JP5475914B1 - Copper alloy sheet with excellent heat dissipation and repeated bending workability - Google Patents

Abstract

Provided is a copper alloy plate excellent in heat dissipation, conductivity, repeated bending workability, and shape maintenance.
Ag is 0 to 1.0 mass%, Ti is 0 to 0.08 mass%, Ni is 0 to 2.0 mass%, Zn is 0 to 3.5 mass%, Cr, Fe, In, One or more selected from the group of P, Si, Sn, and Zr is contained in a total of 0 to 0.5% by mass, the balance is made of Cu and inevitable impurities, the conductivity is 60% IACS or more, and tensile The degree of integration of crystal orientation of box number 36 obtained by performing equal area division used for display by the vector method for stereo triangles having a strength of 350 MPa or more and representing the crystal orientation in the rolling direction of the plate surface. A copper alloy plate that is 6 or less.
[Selection] Figure 2

Description

  The present invention relates to a copper alloy plate suitable for electronic components for heat dissipation, electronic components for large currents, and the like, and in particular, a copper alloy suitable as a flexible printed circuit board (FPC) including LED mounting substrates for lighting and the like. The present invention relates to a plate, a copper alloy plate excellent in heat dissipation and repetitive bending workability, and an electronic device component using the same.

  LED lighting has advantages such as low power consumption, long life, and high-speed response compared to conventional incandescent bulbs and fluorescent lamps, etc., and it is rapidly spreading as product prices decrease. In addition, various applications such as backlights for LCD TVs and LCD monitors, and lighting for automobiles are also expanding.

  Since the LED itself is a semiconductor, the light emitting element itself has a long life when used within the rated range. However, the resin material covering the light emitting element is easily deteriorated by heat, and the transparency is easily lowered by heat generation. Unsuitable for use. In addition, LEDs are manufactured in various package shapes in consideration of light emission characteristics and heat dissipation. However, when used in a small space, various devices such as space saving and molding methods are required. It is.

  In order to deal with the problem of heat generation, in order to efficiently dissipate heat from the FPC, it has been proposed to attach a heat sink to the FPC, and for space saving, an attempt has been made to place an LED on the FPC. (Patent Document 1).

  In addition, as a lighting device, it has been proposed to perform complicated processing on a circuit board on which LEDs are arranged to perform three-dimensional molding (Patent Document 2).

JP 2007-141729 A Japanese Patent Laid-Open No. 2007-5003

When the LED is mounted on the FPC, the heat dissipation of the resin that is the substrate is not sufficient, so that the resin that covers the light emitting element is deteriorated by heat for a long time, and the lifetime as illumination is shortened.
As a countermeasure to heat generation, when an aluminum plate is bonded to the FPC as a heat dissipation plate, there is a problem that warpage occurs in the FPC circuit due to a difference in linear thermal expansion coefficient from the copper wiring constituting the FPC circuit. Furthermore, by repeating expansion and contraction due to heat, the copper wiring of the FPC repeatedly receives tensile stress and may break.
When a copper plate is used as the heat radiating plate, the above problem does not occur. However, since copper has a larger work hardening coefficient than aluminum, cracks are likely to occur in the bent portion when FPC is molded into a complicated shape. When a crack occurs, when it is used in an environment where repeated vibration is applied, such as in-vehicle, a problem such as the crack progressing and breaking occurs.

Such a problem relating to bending workability has also occurred in heat sinks other than those for FPC boards, and one example thereof is a heat dissipating component called a liquid crystal frame used in the liquid crystal of smartphones and tablet PCs.
On the other hand, a copper alloy plate used for a heat dissipation component is often used as a high-current electronic component such as a high-current connector or terminal used in an electric vehicle, a hybrid vehicle, or the like because of its high conductivity. For the purpose of reducing heat generation during energization, parts that pass a large current are often machined from a thick copper alloy plate such as 0.3 to 2.0 mm. However, when the thickness increases, cracks occur during bending. Since it is likely to occur, problems related to bending workability are also serious in high-current electronic components.
This invention is made | formed in order to solve said subject, and makes it a subject to provide the copper alloy plate excellent in heat dissipation, electroconductivity, repeated bending workability, and shape maintenance property.

  The present inventor conducted research to solve the above problems, and obtained by performing equal area division used in the display by the vector method on the stereo triangle representing the crystal orientation in the rolling direction of the surface of the copper alloy plate. It has been found that repeated bending workability and the like can be improved by controlling the degree of integration of crystal orientations at predetermined positions.

  In one aspect, the present invention completed with the above knowledge in the background, Ag is 0 to 1.0 mass%, Ti is 0 to 0.08 mass%, Ni is 0 to 2.0 mass%, and Zn is 0 to 0 mass%. 3.5% by mass, containing 0 to 0.5% by mass in total of at least one selected from the group consisting of Cr, Fe, In, P, Si, Sn, and Zr, with the balance consisting of Cu and inevitable impurities Obtained by performing equal area division used for display by the vector method on a stereo triangle having a conductivity of 60% IACS or more, a tensile strength of 350 MPa or more, and representing a crystal orientation in the rolling direction of the plate surface. This is a copper alloy plate having a degree of integration of crystal orientation of box number 36 of 6 or less.

  In one embodiment, the copper alloy sheet according to the present invention is 0.01 mass in total of at least one selected from the group consisting of Ag, Ti, Ni, Zn, Cr, Fe, In, P, Si, Sn, and Zr. % Or more.

  In another embodiment, the copper alloy plate according to the present invention contains 0.01 to 0.20 mass% of Zr, with the balance being Cu and inevitable impurities.

  In yet another embodiment, the copper alloy plate according to the present invention contains 0.01 to 0.20 mass% of Sn, with the balance being Cu and inevitable impurities.

  In yet another embodiment, the copper alloy plate according to the present invention is 0.05 to 0.35 mass% Fe, 0.01 to 0.12 mass% P, 0 to 0.03 mass% Sn, Ni is contained in an amount of 0 to 0.1 mass%, Zn is contained in an amount of 0 to 0.5 mass%, and the balance is made of Cu and inevitable impurities.

  In still another embodiment of the copper alloy plate according to the present invention, the accumulation degree of the crystal orientation of the box number 36 is 1 or more.

  In yet another embodiment, the copper alloy sheet according to the present invention has a tensile strength of 250 MPa or more after heating at 200 ° C. for 30 minutes.

  In yet another embodiment, the copper alloy plate according to the present invention is used for heat dissipating electronic components.

  In yet another embodiment, the copper alloy plate according to the present invention is used for a high-current electronic component.

  In yet another embodiment, the copper alloy plate according to the present invention is for an FPC board.

  In yet another embodiment, the copper alloy plate according to the present invention is for an FPC board on which LED lighting is mounted.

  In yet another embodiment, the copper alloy plate according to the present invention has a thickness of 0.05 to 0.3 mm.

  Another aspect of the present invention is an electronic device component using the copper alloy plate of the present invention.

  In still another aspect, the present invention is an FPC in which LED lighting using the copper alloy plate of the present invention is mounted.

  ADVANTAGE OF THE INVENTION According to this invention, the copper alloy plate excellent in heat dissipation, electroconductivity, repeated bending workability, and shape maintenance property can be provided.

FIG. 1 shows a stereo projection diagram display of the rotation angle of Williams method and vector method representing crystal orientation. FIG. 2 shows a stereo triangle divided into 36 pieces by equal area division.

(Copper foil components)
As the base Cu to which the alloy element is added, oxygen free copper standardized to JIS H3100 C1020 or tough pitch copper standardized to JIS H3100 C1100 is suitable. The oxygen concentration is usually 0.02 to 0.05 mass% for tough pitch copper and 0.001 mass% or less for oxygen-free copper.
The copper alloy sheet of the present invention is composed of 0 to 1.0 mass% Ag, 0 to 0.08 mass% Ti, 0 to 2.0 mass% Ni, 0 to 3.5 mass% Zn, Cr, One or more selected from the group consisting of Fe, In, P, Si, Sn and Zr is contained in a total amount of 0 to 0.5% by mass, and the balance is made of Cu and inevitable impurities.
In general, Cr, Fe, In, Ni, P, Si, Sn, Ti, Zn, and Zr, which are easily oxidized as compared with Cu, are added to the oxygen-free copper melt. After adding a deoxidizer such as P or Si to the molten copper containing oxygen to reduce the oxygen concentration to 10 ppm or less, these alloy elements may be added. Since Ag is harder to oxidize than Cu, it can be added to both the tough pitch copper melt and the oxygen free copper melt.

In order to improve the heat resistance of the copper foil, a total of 0.01 mass of one or more selected from the group consisting of Ag, Ti, Ni, Zn, Cr, Fe, In, P, Si, Sn, and Zr is added to copper. % Or more may be added. When the total concentration of the additive elements is less than 0.01% by mass, the effects of the additive elements are not exhibited and the heat resistance may be insufficient.
Ag is not particularly limited since the effect of the decrease in conductivity due to the addition is small, but is not more than 1.0% by mass because the concentration increases and the cost increases.
Cr, Fe, In, P, Si, Sn, and Zr, which have a large effect on the decrease in conductivity due to the addition, are 0.5% by mass or less with respect to the total of these elements. % Or less. Ni is 2.0% by mass or less, and Zn is 3.5% by mass or less.

  As an example of a copper alloy plate having high heat resistance and particularly suitable for the present invention, Zr is contained in an amount of 0.01 to 0.20 mass% (preferably 0.01 to 0.15 mass%), and the balance is Cu. And a copper alloy plate made of unavoidable impurities, containing 0.01 to 0.20% by mass (preferably 0.01 to 0.15% by mass) of Sn, with the balance being Cu and unavoidable impurities, 0.05 to 0.35 mass% (preferably 0.08 to 0.35 mass%) of Fe, 0.01 to 0.12 mass% (preferably 0.02 to 0.12 mass%) of P, Sn is 0-0.03% by mass, Ni is 0-0.1% by mass (preferably 0-0.03% by mass), and Zn is 0-0.5% by mass (preferably 0-0.4% by mass). And a copper alloy plate containing the balance of Cu and inevitable impurities.

(Heat dissipation)
In order to efficiently cool the heated material, a material having good heat conduction is required as a heat dissipation material to be joined. In general, the higher the conductivity of the material, the better the thermal conductivity. Considering the heat generated when the LED lighting is turned on, there are influential factors such as the LED mounting density and the shape of the lighting device, but the conductivity may be 60% IACS or more, and more preferably 70% IACS or more.

(Repeated bending workability)
As for the repetitive bending workability, the relationship with the texture was examined. The reason is not clear, but it is used in the display by the vector method for the stereo triangle that represents the crystal orientation in the rolling direction of the copper alloy sheet surface. There was a correlation between the degree of integration of crystal orientations at predetermined positions obtained by area division and repeated bendability. Specifically, the integration degree of the crystal orientation of the box number 36 obtained by performing equal area division used in the display by the vector method for the stereo triangle representing the crystal orientation in the rolling direction on the surface of the copper alloy sheet is 6 It is sufficient if it is less than or equal to 4, more preferably less than or equal to 4. In addition, the lower limit of the degree of integration of the crystal orientation of box number 36 obtained by performing equal area division used in the display by the vector method for the stereo triangle representing the crystal orientation in the rolling direction on the surface of the copper alloy plate is a repeated bending Although it is not necessary to specifically limit from a viewpoint of property, it is 0.01 or more or 0.05 or more, for example, and typically 0.1 or more.
FIG. 1 is a stereo projection diagram display of a rotation angle of a vector method (biaxial pole projection method) representing a crystal orientation of a copper alloy. In FIG. 1, a point RD representing the rolling direction (RD) of the surface of the copper alloy sheet is indicated by coordinates (ψ, ω) on the stereo triangle (T1) on which the point is placed. FIG. 2 shows the stereo triangle divided into 36 by equal area division (by Ruer et al.). Among the crystal orientations in the stereo triangle of FIG. 2, those in the region indicated by the number 36 are “the crystal orientation of the box number 36” (Furubayashi, “Recrystallization and material structure”, 1st edition, Ochida Osamu Tsuruno, see pages 88-89). Further, “the degree of accumulation of crystal orientations of box number 36” represents the average intensity of the section on the pole figure represented by the orientation corresponding to box number 36.

(Shape maintenance)
After the material is formed into a predetermined shape, a certain level of material strength is required to maintain the initial processed shape. Although there are influential factors such as the structure of the processed shape, when the tensile strength, which is the material strength, is less than 350 MPa, it is easily deformed by the force applied to the material. For this reason, the tensile strength needs to be 350 MPa or more. The upper limit of strength is not particularly set, but it is generally known that when the strength is increased by increasing the workability of the material, bending workability is generally deteriorated. Therefore, the balance with bending workability is considered. Then, the material can be processed. Further, the tensile strength is more preferably 400 MPa or more.

(Heat-resistant)
About heat resistance, from the characteristic of LED lighting, it is designed so that it may be normally used at the temperature of less than 150 degreeC so that it can be used as lighting equipment for a long time. When the material is softened by this heat, the initial processed shape cannot be maintained. In order to avoid such a phenomenon, it is important to ensure heat resistance. On the other hand, it is assumed that the lighting equipment will be used for several tens of thousands of hours, but a long-time heating test that reproduces this as it is is not realistic. Heating was carried out at 200 ° C. for 30 minutes, and when the tensile strength was 250 MPa or more, it was judged that the heat resistance was good. Moreover, it is more preferable to maintain 300 MPa or more after heating at 200 ° C. for 30 minutes. Note that the heat resistance has a correlation with the degree of accumulation of crystal orientation, and is obtained by dividing the stereo triangle representing the crystal orientation in the rolling direction on the surface of the copper alloy plate by equal area division used in the display by the vector method. If the degree of integration of the crystal orientation in box number 36 is less than 1, heat resistance may be poor. For this reason, it is preferable that the integration degree of the crystal orientation of the box number 36 is 1 or more.

(Thickness)
The thickness of the copper alloy plate according to the present invention is preferably 0.05 to 0.3 mm. If the thickness of the copper alloy plate is less than 0.05 mm, there is a problem that it is difficult to maintain the shape because the material is thin. If it is more than 0.3 mm, the material is thick in applications such as an FPC board. This may cause a problem that the product becomes too heavy. In addition, as described above, the copper alloy plate according to the present invention includes a form of copper foil.
In addition, a copper alloy plate having a thickness of 0.3 to 2.0 mm may be suitably used in applications such as heat dissipation electronic components other than FPC boards and high current electronic components.
Here, the electronic component for large current is not particularly limited and includes those generally used for large current. For example, it is 10 amperes or more, more typically 30 amperes or more, and more typically 50 amperes or more. An electronic component through which a current flows is shown. Some connectors for electric vehicles and hybrid vehicles carry a current of 100 amperes or more.

(Manufacturing process)
The effects of the present invention are manifested regardless of the manufacturing conditions as long as the components, shape retention, and crystal orientation integration degree of the copper alloy plate are within the above-mentioned characteristic ranges. The copper alloy plate of the present invention can be manufactured, for example, by the following process.

The manufacturing process of a rolled copper foil uses electrolytic copper as a raw material for pure copper, adds an alloying element as necessary, and casts to produce an ingot having a thickness of 100 to 300 mm. This ingot is hot-rolled to a thickness of about 5 to 20 mm, and then cold-rolling and annealing are repeated to finish it to a predetermined thickness by cold-rolling.
The copper foil that satisfies the shape maintenance property and the degree of crystal orientation integration described above is the temperature increase rate of the final recrystallization annealing, and the total workability that is the processing conditions of the final cold rolling performed immediately after the final recrystallization annealing, and It is obtained by adjusting the processing degree of the first pass. Here, the final recrystallization annealing is a recrystallization annealing before the final cold rolling for processing to the thickness of the product. In the final cold rolling, the material is repeatedly passed between a pair of rolls (hereinafter referred to as “pass”) to finish the thickness. Here, the first pass indicates the first pass in the final cold rolling in which the material after the final recrystallization annealing is finished to the product thickness.
The temperature increase rate of the final recrystallization annealing may be 12 to 50 ° C./s. When the rate of temperature increase is less than 12 ° C./s and when it exceeds 50 ° C./s, it is difficult to satisfy the above-described repeated bending workability.
The upper limit value of the total workability of the final cold rolling is not particularly limited. The total degree of work in final cold rolling is generally 85% or less. The degree of work is a percentage obtained by dividing the difference in thickness between before and after rolling by the thickness before rolling. Further, the lower limit value of the total workability varies depending on the alloy components and the concentration, and may be set so as to exceed the lower limit value of the tensile strength. For example, for a copper foil containing 0.12% by mass of Sn, the total degree of work in the final cold rolling may be 50% or more, and more preferably 60% or more.
The degree of processing in the first pass of final cold rolling may be 20% or less. When the degree of workability in the first pass of final cold rolling exceeds 20%, it is difficult to satisfy the provision of the degree of crystal orientation accumulation according to the present invention, and it is difficult to satisfy the above-described repeated bending workability. .

(Use)
The copper alloy plate of the present invention can be used for electronic equipment parts such as lead frames, connectors, terminals, pins, relays, switches, sockets, bus bars, heat sinks, and foil materials for secondary batteries. In particular, the copper alloy plate of the present invention is useful as a heat sink that is an electronic component for heat dissipation, and among them, it is suitably used as an FPC material mounted with LED lighting, a liquid crystal frame used in smartphones and tablet PCs, and the like. Used. Furthermore, it is also particularly suitably used as a high-current electronic component such as a high-current connector or terminal used in an electric vehicle, a hybrid vehicle, or the like.

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

[Manufacture of rolled copper foil]
Various elements described in Tables 1 to 3 were added to various copper base materials described in Tables 1 to 3 to cast ingots having a thickness of 100 mm. Next, the ingot is rolled to 5 mm by hot rolling, and after removing the oxide scale, cold rolling and annealing are repeated, and 0.05 to 1 under the conditions shown in Tables 1 to 3 by final cold rolling. Rolled to 2 mm. The final recrystallization annealing was performed immediately before the final cold rolling. The final recrystallization annealing was performed at the rate of temperature increase described in Tables 1 to 3, and the material temperature was heated to 500 ° C. at maximum, and the rate of temperature increase was calculated from the time to reach 500 ° C. from room temperature (25 ° C.). . And it cooled immediately after material temperature reached | attained 500 degreeC.

[Shape maintenance]
In accordance with JIS Z 2241, a JIS No. 13B test piece collected so that the rolling parallel direction was the longitudinal direction was used as a test material, and the tensile strength was obtained by a tensile test. In the tensile test, UTM-10T manufactured by ORIENTEC Co., Ltd. was used, and the average value measured at n = 2 for the same sample at a tensile speed of 5 mm / min was used as the measured value. When the tensile strength was 350 MPa or more, the shape maintaining property was evaluated as ◯, and when the tensile strength was less than 350 MPa, the shape maintaining property was evaluated as x.

[Heat dissipation]
The plate thickness after the final cold rolling was evaluated by the conductivity (% IACS) measured by the four-terminal method based on JIS H 0505.

[Accumulation degree of crystal orientation]
A sample cut out in a 20 mm square was subjected to measurement of the degree of crystal orientation accumulation. The degree of integration of the crystal orientation of box number 36 obtained by performing equal area division used in the display by the vector method on the stereo triangle representing the crystal orientation in the rolling direction of the plate surface was evaluated. Specifically, first, positive electrode spot measurement was performed by a Schultz reflection method using an X-ray diffractometer RINT-2000 manufactured by Rigaku Corporation. Next, the measured data was converted into a pole figure using Pole Figure DataProcessing manufactured by Rigaku Corporation, and divided as shown in FIG. 2 using Standard ODF and InverseDisp manufactured by Norm Engineering Co., Ltd., and the degree of integration was evaluated.

[Heat-resistant]
Using the above JIS13B test piece, the sample was put in a heating furnace and, after the temperature reached 200 ° C., held for 30 minutes, the sample was taken out, air-cooled, and subjected to a tensile test. The tensile test was performed under the same conditions as described above. When the tensile strength was 250 MPa or more, the heat resistance was judged as good (◯), and when the tensile strength was less than 250 MPa, the heat resistance was judged as poor (x).

[Repeated bending workability]
Repeated bending workability was evaluated by the following procedure.
(1) A sample was cut into a length of 50 mm and a width of 10 mm in the rolling parallel direction and the perpendicular direction.
(2) V-bending was performed at 90 ° at a bending R = 0.5 mm, and this was bent back to the original strip shape, and then 90 ° V bending and bending back were repeated.
(3) The above operation was repeated, and the bent portion when bent 90 ° V every time was magnified 50 times to confirm whether cracks or breakage occurred. Then, the maximum number of bendings at which cracks or breakage did not occur was investigated. The maximum number of bendings at which cracks did not occur was evaluated as “」 ”for 4 times or more,“ ◯ ”for 4 times,“ Δ ”for 3 times, and“ x ”for less than 3 times.
Tables 1 to 3 show the evaluation conditions and results.

In Examples 1 to 43, the concentration of each element is equal to or lower than the upper limit value, the tensile strength is 350 MPa or more, and the stereo triangle representing the crystal orientation in the rolling direction of the plate surface is used for display by the vector method. Since the degree of integration of crystal orientations in box number 36 obtained by performing equal area division was 6 or less, all of them were excellent in shape maintenance, heat dissipation (conductivity), and repeated bending workability.
In Comparative Example 1, since the additive element concentration was too high, the conductivity was low and the heat dissipation was poor.
In Comparative Examples 2 and 6, the degree of workability in the first pass in the final cold rolling exceeded 20%, so the regulation of the degree of crystal orientation accumulation was not satisfied, and repeated bending workability was poor.
In Comparative Examples 3 and 7, the rate of temperature increase in the final recrystallization annealing was less than 12 ° C./s, so the regulation of the degree of crystal orientation was not satisfied, and the repeated bending workability was poor.
In Comparative Example 4, the rate of temperature increase in the final recrystallization annealing exceeded 50 ° C./s, so the regulation of the degree of integration of crystal orientation was not satisfied, and the repeated bending workability was poor.
In Comparative Example 5, since the total degree of rolling in the final cold rolling was too low, the tensile strength was less than 350 MPa, and the shape maintainability was poor.

Claims (14)

Ag is 0 to 1.0 mass%, Ti is 0 to 0.08 mass%, Ni is 0 to 2.0 mass%, Zn is 0 to 3.5 mass%, Cr, Fe, In, P, Si, One or more selected from the group of Sn and Zr is contained in a total of 0 to 0.5% by mass, and the balance consists of Cu and inevitable impurities,
Conductivity is 60% IACS or higher,
The tensile strength is 350 MPa or more,
A copper alloy plate having a degree of integration of crystal orientations of box number 36 obtained by performing equal area division used for display by a vector method on a stereo triangle representing a crystal orientation in the rolling direction of the plate surface is 6 or less.   2. The copper alloy sheet according to claim 1, comprising at least 0.01% by mass in total of at least one selected from the group consisting of Ag, Ti, Ni, Zn, Cr, Fe, In, P, Si, Sn, and Zr. .   The copper alloy plate according to claim 2, comprising Zr in an amount of 0.01 to 0.20 mass%, with the balance being Cu and inevitable impurities.   The copper alloy plate according to claim 2, comprising 0.01 to 0.20 mass% of Sn, with the balance being Cu and inevitable impurities.   Fe: 0.05-0.35 mass%, P: 0.01-0.12 mass%, Sn: 0-0.03 mass%, Ni: 0-0.1 mass%, Zn: 0-0.0 mass%. The copper alloy sheet according to claim 2, wherein the copper alloy sheet is contained in an amount of 5% by mass and the balance is made of Cu and inevitable impurities.   The copper alloy plate according to claim 1, wherein the box number 36 has an accumulation degree of crystal orientation of 1 or more.   The copper alloy sheet according to any one of claims 2 to 6, which has a tensile strength of 250 MPa or more after heating at 200 ° C for 30 minutes.   The copper alloy plate according to any one of claims 1 to 7, which is used for an electronic component for heat dissipation.   The copper alloy plate according to any one of claims 1 to 7, which is used for a high-current electronic component.   The copper alloy sheet according to any one of claims 1 to 7, which is for an FPC board.   The copper alloy plate according to claim 10, which is for an FPC board on which LED lighting is mounted.   The copper alloy sheet according to any one of claims 1 to 11, wherein the thickness is 0.05 to 0.3 mm.   The electronic device component using the copper alloy plate as described in any one of Claims 1-12.   FPC which mounted LED lighting using the copper alloy plate as described in any one of Claims 1-12.

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