JP5590990B2 - Copper alloy - Google Patents

Description

  The present invention relates to a copper alloy manufacturing method and a copper alloy. In particular, the present invention relates to a method for producing a copper alloy for electrical parts, and a copper alloy.

  Materials used for electrical parts such as lead frames, connectors, relays, and switches are required to have characteristics such as high strength, excellent stress relaxation resistance, high conductivity, and excellent bending workability. High strength is required for applying high contact pressure to the material as a spring material, and excellent stress relaxation resistance is to maintain contact pressure even when electrical components are used at high temperatures for long periods of time. As required. In addition, high conductivity is required to suppress the generation of Joule heat when electrical components are energized and to easily dissipate the generated heat. Required not to generate.

  With the recent miniaturization of electrical components, the current density of the current flowing through the material constituting the electrical component is increasing. With increasing current density, there is a need for materials that are more conductive than conventional materials. In addition, since electric components for in-vehicle use require materials that can withstand use in higher temperature environments, there is an increasing demand for materials having excellent stress relaxation resistance. Conventionally, brass and phosphor bronze have been used as materials that can withstand use in high-temperature environments and have excellent stress relaxation properties. However, these materials have recently been required to have high conductivity and stress relaxation properties. It does not have the characteristics to meet the above.

  A Cu—Cr—Zr-based alloy has been proposed as a material having both high conductivity and excellent stress relaxation resistance. The Cu—Cr—Zr alloy is required to be further strengthened because the increase in strength due to precipitation hardening is small compared to the Cu—Ni—Si alloy which is a precipitation hardening type alloy.

  For example, 0.05 to 0.40% Cr, 0.03 to 0.25% Zr, 0.10 to 1.80% Fe, and 0.10 to 0.80% Ti. Or further containing 0.05 to 2.0% Zn and 0.01 to 1% of Sn, In, Mn, P, Mg, and Si in a total amount, and 0. When 10% ≦ Ti ≦ 0.60%, the Fe / Ti weight ratio satisfies 0.66 to 2.6, and when 0.60% <Ti ≦ 0.80%, the Fe / Ti weight ratio is 1.1 to 2. .6, and the remainder is made of a copper alloy material consisting of Cu and inevitable impurities. 1) Solution treatment at a temperature of less than 950 ° C., 2) Cold working at a working degree of 50 to 90%, 3 ) Aging treatment at a temperature of 300 to 580 ° C. 4) Cold working at a working degree of 16 to 83%, 5) An annealing treatment at a temperature of 350 to 700 ° C. in this order. Method of manufacturing an electronic device for high strength high conductivity copper alloy material for producing the copper alloy material is known by performing. (For example, refer to Patent Document 1).

JP 7-258805 A

  However, the method for producing a high-strength, high-conductivity copper alloy material for electronic devices described in Patent Document 1 employs a solution treatment at a high temperature, and in such a solution treatment, the metal structure of the matrix is coarsened. Therefore, there are concerns that the copper alloy material is partially softened, the bending workability of the copper alloy material is deteriorated, and the stress relaxation resistance of the copper alloy material is deteriorated. In order to improve the stress relaxation resistance, strength, and bending workability, it is necessary to control the precipitation of precipitates containing Cr and Zr. In order to control the precipitation of these precipitates, control by adjusting each processing condition such as solution treatment, cold rolling before aging treatment, aging treatment, or control by other additives is required.

  Accordingly, an object of the present invention is to provide a copper alloy production method and a copper alloy that have high conductivity, excellent stress relaxation resistance, high strength, and excellent bending workability.

  (1) For the purpose of solving the above-mentioned problems, the present invention provides copper (Cu) as a parent phase with 0.1 mass% or more and 0.4 mass% or less of chromium (Cr), and 0.01 mass. % To 0.2% by mass of zirconium (Zr), 0.01% to 0.3% by mass of tin (Sn), 0.05% to 0.4% by mass of magnesium (Mg) ) And a copper alloy material containing inevitable impurities, a hot rolling step of hot rolling the copper alloy material, and a copper alloy material subjected to the hot rolling process at 700 ° C. or more and 900 ° C. A cooling process in which the steel alloy is subjected to a heat treatment at a temperature of less than 0 ° C. and then rapidly cooled; a first cold rolling process in which the copper alloy material that has undergone the cooling process is subjected to a cold rolling process with a working degree of 80% or more; Aging treatment is performed at a temperature of 390 ° C. or higher and 450 ° C. or lower on the hot-rolled copper alloy material. An effect treatment step, a second cold rolling step for subjecting a copper alloy material subjected to an aging treatment to a cold rolling process with a working degree of 20% to 40%, and a copper alloy that has undergone a second cold rolling step There is provided a method for producing a copper alloy comprising an annealing process for producing a copper alloy by annealing the material at a temperature of 400 ° C or higher and lower than 600 ° C.

(2) Moreover, this invention is a copper alloy material manufactured by the manufacturing method of the copper alloy as described in said (1) in order to solve the said subject, Comprising: Rolling of a 2nd cold rolling process When a predetermined 600 nm × 400 nm region is selected from the cross section perpendicular to the direction, the crystal grain size of the parent phase in the region is 50 μm or less, and Cr or Zr existing in the region is When 30 precipitates are selected from the included precipitates, the arithmetic mean value of the major axis of each precipitate is 20 nm or less, and when 10 regions with an area of 900 nm ² in the region are selected, A copper alloy is provided in which the arithmetic average value of the number of precipitates having a major axis of 20 nm or less existing in a region having an area of 900 nm ² is 5 or more.

(3) Moreover, in the said copper alloy, it has the electrical conductivity of 80% IACS or more, and the intensity | strength of 550 Mpa or more, Complies with the Japan Electronic Materials Manufacturers Association standard EMMA-1011 and the Japan Copper and Brass Association technical standard JCBA-T309. in the stress relaxation test, preferably 1500 hours retained stress relaxation rate after at 0.99 ° C. has a resistance stress relaxation properties of 20% or less.

  According to the copper alloy manufacturing method and the copper alloy according to the present invention, the copper alloy manufacturing method and the copper alloy have high conductivity, excellent stress relaxation resistance, high strength, and excellent bending workability. Can provide.

[Summary of embodiment]
In the method for producing a Cu—Cr—Zr-based copper alloy, copper (Cu) as a parent phase is added in an amount of 0.1% by mass to 0.4% by mass of chromium (Cr), 0.01% by mass to 0% by mass. 0.2 mass% or less of zirconium (Zr), 0.01 mass% or more and 0.3 mass% or less of tin (Sn), 0.05 mass% or more and 0.4 mass% or less of magnesium (Mg), A casting process for casting a copper alloy material containing inevitable impurities, a hot rolling process for subjecting the copper alloy material to hot rolling, and a temperature of 700 ° C. to 900 ° C. for the copper alloy material subjected to the hot rolling process. A cooling step of rapidly cooling after performing a heat treatment at a temperature of less than ° C., a first cold rolling step of performing a cold rolling process with a working degree of 80% or more on the copper alloy material that has undergone the cooling step, The copper alloy material subjected to the first cold rolling process is 390 ° C. or higher and 450 ° C. or lower. An aging treatment step of performing an aging treatment at a temperature, a second cold rolling step of subjecting the copper alloy material subjected to the aging treatment to a cold rolling process with a working degree of 20% to 40%, and the second There is provided a method for producing a copper alloy comprising: an annealing step for producing a copper alloy by subjecting the copper alloy material that has undergone two cold rolling steps to annealing at 400 ° C. or more and less than 600 ° C.

[Embodiment]

  The copper alloy according to the embodiment of the present invention is a Cu—Cr—Zr based copper alloy. The copper alloy according to the present embodiment can be manufactured as follows.

  First, to copper (Cu) as a parent phase, 0.1 mass% or more and 0.4 mass% or less chromium (Cr), 0.01 mass% or more and 0.2 mass% or less zirconium (Zr), A copper alloy material containing 0.01 mass% or more and 0.3 mass% or less of tin (Sn), 0.05 mass% or more and 0.4 mass% or less of magnesium (Mg), and unavoidable impurities is cast. (Casting process).

  Cr precipitates alone in the matrix during the aging treatment described below. Thereby, the strength and heat resistance of the produced copper alloy are improved. In the present embodiment, for the purpose of precipitating a sufficient amount of Cr in the matrix, the amount of Cr added to the matrix is preferably controlled to 0.1% by mass or more. In addition, during the solution treatment described later, Cr that is not solid-solved in the parent phase may form coarse second-phase precipitates. When this second phase precipitate is present, an increase in strength of the produced copper alloy is suppressed. Therefore, in the present embodiment, the amount of Cr added to the parent phase is 0.4 mass% for the purpose of suppressing a decrease in workability of the copper alloy due to the strength of the copper alloy not increasing. It is preferable to be controlled as follows.

  Zr forms a compound with the parent phase Cu during the aging treatment described later, and the compound precipitates in the parent phase. By precipitating this compound in the parent phase, the strength of the produced copper alloy is improved. In the present embodiment, the amount of Zr added to the mother phase is preferably controlled to 0.01% by mass or more for the purpose of precipitating a sufficient amount of Zr into the mother phase. In addition, Zr that is not solid-solved in the matrix may form coarse second phase precipitates during the solution treatment described later. When this second phase precipitate is present, an increase in strength of the produced copper alloy is suppressed. Therefore, in the present embodiment, the amount of Zr added to the parent phase is 0.2% by mass for the purpose of suppressing a decrease in workability of the copper alloy due to the strength of the copper alloy not increasing. It is preferable to be controlled as follows.

  Sn has a function of suppressing non-uniform precipitation of Cr at high temperatures. With such a function, precipitation of Cr during hot rolling described later and subsequent cooling is suppressed, and the amount of Cr dissolved in the matrix can be increased. On the other hand, in the aging treatment, fine Cr can be precipitated, so that the strength of the copper alloy can be improved. For the purpose of exerting the strengthening action of the copper alloy by solid solution strengthening of Sn, the amount of Sn added to the parent phase is preferably controlled to 0.01% by mass or more. Moreover, it is preferable to control the quantity of Sn added to a mother phase to 0.3 mass% or less for the purpose of suppressing the fall of the electrical conductivity of the copper alloy manufactured.

  Since Mg has an atomic radius larger than the atomic radius of Cu atoms constituting the parent phase, the stress relaxation resistance of the manufactured copper alloy can be improved. Mg has a strengthening action of the copper alloy by solid solution strengthening. In the present embodiment, the amount of Mg added to the matrix phase is preferably controlled to 0.01% by mass or more for the purpose of improving the stress relaxation resistance and exerting a strengthening effect. Moreover, it is preferable that the amount of Mg added to the matrix phase is controlled to 1.0% by mass or less for the purpose of suppressing the decrease in the electrical conductivity of the produced copper alloy.

  Next, hot rolling is performed on the copper alloy material obtained by the casting process (hot rolling process). Precipitates generated from the copper alloy material in the casting process due to heating during the hot rolling process are once dissolved in the matrix. That is, in the hot rolling process, the precipitate is formed into a solution in the parent phase. Here, Sn added to the copper alloy material suppresses precipitation of Cr dissolved in the copper alloy material at a high temperature. And the distribution state in the copper alloy of the precipitate produced | generated in the aging treatment mentioned later can be made into a uniform and fine state. Thereby, each characteristic of the copper alloy manufactured improves.

  Subsequently, heat treatment is performed on the copper alloy material that has been hot-rolled. Further, after the heat treatment, the heat-treated copper alloy material is rapidly cooled (cooling step). Specifically, the cooling step is performed by cooling the copper alloy material from the temperature during the heat treatment to room temperature. As an example, the cooling step can be performed by performing heat treatment on the copper alloy material in a heat treatment furnace at 700 ° C. to 900 ° C. and then moving the heat-treated copper alloy material into the atmosphere. By this heat treatment and cooling step, distortion generated in the copper alloy material by hot rolling can be eliminated, and a decrease in bending workability of the manufactured copper alloy material can be prevented. Moreover, since the crystal grain size of each crystal constituting the copper alloy material is refined by this heat treatment and cooling step, the strength of the copper alloy material can be improved. Note that the temperature of heat treatment is controlled to a temperature of 700 ° C. or higher and lower than 900 ° C. Such heat treatment eliminates all of the rolled structure generated by hot rolling, and the crystal grain size generated by recrystallization is 50 μm or less, so that the roughness of the bent portion during bending of the produced copper alloy is reduced. Can be prevented.

  Next, cold rolling is performed on the copper alloy material that has undergone the heat treatment and cooling process (first cold rolling process). In the cold rolling process, the copper alloy material is subjected to cold rolling with a working degree of 80% or more. A number of dislocations are introduced into the copper alloy material by the first cold rolling process. Thereby, the strength of the copper alloy material is improved by work hardening. Moreover, the dislocation introduced into the copper alloy material functions as a starting point of precipitates in an aging treatment described later, and has the effect of promoting precipitation that is uniformly dispersed in the copper alloy material.

  Subsequently, an aging treatment is performed on the copper alloy material subjected to the first cold rolling process (aging treatment process). The aging treatment causes precipitation of Cr and Zr compounds in the copper alloy material. Thereby, the electrical conductivity and intensity | strength of the copper alloy manufactured can be improved. Moreover, the ductility of the copper alloy material that has decreased in the first cold rolling step can be recovered. The aging treatment is preferably performed at a temperature of 390 ° C. or more for the purpose of sufficiently promoting the precipitation of Cr and Zr compounds and sufficiently improving the conductivity and strength of the produced copper alloy. The aging treatment is preferably carried out at a temperature of 450 ° C. or lower for the purpose of suppressing a decrease in strength of the produced copper alloy due to coarsening of precipitates due to overaging.

  Next, the copper alloy material that has been subjected to the aging treatment is subjected to cold rolling and controlled to a predetermined thickness (second cold rolling step). Through the second cold rolling process, the strength of the copper alloy material is improved by work hardening. Here, in order to sufficiently work harden the copper alloy material and improve the strength of the produced copper alloy, the workability is preferably controlled to 20% or more. In addition, the degree of workability is controlled to 40% or less for the purpose of suppressing the decrease in conductivity and ductility of the manufactured copper alloy and ensuring sufficient conductivity and sufficient bending workability of the manufactured copper alloy. It is preferable to do.

  Furthermore, a copper alloy is manufactured by performing annealing as strain relief annealing on the copper alloy material that has undergone the second cold rolling process (annealing process). By the annealing process, strain of the copper alloy material is removed and ductility is restored. Moreover, it is preferable to control the temperature of annealing to 400 degreeC or more for the purpose of ensuring sufficient ductility of the copper alloy manufactured. Moreover, it is preferable to control the temperature of annealing to less than 600 degreeC in order to prevent the intensity | strength of the copper alloy manufactured by generation | occurrence | production of the re-solution of a precipitate falling.

(Effect of embodiment)
According to the copper alloy manufacturing method according to the embodiment of the present invention, a copper alloy manufacturing process, for example, a cooling process, a first cold rolling process, an aging treatment process, a second cold rolling process, and an annealing process are performed. By optimizing, a copper alloy excellent in strength, conductivity, bending workability, and stress relaxation resistance can be produced. And the copper alloy manufactured with the manufacturing method of the copper alloy which concerns on this Embodiment can contribute to size reduction and high mounting of an electrical component, for example, can be used for electrical components, such as a lead frame. .

  A copper alloy having the alloy composition shown in Table 1 was melted using oxygen-free copper as a parent phase and cast into an ingot. And the processing and heat processing were given to the ingot on the predetermined conditions shown in Table 1, and the copper alloy which concerns on Examples 1-7 and the copper alloy which concerns on Comparative Examples 1-12 were manufactured. Table 1 shows the alloy components for each of the copper alloys according to Examples 1 to 7 and Comparative Examples 1 to 12, the production conditions of the copper alloy, and the average of precipitates in the copper alloy produced through all the steps. The particle size, the density of the precipitate, the stress relaxation resistance, the conductivity, the tensile strength, and MBR / t, which is an index of bending workability, are shown.

  About each of the copper alloys which concern on Examples 1-7 and Comparative Examples 1-12, after a hot rolling process, a part of copper alloy immediately after heat processing was sampled, and it was set as the test piece. And about each test piece, grinding | polishing and the etching were given to the cross section perpendicular | vertical to a rolling direction. As a result, the cross section was revealed, the average value of the crystal grains in the plate width direction was calculated, and defined as the average crystal grain size.

  Moreover, the tension test was implemented about each of the copper alloys which concern on Examples 1-7 and Comparative Examples 1-12. In the tensile test, the tensile strength in the rolling parallel direction was measured according to JIS Z2201. Further, according to JIS H 3130, a W-bending test of Bad Way (that is, the bending axis is the same direction as the rolling direction) is carried out, and the ratio is the ratio of the minimum bending radius (MBR) to the plate thickness (t) at which no crack occurs. The MBR / t value was calculated. Furthermore, a stress relaxation test was carried out in accordance with the Japan Electronic Materials Manufacturers Association Standard EMAS-1011 and the Japan Copper and Brass Association Technical Standard JCBA-T309, and the stress relaxation rate at 150 ° C. for 1000 hours was measured as the stress relaxation resistance. .

Each of the copper alloys according to Examples 1 to 7 and Comparative Examples 1 to 12 was subjected to thin film treatment, and images were taken with an electron microscope. And from each image, the average value of the particle diameters (however, the major axis) of 30 precipitates was calculated as the average particle diameter of the precipitates. In addition, the image image | photographed with the electron microscope is a 577 nm x 404 nm area | region of the thin film of a copper alloy, and the magnification of a microscope is 220 times. Further, the average value of the number of precipitates at 10 locations in the 90 nm ² region was calculated as the density of the precipitates.

  The copper alloys according to Comparative Example 1 and Comparative Example 2 contain a different amount of Cr from Examples 1 to 7, and the copper alloys according to Comparative Example 3 and Comparative Example 4 are different from Examples 1 to 7. The copper alloys according to Comparative Example 5 and Comparative Example 6 contain a different amount of Sn from Examples 1 to 7, and the copper alloys according to Comparative Example 7 and Comparative Example 8 are It contains an amount of Mg different from ˜7.

  Moreover, the copper alloy which concerns on the comparative example 9 is a particle size from which the average crystal grain diameter after heat processing differs from Examples 1-7, and the copper alloy which concerns on the comparative example 10 has intermediate rolling work degree of Examples 1- 7, the copper alloys according to Comparative Example 11 and Comparative Example 12 are different in aging temperature from Examples 1 to 7, and the copper alloys according to Comparative Example 13 and Comparative Example 14 are The finish rolling work degree is a work degree different from those of Examples 1 to 7, and the copper alloys according to Comparative Example 15 and Comparative Example 16 have a strain relief annealing temperature different from those of Examples 1 to 7.

Referring to Table 1, in Examples 1 to 7, when a predetermined 600 nm × 400 nm region was selected from the cross section perpendicular to the rolling direction of the second cold rolling process, When the crystal grain size of the mother phase is 50 μm or less and 30 precipitates are selected from the precipitates containing Cr or Zr present in the region, the arithmetic average value of the major axis of each precipitate is 20 nm or less. Yes, when 10 regions of 900 nm ² area in the region are selected, the arithmetic average value of the number of precipitates having a major axis of 20 nm or less present in each region of 900 nm ² area is 5 or more. It has been shown that certain copper alloys can be obtained. Moreover, in Examples 1-7, it has the electrical conductivity of 80% IACS or more, and the intensity | strength of 550 Mpa or more, Complies with the Japan Electronic Materials Industry Standard EMA-1011 and the Japan Copper and Brass Association technical standard JCBA-T309. in the stress relaxation test, 1500 hours retained stress relaxation rate after at 0.99 ° C. it has been shown that copper alloys having resistance to stress relaxation properties of 20% or less is obtained.

  While the embodiments and examples of the present invention have been described above, the embodiments and examples described above do not limit the invention according to the claims. It should be noted that not all combinations of features described in the embodiments and examples are necessarily essential to the means for solving the problems of the invention.

Claims (2)

To copper (Cu) as a parent phase, 0.1 mass% or more and 0.4 mass% or less of chromium (Cr), 0.01 mass% or more and 0.2 mass% or less of zirconium (Zr); A casting process for casting a copper alloy material containing tin (Sn) of not less than 01 mass% and not more than 0.3 mass%, magnesium (Mg) of not less than 0.05 mass% and not more than 0.4 mass%, and unavoidable impurities When,
A hot rolling step of subjecting the copper alloy material to hot rolling,
A cooling step of cooling the copper alloy material that has been subjected to the hot rolling process after performing a heat treatment at a temperature of 700 ° C. or more and less than 900 ° C .;
A first cold rolling step for subjecting the copper alloy material that has undergone the cooling step to cold rolling with a workability of 80% or more;
An aging treatment step of performing an aging treatment at a temperature of 390 ° C. or higher and 450 ° C. or lower on the copper alloy material subjected to the first cold rolling process;
A second cold rolling process in which the copper alloy material subjected to the aging treatment is subjected to a cold rolling process with a working degree of 20% or more and 40% or less;
A copper alloy manufactured by a copper alloy manufacturing method comprising: an annealing process for manufacturing a copper alloy by annealing the copper alloy material that has undergone the second cold rolling process at a temperature of 400 ° C. or higher and lower than 600 ° C. And
When a predetermined 600 nm × 400 nm region is selected from within a cross section perpendicular to the rolling direction of the second cold rolling step,
The crystal grain size of the matrix in the region is 50 μm or less,
When 30 precipitates are selected from the precipitates containing Cr or Zr present in the region, the arithmetic average value of the major axis of each precipitate is 20 nm or less,
When ten regions with an area of 900 nm ² in the region are selected , the arithmetic average value of the number of precipitates having a major axis of 20 nm or less present in each region with an area of 900 nm ² is 5 or more. Copper alloy. It has a conductivity of 80% IACS or more and a strength of 550 MPa or more, and is 1500 at 150 ° C. in a stress relaxation test in accordance with the Japan Electronic Materials Industries Association standard EMMA-1011 and the Japan Copper and Brass Association technical standard JCBA-T309. copper alloy according to claim 1, retention time and stress relaxation rate after having a resistance stress relaxation properties of 20% or less.