KR20140145556A - Copper alloy plate having superior conductivity and modulus of bending deflection - Google Patents

Abstract

An object of the present invention is to provide a copper alloy plate with high strength, high electric conductivity, high modulus of bending deflection, and excellent stress relaxation characteristic; and a high-current electronic part and a heat-radiating electronic part by the copper alloy plate. The copper alloy plate contains 0.005-0.25 wt% of Sn, has a remaining portion formed of copper and inevitable impurities, has tensile strength equal to or greater than 350 MPa, and has an A value calculated by the following equation equal to or greater than 0.5. A = 2X_(111) + X_(220) - X_(200) X_(hk1) = I_(hk1)/I_0(hk1) (provided that I_(hk1) and I_0(hk1) are diffraction integral strengths of the (hk1) surface calculated with respect to a rolling surface and copper ashes using an x-ray diffraction method).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper alloy plate having excellent conductivity and a high coefficient of flexural deformation,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper alloy plate and an electronic component for exclusive use or heat dissipation and more particularly to an electronic component such as a terminal, a connector, a relay, a switch, a socket, a bus bar, a lead frame, A copper alloy plate used as a material of the copper alloy plate, and an electronic part using the copper alloy plate. Among them, a copper alloy plate and a copper alloy plate which are suitable for the use of electronic components for large current such as connectors and terminals for large currents used in electric vehicles and hybrid cars, and for applications of heat dissipation electronic components such as liquid crystal frames used in smart phones and tablet PCs And an electronic component using the copper alloy plate.

BACKGROUND ART Electric / electronic devices and automobiles are equipped with components for transmitting electricity or heat such as terminals, connectors, switches, sockets, relays, bus bars, lead frames, and heat sinks. Copper alloys are used for these components. Here, the electrical conductivity and the thermal conductivity are in a proportional relationship.

In recent years, with the miniaturization of electronic components, it is required to increase the flexural deformation coefficient. When the connector or the like is miniaturized, it becomes difficult to take a large displacement of the leaf spring. Therefore, it is necessary to obtain a high contact force with a small displacement, and a higher flexural strain coefficient is required.

If the coefficient of flexural deformation is high, the spring back at the time of bending is reduced, and the press forming process is facilitated. This advantage is especially great for high current connectors where thicker materials are used.

A liquid crystal of a smart phone or a tablet PC uses a heat-dissipating component called a liquid crystal frame, but a higher flexural deformation coefficient is also required for such a copper alloy plate for heat radiation. When the flexural strain coefficient is increased, the deformation of the heat sink when external force is added is reduced, and the protection against liquid crystal parts, IC chips, and the like disposed around the heat sink is improved.

Here, the plate spring portion of a connector or the like is usually taken in a direction in which the longitudinal direction thereof is orthogonal to the rolling direction (the bending axis at the time of bending deformation is parallel to the rolling direction). Hereinafter, this direction will be referred to as a board width direction (TD). Therefore, the increase of the flexural strain coefficient is particularly important for TD.

On the other hand, with miniaturization of electronic parts, the cross-sectional area of the copper alloy in the conductive part tends to be small. As the cross-sectional area becomes smaller, the heat generation from the copper alloy when energized increases. In electronic parts used in an electric vehicle or a hybrid electric vehicle in which growth is remarkable, there is a part in which a remarkably high current flows such as a connector of a battery part, and heat generation of the copper alloy in the communication becomes a problem. When the heat generation becomes excessive, the copper alloy is exposed to the high temperature environment.

In the electrical contacts of electronic components such as connectors, the copper alloy plate is warped, and the contact force at the contacts is obtained by the stress generated by the warping. If the copper alloy plate which has given the flexure is kept 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 electrical resistance is increased. In order to cope with this problem, it is required that the copper alloy plate is required to have better conductivity so that the calorific value is reduced, and that the stress relaxation property is better so that the contact force is not lowered even when heat is generated. Likewise, it is desired that the copper alloy plate for heat radiation use also has excellent stress relaxation property because it suppresses creep deformation of the heat sink due to external force.

As a material having a high conductivity and a relatively high strength, a Cu-Sn-based alloy is known. For example, a copper alloy containing 0.10 to 0.15 mass% of Sn is provided practically as a CDA (Copper Development Association) alloy number C14415. In addition, Cu-Sn alloy is used as a negative electrode current collector material of a secondary battery such as a flexible printed circuit board of a cellular phone or a lithium ion secondary battery as a copper alloy foil (Patent Documents 1 and 2).

Japanese Patent Application Laid-Open No. 2003-286528 Japanese Laid-Open Patent Publication No. 2011-142071

However, the Cu-Sn based alloy has a high electric conductivity and strength, but the flexural deformation coefficient of the TD is not a satisfactory level for the use of a component that flows a large current or a component that dissipates large heat. In addition, the level of the stress relaxation property of the conventional Cu-Sn based alloy can not necessarily be said to be sufficient for the use of a component that flows a large current or a component that dissipates a large amount of heat. In particular, a Cu-Sn-based alloy having a high flexural modulus and an excellent stress relaxation property has not been reported so far.

For example, Patent Document 1 discloses a Cu-Sn alloy foil whose hydrogen and oxygen concentrations are adjusted to be low to improve the composition, quality and characteristics. However, in the Cu-Sn alloy foil of Patent Document 1, the control of the flexural strain coefficient is not performed.

In Patent Document 2, a Cu-Sn alloy foil having a thickness of 0.01 mm with a TD Young's modulus (measured by a vibration method) of 133.5 mm is disclosed. However, the bending strain coefficient and the Young's modulus by the vibration method of Patent Document 2 are similar in terms of elastic modulus, but the values of both are not coincident. In Patent Document 2, the Young's modulus is controlled by adjusting the final cold rolling conditions. However, in this method, the coefficient of flexural deformation of the Cu-Sn based alloy plate having a thickness of 0.1 mm or more could not be controlled. This is because the deformation behavior of the metal structure during rolling varies greatly with a thickness of 0.1 mm.

On the other hand, as will be described later, in order to improve the stress relaxation characteristics of the Cu-Sn based alloy sheet, it is necessary to perform deformation removal annealing after the final rolling. However, both of the Cu- No removal annealing was performed.

It is therefore an object of the present invention to provide a copper alloy plate having high strength, high electrical conductivity, high flexural modulus, and excellent stress relaxation characteristics, and an electronic component suitable for use in a large current or heat radiation.

As a result of intensive studies, the present inventor has found that the orientation of crystal grains oriented on the rolled surface affects the flexural strain modulus of TD with respect to the Cu-Sn based alloy sheet. Specifically, in order to increase the flexural strain coefficient, it is effective to increase the (111) plane and the (220) plane on the rolled surface, while the increase of the (200) plane is harmful.

Then, after an experimental examination, a crystal orientation index which is an index of the bending strain coefficient was invented, and by controlling this index, it was possible to improve the bending strain coefficient. Further, in addition to the crystal orientation control, it has also been found that the stress relaxation characteristic is remarkably improved by adjusting the heat expansion / contraction ratio to an appropriate range.

The present invention, which is completed on the basis of the above findings, is a copper alloy sheet comprising, in one aspect, a copper alloy containing 0.005 to 0.25 mass% of Sn and the balance copper and inevitable impurities and having a tensile strength of 350 MPa or more, 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)} is an integrated intensity of the diffraction obtained (hkl) plane to the rolling plane and dongbun (銅粉) by using the X-ray diffraction, respectively.

In one embodiment, the copper alloy sheet according to the present invention contains 0.2 mass% or less of at least one of Ag, Fe, Co, Ni, Cr, Mn, Zn, Mg, Si, P,

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

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

The copper alloy sheet according to the present invention is a copper alloy sheet according to another embodiment of the present invention which has a conductivity of 80% IACS or more, a flexural modulus in the direction of the width of the laminate of 115 ㎬ or more, and a stress relaxation rate of 50% or less to be.

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

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

According to another aspect of the present invention, there is provided a heat dissipation electronic component using the copper alloy plate.

According to the present invention, it is possible to provide a copper alloy plate having high strength, high electrical conductivity, high flexural modulus and excellent stress relaxation characteristics, and electronic parts suitable for use in a large current or heat radiation. This copper alloy plate can be preferably used as a material for an electronic part such as a terminal, a connector, a switch, a socket, a relay, a bus bar, a lead frame and a heat sink. Particularly, And is useful as a material for an electronic component.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a view for explaining a test piece for measuring a heat expansion / contraction ratio. FIG.
2 is a view for explaining the principle of measurement of the stress relaxation rate.
3 is a view for explaining the principle of measurement of the stress relaxation rate.

Hereinafter, the present invention will be described.

(Target characteristics)

The Cu-Sn alloy sheet 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 conductivity is more than 80% IACS, the calorific value of the communication can be said to be equal to the pure motion. If the tensile strength is 350 MPa or more, it can be said that the material has a strength required as a material of a part for energizing a large current or a part for dissipating a large heat quantity.

The flexural modulus of TD of the Cu-Sn alloy sheet according to the embodiment of the present invention is 115 ㎬ or more, more preferably 120 ㎬ or more. The spring flexural coefficient is a value calculated by applying a load to the cantilever in a range not exceeding the elastic limit and calculating the amount of deflection at that time. As the index of elastic modulus of the copper alloy sheet, there is a Young's modulus obtained by a tensile test, but the spring flexural modulus shows a better correlation with the contact force at the plate spring contact of a connector or the like. The conventional Cu-Sn alloy plate has a flexural strain coefficient of about 110 이고. By adjusting it to not less than 115 ㎬, the contact force is obviously improved after machining with a connector or the like. Further, It becomes difficult to evidently deform elastically.

Regarding the stress relaxation characteristics of the copper alloy sheet according to the embodiment of the present invention, the stress relaxation rate (hereinafter referred to as " stress relaxation rate ") of the copper alloy sheet when stress of 80% ) Is not more than 50%, more preferably not more than 40%, further preferably not more than 30%. The stress relaxation rate of a typical Cu-Sn alloy sheet is about 70 to 80%. However, by setting this to 50% or less, it is difficult to increase the contact electrical resistance accompanied by a decrease in contact force even when a large current is applied after machining into a connector , And creep deformation is less likely to occur even when heat and external force are applied simultaneously after machining with a heat sink.

(Alloy component concentration)

The Sn concentration is 0.005 to 0.25 mass%, preferably 0.05 to 0.20 mass%. When Sn exceeds 0.25 mass%, it becomes difficult to obtain a conductivity of 80% IACS or higher. When Sn is less than 0.005 mass%, it becomes difficult to obtain a tensile strength of 350 MPa or more and a stress relaxation rate of 50% or less.

The Cu-Sn-based alloy may contain at least one of Ag, Fe, Co, Ni, Cr, Mn, Zn, Mg, Si, P and B in order to improve strength and heat resistance. However, if the addition amount is too large, the electric conductivity lowers to 80% IACS or the composition deteriorates. Therefore, the addition amount is preferably 0.2 mass% or less, more preferably 0.1 mass% or less, still more preferably 0.05 mass% % ≪ / RTI > In order to obtain the effect of addition, it is preferable that the addition amount is 0.001 mass% or more in total amount.

(Crystal orientation of the rolled 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 Io _(hkl) are the diffraction integral intensities of the (hkl) planes obtained for the rolled surface and the equivalent by X-ray diffractometry, respectively.

A = 2X ₍₁₁₁₎ + X ₍₂₂₀₎ - X ₍₂₀₀₎

_{X (hkl) = I (hkl} ) / I 0 (hkl)

When the value of A is adjusted to 0.5 or more, the flexural strain coefficient becomes 115 ㎬ or more, and at the same time, the stress relaxation characteristic is also improved. The upper limit of the A value is not limited in terms of improving the flexural strain coefficient and the stress relaxation property, but the A value typically takes a value of 10.0 or less.

(Thermal expansion / contraction ratio)

When heat is applied to the copper alloy plate, a very small dimensional change occurs. In the present invention, this ratio of dimensional change is referred to as " heat expansion / contract ratio ". The inventor of the present invention has found that the stress relaxation rate can be remarkably improved by adjusting the heat expansion coefficient of a Cu-Sn-based copper alloy whose A value is controlled.

In the present invention, the dimensional change ratio in the rolling direction when heated at 250 DEG C for 30 minutes is used as the heat expansion coefficient. The absolute value of the heat expansion / contraction ratio (hereinafter, simply referred to as heat expansion / expansion ratio) is preferably adjusted to 80 ppm or less, more preferably 50 ppm or less. The lower limit of the heat expansion / contraction ratio is not limited in terms of the properties of the copper alloy plate, but the heat expansion / contraction ratio is less than 1 ppm. In addition to adjusting the A value to 0.5 or more, the stress relaxation rate becomes 50% or less by adjusting the thermal expansion coefficient to 80 ppm or less.

(thickness)

The thickness of the product is preferably 0.1 to 2.0 mm. If the thickness is excessively thin, the cross-sectional area of the conductive part becomes small, heat generation in the passage increases, it is unsuitable as a material for a connector or the like that flows a large current, and is deformed by a slight external force. . On the other hand, if the thickness is excessively large, bending becomes difficult. From this viewpoint, the more preferable thickness is 0.2 to 1.5 mm. When the thickness is within the above range, the bending workability can be improved while suppressing heat generation in communication.

(Usage)

The copper alloy sheet according to the embodiment of the present invention can be suitably used for electronic parts such as terminals, connectors, relays, switches, sockets, bus bars, lead frames and heat sinks used in electric and electronic devices and automobiles , And is particularly useful for applications of high current electric components such as connectors and terminals for large currents used in electric vehicles and hybrid vehicles, and applications of heat dissipation electronic components such as liquid crystal frames used in smart phones and tablet PCs.

(Manufacturing method)

After dissolving copper or the like as a pure raw material, Sn and other alloying elements as necessary are added, and cast into an ingot having a thickness of about 30 to 300 mm. This ingot is formed into a plate having a thickness of about 3 to 30 mm by hot rolling, for example, at 800 to 1000 DEG C, and then cold rolling and recrystallization annealing are repeated, and the final ingot is finished to a predetermined product thickness by final cold rolling, Deformation removal annealing is performed.

The method of adjusting the A value to 0.5 or more is not limited to a specific method, but is possible by, for example, controlling the hot rolling condition.

In the hot rolling of the present invention, ingots heated to 850 to 1000 占 폚 are passed between a pair of rolling rolls repeatedly to finish with the target plate thickness. The processing degree per pass affects the A value. Here, the processing degree R (%) per one pass means a reduction rate of the plate thickness after passing through the rolling roll once, and R = (T ₀ - T) / T ₀ × 100 (T ₀ : thickness before rolling roll, T: thickness after rolling roll).

For this R, it is preferable that the maximum value Rmax of the entire paths is 25% or less and the average value Rave of the entire 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 the recrystallization annealing, part or all of the rolled 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 占 퐉 or less. If 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 of the recrystallization annealing before the final cold rolling are determined based on the target crystal grain size after annealing. Specifically, annealing may be carried out by using a batch or continuous annealing furnace at a furnace temperature of 250 to 800 占 폚. In the batch furnace, the heating time may be appropriately adjusted within the range of 30 minutes to 30 hours at the furnace temperature of 250 to 600 ° C. In the 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 the pair of rolling rolls to finish with the target plate thickness. The degree of processing of the final cold rolling is preferably 25 to 99%. Here, the processing degree r (%) is r = (t ₀ - t) / t ₀ × 100 (t ₀ : plate thickness before rolling, and t: plate thickness after rolling). When r is too small, it is difficult to adjust the tensile strength to 350 MPa or more. If r is excessively large, the edge of the rolled material may be cracked.

In addition to the adjustment of the A value by the control of the hot rolling condition, the stress relaxation rate becomes 50% or less by adjusting the thermal expansion / contraction ratio of the product to 80 ppm or less. The method of adjusting the heat expansion / contraction ratio to 80 ppm or less is not limited to the specific method, but can be performed, for example, by performing deformation removal annealing under appropriate conditions after the final rolling.

That is, by adjusting the tensile strength after deformation-removing annealing to a value lower by 10 to 100 MPa, preferably by 20 to 80 MPa, relative to the tensile strength before deformation-removing annealing (finally rolled), the thermal expansion rate is 80 ppm Or less. If the lowering amount of the tensile strength is too small, it becomes difficult to adjust the heat stretching ratio to 80 ppm or less. If the amount of decrease in the tensile strength is excessively large, the tensile strength of the product may be less than 350 MPa.

Specifically, in the case of using a batch furnace, the heating time is appropriately adjusted within a range of 30 minutes to 30 hours at a furnace temperature of 100 to 500 DEG C, and 300 to 700 DEG C The heating time may be appropriately adjusted within a range of 5 seconds to 10 minutes at the furnace temperature of the furnace.

Example

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

The alloy element was added to molten copper and then cast into an ingot having a thickness of 200 mm. The ingot was heated at 850 占 폚 for 3 hours and hot rolled to form a plate having a thickness of 15 mm. After the oxide scale of the surface of the plate after hot rolling was ground and removed, annealing and cold rolling were repeated and finished to a predetermined product thickness by final cold rolling. Finally, deformation removal annealing was performed.

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

Annealing (final recrystallization annealing) before the final cold rolling was performed using a batch furnace when the thickness at the time of annealing exceeds 2 mm and a continuous annealing furnace when the thickness was 2 mm or less. In the case of the batch furnace, the heating time was set to 5 hours, and the temperature in the furnace was adjusted in the range of 250 to 600 ° C to change the crystal grain size after annealing. In the case of the continuous annealing furnace, the temperature of the furnace was set at 700 캜, 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 processing (r) was variously changed.

In the deformation removing annealing, the continuous annealing furnace was used to adjust the furnace temperature to 500 deg. C and the heating time between 1 second and 10 minutes to vary the amount of decrease in tensile strength in various ways. Further, deformation-removing annealing was not performed in some embodiments.

Materials and deformation during manufacture The materials (product) after annealing were subjected to the following measurements.

(ingredient)

Alloying element concentration of the material after deformation removal annealing was analyzed by ICP-mass spectrometry.

(Average crystal grain size after final recrystallization annealing)

The cross section orthogonal to the rolling direction was mirror finished by mechanical polishing, and then crystal grain boundaries were formed by etching. The average crystal grain size of this metal structure was measured according to the cutting method of JIS H 0501 (1999).

(Crystal orientation of product)

X-ray diffraction integrated intensity (I _{( hkl )} ) of the _{( hkl )} plane in the thickness direction was measured on the rolled surface of the material after the deformation-removing annealing. The X-ray diffraction integrated intensity (I _{0 ( hkl )} ) of the (hkl) plane was also measured for a copper powder (copper (powder), 2N5,> 99.5%, 325 mesh manufactured by Kanto Kagaku Co., Ltd.). As the X-ray diffraction apparatus, RINT2500 manufactured by RIGAKU CO., LTD. Was used, and measurements were made with Cu tube spheres at a tube voltage of 25 kV and a tube current of 20 mA. The measurement plane ((hkl)) has three faces of (111), (220) and (200), and the A value was calculated by the following equation.

A = 2X ₍₁₁₁₎ + X ₍₂₂₀₎ - X ₍₂₀₀₎

_{X (hkl) = I (hkl} ) / I 0 (hkl)

(The tensile strength)

For the material after the final cold rolling and after the deformation removing annealing, the test piece No. 13B specified in JIS Z 2241 was taken in such a manner that the tensile direction was parallel to the rolling direction, and a tensile test was conducted in parallel with the rolling direction in accordance with JIS Z 2241 To determine the tensile strength.

(Thermal expansion / contraction ratio)

A test piece having a shape of a short width of 20 mm in width and 210 mm in length was taken from the material after deformation removal annealing so that the longitudinal direction of the test piece was parallel to the rolling direction and the distance L ₀ (= 200 mm) And two marks were imprinted. Thereafter, the wafer was heated at 250 DEG C for 30 minutes, and the interval (L) of the dents after heating was measured. Then, the absolute value of the value calculated by the formula (L - L ₀ ) / L ₀ × 10 ⁶ was obtained as the thermal expansion coefficient (ppm).

(Conductivity)

From the material after the deformation-removing annealing, a test piece was taken so that the longitudinal direction of the test piece was parallel to the rolling direction, and the conductivity at 20 캜 was measured by the four-terminal method according to JIS H 0505.

(Flexural strain coefficient)

The flexural modulus of TD was measured in accordance with JACBA technical standard "Method of measuring the flexural modulus of a copper and copper alloy plate cantilever".

A test piece having a plate thickness t and a width w (= 10 mm) was sampled so that the longitudinal direction of the test piece was perpendicular to the rolling direction. A load of P (= 0.15 N) was applied to the position of L (= 100 t) from the fixed end by fixing one end of the specimen and the flexural strain coefficient E was obtained.

E = 4 · P · (L / t) ³ / (w · d)

(Stress relaxation rate)

A test piece having a width of 10 mm and a length of 100 mm was sampled from the material after deformation-removing annealing such that the longitudinal direction of the test piece was perpendicular to the rolling direction. As shown in FIG. 2, l = in the position of 50 ㎜ the point of action, and imposing a stress (s) corresponding to 80% of y ₀ 0.2% of the deflection given TD strength of (measured in accordance with JIS Z 2241) to the specimen . y ₀ was obtained from the following equation.

y ₀ = (2/3) · l ² · s / (E · t)

Where E is the flexural strain modulus of TD and t is the thickness of the sample. At 150 ℃ after 1,000 hours heating was calculated for the permanent deformation amount (height) by measuring the y, the stress relaxation ratio {[y (㎜) / y 0 (㎜)] × 100 (%)} as shown in Figure 3 to remove the load, and .

Table 1 shows the evaluation results. The notation of " < 10 mu m " in the crystal grain size after the final recrystallization annealing in Table 1 indicates the case where the whole rolled structure is recrystallized and the average crystal grain size is less than 10 mu m and the case where only a part of the rolled structure is recrystallized It includes both sides. The notation of " 0 MPa " in the lowering of the tensile strength of the deformation removing annealing indicates that deformation removing annealing is not performed.

Table 2 shows the inventive examples 1, 4, and 1 and 2 in Table 1 as the finishing thickness of the material in each pass of the hot rolling and the degree of processing per pass.

In the copper alloy sheets of Inventive Examples 1 to 26, the Sn concentration was adjusted to 0.005 to 0.25%, the Rmax was set to 25% or less and the Rave was set to 20% or less in the hot rolling and the crystal grain size in the final recrystallization annealing was set to 50 탆 Or less, and the processing degree in the final cold rolling was set to 25 to 99%. As a result, an A value was 0.5 or more, and a conductivity of 80% IACS or more, a tensile strength of 350 MPa or more, and a flexural modulus of 115 ㎬ or more were obtained.

In Inventive Examples 1 to 23, since the tensile strength was lowered by 10 to 100 MPa in the deformation removing annealing after the final rolling, the thermal expansion 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 Inventive Examples 24 and 25, the amount of decrease in tensile strength in deformation-removing annealing was less than 10 MPa, and in Inventive Example 26, deformation removal annealing was not performed. The resulting stress relaxation rate exceeded 50%.

In Comparative Examples 1 to 6, the value of A was less than 0.5 because Rmax or Rave deviated from the specification of the present invention. As a result, the flexural modulus was less than 115..

In Comparative Examples 1 to 3, 5 and 6, the stress relaxation rate was 50% or less even though the heat expansion rate was adjusted to 80 ppm or less by performing the deformation removal annealing under the condition that the tensile strength was lowered by 10 to 100 MPa. Respectively.

In addition, in Comparative Example 4, in addition to the A value of less than 0.5, the strain relaxation annealing was not performed and the heat expansion rate exceeded 80 ppm, so that the stress relaxation rate increased to nearly 80%. Comparing Comparative Example 4 and Inventive Example 26, it can be seen that the stress relieving rate is obviously reduced by adjusting the value A to 0.5 or more even if the deformation removal annealing is not performed and the heat expansion rate exceeds 80 ppm. Further, in the case of the Cu-Sn alloy foil of Patent Documents 1 and 2, since the Rmax and Rave were not controlled and deformation removal annealing was not performed, it is said that the level of the stress relaxation characteristic is close to that of Comparative Example 4 .

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

In Comparative Example 8, since the processing degree in the final cold rolling was less than 25%, and in Comparative Example 9, the grain size of the recrystallized annealed before final cold rolling exceeded 50 탆, and therefore, the tensile strength after deformation- Was less than 350 ㎫. In Comparative Example 10, since the Sn concentration exceeded 0.25 mass%, the conductivity became less than 80% IACS.

Claims (8)

, Sn in an amount of 0.005 to 0.25 mass%, the balance of copper and inevitable impurities, a tensile strength of 350 MPa or more, and an A value given by the following formula: 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)} is an integrated intensity of the diffraction (hkl) obtained with respect to the rolling plane and dongbun surface using X-ray diffraction method, respectively) The method according to claim 1,
Wherein at least one of Ag, Fe, Co, Ni, Cr, Mn, Zn, Mg, Si, P, Sn and B is contained in an amount of 0.2 mass% or less. 3. The method according to claim 1 or 2,
And the thermal expansion coefficient in the rolling direction when heated at 250 占 폚 for 30 minutes is adjusted to 80 ppm or less. 3. The method according to claim 1 or 2,
Wherein the copper alloy plate has a conductivity of 80% IACS or more and a flexural modulus in the direction of the width of the plate of 115 ㎬ or more. 3. The method according to claim 1 or 2,
The thermal expansion / contraction ratio in the rolling direction when heated at 250 占 폚 for 30 minutes is adjusted to 80 ppm or less, the electric conductivity is 80% IACS or more, the bending deformation coefficient in the width direction is 115 占 ㎬ or more, And a stress relaxation rate of 50% or less. 3. The method according to claim 1 or 2,
Wherein the copper alloy sheet has a thickness of 0.1 to 2.0 mm. An electronic component for a large current using the copper alloy plate according to claim 1 or 2. A heat dissipation electronic component using the copper alloy sheet according to any one of claims 1 to 3.

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