WO2014157248A1

WO2014157248A1 - Copper alloy sheet having outstanding electro-conductivity and

Info

Publication number: WO2014157248A1
Application number: PCT/JP2014/058361
Authority: WO
Inventors: 波多野　隆紹
Original assignee: Jx日鉱日石金属株式会社
Priority date: 2013-03-25
Filing date: 2014-03-25
Publication date: 2014-10-02
Also published as: JP5427971B1; CN104334759A; TWI522482B; CN104334759B; JP2014208858A; JP2014208872A; KR20150000495A; KR101631402B1; TW201444988A

Abstract

　Provided are: a copper alloy sheet having high strength, high electro-conductivity, high bending deflection coefficient and outstanding stress release characteristics; and high-current electronic components and heat-radiating electronic components using this copper alloy sheet.　This copper steel sheet contains 0.01-0.50 mass% of a total of Zr and/or Ti, with the remainder being made up of copper and unavoidably impurities, has a tensile strength of 350MPa or more, and the A value determined according to the following formula is 0.5 or more.　A = 2X₍₁₁₁₎+X₍₂₂₀₎-X₍₂₀₀₎　X_(hkl)= I_(hkl)/I_0(hkl) (where I_(hkl) and I_0(hkl) are the diffraction integral strengths of the rolling plane obtained by X-ray diffraction and the (hkl) plane obtained with respect to the copper powder respectively.)

Description

Copper alloy sheet with excellent conductivity and bending deflection coefficient

TECHNICAL FIELD The present invention relates to a copper alloy plate and electronic parts for energization or heat dissipation, and in particular, electronic parts such as terminals, connectors, relays, switches, sockets, bus bars, lead frames, heat sinks, etc. mounted on electric machines / electronic devices, automobiles and the like. The present invention relates to a copper alloy plate used as a material for the above and an electronic component using the copper alloy plate. Among these, copper alloys suitable for use in high current electronic parts such as high current connectors and terminals used in electric vehicles, hybrid cars, etc., or in heat dissipation electronic parts such as liquid crystal frames used in smartphones and tablet PCs. The present invention relates to a plate and an electronic component using the copper alloy plate.

Electrical and electronic equipment, automobiles, etc. have built-in components for conducting electricity or heat, such as terminals, connectors, switches, sockets, relays, bus bars, lead frames, heat sinks, etc. These components are made of copper alloy. It is used. Here, electrical conductivity and thermal conductivity are in a proportional relationship.

In recent years, with the miniaturization of electronic components, it is required to increase the bending deflection coefficient. If the connector or the like is downsized, it becomes difficult to increase the displacement of the leaf spring. For this reason, it is necessary to obtain a high contact force with a small displacement, and a higher bending deflection coefficient is required.

Also, if the bending deflection coefficient is high, the spring back during bending becomes small and press molding becomes easy. This advantage is particularly great in a high-current connector or the like in which a thick material is used.

Furthermore, although heat dissipation parts called liquid crystal frames are used for the liquid crystal of smartphones and tablet PCs, a higher bending deflection coefficient is required even for such a copper alloy plate for heat dissipation. This is because when the bending deflection coefficient is increased, the deformation of the heat sink when an external force is applied is reduced, and the protection against liquid crystal components, IC chips and the like disposed around the heat sink is improved.

Here, the leaf spring portion of the connector or the like is usually collected in a direction in which the longitudinal direction is perpendicular to the rolling direction (the bending axis in bending deformation is parallel to the rolling direction). Hereinafter, this direction is referred to as a plate width direction (TD). Therefore, an increase in the bending deflection coefficient is particularly important in TD.

On the other hand, along with the downsizing of electronic parts, the cross-sectional area of the copper alloy in the current-carrying part tends to become smaller. When the cross-sectional area becomes small, heat generation from the copper alloy when energized increases. In addition, electronic parts used in fast-growing electric vehicles and hybrid electric vehicles include parts through which a remarkably high current flows, such as a connector of a battery unit, and heat generation of a copper alloy during energization is a problem. When the heat generation becomes excessive, the copper alloy is exposed to a high temperature environment.

At the electrical contacts of electronic parts such as connectors, the copper alloy plate is deflected, and the contact force is obtained by the stress generated by this deflection. When a bent copper alloy plate is held at a high temperature for a long time, the stress, that is, the contact force is lowered due to the stress relaxation phenomenon, and the contact electric resistance is increased. In order to cope with this problem, the copper alloy is required to be more excellent in conductivity so that the amount of generated heat is reduced, and is also required to be superior in stress relaxation characteristics so that the contact force does not decrease even if heat is generated. Similarly, a copper alloy plate for heat dissipation is also desired to have excellent stress relaxation characteristics from the viewpoint of suppressing creep deformation of the heat dissipation plate due to external force.

It is known that stress relaxation characteristics are improved when Zr or Ti is added to Cu (for example, see Patent Documents 1 and 2). Examples of materials having high electrical conductivity, relatively high strength, and good stress relaxation characteristics include C15100 (0.1 mass% Zr-residual Cu), C15150 (0.02 mass% Zr-residual Cu), C18140 (0 .1 mass% Zr-0.3 mass% Cr-0.02 mass% Si-residual Cu), C18145 (0.1 mass% Zr-0.2 mass% Cr-0.2 mass% Zn-residual Cu) C18070 (0.1% by mass Ti-0.3% by mass Cr-0.02% by mass Si-residual Cu), C18080 (0.06% by mass Ti-0.5% by mass Cr-0.1% by mass Ag) Alloys such as -0.08 mass% Fe-0.06 mass% Si-residual Cu) are registered in CDA (Copper Development Association).

JP 2012-180593 A JP 2011-117055 A

However, a copper alloy obtained by adding Zr or Ti to Cu (hereinafter referred to as a Cu-Zr-Ti alloy) has high electrical conductivity and strength, but its bending deflection coefficient of TD is used for parts that carry a large current. Or it was not the level which can be satisfied as a use of the part which dissipates a large amount of heat. In addition, although the conventional Cu-Zr-Ti alloy has relatively good stress relaxation characteristics, the level of the stress relaxation characteristics is not necessarily sufficient for the use of parts that carry a large current or the use of parts that dissipate a large amount of heat. I couldn't. In particular, a Cu—Zr—Ti alloy having both a high bending deflection coefficient and excellent stress relaxation properties has not been reported so far.

For example, in Patent Document 1, in a Cu—Zr—Ti alloy, the bending rate of TD is adjusted by adjusting the area ratio of a crystal whose (111) plane normal to TD has an angle of 20 degrees or less to more than 50%. The deflection coefficient has been improved. However, according to the example, the stress relaxation rate after holding for 1000 hours at 150 ° C. of the alloy whose bending deflection coefficient is improved by this method is 16.9 to 47.2%, which is not a sufficient level. Further, for the above crystal orientation control, a special process called second type high temperature rolling is added after normal hot rolling, which leads to a significant increase in manufacturing cost.

In addition, the copper alloy plate disclosed in Patent Document 2 contains 0.05 to 0.3% by mass of Zr, and includes Mg, Ti, Zn, Ga, Y, Nb, Mo, Ag, In, and Sn. The stress relaxation characteristics were improved by adding 0.01 to 0.3% by mass of one or more of the above and further adjusting the crystal grain size after intermediate annealing to 20 to 100 μm. The stress relaxation rate after holding for 1000 hours is 17.2 to 18.6%, which cannot be said to be sufficiently improved. In the invention, improvement of the bending deflection coefficient is not studied.

Therefore, an object of the present invention is to provide a copper alloy plate having high strength, high conductivity, a high bending deflection coefficient, and excellent stress relaxation characteristics, and an electronic component suitable for large current use or heat radiation use.

As a result of intensive studies, the present inventors have found that the orientation of crystal grains oriented on the rolling surface affects the bending deflection coefficient of TD in the Cu—Zr—Ti alloy plate. Specifically, in order to increase the bending deflection coefficient, it is effective to increase the (111) plane and the (220) plane on the rolled surface, and conversely, the increase of the (200) plane is harmful.

Then, through an experimental study, the inventors have invented a crystal orientation index that serves as an index of the bending deflection coefficient, and the bending deflection coefficient can be improved by controlling this index. Furthermore, in addition to the above-mentioned crystal orientation control, it has also been found that the stress relaxation characteristics are remarkably improved by adjusting the thermal expansion / contraction rate to an appropriate range.

The present invention completed on the basis of the above knowledge, in one aspect, contains one or two of Zr and Ti in a total of 0.01 to 0.50 mass%, with the balance consisting of copper and inevitable impurities, A copper alloy plate having a tensile strength of 350 MPa or more and an A value given by the following formula of 0.5 or more.
A = 2X ₍₁₁₁₎ + X ₍₂₂₀₎ -X ₍₂₀₀₎
X _(hkl) = I _(hkl) / I _{0 (hkl)}
Here, I _(hkl) and I _{0 (hkl)} are diffraction integrated intensities of the (hkl) plane obtained for the rolled surface and the copper powder using the X-ray diffraction method, respectively.

In another aspect of the present invention, one or two of Zr and Ti are contained in a total amount of 0.01 to 0.50 mass%, and Ag, Fe, Co, Ni, Cr, Mn, Zn, Mg , Si, P, Sn and B are contained in an amount of 1.0% by mass or less, the balance is made of copper and inevitable impurities, the tensile strength is 350 MPa or more, and the A value given by the following formula: Is a copper alloy plate having 0.5 or more.
A = 2X ₍₁₁₁₎ + X ₍₂₂₀₎ -X ₍₂₀₀₎
X _(hkl) = I _(hkl) / I _{0 (hkl)}
Here, I _(hkl) and I _{0 (hkl)} are diffraction integrated intensities of the (hkl) plane obtained for the rolled surface and the copper powder using the X-ray diffraction method, respectively.

In one embodiment, the copper alloy sheet according to the present invention has a thermal expansion / contraction rate in the rolling direction adjusted to 80 ppm or less when heated at 250 ° C. for 30 minutes.

In another embodiment, the copper alloy plate according to the present invention has a conductivity of 70% IACS or more and a bending deflection coefficient in the plate width direction of 115 GPa or more.

In another embodiment of the copper alloy plate according to the present invention, the electrical conductivity is 70% IACS or more, the bending deflection coefficient in the plate width direction is 115 GPa or more, and the stress relaxation rate in the plate width direction after holding at 150 ° C. for 1000 hours is 15% or less.

In another aspect, the present invention is a high-current electronic component using the copper alloy plate.

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

According to the present invention, it is possible to provide a copper alloy plate having high strength, high conductivity, a high bending deflection coefficient, and excellent stress relaxation characteristics, and an electronic component suitable for large current use or heat radiation use. 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 test piece for thermal expansion-contraction rate measurement. 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.

The present invention will be described below.
(Target characteristics)
The Cu—Zr—Ti alloy plate according to the embodiment of the present invention has a conductivity of 70% IACS or more and a tensile strength of 350 MPa or more. If the electrical conductivity is 70% IASC or more, it can be said that the amount of heat generated when energized is equivalent to that of pure copper. Further, if the tensile strength is 350 MPa or more, it can be said that the material has a strength necessary for a material for a component that conducts a large current or a material for a component that dissipates a large amount of heat.

The bending deflection coefficient of TD of the Cu—Zr—Ti alloy plate according to the embodiment of the present invention is 115 GPa or more, more preferably 120 GPa or more. The spring deflection coefficient is a value calculated from the amount of deflection at the time when a load is applied to the cantilever beam within a range not exceeding the elastic limit. As an index of the elastic modulus, there is a Young's modulus obtained by a tensile test, but the spring deflection coefficient shows a better correlation with the contact force at a leaf spring contact such as a connector. The bending deflection coefficient of the conventional Cu-Zr-Ti alloy plate is about 110 GPa, and by adjusting this to 115 GPa or more, the contact force is clearly improved after being processed into a connector or the like. After processing, it becomes apparently difficult to elastically deform against external force.

Regarding the stress relaxation characteristics of the Cu—Zr—Ti alloy plate according to the embodiment of the present invention, the stress relaxation rate when 80% stress of 0.2% proof stress is added to TD and held at 150 ° C. for 1000 hours. (Hereinafter simply referred to as stress relaxation rate) is 15% or less, more preferably 10% or less. The stress relaxation rate of the conventional Cu—Zr—Ti alloy plate is about 25 to 35%. By reducing this to 15% or less, the contact force decreases even when a large current is applied after processing the connector. Increase in contact electrical resistance is unlikely to occur, and creep deformation is unlikely to occur even if heat and external force are applied simultaneously after processing into a heat sink.

(Alloy component concentration)
In the Cu—Zr—Ti alloy plate according to the embodiment of the present invention, a total of one or two of Zr and Ti is 0.01 to 0.50% by mass, more preferably 0.02 to 0.00. Contains 20% by mass. When the total of one or two of Zr and Ti is less than 0.01% by mass, it becomes difficult to obtain a tensile strength of 350 MPa or more and a stress relaxation rate of 15% or less. If the total of one or two of Zr and Ti exceeds 0.5% by mass, it becomes difficult to produce an alloy due to hot rolling cracks or the like. When adding Zr, the amount added is preferably adjusted to 0.01 to 0.45 mass%, and when adding Ti, the amount added is adjusted to 0.01 to 0.20 mass%. It is preferable. When the addition amount is less than the lower limit value, it is difficult to obtain the effect of improving the stress relaxation characteristics, and when the addition amount exceeds the upper limit value, conductivity and manufacturability may be deteriorated.

Cu-Zr-Ti alloy contains at least one of Ag, Fe, Co, Ni, Cr, Mn, Zn, Mg, Si, P, Sn and B in order to improve strength and heat resistance. Can be made. However, if the amount added is too large, the electrical conductivity may be reduced to be less than 70% IACS, or the manufacturability of the alloy may be deteriorated. Therefore, the amount added is preferably 1.0% by mass or less in total. Is 0.5 mass% or less. Moreover, in order to acquire the effect by addition, it is preferable to make addition amount into 0.001 mass% or more in total amount.

(Crystal orientation of rolling surface)
The crystal orientation index A (hereinafter simply referred to as A value) given by the following formula is adjusted to 0.5 or more, more preferably 1.0 or more. Here, I _(hkl) and I _{0 (hkl)} are diffraction integrated intensities of the (hkl) plane obtained for the rolled surface and copper powder using the X-ray diffraction method, respectively.
A = 2X ₍₁₁₁₎ + X ₍₂₂₀₎ -X ₍₂₀₀₎
X _(hkl) = I _(hkl) / I _{0 (hkl)}
When the A value is adjusted to 0.5 or more, the bending deflection coefficient becomes 115 GPa or more, and at the same time, the stress relaxation characteristics are improved. Although the upper limit value of the A value is not limited in terms of the bending deflection coefficient and the improvement of the stress relaxation characteristics, the A value typically takes a value of 10.0 or less.

(Thermal expansion and contraction rate)
When heat is applied to a copper alloy plate, a very small dimensional change occurs. In the present invention, the ratio of the dimensional change is referred to as “thermal expansion / contraction rate”. The present inventor has found that the stress relaxation rate can be remarkably improved by adjusting the thermal expansion / contraction rate of the Cu—Zr—Ti based copper alloy sheet in which the A value is controlled.
In the present invention, a dimensional change rate in the rolling direction when heated at 250 ° C. for 30 minutes is used as the thermal expansion / contraction rate. The absolute value of the thermal expansion / contraction rate (hereinafter simply referred to as thermal expansion / contraction rate) is preferably adjusted to 80 ppm or less, and more preferably adjusted to 50 ppm or less. The lower limit value of the thermal expansion / contraction rate is not limited from the viewpoint of the characteristics of the copper alloy sheet, but the thermal expansion / contraction rate is rarely 1 ppm or less. In addition to adjusting the A value to 0.5 or more, by adjusting the thermal expansion / contraction rate to 80 ppm or less, the stress relaxation rate becomes 15% or less.

(Thickness)
The thickness of the product is preferably 0.1 to 2.0 mm. If the thickness is too thin, the cross-sectional area of the current-carrying part will decrease and heat generation will increase during energization, making it unsuitable as a material for connectors that carry large currents, and because it will deform with a slight external force, It is also unsuitable as a material. On the other hand, if the thickness is too thick, bending becomes difficult. From such a viewpoint, a more preferable thickness is 0.2 to 1.5 mm. When the thickness is in the above range, the bending workability can be improved while suppressing heat generation during energization.

(Use)
The copper alloy plate according to the embodiment of the present invention can be suitably used for applications of electronic parts such as terminals, connectors, relays, switches, sockets, bus bars, lead frames, etc. used in electric / electronic devices, automobiles and the like. In particular, it is useful for applications of high current electronic components such as connectors and terminals for high current used in electric vehicles, hybrid vehicles, etc., or for heat dissipation electronic components such as liquid crystal frames used in smartphones and tablet PCs. is there.

(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, one or two of Zr and Ti and, if necessary, other alloy elements are added, and a thickness of 30 to 300 mm Cast into a moderate ingot. This ingot is made into a plate having a thickness of about 3 to 30 mm by hot rolling, and then cold rolling and recrystallization annealing are repeated to finish to a predetermined product thickness by final cold rolling, and finally strain relief annealing is performed.
The method of adjusting the A value to 0.5 or more is not limited to a specific method, but can be achieved by controlling hot rolling conditions, for example.
In the hot rolling of the present invention, an ingot heated to 850 to 1000 ° C. is repeatedly passed between a pair of rolling rolls to finish the target plate thickness. The degree of processing per pass affects the A value. Here, the working degree R (%) per pass is a sheet thickness reduction rate when the rolling roll passes once, and R = (T ₀ −T) / T ₀ × 100 (T ₀ : rolling) Thickness before passing through roll, T: Thickness after passing through rolling roll).
Regarding R, it is preferable that the maximum value (Rmax) of all paths is 25% or less and the average value (Rave) of all paths is 20% or less. By satisfying both of these conditions, the A value becomes 0.5 or more. More preferably, Rave is set to 19% or less.

In recrystallization annealing, part or all of the rolled structure is recrystallized. Further, by annealing under appropriate conditions, Zr, Ti, etc. are precipitated, and the electrical conductivity of the alloy is increased. In the recrystallization annealing before the final cold rolling, the average crystal grain size of the copper alloy sheet is adjusted to 50 μm or less. When the average crystal grain size is too large, it becomes difficult to adjust the tensile strength of the product to 350 MPa or more.

The conditions for recrystallization annealing before final cold rolling are determined based on the target crystal grain size after annealing and the target product conductivity. Specifically, the annealing may be performed using a batch furnace or a continuous annealing furnace at a furnace temperature of 250 to 800 ° C. In a batch furnace, the heating time may be appropriately adjusted within the range of 30 minutes to 30 hours at a furnace temperature of 250 to 600 ° C. In a continuous annealing furnace, the heating time may be appropriately adjusted within the range of 5 seconds to 10 minutes at a furnace temperature of 450 to 800 ° C. In general, when annealing is performed at a lower temperature for a longer time, higher conductivity can be obtained with the same crystal grain size.

In the final cold rolling, the material is repeatedly passed between a pair of rolling rolls to finish the target plate thickness. The working degree of the final cold rolling is preferably 25 to 99%. Here, the working degree r (%) is given by r = (t ₀ −t) / t ₀ × 100 (t ₀ : plate thickness before rolling, t: plate thickness after rolling). If r is too small, it becomes difficult to adjust the tensile strength to 350 MPa or more. If r is too large, the edge of the rolled material may be broken.

In addition to the adjustment of the A value by controlling the hot rolling conditions, the stress relaxation rate is 15% or less by adjusting the thermal expansion / contraction rate of the product to 80 ppm or less. The method for adjusting the thermal expansion / contraction rate to 80 ppm or less is not limited to a specific method, but it can be performed, for example, by performing strain relief annealing under appropriate conditions after the final rolling.

That is, by adjusting the tensile strength after strain relief annealing to a value that is 10 to 100 MPa lower, preferably 20 to 80 MPa lower than the tensile strength before strain relief annealing (after final rolling), the thermal expansion / contraction rate is reduced. 80 ppm or less. If the amount of decrease in tensile strength is too small, it is difficult to adjust the thermal expansion / contraction rate to 80 ppm or less. If the decrease in tensile strength is too large, the tensile strength of the product may be less than 350 MPa.

Specifically, when a batch furnace is used, the heating time is appropriately adjusted in the range of 30 minutes to 30 hours at a furnace temperature of 100 to 500 ° C., and when a continuous annealing furnace is used, 300 to 700 ° C. What is necessary is just to adjust the fall amount of tensile strength to the said range by adjusting a heating time suitably in the range for 5 second to 10 minutes in the furnace temperature of this. *

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

After adding the 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 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 plate after hot rolling, annealing and cold rolling were repeated and finished to a predetermined product thickness by final cold rolling. Finally, strain relief annealing was performed.

In hot rolling, the maximum value (Rmax) and the average value (Rave) of the degree of processing per pass were variously changed.

For annealing before final cold rolling (final recrystallization annealing), a batch furnace is used, the heating time is 5 hours, the furnace temperature is adjusted in the range of 250 to 700 ° C, and the crystal grain size and conductivity after annealing are adjusted. Changed.
In the final cold rolling, the degree of work (r) was varied.
In strain relief annealing, a continuous annealing furnace was used, the furnace temperature was 500 ° C., the heating time was adjusted between 1 second and 10 minutes, and the amount of decrease in tensile strength was variously changed. In some examples, strain relief annealing was not performed.

The following measurements were performed for materials in the process of manufacture and materials (products) after strain relief annealing.
(component)
The alloy element concentration of the material after strain relief annealing was analyzed by ICP-mass spectrometry.

(Average grain size after final recrystallization annealing)
After the cross section perpendicular to the rolling direction was finished to a mirror surface by mechanical polishing, crystal grain boundaries were revealed by etching. On this metal structure, the average crystal grain size was determined by measurement according to the cutting method of JIS H 0501 (1999).

(Crystal orientation of the product)
The X-ray diffraction integrated intensity (I _(hkl) ) of the (hkl) plane was measured in the thickness direction with respect to the rolled surface of the material after strain relief annealing. Further, the X-ray diffraction integrated intensity (I _{0 (hkl)} ) of the (hkl) plane is also applied to the copper powder copper powder (manufactured by Kanto Chemical Co., Inc., copper (powder), 2N5,> 99.5%, 325 mesh). Was measured. RINT 2500 manufactured by Rigaku Corporation was used as the X-ray diffractometer, and measurement was performed with a Cu tube bulb at a tube voltage of 25 kV and a tube current of 20 mA. The measurement surface ((hkl)) was defined as three surfaces (111), (220), and (100), and the A value was calculated by the following equation.
A = 2X ₍₁₁₁₎ + X ₍₂₂₀₎ -X ₍₂₀₀₎
X _(hkl) = I _(hkl) / I _{0 (hkl)}

(Tensile strength)
For the material after the final cold rolling and strain relief annealing, sample No. 13B specified in JIS Z2241 was taken so that the tensile direction was parallel to the rolling direction, and pulled in parallel with the rolling direction in accordance with JIS Z2241. A test was conducted to determine the tensile strength.

(Thermal expansion and contraction rate)
A strip-shaped test piece having a width of 20 mm and a length of 210 mm was taken from the material after strain relief annealing so that the longitudinal direction of the test piece was parallel to the rolling direction, and L ₀ (= 200 mm) as shown in FIG. Two dents were engraved with an interval of. Then, it heated at 250 degreeC for 30 minutes, and measured the dent space | interval (L) after a heating. Then, the absolute value of the value calculated by the formula of (L−L ₀ ) / L ₀ × 10 ⁶ was obtained as the thermal expansion / contraction rate (ppm).

(conductivity)
A test piece was taken from the material after strain relief annealing 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.

(Bending deflection coefficient)
The bending deflection coefficient of TD was measured according to the Japan Copper and Brass Association (JACBA) technical standard “Method of measuring bending deflection coefficient by cantilever of copper and copper alloy strip”.
A strip-shaped test piece having a thickness t and a width w (= 10 mm) was taken so that the longitudinal direction of the test piece was orthogonal to the rolling direction. One end of this sample was fixed, a load of P (= 0.15 N) was applied to a position L (= 100 t) from the fixed end, and a bending deflection coefficient B was obtained from the deflection d at this time using the following equation.
B = 4 · P · (L / t) ³ / (w · d)

(Stress relaxation rate)
A strip-shaped test piece having a width of 10 mm and a length of 100 mm was collected from the material after strain relief annealing so that the longitudinal direction of the test piece was orthogonal to the rolling direction. As shown in FIG. 2, 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) of TD. Stress (s) was applied. y ₀ was determined by the following equation.
y ₀ = (2/3) · l ² · s / (E · t)
Here, E is the bending deflection coefficient of TD, and t is the thickness of the sample. After unloading after heating at 150 ° C. for 1000 hours, the amount of permanent deformation (height) y is measured as shown in FIG. 3, and the stress relaxation rate {[y (mm) / y ₀ (mm)] × 100 (%) } Was calculated.

Table 1 shows the evaluation results. The notation of “<10 μm” in the crystal grain size after the final recrystallization annealing in Table 1 indicates that when all of the rolling structure is recrystallized and the average crystal grain size is less than 10 μm, and only a part of the rolling structure is used. Both cases of recrystallization are included.

Table 2 also shows examples of Invention Example 1, Invention Example 4, Comparative Example 1, and Comparative Example 3 in Table 1 as the finished thickness of the material in each pass of hot rolling and the degree of processing per pass.

In the copper alloy sheets of Invention Examples 1 to 25, the total concentration of Zr and Ti was adjusted to 0.01 to 0.50 mass%, Rmax was 25% or less and Rave was 20% or less in hot rolling, and the final re- The crystal grain size was adjusted to 50 μm or less in the crystal annealing, and the workability was set to 25 to 99% in the final cold rolling. As a result, the A value was 0.5 or more, and an electrical conductivity of 70% IACS or higher, a tensile strength of 350 MPa or higher, and a bending deflection coefficient of 115 GPa or higher were obtained.

Furthermore, in Invention Examples 1 to 22, since the tensile strength was reduced by 10 to 100 MPa in the stress relief annealing after the final rolling, the thermal expansion / contraction rate became 80 ppm or less, and as a result, a stress relaxation rate of 15% or less was obtained. On the other hand, in Examples 23 and 24, the amount of decrease in tensile strength during strain relief annealing was less than 10 MPa, and because Example 25 was not subjected to strain relief annealing, the thermal expansion / contraction rate exceeded 80 ppm, resulting in stress. The relaxation rate exceeded 15%.

In Comparative Examples 1 to 5, Rmax or Rave deviated from the definition of the present invention, so the A value was less than 0.5. As a result, the bending deflection coefficient was less than 115 GPa. Further, the stress relaxation rate exceeded 15% even though the thermal expansion / contraction rate was adjusted to 80 ppm or less by performing strain relief annealing under the condition that the tensile strength was reduced by 10 to 100 MPa.

In Comparative Example 6, since the total concentration of Zr and Ti was less than 0.01% by mass, the tensile strength after strain relief annealing was less than 350 MPa, and the stress relaxation rate exceeded 15%.

In Comparative Example 7, the degree of work in final cold rolling was less than 25%, and in Comparative Example 8, the crystal grain size after recrystallization annealing before final cold rolling exceeded 50 μm. The tensile strength was less than 350 MPa.

Comparative Example 9 is obtained by processing an ingot to a thickness of 15 mm according to the process disclosed in Patent Document 1. A 200 mm thick ingot heated at 950 ° C. for 3 hours (homogenized heat treatment) is rolled to a thickness of 100 mm at a processing temperature of 700 to 1000 ° C. (first type high temperature rolling, processing degree 50%), and then 5 to Cooled to room temperature at 100 ° C./second. Thereafter, it was reheated to 550 ° C. and rolled to a thickness of 15 mm at a processing temperature of 400 to 550 ° C. (second type high temperature rolling, processing degree 70%). Here, Rmax and Rave in Table 1 are those during the first type high temperature rolling. In addition, the process after thickness 15mm was performed similarly to the other Example.

In comparison with Comparative Example 9, when the area ratio of the region having an atomic plane whose angle formed by the normal of the (111) plane and TD is within 20 degrees was measured by the EBSD method disclosed in Patent Document 1, the area ratio was 50%. It was over. Although the bending deflection coefficient of Comparative Example 9 was 115 GPa or more, the stress relaxation rate was reduced despite the fact that the stress relief annealing was performed under the condition that the tensile strength was reduced by 10 to 100 MPa and the thermal expansion / contraction rate was adjusted to 80 ppm or less. It exceeded 15%.

Claims

One or two of Zr and Ti are contained in a total of 0.01 to 0.50% by mass, the balance is made of copper and inevitable impurities, has a tensile strength of 350 MPa or more, and is given by the following formula A copper alloy sheet characterized by having an A value of 0.5 or more.
A = 2X (111) + X (220) -X (200)
X (hkl) = I (hkl) / I 0 (hkl)
(However, I (hkl) and I 0 (hkl) are diffraction integrated intensities of the (hkl) plane obtained for the rolled surface and copper powder, respectively, using the X-ray diffraction method.)
One or two of Zr and Ti are contained in a total of 0.01 to 0.50% by mass, and Ag, Fe, Co, Ni, Cr, Mn, Zn, Mg, Si, P, Sn, and B One or more of them are contained at 1.0% by mass or less, the balance is made of copper and inevitable impurities, has a tensile strength of 350 MPa or more, and the A value given by the following formula is 0.5 or more. Features copper alloy sheet.
A = 2X (111) + X (220) -X (200)
X (hkl) = I (hkl) / I 0 (hkl)
(However, I (hkl) and I 0 (hkl) are diffraction integrated intensities of the (hkl) plane obtained for the rolled surface and copper powder, respectively, using the X-ray diffraction method.)
The copper alloy sheet according to claim 1 or 2, wherein a thermal expansion / contraction ratio in a rolling direction when heated at 250 ° C for 30 minutes is adjusted to 80 ppm or less.
The copper alloy plate according to claim 1 or 2, wherein the electrical conductivity is 70% IACS or more, and the bending deflection coefficient in the plate width direction is 115GPa or more.
The electrical conductivity is 70% IACS or more, the bending deflection coefficient in the plate width direction is 115 GPa or more, and the stress relaxation rate in the plate width direction after holding at 150 ° C. for 1000 hours is 15% or less. The copper alloy plate as described.
A high-current electronic component using the copper alloy plate according to any one of claims 1 to 5.
An electronic component for heat dissipation using the copper alloy plate according to any one of claims 1 to 5.