JP2017179502A - Copper alloy sheet excellent in strength and conductivity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper alloy sheet having high strength, high conductivity, flexure processability and excellent stress relaxation characteristics.SOLUTION: A copper alloy sheet contains Cr of 0.1 to 0.6 mass%, one or both of Zr and Ti with a total 0.01 to 0.30 mass% and the balance copper with inevitable impurities, satisfies 5≤I(220)/I(220)≤15, where I(220)/I(220) is calculated by the X ray diffraction of a material surface and provides a relationship of spring deflection limit Kb (MPa) and 0.2% bearing force σ (MPa) of (σ-150)≤Kb≤(σ-50).SELECTED DRAWING: None

Description

  The present invention relates to a copper alloy plate and an electronic component for energization or heat dissipation that can be suitably used for manufacturing electronic components such as electronic materials. The present invention relates to a copper alloy plate used as a material for electronic components such as sockets, bus bars, lead frames, and heat sinks, and an electronic component using the copper alloy plate. Among them, a copper alloy plate suitable for use in energizing electronic components such as connectors and terminals used in electric vehicles, hybrid vehicles, etc., or in heat dissipating electronic components such as liquid crystal frames used in smartphones and tablet PCs, and the copper The present invention relates to an electronic component using an alloy plate.

  As a material for transmitting electricity or heat such as terminals, connectors, switches, sockets, relays, bus bars, lead frames, and heat sinks of electronic devices, copper alloy plates having excellent strength and conductivity are widely used. Here, electrical conductivity and thermal conductivity are in a proportional relationship. By the way, in recent years, high currents have been developed in connectors of electronic devices, and it is considered necessary to have good bendability, conductivity of 80% IACS or more, and proof stress of 600 MPa or more. In addition, it is also required to have better stress relaxation characteristics so that the contact force does not decrease even when heat is generated.

  On the other hand, for example, a heat radiating component called a liquid crystal frame is used for a liquid crystal of a smartphone or a tablet PC. Even in such a copper alloy plate for heat dissipation, high thermal conductivity is progressing, and it is considered necessary to have good bendability and high strength. For this reason, it is considered that a copper alloy plate for heat dissipation needs to have a conductivity of 80% IACS or more and a proof stress of 600 MPa or more.

  However, since it is difficult to achieve a conductivity of 80% IACS or higher with a Corson alloy-based copper alloy, the development of Cu-Cr-based and Cu-Zr-based copper alloys has been promoted. For example, as a Cu—Cr—Zr-based copper alloy, a copper alloy excellent in bending workability is disclosed by increasing I (200) (Patent Document 1).

Japanese Patent No. 5834528

  However, although the Cu-Cr-Zr-based copper alloy has relatively good stress relaxation characteristics, the level of the stress relaxation characteristics is not necessarily used as a part that conducts a large current or a part that dissipates a large amount of heat. In some cases, it was not enough. In addition, as in Patent Document 1, in order to improve the bending workability while maintaining the strength, there is a case in which the stress relaxation characteristics may be deteriorated.

  Therefore, the present invention aims to provide a copper alloy plate having high strength, high conductivity, bending workability and excellent stress relaxation characteristics. Specifically, the bending workability and stress relaxation characteristics are improved. It is an object of the present invention to provide a Cu-Cr-Zr-Ti-based alloy plate. Furthermore, an object of the present invention is to provide a method for producing the copper alloy plate and an electronic component suitable for energization use or heat dissipation use.

In one aspect, the copper alloy plate according to the present invention contains 0.1 to 0.6% by mass of Cr, 0.01 to 0.30% by mass in total of one or two of Zr and Ti, and the balance There of copper and unavoidable impurities, per _{I (220) / I 0 (} 220) determined by X-ray diffraction of the material surface, satisfies the 5 ≦ I (220) / I 0 (220) ≦ 15, the spring limit value The relationship between Kb (MPa) and 0.2% yield strength σ (MPa) is given by (σ−150) ≦ Kb ≦ (σ−50).

  In one embodiment, the copper alloy plate according to the present invention has a crystal grain thickness of 1 μm or less in a rolled parallel section.

  In another embodiment, the copper alloy sheet according to the present invention contains at least 1.0% by mass in total of at least one of Ag, Fe, Co, Ni, Mn, Zn, Mg, Si, P, Sn and B. To do.

  In another aspect, the present invention is an electronic component for energization using the copper alloy plate.

  In another aspect of the present invention, there is provided a heat dissipating electronic component using the copper alloy plate.

  According to the present invention, a Cu—Cr—Zr—Ti alloy plate excellent in bending workability and stress relaxation characteristics while maintaining conductivity and strength, and an electronic component suitable for energization use or heat dissipation use are provided. It is possible. This copper alloy plate can be suitably used as a material for electronic parts such as terminals, connectors, switches, sockets, relays, bus bars, lead frames, etc., and particularly dissipates the material or large amount of heat of electronic parts that carry a large current. It is useful as a material for electronic parts.

It is a figure explaining the measurement principle of a stress relaxation rate. It is a figure explaining the measurement principle of a stress relaxation rate.

  Hereinafter, a Cu—Cr—Zr—Ti alloy plate according to an embodiment of the present invention will be described. In the present invention, “%” means mass% unless otherwise specified.

<Ingredient concentration>
The copper alloy plate according to the embodiment of the present invention includes 0.1 to 0.6% of Cr and 0.01 to 0.30% in total of one or two of Zr and Ti. In one embodiment, it is preferable to contain 0.15 to 0.3% of Cr and 0.05 to 0.20% in total of one or two of Zr and Ti. If Cr exceeds 0.6%, the bending workability decreases, and if it is less than 0.1%, it becomes difficult to obtain a 0.2% yield strength of 600 MPa or more. When the total of one or two of Zr and Ti exceeds 0.3%, the bending workability deteriorates, and when less than 0.01%, the 0.2% proof stress of 600 MPa or more and the stress relaxation of 15% or less. It becomes difficult to get a rate.

  Furthermore, the copper alloy plate according to the embodiment of the present invention has a total of 1.0% of at least one selected from the group consisting of Ag, Fe, Co, Ni, Mn, Zn, Mg, Si, P, Sn, and B. It is preferable to contain below. These elements contribute to an increase in strength by solid solution strengthening or precipitation strengthening. If the total amount of these elements exceeds 1.0%, the electrical conductivity may decrease, or may be cracked by hot rolling. In addition, it is understandable by those skilled in the art that in a copper alloy plate having high strength and high conductivity, the amount of each additive is changed depending on the combination of additive elements to be added. In one exemplary embodiment, for example, Ag is 1.0% or less, Fe is 0.1% or less, Co is 0.1% or less, Ni is 0.2% or less, and Mn is 0.1% or less. Zn is 0.5% or less, Mg is 0.1% or less, Si is 0.1% or less, P is 0.05% or less, Sn is 0.1% or less, and B is 0.05% or less. However, the copper alloy sheet of the present invention is not necessarily limited to these upper limit values as long as the combination and addition amount of additive elements whose conductivity does not fall below 80% IACS.

  The thickness of the Cu—Cr—Zr—Ti alloy plate of the present invention is not particularly limited, but may be, for example, 0.03 to 0.6 mm.

(Spring limit value)
By adjusting the metal structure using the spring limit value as an index, the bending workability and stress relaxation characteristics of the copper alloy plate are improved. In the copper alloy plate according to the present invention, when the spring limit value of the product is Kb (MPa) and the 0.2% proof stress is σ (MPa), (σ−150) ≦ Kb ≦ (σ−50) By adjusting the relationship, the balance of 0.2% proof stress, electrical conductivity, bending workability, and stress relaxation characteristics is improved. According to the copper alloy according to the embodiment of the present invention, 0.2% proof stress is 600 MPa or more, conductivity is 80% IACS or more, MBR / t is 0, and stress relaxation rate is 15% or less. An excellent copper alloy sheet can be obtained. In the case of Kb <(σ−150), the stress relaxation rate exceeds 15%. In the case of Kb> (σ-50), the 0.2% proof stress is less than 600 MPa.

(Crystal orientation of rolling surface)
By controlling the orientation of crystal grains oriented on the rolling surface, the stress relaxation characteristics of the copper alloy sheet are further improved. In the copper alloy sheet according to the present invention, by adjusting I (220) / I ₀ (220) to 5 ≦ I (220) / I ₀ (220) ≦ 15 on the rolled surface of the product, 0.2% The balance of% yield strength, electrical conductivity, bending workability, and stress relaxation characteristics is good. Here, I (220) is the diffraction integral intensity of the (220) plane obtained in the thickness direction of the copper alloy plate using the X-ray diffraction method, and I ₀ (220) is fine powder copper obtained by X-ray diffraction. The integrated intensity of the (220) diffraction peak. When I (220) / I ₀ (220) exceeds 15, bending workability is deteriorated. When I (220) / I ₀ (220) is less than 5, the 0.2% yield strength is less than 600 MPa.

(Crystal grain thickness)
By controlling the crystal grain size, the strength and 0.2% proof stress are improved without lowering the bending workability and stress relaxation characteristics. By adjusting the diameter in the plate thickness direction of the crystal grains when observing the rolling parallel cross section to 1 μm or less, the balance of 0.2% proof stress, bending workability, and stress relaxation characteristics is improved. When the thickness of the crystal grains of the rolled parallel cross section exceeds 1 μm, the bending workability is lowered.

(Use)
The copper alloy plate according to the embodiment of the present invention can be suitably used for applications of electronic components such as terminals, connectors, relays, switches, sockets, bus bars, lead frames, heat sinks, in particular, electric vehicles, This is useful for energizing applications such as connectors and terminals used in hybrid vehicles and the like, or for heat-dissipating electronic components such as liquid crystal frames used in smartphones and other tablet PCs.

(Production method)
After dissolving electrolytic copper or the like as a pure copper raw material and reducing the oxygen concentration by carbon deoxidation or the like, Cr, one or two of Zr and Ti, and other alloy elements as necessary, thickness Cast into an ingot of about 30 to 300 mm. After this ingot is made into a plate having a thickness of about 3 to 30 mm by hot rolling at 800 to 1000 ° C., for example, first cold rolling, solution treatment, second cold rolling, and aging treatment are performed in this order.

  The solution treatment is performed by water cooling after holding at 850 to 900 ° C. for 5 seconds to 2 minutes. When the temperature is lower than 850 ° C., the amount of the additive element that dissolves in copper decreases, and when the amount of the solid solution is insufficient, the degree of aggregation of the (220) plane hardly increases, and the amount of precipitation in the subsequent aging treatment step decreases. The 0.2% yield strength of the product is lowered. If it exceeds 900 ° C., the crystal grain size becomes too large, and it becomes difficult to make the thickness 1 μm or less by subsequent cold rolling.

In the second cold rolling, it is necessary that the workability is 85% or more and the thickness of the crystal grains coarsened by the solution treatment is 1 μm or less. When the cold rolling work degree is 95% or more, since I (220) / I ₀ (220) becomes too high, bending workability is lowered.

The aging treatment is preferably performed at a low temperature for a long time, and preferably at 300 to 400 ° C. for 15 to 20 hours. When the temperature is higher than 400 ° C. as in the prior art, recrystallization proceeds and I (220) / I ₀ (220) decreases. If it is lower than 300 ° C., the time becomes too long, which is inefficient. In this aging treatment, (σ−150) ≦ Kb ≦ (σ−50) is obtained.

  After adding the alloy element to the molten copper, it was cast into an ingot having a thickness of 200 mm. The ingot was heated at 950 ° C. for 3 hours and formed into a plate having a thickness of 15 mm by hot rolling. After grinding and removing the oxide scale on the surface of the hot rolled plate with a grinder, the plate was formed into a 1 mm thick plate by cold rolling, and then subjected to a solution treatment. In the solution treatment, the furnace temperature was adjusted to 850 to 900 ° C., held for 5 seconds to 2 minutes, and then cooled with water. Then, it was set as the 0.1 mm board by cold rolling, and the aging process was implemented for 15 to 20 hours at 300 to 400 degreeC.

  In the comparative example, the sample was prepared by changing the sheet thickness (solution solution thickness), solution treatment temperature, aging treatment temperature, and aging treatment time in cold rolling after hot rolling to the conditions shown in Table 1.

Each sample was evaluated as follows.
<Tensile strength (TS)>
The tensile strength (TS) in a direction parallel to the rolling direction was measured with a tensile tester according to JIS-Z2241.

<0.2% yield strength (YS)>
A 0.2% proof stress (YS) in a direction parallel to the rolling direction was measured with a tensile tester in accordance with JIS-Z2241. 0.2% yield strength (YS) was taken as the yield strength.

<Conductivity (% IACS) (ES)>
The test piece was sampled so that the longitudinal direction of the test piece was parallel to the rolling direction, and the conductivity at 20 ° C. was measured by a four-terminal method in accordance with JIS H0505.

<Integral intensity ratio>
Using RINT-TTR manufactured by Rigaku Corporation, the integrated intensity of the (220) diffraction peak was evaluated by X-ray diffraction in the thickness direction of the copper alloy plate surface: I (220), and further by X-ray diffraction of fine powder copper (220) Integrated intensity of diffraction peak: I ₀ (220) was evaluated. Subsequently, these ratios: I (220) / I ₀ (220) were calculated.

<Spring limit value>
A strip-shaped test piece having a width of 10 mm and a length of 100 mm was taken so that the longitudinal direction of the test piece was parallel to the rolling direction, and the test piece in the direction parallel to the rolling direction was measured by a moment formula test specified in JIS-H3130. The spring limit value was measured.

<Stress relaxation rate>
A strip-shaped test piece having a width of 10 mm and a length of 100 mm was collected so that the longitudinal direction of the test piece was parallel to the rolling direction. As shown in FIG. 1, with the position of l = 50 mm as the working point, the test piece is given a deflection of y ₀ , which corresponds to 80% of the 0.2% yield strength (measured in accordance with JIS-Z2241) in the rolling direction. Stress (s) was applied. y ₀ was determined by the following equation.
y ₀ = (2/3) · I ² · s / (E · t)
Here, E is the Young's modulus in the rolling direction, and t is the thickness of the sample. Unloading after heating at 150 ° C. for 1000 hours, and measuring the amount of permanent deformation (height) y as shown in FIG. 2, stress relaxation rate {[y (mm) / y ₀ (mm)] × 100 (%) } Was calculated.

<Thickness of crystal grains>
The test piece was resin-filled so that the observation surface had a cross section in the thickness direction parallel to the rolling direction, the observation surface was mirror-finished by mechanical polishing, and subsequently a mass concentration of 36% with respect to 100 volume parts of water. In a solution mixed with 10 parts by volume of hydrochloric acid, ferric chloride having a weight of 5% with respect to the weight of the solution was dissolved. The sample was immersed in the resulting solution for 10 seconds to reveal the metal structure. Next, this metal structure was magnified 100 times with an optical microscope, and a photograph was taken in the range of an observation visual field of 0.5 mm ² . Subsequently, an average of the maximum diameter in the thickness direction of each crystal grain is obtained for each crystal based on the photograph, an average value is calculated for each observation field, and an average value of 15 observation fields (average crystal thickness) ) Was evaluated as “crystal grain thickness”, and those having a thickness of 1 μm or less were evaluated as “◯” and those having a thickness exceeding 1 μm as “X”.

<Bending workability>
A sample cut into a width of 10 mm and a length of 200 mm was used as a bending test piece. The test piece was subjected to a W-bend test in which the bending axis was perpendicular to the rolling direction using a W-shaped mold, and the minimum bending radius (MBR) at which no crack occurred in the bent portion was divided by the plate thickness (t). MBR / t, which was the calculated value, was obtained.

  Table 2 shows the composition of each test piece and the obtained results. In each example, YS was 600 MPa or more, conductivity was 80% IACS or more, MBR / t was 0, and stress relaxation rate was 15% or less.

  As is apparent from Table 2, the solution treatment was performed at 850 to 900 ° C. for 5 seconds to 2 minutes, the second cold pressing degree was 90%, and the aging treatment was performed at 300 to 400 ° C. for 15 to 20 hours. In the case of the examples, YS was 600 MPa or more, conductivity was 80% IACS or more, MBR / t was 0, and stress relaxation rate was 15% or less, and good characteristics could be obtained.

  On the other hand, in the case of Comparative Examples 1 and 2 having high component concentrations of Cr, Zr, and Ti, bending workability was inferior. In Comparative Examples 3 and 4 having low component concentrations of Cr, Zr, and Ti, the 0.2% proof stress and stress relaxation characteristics were inferior.

In Comparative Example 5 where the solution treatment temperature was low, the amount of solid solution was small and I (220) / I ₀ (220) was low, and the 0.2% proof stress was inferior.

In Comparative Example 6 having a high second rolling degree, bending workability was inferior and I (220) / I ₀ (220) was high. In the case of Comparative Example 7 in which the second cold rolling work degree was 50%, I (220) / I ₀ (220) was low, the crystal grains became thick, and the 0.2% yield strength was inferior.

  In Comparative Example 8 where the aging treatment temperature was high and Comparative Example 9 where the aging treatment time was long, the crystal grains were increased by the aging treatment, and the 0.2% yield strength was poor.

  In Comparative Example 10 where the aging treatment time was short and Comparative Example 11 where the aging treatment temperature was low, Kb was low and the conductivity, stress relaxation characteristics (rate), and bending workability were poor.

Claims (5)

0.1 to 0.6% by mass of Cr, one or two of Zr and Ti are contained in a total of 0.01 to 0.30% by mass, and the balance is made of copper and unavoidable impurities. For I (220) / I ₀ (220) determined by X-ray diffraction, 5 ≦ I (220) / I ₀ (220) ≦ 15 is satisfied, the spring limit value Kb (MPa), and 0.2% yield strength σ A copper alloy sheet having a relationship with (MPa) given by (σ−150) ≦ Kb ≦ (σ−50).   The copper alloy sheet according to claim 1, wherein the thickness of the crystal grains is 1 μm or less in a rolled parallel section.   The copper alloy plate according to claim 1 or 2, containing a total of 1.0% by mass or less of at least one of Ag, Fe, Co, Ni, Mn, Zn, Mg, Si, P, Sn, and B.   The electronic component for electricity_supply using the copper alloy plate of any one of Claims 1-3.   The electronic component for thermal radiation using the copper alloy plate of any one of Claims 1-3.

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