JP6879968B2 - Copper alloy plate, electronic parts for energization, electronic parts for heat dissipation - Google Patents

Description

The present invention relates to a copper alloy plate that can be suitably used for manufacturing electronic components such as electronic materials and electronic components for energization or heat dissipation, and in particular, terminals, connectors, relays, and switches mounted on electric / electronic devices, automobiles, and the like. , A copper alloy plate used as a material for electronic parts such as sockets, bus bars, lead frames, and heat sinks, and electronic parts using the copper alloy plate. Among them, copper alloy plates and copper suitable for applications of energizing electronic parts such as connectors and terminals used in electric vehicles and hybrid vehicles, or applications of heat dissipation electronic parts such as liquid crystal frames used in smartphones and tablet PCs. It relates to an electronic component using an alloy plate.

Copper alloy strips with excellent strength and conductivity are widely used as materials for transmitting electricity or heat such as terminals, connectors, switches, sockets, relays, bus bars, lead frames, and heat sinks of electronic devices. Here, electrical conductivity and thermal conductivity are in a proportional relationship. By the way, in recent years, the current has been increased in connectors of electronic devices, and it is considered necessary to have good bendability, a conductivity of 75% IACS or more, and a proof stress of 550 MPa or more.

On the other hand, for example, a heat radiating component called a liquid crystal frame is used for the liquid crystal of a smartphone or a tablet PC. It is considered necessary for such copper alloy plates for heat dissipation to have high thermal conductivity, good bendability, and high strength. Therefore, it is considered necessary for a copper alloy plate for heat dissipation to have a conductivity of 75% IACS or more and a proof stress of 550 MPa or more. In addition to these characteristics, the bent surface of the bent portion needs to be good. The reason for this is that, for example, when the bent surface is not good, the contact area of the bent portion is reduced in a connector or the like, and the electrical conductivity is deteriorated. Here, the bent skin means the depth of wrinkles on the surface after the bending test, and the details of the evaluation method will be described later.

However, since it is difficult to achieve a conductivity of 75% 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, by performing melt casting, homogenization heat treatment, hot rolling, cold rolling, recrystallization heat treatment, cold rolling, and aging heat treatment, it is particularly excellent in stress relaxation resistance, and has moderate strength and high conductivity. It is disclosed that a copper alloy material centered on a Cu—Cr system can be obtained (Patent Document 1). Further, as a Cu-Cr-Zr-Ti-based copper alloy, a copper alloy having excellent bending workability by increasing I (200) is disclosed (Patent Document 2).

Japanese Unexamined Patent Publication No. 2013-129889 Japanese Patent No. 5834528

However, although the Cu-Cr-Zr-Ti copper alloy has relatively good stress relaxation characteristics, the level of the stress relaxation characteristics is used for parts that carry a large current or dissipate a large amount of heat. In some cases, it was not always sufficient. Further, there is a limit in increasing the yield strength while ensuring high conductivity of 75% IACS or more and good bending workability, and there is a case where sufficient contact pressure cannot always be secured when used as a connector. Further, in Patent Documents 1 and 2, the bending workability is determined by the presence or absence of cracks, but even if there are no cracks, the bending surface may be poor, so that these techniques are not always good for bending. You don't always get skin.

Therefore, an object of the present invention is to provide a Cu-Cr-Zr-Ti-based copper alloy plate having a good bending surface in a copper alloy plate having both high strength and high conductivity. Furthermore, it is also an object of the present invention to provide an electronic component suitable for energization use or heat dissipation use using the copper alloy plate.

The copper alloy plate according to the present invention contains 0.1 to 0.6% by mass of Cr and 0.01 to 0.30% by mass of one or two of Zr and Ti in total on one side, and the balance. Is composed of copper and unavoidable impurities, and is a Schmid factor when a tensile stress is applied in the direction parallel to the TD with respect to the peak direction of the accumulated strength in the reverse pole diagram of the rolling orthogonal direction (TD) obtained from the XRD measurement. A copper alloy plate having a value of 0.40 or more is provided.

In another embodiment, the copper alloy plate according to the present invention has a 0.2% proof stress (MPa) / tensile strength (MPa) value of 0.95 or more.

In still another embodiment, the copper alloy plate according to the present invention has a tensile strength of 550 MPa or more, a conductivity of 75% IACS or more, and a stress relaxation rate of 15% or less.

In still another embodiment, the copper alloy plate according to the present invention comprises Ag, Fe, Co, Ni, Mn, Zn, Mg, Si, P, Sn, Al, Ca, Y, Nb, Mo, At least one selected from the group consisting of Hf, W, Pt, Au and B is contained in a total of 1.0% by mass or less.

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

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

According to the present invention, a Cu-Cr-Zr-Ti copper alloy plate having a good bending surface while maintaining conductivity and strength, and an electronic component suitable for energization or heat dissipation are provided. 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 a large amount of heat or a material for electronic parts that carry a large current. It is useful as a material for electronic components.

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. It is a figure explaining the Schmidt factor.

Hereinafter, the copper alloy plate (Cu-Cr-Zr-Ti alloy plate) according to the embodiment of the present invention will be described. In the present invention, "%" means mass% unless otherwise specified.

(Component concentration)
The copper alloy plate according to the embodiment of the present invention contains 0.1 to 0.6% of Cr, 0.01 to 0.30% in total of one or two of Zr and Ti, and the balance is copper. And consists of unavoidable impurities. In one embodiment, it is preferable that Cr is contained in an amount of 0.15 to 0.3%, and one or two of Zr and Ti are contained in a total amount of 0.05 to 0.20%. If Cr exceeds 0.6%, the bending workability is lowered, and if it is less than 0.1%, it becomes difficult to obtain a 0.2% proof stress of 550 MPa or more. If the total of one or two of Zr and Ti exceeds 0.30%, the bending workability is lowered, and if it is less than 0.01%, it becomes difficult to obtain a 0.2% proof stress of 550 MPa or more.
In addition, when it is referred to as "Cu-Cr-Zr-Ti copper alloy plate" in this specification, it does not mean that it contains all Cu, Cr, Zr and Ti, and the above Cr is 0.1 to 0.6%. , Zr and Ti are collectively referred to as a copper alloy plate containing 0.01 to 0.30% in total.

Further, the copper alloy plate according to the embodiment of the present invention includes Ag, Fe, Co, Ni, Mn, Zn, Mg, Si, P, Sn, Al, Ca, Y, Nb, Mo, Hf, W and Pt. , Au and B, preferably at least 1.0% or less in total. These elements contribute to the increase in strength by strengthening solid solution and strengthening precipitation. If the total amount of these elements exceeds 1.0%, the conductivity may decrease or the elements may be cracked by hot rolling.

It should be understood by those skilled in the art that in a copper alloy plate having high strength and high conductivity, the individual addition amount is changed depending on the combination of the additive elements to be added. In one typical 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, Al is 0.1% or less, Ca Is 0.1% or less, Y is 0.1% or less, Nb is 0.1% or less, Mo is 0.1% or less, Hf is 0.1% or less, W is 0.1% or less, Pt is 0. .1% or less, Au can be added 0.1% or less, B can be added 0.05% or less, but if the combination and amount of added elements whose conductivity is not less than 75% IACS, the present invention can be added. The copper alloy plate is not necessarily limited to these upper limits.

The thickness of the copper alloy plate according to the embodiment of the present invention is not particularly limited, but may be, for example, 0.03 to 0.6 mm.

(Schmidt factor)
It is often difficult for the present inventor to create a good bent skin, B.I. W. : It was considered important to improve the bending surface of Bad Way (the bending axis is in the same direction as the rolling direction).
It was found that when the value of the Schmidt factor was increased when a tensile stress was applied in the vertical direction of rolling, a good bending surface was obtained. The reason for this is that the larger the value of the Schmidt factor, the easier it is for the slip surface to slip (note that the maximum value of the Schmidt factor is 0.5). Therefore, by increasing the Schmidt factor in the above direction, B.I. W. It is presumed that this is because slip deformation is likely to occur when a bending load is applied to the surface.

FIG. 3 shows a model for simply explaining the tensile decomposition shear stress of a single crystal.
Specifically, FIG. 3 is a model diagram for simply explaining the Schmid factor, and is a diagram schematically showing the plastic deformation of a single crystal. That is, when the single crystal round bar 10 having the cross-sectional area A is pulled by the uniaxial load F, decomposition shear stress is generated on the slip surface 20 and the slip direction 25 in the crystal grains of the single crystal round bar 10. When this decomposition shear stress τ reaches the critical shear stress τc peculiar to the material, slip deformation (plastic deformation) occurs. The decomposition shear stress τ is τ = (F / A) · cosλ ·, where σ is the axial stress, φ is the angle between the load axis and the normal of the slip surface, and λ is the angle between the load axis and the slip direction. It is represented by cosφ = σ ・ cosλ ・ cosφ. This is Schmidt's law, and cosλ · cosφ is the Schmidt factor. The Schmidt factor reaches its maximum value when λ = φ = 45 ° (for the Schmidt factor, refer to Plastic Machining Technology Series 2 “Materials”, edited by the Japan Society for Plastic Machining, Corona Publishing Co., Ltd., p. 12).

The above-mentioned Schmid factor was calculated as a value when a tensile stress was applied in a direction parallel to the TD with respect to the peak direction of the accumulated strength in the reverse pole figure in the direction perpendicular to rolling (TD). The reverse pole figure was obtained from XRD (X-ray division) measurement. Good bent skin was obtained when the Schmidt factor obtained by this method showed a value of 0.40 or more. When the Schmid factor is 0.40 or more, the dislocation motion becomes relatively easy when a bending load is applied to the copper alloy plate. It is presumed that the cause is that slip deformation occurs due to the movement of dislocations, which enables continuous deformation and makes it difficult for large dents and the like to occur on the surface of the material.
The Schmidt factor was calculated using the following formula.
(Schmidt factor) = cosλ ・ cosφ
cosλ = t · n / | t || n |
cosφ = t · s / | t || s |
However,
φ: Angle formed by the load axis and the normal of the sliding surface λ: Angle formed by the load axis and the sliding direction t: Unit vector parallel to the tensile load load direction n: Unit vector parallel to the normal vector of the sliding surface s : Unit vector parallel to the sliding direction

(Bent skin)
The surface roughness Ra of the bent portion is used for the evaluation of the bent skin. The lower the Ra value, the smaller the unevenness of the sample surface, and the larger the contact area when used in a connector or the like, so that good electrical conductivity is ensured. In the present invention, Ra is set to 2.0 μm or less, preferably 1.5 μm or less.

(0.2% proof stress / tensile strength)
In one embodiment of the present invention, the value of the ratio of 0.2% proof stress (YS) to tensile strength (TS) is preferably 0.95 or more. When the value of 0.2% proof stress / tensile strength is 0.95 or more, the rolled texture is sufficiently formed and the accumulated strength of the peak becomes large. The higher the accumulation intensity of the peak, the higher the influence of the Schmid factor in the direction indicating the peak on the bent skin.

(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, and heat sinks, and in particular, electric vehicles. It is useful for energizing 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 tablet PCs.

(Production method)
The copper alloy plate according to the embodiment of the present invention can be manufactured by the following manufacturing process. First, electrolytic copper or the like is dissolved as a pure copper raw material, the oxygen concentration is reduced by carbon deoxidation or the like, and then Cr, one or two of Zr and Ti, and other alloying elements are added as necessary. , Cast into an ingot with a thickness of about 30 to 300 mm. After the ingot is hot-rolled at 800 to 1000 ° C. to form a plate having a thickness of about 3 to 30 mm, the first cold rolling, solution treatment, second cold rolling, and aging treatment are performed in this order.

In hot rolling, the total workability is set to 80% or more, and the strain rate of the final pass is set to 1.0 / s ^-1 or more. By performing hot rolling under the above conditions, dynamic recrystallization is sufficiently developed, and as a result, tension is applied in the direction parallel to TD with respect to the peak direction of the accumulated strength in the reverse pole diagram in the direction perpendicular to rolling (TD). It is possible to obtain an alloy having a Schmid factor of 0.40 or more when the stress of is applied.
The total workability is calculated by (thickness before hot rolling-thickness after hot rolling) / thickness before hot rolling x 100%.
The strain rate of the final pass can be calculated using the following equation.
dε / dt = (2πn / 60r ^1/2 ) ・ (R / H) ^1/2・ln (1 / (1-r))
here,
dε / dt: Strain rate of the final pass n: Roll rotation speed (rpm)
r: Degree of processing (%) / 100
R: Roll radius (mm)
H: Plate thickness (mm) before the final pass
Means.

After hot rolling, the first cold rolling is performed. In the first cold rolling, the thickness is 0.15 to 5 mm, preferably 0.25 to 1.0 mm.

The solution treatment is carried out by holding at 800 to 1000 ° C. and then cooling with water.

In the second cold rolling after the solution treatment, the total workability is preferably 75% or more. As a result, the value of 0.2% proof stress (MPa) / tensile strength (MPa) after the final aging can be set to 0.95 or more, and a rolled texture can be sufficiently formed.

The aging treatment is preferably carried out at 300 to 500 ° C. for 5 to 30 hours.

Based on the above, the method for producing a copper alloy plate according to the present invention contains 0.1 to 0.6% by mass of Cr and 0.01 to 0.30% by mass of one or two of Zr and Ti in total. After hot rolling a copper alloy ingot whose balance is copper and unavoidable impurities, a copper alloy plate including a first cold rolling step, a solution treatment step, a second cold rolling step, and an aging treatment step. It is a manufacturing method of
A method for producing a copper alloy plate, characterized in that the total workability in the hot rolling step is 80% or more and the strain rate of the final pass is 1.0 / s ^{-1 or more.}

By the above manufacturing method, it is possible to manufacture a copper alloy plate having a good bending surface, a tensile strength of 550 MPa or more, a conductivity of 75% IACS, and a stress relaxation rate of 15% or less.

Examples of the present invention are shown below together with comparative examples, but these examples are provided for a better understanding of the present invention and its advantages, and are not intended to limit the invention.

After adding an alloying 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 hot rolling with the degree of processing shown in Table 1 was performed. The strain rates of the final pass in hot rolling are as shown in Table 1. Next, the oxide scale on the surface of the hot-rolled plate was ground and removed with a grinding machine, and then cold-rolled to obtain a plate having a thickness of 0.25 to 1.0 mm. Further, the solution treatment was performed at 900 ° C., and then cold rolling with the degree of processing shown in Table 1 was performed to obtain a plate thickness of 0.1 mm. Subsequent aging treatment was carried out at 500 ° C. for 10 hours.

<Tensile strength (TS)>
The tensile strength (TS) in the direction parallel to the rolling direction was measured by a tensile tester according to JIS-Z2241.

<0.2% proof stress (YS)>
The 0.2% proof stress (YS) in the direction parallel to the rolling direction was measured by a tensile tester according to JIS-Z2241. The yield strength was defined as 0.2% proof stress (YS).

<Conductivity (EC, unit:% IACS)>
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 the four-terminal method in accordance with JIS-H0505.

<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 point of action, the test piece _{is given a deflection of y 0} , which corresponds to 80% of the 0.2% proof stress in the rolling direction (measured according to JIS-Z2241). The stress (s) was applied. y ₀ was calculated by the following equation.
y ₀ = (2/3) ・l ² ・ s / (E ・ t)
Here, E is Young's modulus in the rolling direction, and t is the thickness of the sample. After heating at 150 ° C. for 1000 hours, the load is unloaded, the amount of permanent deformation (height) y is measured as shown in FIG. 2, and the stress relaxation rate {[y (mm) / y ₀ (mm)] × 100 (%). } Was calculated.

<Bent skin>
In the evaluation of the bent skin, a sample cut out to a width of 1 mm and a length of 20 mm was used as a bending test piece. According to JIS-H3130, B.I. W. A W bending test (the bending axis is in the same direction as the rolling direction) was performed, the surface of the bent portion was analyzed with a confocal laser scanning microscope, and Ra (μm) defined in JIS-B0601 (2013) was calculated. Bent skin is ⊚ if Ra is 1.5 μm or less, ○ if it is larger than 1.5 μm and 2.0 μm or less, Δ if it is larger than 2.0 μm and 3.0 μm or less, and × if it is larger than 3.0 μm. Notated.

<Reverse pole diagram>
The reverse pole figure was obtained using XRD measurement. For the XRD measurement, RINT-TTR manufactured by Rigaku Co., Ltd. was used to measure the X-ray diffraction in the thickness direction of the surface of the copper alloy plate. Furthermore, the X-ray diffraction of fine powdered copper was measured. Here, the X-ray was Kα ray, the tube voltage was 30 KV, and the tube current was 100 mA. By dividing the accumulation strength of the copper alloy plate in each direction by the accumulation strength of the fine powder copper, a normalized rolling orthogonal direction (TD) reverse pole point diagram was created. From the obtained reverse pole figure, the direction in which the accumulated intensity peaks was determined.

<Schmidt Factor>
Since the copper alloy of this component has a face-centered cubic structure (FCC), its main slip system is {111} <110>. The Schmidt factor was calculated as a value in the main slip system when a tensile load was applied parallel to the direction perpendicular to rolling (TD) with respect to the direction in which the accumulated strength when viewed from TD showed a peak .
The upper SL as specifically for using the following equation can be obtained Schmidt factor.
(Schmidt factor) = cosλ ・ cosφ
cosλ = t · n / | t || n |
cosφ = t · s / | t || s |
However,
φ: Angle formed by the load axis and the normal of the sliding surface λ: Angle formed by the load axis and the sliding direction t: Unit vector parallel to the tensile load load direction n: Unit vector parallel to the normal vector of the sliding surface s : unit parallel to the sliding direction vector
Among the main slip systems, the slip system that is actually active has the maximum value of the Schmid factor, so it is necessary to select a combination of n and s that has the maximum value of the Schmid factor specified by the above equation. ..

Table 1 shows the composition and production conditions of each test piece and the results obtained for each Example and Comparative Example. The comparative example was manufactured under the same conditions as in the examples except for the manufacturing conditions shown in Table 1.

As is clear from Table 1, the tensile strength is increased by setting the composition of the present invention, setting the total workability of hot rolling to 80% or more, and setting the strain rate of the final pass to 1.0 / s ^{-1 or more.} Good characteristics were obtained, such as 550 MPa or more, conductivity of 75% IACS or more, stress relaxation rate of 15% or less, and bending surface of ⊚ or 〇.

In Example 19, the degree of workability of the second cold rolling was not within the preferable range, and the value of 0.2% proof stress / tensile strength was low, so that the bending surface was slightly deteriorated, but at a sufficiently satisfactory level. there were.

On the other hand, in the cases of Comparative Examples 1 and 2 in which the component concentrations of Cr and Zr were high, the conductivity and the bent surface were inferior. In the cases of Comparative Examples 3, 4, and 5 in which the component concentrations of Cr, Zr, and Ti were low, the tensile strength and stress relaxation rate were inferior.

In Comparative Examples 6 and 7 having a high concentration of additive elements, cracks were generated by hot rolling.

In Comparative Example 8 in which the degree of hot rolling was low, the Schmidt factor was low and the bending surface was inferior.

In Comparative Example 9 in which the strain rate of the final pass of hot rolling was low, the Schmidt factor was low and the bending surface was inferior.

In Comparative Example 10, the strain rate of the final pass of hot rolling is low, and the Schmidt factor is low. Further, since the workability of the second cold rolling is also low, the value of 0.2% proof stress / tensile strength is low. Bent skin was also inferior due to these causes.

10 Single crystal round bar 20 Sliding surface in the crystal grain of the single crystal round bar 25 Sliding direction of the single crystal round bar 30 Normal of the sliding surface

Claims (5)

Cr is 0.1 to 0.6% by mass, one or two of Zr and Ti are contained in a total of 0.01 to 0.30% by mass, and the balance is composed of copper and unavoidable impurities. relative peak direction of the integrated intensity in the inverse pole figure of the obtained perpendicular to the rolling direction (TD), Ri der Schmidt factor 0.40 or more when the stress of the tensile TD direction parallel-loaded,
A copper alloy plate having a 0.2% proof stress of 550 MPa or more, a conductivity of 75% IACS or more, and a stress relaxation rate of 15% or less. The copper alloy plate according to claim 1, wherein the value of 0.2% proof stress (MPa) / tensile strength (MPa) is 0.95 or more. A total of at least one selected from the group consisting of Ag, Fe, Co, Ni, Mn, Zn, Mg, Si, P, Sn, Al, Ca, Y, Nb, Mo, Hf, W, Pt, Au and B. The copper alloy plate according to claim 1 or 2, which contains 1.0% by mass or less. An electronic component for energization using the copper alloy plate according to any one of claims 1 to 3. An electronic component for heat dissipation using the copper alloy plate according to any one of claims 1 to 3.

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