JP5453565B1 - Copper alloy sheet with excellent conductivity and bending deflection coefficient - Google Patents

Abstract

A copper alloy plate having high strength, high conductivity, a high bending deflection coefficient and excellent stress relaxation characteristics, and a high-current electronic component and a heat dissipation electronic component using the copper alloy plate are provided.
SO is contained in an amount of 0.005 to 0.25% by mass, the balance is made of copper and inevitable impurities, has a tensile strength of 350 MPa or more, and an A value given by the following formula is 0.5 or more. It is a copper alloy plate.
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.)
[Selection figure] None

Description

  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, etc. 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 them, copper alloys suitable for use in high current electronic parts such as connectors and terminals for large currents used in electric cars, hybrid cars, etc., or for use in electronic parts for heat dissipation 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 parts for conducting electricity or heat, such as terminals, connectors, switches, sockets, relays, bus bars, lead frames, heat sinks, etc. These parts 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.

  Further, when 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 the heat dissipation component called a liquid crystal frame is used for the liquid crystal of a smart phone or a tablet PC, a higher bending deflection coefficient is required even in such a copper alloy plate for heat dissipation. This is because when the bending deflection coefficient is increased, 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 orthogonal to the rolling direction (the bending axis at the time of 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, with the miniaturization of electronic components, the cross-sectional area of the copper alloy in the current-carrying part tends to be small. 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.

  In an electrical contact of an electronic component such as a connector, a deflection is given to the copper alloy plate, and a contact force at the contact is obtained by a stress generated by the 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 plate is required to be excellent in conductivity so that the amount of heat generation is reduced, and is also required to be excellent 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.

  A Cu—Sn alloy is known as a material having high conductivity and relatively high strength. For example, a copper alloy containing 0.10 to 0.15% by mass of Sn has been put into practical use as CDA (Copper Development Association) alloy number C14415. Cu-Sn alloys have also been used as copper alloy foils for negative electrode current collector materials for secondary batteries such as mobile phone flexible printed boards and lithium ion secondary batteries. (Patent Documents 1 and 2).

JP 2003-286528 A JP 2011-142071 A

  However, although Cu—Sn alloys have high electrical conductivity and strength, the bending deflection coefficient of TD is not at a level that can be satisfied as an application of a component that carries a large current or a component that dissipates a large amount of heat. Further, the level of stress relaxation characteristics of conventional Cu-Sn alloys has not always been sufficient for applications of parts that carry large currents or parts that dissipate large amounts of heat. In particular, a Cu—Sn alloy having a high bending deflection coefficient and an excellent stress relaxation property has not been reported so far.

  For example, Patent Document 1 discloses a Cu—Sn alloy foil in which the concentration of hydrogen and oxygen is adjusted to be low and the productivity, quality, and characteristics are improved. However, in the Cu-Sn alloy foil of Patent Document 1, the bending deflection coefficient is not controlled.

  Patent Document 2 discloses a Cu—Sn alloy foil having a thickness of 0.01 mm and a Young's modulus (measured by a vibration method) of TD of 133.5 GPa. However, although the bending deflection coefficient and the Young's modulus by the vibration method of Patent Document 2 are similar in terms of the elastic coefficient, the values of both do not match. In Patent Document 2, Young is controlled by adjusting the final cold rolling conditions. However, in this method, it is possible to control the bending deflection coefficient of a Cu-Sn alloy plate having a thickness of 0.1 mm or more. could not. This is because the deformation behavior of the metal structure during rolling changes greatly with a thickness of 0.1 mm as a boundary.

  On the other hand, as described later, in order to improve the stress relaxation characteristics of the Cu—Sn alloy plate, it is necessary to perform strain relief annealing after the final rolling. No strain relief annealing is performed.

  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—Sn 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.

  Through an experimental study, the inventors have invented a crystal orientation index that is 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 contains, in one aspect, 0.005 to 0.25% by mass of Sn, the balance is made of copper and inevitable impurities, and has a tensile strength of 350 MPa or more. The copper alloy plate is characterized in that the A value given by the formula is 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.

Copper alloy sheet according to the present invention in one embodiment, Ag, Fe, Co, Ni , Cr, Mn, Zn, Mg, Si, containing more than 0.2 wt% of one or more of the P contact and B.

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

  In yet another embodiment of the copper alloy plate according to the present invention, the electrical conductivity is 80% IACS or more, and the bending deflection coefficient in the plate width direction is 115 GPa or more.

  In another embodiment of the copper alloy plate according to the present invention, the electrical conductivity is 80% 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 50% or less.

  In another embodiment, the copper alloy plate according to the present invention has a thickness of 0.1 to 2.0 mm.

  Another aspect of the present invention is an electronic component for large current using the copper alloy plate.

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

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the copper alloy board which has high intensity | strength, high electroconductivity, a high bending deflection coefficient, and the outstanding stress relaxation characteristic, and an electronic component suitable for a large current use or a heat dissipation 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, heat sinks, etc. It is useful as a material for electronic parts that dissipate heat.

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—Sn based alloy plate according to the embodiment of the present invention has a conductivity of 80% IACS or more and a tensile strength of 350 MPa or more. If the electrical conductivity is 80% IACS or higher, it can be said that the amount of heat generated during energization 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-Sn 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. Although the Young's modulus obtained by a tensile test is an index of the elastic coefficient of a copper alloy plate, the spring deflection coefficient shows a better correlation with the contact force at a leaf spring contact such as a connector. A conventional Cu-Sn alloy plate has a bending deflection coefficient of about 110 GPa, and by adjusting it to 115 GPa or more, the contact force is clearly improved after processing into a connector or the like, and processing into a heat sink or the like. It becomes difficult to elastically deform after an external force.

  Regarding the stress relaxation characteristics of the copper alloy sheet according to the embodiment of the present invention, the stress relaxation rate of the copper alloy sheet when 80% stress of 0.2% proof stress is applied to TD and held at 150 ° C. for 1000 hours. (Hereinafter, simply referred to as stress relaxation rate) is 50% or less, more preferably 40% or less, and still more preferably 30% or less. The stress relaxation rate of a normal Cu-Sn alloy plate is about 70 to 80%. By making this 50% or less, contact with a decrease in contact force even when a large current is applied after processing into a connector. Electrical resistance is unlikely to increase, 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)
The Sn concentration is 0.005 to 0.25% by mass, preferably 0.05 to 0.20% by mass. When Sn exceeds 0.25% by mass, it becomes difficult to obtain a conductivity of 80% IACS or more. When Sn is less than 0.005%, a tensile strength of 350 MPa or more and a stress relaxation rate of 50% or less are obtained. It becomes difficult to obtain.

  In order to improve strength and heat resistance, the Cu—Sn alloy can contain one or more of Ag, Fe, Co, Ni, Cr, Mn, Zn, Mg, Si, P and B. . However, if the addition amount is too large, the electrical conductivity decreases and falls below 80% IACS, or the manufacturability deteriorates. Therefore, the addition amount is 0.2% by mass or less, more preferably 0.1% by mass. % Or less, more preferably 0.05% by mass or less. Moreover, in order to acquire the effect by addition, it is preferable to make addition amount 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-Sn based copper alloy plate 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 this 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 in terms 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 50% 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 is suitably used for applications of electronic parts such as terminals, connectors, relays, switches, sockets, bus bars, lead frames, heat sinks, etc. used in electric / electronic devices, automobiles, etc. In particular, applications of high-current electronic components such as connectors and terminals for large currents used in electric vehicles, hybrid vehicles, etc., or uses of electronic components for heat dissipation such as liquid crystal frames used in smartphones and tablet PCs Useful for.

(Production method)
After melting electrolytic copper or the like as a pure copper raw material, Sn and other alloy elements are added as necessary, and cast into an ingot having a thickness 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, cold rolling and recrystallization annealing are repeated, and finally finished to a predetermined product thickness by cold rolling. Apply strain relief annealing.

  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 processing 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 rolling structure is recrystallized. 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 recrystallization annealing conditions before the final cold rolling are determined based on the target crystal grain size after annealing. Specifically, annealing may be performed by using a batch furnace or a continuous annealing furnace and setting the furnace temperature to 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 a range of 5 seconds to 10 minutes at a furnace temperature of 450 to 800 ° C.

In the final cold rolling, the material is repeatedly passed between a pair of rolling rolls to finish the target plate thickness. The degree of work 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 adjusting the A value by controlling the hot rolling conditions, the stress relaxation rate is 50% 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 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 alloy element to the molten copper, it was cast into an ingot having a thickness of 200 mm. The ingot was heated at 850 ° 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 average value (Rave) of the degree of processing per pass were variously changed.

  The annealing before the final cold rolling (final recrystallization annealing) was performed using a batch furnace when the thickness during annealing exceeded 2 mm, and a continuous annealing furnace when the thickness was 2 mm or less. In the case of a batch furnace, the heating time was 5 hours, the furnace temperature was adjusted in the range of 250 to 600 ° C., and the crystal grain size after annealing was changed. In the case of a continuous annealing furnace, the furnace temperature was set to 700 ° C., and the heating time was appropriately adjusted between 5 seconds and 15 minutes to change the crystal grain size after annealing. 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 copper powder (copper powder, 2N5,> 99.5%, 325 mesh, manufactured by Kanto Chemical Co., Inc.) 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 is fixed, a load of P (= 0.15 N) is applied to the position of L (= 100 t) from the fixed end, and the bending deflection coefficient E of TD is calculated from the deflection d at this time using the following equation. Asked.
E = 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 was given a deflection of y ₀ , and the stress corresponding to 80% of the TD 0.2% proof stress (measured according to JIS Z2241) ( s) was loaded. 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. Moreover, the description of “0 MPa” in the decrease in the tensile strength of strain relief annealing indicates that strain relief annealing is not performed.

  Table 2 shows examples of Invention Example 1, Invention Example 4, Comparative Example 1 and Comparative Example 2 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 26, the Sn concentration is adjusted to 0.005 to 0.25%, Rmax is set to 25% or less and Rave is set to 20% or less in hot rolling, and crystal grains are subjected to final recrystallization annealing. The diameter was adjusted to 50 μm or less, and the workability was 25 to 99% in the final cold rolling. As a result, the A value was 0.5 or more, and an electrical conductivity of 80% 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 23, the tensile strength was reduced by 10 to 100 MPa in the stress relief annealing after the final rolling, so that the thermal expansion / contraction rate was 80 ppm or less, and as a result, a stress relaxation rate of 50% or less was also obtained. On the other hand, in Examples 24 and 25, the amount of decrease in tensile strength in strain relief annealing was less than 10 MPa, and in Example 26, strain relief annealing was not performed, so the thermal expansion / contraction rate exceeded 80 ppm, resulting in stress. The relaxation rate exceeded 50%.

  In Comparative Examples 1 to 6, since Rmax or Rave deviated from the definition of the present invention, the A value was less than 0.5. As a result, the bending deflection coefficient was less than 115 GPa.

  Among these, in Comparative Examples 1-3, 5, and 6, the stress relaxation rate was 50 despite the fact that the thermal expansion / contraction rate was adjusted to 80 ppm or less by performing strain relief annealing under the condition of reducing the tensile strength by 10 to 100 MPa. % Exceeded.

  Further, in Comparative Example 4, in addition to the A value being less than 0.5, the stress relaxation rate increased to nearly 80% because the thermal expansion / contraction rate exceeded 80 ppm without performing strain relief annealing. Comparing Comparative Example 4 and Inventive Example 26, it can be seen that the stress relaxation rate is clearly reduced by adjusting the A value to 0.5 or higher even if the thermal expansion / contraction rate exceeds 80 ppm without performing strain relief annealing. . In the case of the Cu-Sn alloy foils of Patent Documents 1 and 2, since the Rmax and Rave are not controlled and the strain relief annealing is not performed, the level of the stress relaxation characteristic is Comparative Example 4. It can be said that it is close.

  In Comparative Example 7, since the Sn concentration was less than 0.005% by mass, the tensile strength after strain relief annealing was less than 350 MPa, and the stress relaxation rate exceeded 50%.

  In Comparative Example 8, the degree of work in the final cold rolling was less than 25%. In Comparative Example 9, the crystal grain size after recrystallization annealing before the final cold rolling exceeded 50 μm. The tensile strength was less than 350 MPa. In Comparative Example 10, since the Sn concentration exceeded 0.25% by mass, the conductivity was less than 80% IACS.

Claims (8)

It contains 0.005-0.25 mass% of Sn, the balance consists 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.) Ag, Fe, Co, Ni, Cr, Mn, Zn, Mg, Si, copper alloy plate according to claim 1, characterized in that it contains less than 0.2 wt% of one or more of the P contact and B .   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 conductivity is 80% IACS or more and the bending deflection coefficient in the plate width direction is 115GPa or more.   The electrical conductivity is 80% 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 50% or less. The copper alloy plate as described.   The copper alloy sheet according to any one of claims 1 to 5, wherein the thickness is 0.1 to 2.0 mm.   The electronic component for large currents using the copper alloy plate of any one of Claims 1-6.   A heat dissipating electronic component using the copper alloy plate according to claim 1.

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