis and minor axis of one compound are measured, the average is the particle diameter of the compound, and the particle diameters of 20 compounds are averaged.

FIG. 2 is an explanatory view schematically showing how to obtain the width W of the precipitation-free zone and the particle diameter L of the compound on the grain boundary in the present invention. In the figure, 1 is a crystal grain boundary, 2 is a compound on the crystal grain boundary, and 3 is a Ni ₂ Si precipitate in the crystal grain. As shown in the figure, the width W of the precipitation-free zone is obtained by measuring the distance from the crystal grain boundary 1 to the boundary of the range formed by one crystal grain. The average particle diameter L of the compound on the grain boundary is obtained by measuring the major axis and minor axis of the compound 2 on the grain boundary, setting the average as the particle diameter of the compound, and further averaging the particle diameters of 20 compounds. Desired.

  Crystal grains, precipitation-free zones, and grain boundary compounds interact when a copper alloy is subjected to deformation or repeated stress. For this reason, it is not sufficient that the average crystal grain size d, the width W of the precipitation-free zone, and the average grain size L of the grain boundary compound each satisfy the above-mentioned regulations. Can be relaxed.

Next, the preferable manufacturing method of the copper alloy material which concerns on this invention is demonstrated.
Casting is performed by a general semi-continuous casting method, such as a so-called DC (direct chill) casting method. Next, the ingot is hot-rolled at a temperature of 600 to 1000 ° C. immediately after, for example, homogenization treatment for 0.5 to 6 hours at a temperature of 850 to 1000 ° C. After hot rolling, cold rolling is performed in a timely manner. Precipitates formed during cooling after hot rolling tend to be coarse, and coarse compounds of 1000 nm or more remain on the grain boundaries of the final product, which may deteriorate bending workability and fatigue characteristics. In order to prevent precipitation during cooling, it is desirable to cool with water after hot rolling. After cooling, it is preferable to perform dough rolling after chamfering the oxide film. In the dough rolling, it is preferable to perform rolling to a plate thickness that can obtain a predetermined processing rate in the cold processing after the next step.

The subsequent solution treatment is performed by determining the temperature according to the Ni content C. It is preferable to carry out in a range where the actual temperature Tst (° C.) of the material satisfies the equation (5).
54 × C + 625 ≦ Tst ≦ 54 × C + 725 (5)
The higher the solution treatment temperature, the smaller the average particle diameter L of the precipitates on the grain boundaries, the narrower the width W of the precipitation-free zone, and the better solute state is obtained, and the aging in the subsequent steps. High strength can be obtained in the process. However, in the range where Tst exceeds the upper limit formula, the crystal grains become coarse and the average crystal grain size d does not satisfy the above range, and the bending workability may be deteriorated. When Tst is less than the lower limit formula, a dislocation structure due to cold working in the raw rolling may remain and bend workability may deteriorate.

The subsequent aging treatment uniformly disperses and precipitates the Ni ₂ Si compound in the copper alloy, thereby improving the strength and electrical conductivity. It is preferable to use a batch type furnace and hold at an actual temperature of 350 to 600 ° C. for 0.5 to 12 hours. If the temperature during the aging treatment is lower than 350 ° C., it takes a long time to obtain a sufficient amount of deposited Ni ₂ Si, resulting in an increase in cost or insufficient tensile strength and electrical conductivity. If the temperature during the aging treatment is higher than 600 ° C., coarse Ni ₂ Si is formed in the crystal grains and the strength is lowered, and the width W of the precipitation-free zone is expanded in the vicinity of the grain boundary. Therefore, bending workability and fatigue characteristics are improved. May deteriorate. If the time is less than 0.5 hours, sufficient characteristics may not be obtained. If the time is longer than 12 hours, not only the cost is increased, but also the width W of the precipitation-free zone is widened, so that bending workability and fatigue characteristics are increased. May deteriorate.
In order to further improve the tensile strength, cold rolling may be applied during the aging treatment after the solution treatment. The dislocations introduced by this cold rolling work to promote precipitation of the Ni ₂ Si compound and also have the function of reducing the width of the precipitation-free zone W. If this cold work rate is too high, bending workability is deteriorated, so it is desirable to carry out at 50% or less.

In addition, the aging treatment may be performed twice because it has a function of reducing the width W of the precipitation-free zone. In order to reduce the width W of the precipitation-free zone by aging treatment twice, the above aging treatment temperature is divided into temperature range 1: 350 to 450 ° C. and temperature range 2: 450 to 600 ° C., and temperature range 1 and temperature range It is preferable to perform the process in 2 once each. At this time, the order of performing the processing in the temperature range 1 and the temperature range 2 may be either first. In the temperature range 1, it is desirable to carry out in a relatively long time of 4 to 12 hours, and in the temperature range 2 in a relatively short time of 0.5 to 6 hours. In order to promote precipitation of the Ni ₂ Si compound between the two aging treatments, cold rolling of 50% or less may be performed.

  Following the aging treatment, finish cold rolling is performed for the purpose of improving the tensile strength. When the tensile strength after the aging treatment is sufficient, it is not necessary to introduce finish cold rolling. When the rolling ratio of finish cold rolling is too high, bending workability is deteriorated and stress relaxation resistance is deteriorated. Therefore, the rolling rate of finish rolling is desirably 50% or less.

  The low temperature annealing performed after the finish rolling is performed for the purpose of restoring the elongation, bending workability and spring limit value while maintaining the strength to some extent. When finish rolling is not performed, the low-temperature annealing step may be omitted. It is desirable to perform annealing in a short time of 5 to 60 seconds at an actual temperature of 300 to 600 ° C. When the temperature during annealing is lower than 300 ° C., the elongation, bending workability, and recovery of the spring limit value may be insufficient, and when the temperature during annealing is higher than 600 ° C., strength may be reduced.

Hereinafter, the present invention will be described in more detail with respect to examples based on the present invention as compared with comparative examples. However, the present invention is not limited to these examples.
The copper alloy material of the Example of this invention and a comparative example is formed with the copper alloy (alloy No. 1-25) of the chemical composition shown in Table 1 (the remainder is Cu). These copper alloys are melted in a high-frequency melting furnace, cast into ingots having a thickness of 30 mm, a width of 120 mm, and a length of 150 mm, and then the ingots are heated to 980 ° C. and held at this temperature for 1 hour, It was hot-rolled to a thickness of 12 mm and quickly cooled.
At this time, Alloy No. Regarding No. 19, since the amount of Ni was too large, alloy no. Regarding No. 20, since the amount of S was too large, alloy no. Regarding No. 21, since the amount of Si was too large, alloy no. No. 23 had too much Cr, so alloy no. Regarding 24 and 25, since the total amount of Zr, Ti, and Hf and the total amount of V, Mo, and Y were too large, cracks occurred during hot rolling and the subsequent steps were stopped.

  Next, both sides were cut 1.5 mm each to remove the oxide film, and then processed to a thickness of 0.16 to 0.50 mm by cold rolling. At this time, Alloy No. Since 22 had too much Sn, edge cracks occurred during cold rolling, and the subsequent steps were stopped. Then, it heat-processed for 30 seconds at 800-950 degreeC, and cooled immediately with the cooling rate of 15 degreeC / second or more.

After performing cold rolling at various rolling rates of 0 to 50% before aging treatment (without cold rolling when the rolling rate is 0%), 500 ° C in an inert gas atmosphere, 2 Time aging treatment was applied. A rolling rate of 0% means that no rolling is performed. Further, as the heat treatment, in place of the aging treatment, a heat treatment with two aging treatments was performed, or a heat treatment at 400 ° C. was performed for 4 hours in an inert gas atmosphere, and then for 2 hours at 500 ° C. Either heat treatment was performed, or heat treatment at 500 ° C. for 2 hours followed by heat treatment at 400 ° C. for 4 hours. Details of this will be described later.
Thereafter, finish rolling was performed at various rolling rates, and the final thickness was adjusted to 0.15 mm. After finish rolling, a low temperature annealing treatment was performed at 400 to 600 ° C. for 30 seconds to prepare copper alloy materials of Examples and Comparative Examples, and the following various characteristics were evaluated.

  For each copper alloy plate produced in Examples and Comparative Examples, (a) average crystal grain size, (b) width of precipitation-free zone, (c) average particle size of precipitates on grain boundaries, (d) tensile strength , (E) conductivity, (f) bending workability, (g) stress relaxation resistance, and (h) fatigue characteristics were examined.

The average crystal grain size of (a) was calculated based on the crystal grain size measured by the cutting method (JIS H 0501) defined by JIS. The measurement cross section of the crystal grain size was measured in a cross section parallel to the final cold rolling direction. The crystal structure of the copper alloy plate is magnified 1000 times with a scanning electron microscope to take a photograph, a 200 mm line segment is drawn on the photograph, the number n of crystal grains cut by the line segment is counted, and [200 mm / (n × 1000)]. When the number of crystal grains cut by the line segment is less than 20, the number n of crystal grains cut by the line segment having a length of 200 mm is counted in a 500 × photograph, and obtained from the formula [200 mm / (n × 500)]. It was. The crystal grain size d is shown by rounding the average of the four values of the major axis and the minor axis obtained in the cross sections A and B to an integer multiple of 0.005 mm.
The width of the precipitation-free zone in (b) was determined by taking two views of a transmission electron micrograph at a magnification of 50,000 times in the vicinity of the grain boundary of the copper alloy plate and aligning the incident direction of the beam with the (100) plane. The PFZ widths of the places were measured, and the average value of a total of 10 places was defined as the width W of the precipitation-free zone and rounded to an integer multiple of 10 nm.
The particle diameter of the compound on the grain boundary in (c) is a total of 20 grains of a copper alloy plate taken at five fields of view at 50,000 times with the incident direction of the beam aligned with the (100) plane. The particle size of the compound was measured. The major axis and minor axis of one compound were measured, and the average was taken as the particle diameter of the compound. Furthermore, the particle diameter of 20 compounds was averaged, and the average particle diameter L of the compound on the grain boundary of the copper alloy plate was rounded to an integer multiple of 10 nm.

The tensile strength of (d) was determined according to JIS Z 2241 using a No. 5 test piece described in JIS Z 2201. A test was performed in a direction parallel to the rolling direction.
The electrical conductivity of (e) was determined according to JIS H 0505.
(F) Bending workability was evaluated by dividing the level of tensile strength. For copper alloys with a tensile strength of less than 750 MPa, perform 180 ° bending with an inner bending radius of 0 mm, and determine that no cracks occur in the bent part (good), and those with cracks are determined to be defective (x). did. For a copper alloy having a tensile strength of 750 MPa or more, a 90 ° bending jig with an inner bending radius of 0.15 mm is used, and the ratio R / t of bending radius (mm) / plate thickness (mm) is 1.0. A 90 ° W bending test was conducted, and a case where no crack occurred in the bent portion was judged as good (◯), and a case where a crack occurred was judged as poor (×).
(G) For the stress relaxation resistance, the Japan Copper and Brass Association Technical Standard (JBMA-T309) cantilever type is adopted, the load stress is set so that the maximum surface stress is 80% of the proof stress, and a constant temperature of 150 ° C. The stress relaxation rate was obtained by holding in a bath for 1000 hours.
The fatigue characteristics of (h) were collected in accordance with JIS Z 2273 by performing a double-bending plane bending fatigue test. The test piece was a strip with a width of 10 mm, and the parallel direction of the rolling and the length direction of the test piece were matched. The test conditions were the thickness t (mm) of the test piece, the maximum bending stress σB (MPa) applied to the surface of the test piece, the piece amplitude δ (mm) applied to the test piece, the Young's modulus E (130 GPa) of the alloy, the fulcrum − The distance l (mm) between stress points is
l = √ (3 Etδ / (2σB))
The test piece was installed so as to satisfy the above relationship, the maximum bending stress σB was set to 500 (MPa), and the number N of times when the sample broke was measured. The test and measurement were performed four times, the average value of the number N was determined, and the fatigue life of each test piece was determined.

The evaluation results are shown in Table 2. Here, Examples 1-1 to 1-6 and Comparative Examples 1-7 to 1-10 are alloy nos. 1 and Examples 2-1 to 2-2 are alloy nos. 2 is subjected to different heat treatment and rolling conditions within the above-mentioned range. No. 3 to 18 are alloy nos. It was created from 3-18.
Hereinafter, the conditions of Examples 1-1 to 1-6 and Comparative Examples 1-7 to 1-10 were as follows. The conditions not described in Examples 1-2 to 1-6 and Comparative Examples 1-7 to 1-10 were the same as those in Example 1-1.
<Process of Example>
Example 1-1: After solution treatment at 875 ° C., aging treatment was performed at 500 ° C. for 2 hours without performing cold rolling, and 5% finish rolling and low-temperature annealing treatment were continuously performed.
Example 1-2: Instead of the aging treatment of Example 1-1, two aging treatments were performed in which treatment at 400 ° C. for 4 hours was followed by treatment at 500 ° C. for 2 hours.
Example 1-3: Instead of the aging treatment of Example 1-1, two aging treatments were performed in which treatment at 500 ° C. for 2 hours was followed by treatment at 400 ° C. for 4 hours.
Example 1-4: Solution treatment was performed at 885 ° C.
Example 1-5: After the solution treatment, 5% cold rolling treatment was performed before the aging treatment.
Example 1-6: A 10% cold rolling treatment was performed after the solution treatment and before the aging treatment.
<Process of Comparative Example>
Comparative Example 1-7: Solution treatment was performed at 950 ° C.
Comparative Example 1-8: Solution treatment was performed at 800 ° C.
Comparative Example 1-9: The solution heating treatment was performed at a treatment temperature of 800 ° C. with a lower temperature increase rate.
Comparative Example 1-10: The finish rolling rate was 60%.

  In Examples 1-1 to 1-6, 2-1, 2-2, and 3 to 13, all of the copper alloy materials are excellent in high strength, good bending workability, and fatigue characteristics.

  In Comparative Example 1-7, since the value of the crystal grain size d was too large, bending workability was deteriorated. In Comparative Example 1-8, since the value of the width W of the precipitation-free zone was too large, bending workability and fatigue characteristics were deteriorated. In Comparative Example 1-9, since the particle diameter L of the compound on the grain boundary was too large, bending workability and fatigue characteristics deteriorated. In Comparative Example 1-10, since the tensile strength was too high, the bending workability deteriorated.

  In Comparative Example 14, since the Ni concentration and the Si concentration were too low, the fatigue life was short and the stress relaxation resistance was inferior. In Comparative Example 15, since the Mg concentration was too high, bending workability deteriorated. In Comparative Examples 16 and 17, the conductivity decreased because the Mn and Zn concentrations were too high. In Comparative Example 18, since the Co concentration was too high, the bending workability was poor and the fatigue life was also deteriorated.

  The copper alloy material of the present invention can be suitably used as a material for lead frames, connectors, terminal materials, relays, switches and the like for electric and electronic devices.

  While the invention has been described in conjunction with its embodiments, it is not intended that the invention be limited in any detail to the description unless otherwise specified, which is contrary to the spirit and scope of the invention as set forth in the appended claims. I think it should be interpreted widely.

  This application claims priority based on Japanese Patent Application No. 2008-036694 filed in Japan on February 18, 2008, the contents of which are hereby incorporated by reference. take in.

Claims (5)

Ni is included in 1.8 to 5.0 mass%, Si is included in 0.3 to 1.7 mass%, Ni / Si content ratio is 3.0 to 6.0, and S content Is a copper alloy material consisting of Cu and inevitable impurities, and satisfying the following formulas (1) to (4).
130 × C + 300 ≦ TS ≦ 130 × C + 650 (1)
0.001 ≦ d ≦ 0.020 (2)
W ≦ 150 (3)
10 ≦ L ≦ 800 (4)
(Where TS is the tensile strength (MPa) of the copper alloy material in the rolling parallel direction (LD), C is the Ni content (mass%) of the copper alloy material, and d is the average crystal grain size (mm) of the copper alloy material. W represents the width (nm) of the precipitation-free zone, and L represents the average particle size (nm) of the compound on the grain boundary.)   Furthermore, Mg contains 0.01-0.20 mass%, The copper alloy material of Claim 1 characterized by the above-mentioned.   Furthermore, 0.05-1.5 mass% of Sn is contained, The copper alloy material of Claim 1 or 2 characterized by the above-mentioned.   Furthermore, 0.2-1.5 mass% of Zn is contained, The copper alloy material of any one of Claims 1-3 characterized by the above-mentioned. The copper according to any one of claims 1 to 4, further comprising 0.005 to 2.0 mass% of one or more of the following (I) to (IV): Alloy material.
(I) 0.005-0.3 mass% of one or more selected from the group consisting of Sc, Y, Ti, Zr, Hf, V, Mo, and Ag
(II) Mn is 0.01 to 0.5 mass%.
(III) Co is 0.05 to 2.0 mass%.
(IV) 0.005 to 1.0 mass% of Cr