JP2014198891A - Copper alloy sheet and electronic component for heat release having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper alloy sheet having high strength, high conductivity and excellent processability, and an electronic component for heat release having the same.SOLUTION: The copper alloy sheet contains Fe of 0.01 to 0.5 mass% and P with a ratio of the mass% concentration of Fe (%Fe) to the mass% concentration of P (%P) of 1.0 to 6.0 and the balance copper with inevitable impurities, has a conductivity of 65% IACS or more and 0.2% bearing force of 400 MPa or more, and a sheet thickness anisotropy r defined by (r+r+2×r)/4 of 1.2 or more, where r, rand rare respective Lankford values of a parallel direction, a right angle direction and a direction having 45° to a rolling direction.

Description

  The present invention relates to a copper alloy plate excellent in heat dissipation, conductivity and drawing workability, and more specifically for use in electronic parts such as terminals, connectors, relays, switches, sockets, bus bars, lead frames, particularly smartphones and personal computers. The present invention relates to a copper alloy plate suitable for use in heat-radiating components and high-current components.

Parts for obtaining electrical connections such as terminals, connectors, switches, sockets, relays, bus bars, lead frames, and the like are incorporated in electric / electronic devices such as smartphones, tablet PCs, and personal computers.
In recent years, with the miniaturization of smartphones, tablet PCs, and personal computers, heat storage tends to increase when power is supplied to liquid crystal components or IC chips in electric / electronic devices. When heat storage is large, the thermal damage to the IC chip and the substrate is large, and the heat dissipation of the heat dissipation component is a problem.

Conventionally, austenitic stainless steel, pure aluminum, and the like have been mainly used for heat dissipation components in electric and electronic devices such as smartphones, tablet PCs, and personal computers. For example, a heat dissipation component (liquid crystal frame) attached to a liquid crystal of a smartphone or a tablet PC is required to have strength as a structure and bendability or drawability necessary for fixing to a liquid crystal in addition to high heat dissipation.
Austenitic stainless steel has good bendability and drawability, but has low thermal conductivity, and an expensive thermal conductive sheet or the like is used in combination to compensate for it. Therefore, the unit price of the heat dissipating component is increased. On the other hand, pure aluminum and aluminum alloys have good bendability and drawability, but lack thermal conductivity and strength as a structure.

  On the other hand, among copper alloys, Cu-Fe-P alloys have a relatively high electrical conductivity, which is known to be proportional to thermal conductivity, and have the required strength and are manufactured at low cost. In particular, for example, JIS alloy number C1921 (Cu-0.1 mass% Fe-0.03 mass% P), C1940 (Cu-2.4 mass% Fe-0.1 mass% P-0.1 mass) % Zn) and the like are put to practical use as heat dissipation parts for the above-mentioned electric and electronic devices. Improvement techniques for Cu—Fe—P alloys are disclosed in, for example, Patent Documents 1 to 5.

JP 2004-099978 A JP 2005-139501 A JP 2005-206871 A JP 2006-083465 A JP 2007-031794 A

  However, although the conventional Cu-Fe-P alloy has high strength and heat conduction characteristics, it does not satisfy the required bendability or drawability, or in some cases.

  Therefore, it can be said that it is industrially significant to improve the bendability and the drawing workability while maintaining the strength and the electrical conductivity in the Cu—Fe—P alloy.

  Then, this invention makes it a subject to provide the copper alloy board which has high intensity | strength, high electroconductivity, and the outstanding drawability and bending workability, and an electronic component for heat dissipation provided with the same.

By controlling the thickness anisotropy value obtained from the Rankford value measured in three in-plane directions in the Cu—Fe—P based alloy, the inventors have made drawing workability and bending workability. Found to improve.
Based on the above findings, the following invention has been completed.
The copper alloy sheet of the present invention contains 0.01 to 0.5% by mass of Fe, and further contains P. The mass% concentration of Fe (% Fe) with respect to the mass% concentration (% P) of P The ratio (% Fe /% P) is 1.0 to 6.0, the balance is made of copper and its inevitable impurities, has a conductivity of 65% IACS or more, and a 0.2% proof stress of 400MPa or more, When the rankford values in the direction parallel to the rolling direction, the direction perpendicular to the rolling direction, and the direction forming 45 ° are r ₀ , r ₉₀ , and r ₄₅ , respectively, (r ₀ + r ₉₀ + 2 × r ₄₅ ) The plate thickness anisotropy r defined by / 4 is 1.2 or more.

  In the copper alloy sheet of the present invention, the minimum bending radius / sheet thickness (MBR / t) in the rolling parallel direction (GW direction) and the perpendicular direction (BW direction) in the W bending test is given by MBR / t ≦ 2.0. It is preferable that

  In addition, it is preferable that the copper alloy plate of the present invention further contains 0.5% by mass or less of Sn and 1.0% by mass or less of Zn, respectively, and Ag, Co, Ni, Cr It is preferable to further contain at least 2.0% by mass of one or more elements selected from the group consisting of Mn, Mg, Si and B.

  Moreover, the electronic component for heat dissipation of this invention is provided with one of said copper alloy plates.

  According to the present invention, it is possible to provide a copper alloy plate having high strength, high conductivity, and excellent drawing workability. This copper alloy plate can be suitably used as a material for electronic parts such as terminals, connectors, switches, sockets, relays, busbars, lead frames, etc., and is used for heat dissipation and high current parts used in smartphones and personal computers. The present invention relates to a copper alloy suitable for use.

Hereinafter, embodiments of the present invention will be described in detail.
The copper alloy plate according to an embodiment of the present invention contains 0.01 to 0.5 mass% Fe and P, and the mass% concentration of Fe (% Fe) relative to the mass% concentration (% P) of P. ) Ratio (% Fe /% P) is 1.0 to 6.0, and the balance is composed of copper and inevitable impurities, and this copper alloy sheet has a conductivity of 65% IACS or higher. The 0.2% proof stress is 400 MPa or more, and the plate thickness anisotropy obtained from the Rankford value is adjusted to 1.2 or more. The copper alloy plate of the present invention having such characteristics is suitable for use as an electronic component for heat dissipation.

(Alloy component concentration)
Fe concentration shall be 0.01-0.5 mass%. When Fe exceeds 0.5 mass%, it becomes difficult to obtain a conductivity of 65% IACS or more. When Fe is less than 0.01% by mass, it becomes difficult to obtain a 0.2% yield strength of 400 MPa or more. From such a viewpoint, the Fe concentration is preferably 0.05 to 0.5.

In addition to Fe, P is added to the copper alloy of the present invention. The ratio (% Fe /% P) of the mass% concentration (% P) of P to the mass% concentration (% Fe) of Fe is 1.0 to 6.0, preferably 2.0 to 5.0. Adjust so that By adjusting% Fe /% P in this way, higher conductivity can be obtained.
More specifically, the P concentration is preferably 0.01 to 0.3% by mass. P has the effect of deoxidizing the molten metal in the alloy manufacturing process. Further, by forming a compound with Fe, there is an effect of increasing the conductivity and strength of the alloy.

0.5 mass% or less of Sn can be added to the Cu-Fe-P alloy of the present invention. Sn has the effect of promoting work hardening of the alloy during rolling and improving the strength of the alloy.
When Sn exceeds 0.5% by mass, the decrease in conductivity is increased. In order to acquire the effect of Sn addition, it is preferable to make the addition amount of Sn 0.001 mass% or more. A more preferable Sn concentration range is 0.005 to 0.3% by mass, and a further preferable Sn concentration range is 0.01 to 0.1% by mass.
In addition, since Sn does not easily form an oxide in molten copper, as long as it is added at a concentration of 0.5% by mass or less, Sn addition does not deteriorate the productivity and quality of the alloy.

  Moreover, in order to improve the heat-resistant peelability of Sn plating, 1.0 mass% or less of Zn can be added to the Cu-Fe-P alloy of the present invention. When Zn exceeds 1.0 mass%, the fall of electrical conductivity will become large. In order to obtain the effect of adding Zn, the amount of Zn added is preferably 0.001% by mass or more. A more preferable range of Zn concentration is 0.01 to 0.5% by mass. Since Zn does not easily form an oxide in molten copper, as long as it is added at a concentration of 1.0% by mass or less, the manufacturability and quality of the alloy are not deteriorated.

  Furthermore, in order to improve strength and heat resistance, the Cu—Fe—P alloy of the present invention includes one or more elements selected from the group consisting of Ag, Co, Ni, Cr, Mn, Mg, Si, and B. Can further be contained. However, if the addition amount is too large, the electrical conductivity decreases or the manufacturability deteriorates, so the addition amount is 2.0% by mass or less, more preferably 0.5% by mass or less, more preferably, in total. It is limited to 0.1% 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.

(conductivity)
In the present invention, the conductivity measured according to JIS H0505 is set to 65% IACS or more. If the electrical conductivity is 65% IASC or more, the thermal conductivity is good and good heat dissipation can be secured.

(0.2% yield strength)
In the present invention, the 0.2% proof stress of the copper alloy plate is set to 400 MPa or more. In this case, it can be said that the copper alloy plate has a strength necessary as a material for the structural material.

(Drawing workability)
The test piece was subjected to 2.5% elongation strain in the rolling parallel, right-angle, and 45 ° directions, respectively. From the dimensional change in the length and width direction of the test piece, the rankford values in each direction, r ₀ and r ₉₀ , R ₄₅ was determined, and the plate thickness anisotropy r defined by r = (r ₀ + r ₉₀ + 2 × r ₄₅ ) / 4 was calculated. It is known that the plate thickness anisotropy r generally has better drawing workability as the value increases. Moreover, the plate | board thickness anisotropy r of a general copper-stretched product is about 0.8-1.1, and the outstanding drawability is obtained by adjusting so that this value may be 1.2 or more.
The Rankford value here is defined in JIS Z2254, and the above-mentioned Rankford values r ₀ , r ₉₀ , and r ₄₅ are measured according to JIS Z2254. . However, the product of the present invention is low in elongation to maintain the strength required as a structural material, and the load strain is 2.5%.

(Thickness)
The thickness of the product, that is, the plate thickness (t) is preferably 0.05 to 2.0 mm. If the thickness is too small, sufficient heat dissipation cannot be obtained, which is unsuitable as a material for heat dissipation electronic components. On the other hand, if the thickness is too large, drawing and bending become difficult. From such a viewpoint, a more preferable thickness is 0.08 to 1.5 mm. When the thickness is in the above range, heat dissipation is excellent and bending workability can be improved.

(Bending workability)
The minimum bending radius (MBR) of the copper alloy plate is measured according to JIS H3130. The ratio (MBR / t) of the minimum bending radius (MBR) to the plate thickness (t) is 2. It is preferable to make it 0 or less from the viewpoint of securing good bendability. More preferably, MBR / t is 1.8 or less.

(Production method)
Hereinafter, an example of the suitable manufacturing method of the copper alloy plate which concerns on this invention is demonstrated.
Electro copper or the like is melted as a pure copper raw material, Fe, P and other alloy elements are added as required, 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 elongation after the final cold rolling is so low that it is less than 2%, but increases by subsequent strain relief annealing.

In recrystallization annealing, part or all of the rolling structure is recrystallized. Further, by annealing under appropriate conditions, Fe or a compound of Fe and P is precipitated, and the electrical conductivity of the alloy is increased.
In the recrystallization annealing before the final cold rolling, the average crystal grain size of the copper alloy sheet is adjusted to 50 μm or less. If the average crystal grain size is too large, it will be difficult to adjust the 0.2% yield strength to 400 MPa or more.

  The conditions for recrystallization annealing before the final cold rolling are determined based on the target crystal grain size after annealing and the target product conductivity. Specifically, annealing may be performed by using a batch furnace or a continuous annealing furnace and setting the furnace temperature to 350 to 800 ° C. In a batch furnace, the heating time may be appropriately adjusted at a temperature in the furnace of 350 to 600 ° C. in the range of 30 minutes to 30 hours. 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. Generally, when annealing is performed at a lower temperature for a longer time, higher conductivity can be obtained with the same crystal grain size.

In the final cold rolling, the material is repeatedly passed between a pair of rolling rolls to finish the target plate thickness. Control the total degree of work in the final cold rolling.
The total workability R (%) is given by R = (t ₀ −t) / t ₀ × 100 (t ₀ : plate thickness before final cold rolling, t: plate thickness after final cold rolling).
The total processing degree R is 40 to 99%, preferably 45 to 98.5, and more preferably 50 to 98. If R is too small, it is difficult to adjust the 0.2% proof stress to 400 MPa or more. If R is too large, the edge of the rolled material may be cracked.

  The strain relief annealing of the present invention is performed using a continuous annealing furnace capable of holding a copper alloy plate in a flat plate shape in the furnace. In the case of a batch furnace, the material is heated in a coiled state, so that the material undergoes plastic deformation during the heating, and the material is warped. Therefore, the batch furnace is not suitable for the strain relief annealing of the present invention.

  In the strain relief annealing after rolling, the tension applied to the material in the continuous annealing furnace is adjusted to 1 to 5 MPa, more preferably 2 to 4 MPa. If the tension is too large, the plate thickness anisotropy r decreases and it becomes difficult to adjust the thickness to 1.2 or more. On the other hand, if the tension is too small, the material passing through the annealing furnace may come into contact with the furnace wall and the surface of the material or the edge may be damaged, leading to a decrease in productivity.

In a continuous annealing furnace, the furnace temperature is set to 300 to 700 ° C., preferably 350 to 650 ° C., the heating time is appropriately adjusted in the range of 5 seconds to 10 minutes, and 0.2% yield strength (σ) after strain relief annealing. Is adjusted to a value 10 to 50 MPa lower, preferably 15 to 45 MPa lower than the 0.2% proof stress (σ ₀ ) before strain relief annealing. As a result, the elongation which was low after the final cold rolling is increased and the bendability is improved.

In addition to the above-described strain relief annealing, the present invention provides a Cu-Fe-P-based alloy with a feature that the plate thickness anisotropy r ≧ 1.2 determined from the Rankford value, thereby reducing drawability and bending. One of the features is to improve the workability. The manufacturing conditions for this purpose are summarized as follows.
a. In the strain relief annealing, (σ ₀ −σ) = 10 to 50 MPa is adjusted.
b. The furnace tension in the strain relief annealing is adjusted to 5 MPa or less.
c. The total degree of finish rolling is 99% or less.

  The copper alloy plate manufactured as described above is processed into a copper product having various plate thicknesses, and is used as, for example, an electronic component for heat dissipation in an electric / electronic device such as a smartphone, a tablet PC, and a personal computer. Can do.

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 950 ° C. for 3 hours, and hot rolled at 950 ° C. to form a plate having a thickness of 15 mm. After grinding and removing the oxide scale on the surface of the hot rolled plate with a grinder, annealing and cold rolling were repeated, and the product was finished to a predetermined product thickness by final cold rolling. Finally, strain relief annealing was performed using a continuous annealing furnace.

  Annealing before final cold rolling (final recrystallization annealing) uses a batch furnace, adjusts the furnace temperature in the range of 300 to 700 ° C. with a heating time of 5 hours, and sets the crystal grain size and conductivity after annealing. Changed. In the measurement of the crystal grain size after annealing, a cross section perpendicular to the rolling direction was subjected to chemical corrosion after mirror polishing, and the average crystal grain size was determined by a cutting method (JIS H0501 (1999)).

In the final cold rolling, the total workability and the workability per pass were controlled. Moreover, the 0.2% yield strength of the material after final cold rolling was calculated | required.
In strain relief annealing using a continuous annealing furnace, the furnace temperature was 500 ° C., the heating time was adjusted between 1 second and 15 minutes, and the 0.2% proof stress after annealing was variously changed. In addition, various tensions were added to the material in the furnace. For some materials, strain relief annealing was omitted.
The following measurement was performed on the material in the process of manufacturing and the material after strain relief annealing.

(component)
The alloy element concentration of the material after strain relief annealing was analyzed by ICP-mass spectrometry.

(0.2% yield 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. Tests were performed to determine 0.2% yield strength.

(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.

(Thickness anisotropy)
A JIS No. 13B test piece defined in JIS Z2241 was taken in the rolling parallel, right-angle, 45 ° direction of the test piece. Each test piece was subjected to an elongation strain of 2.5% using a tensile tester, and the thickness anisotropy was calculated.

(MBR / t)
A strip-shaped test piece having a width of 10 mm and a length of 30 mm was prepared and subjected to a W bending test (JIS H3130). The specimen collection direction was a rolling parallel direction (GW) and a rolling perpendicular direction (BW), and evaluation was performed by a ratio MBR / t of a minimum bending radius MBR (Minimum Bend Radius) and a thickness t where no cracks occurred.

  Table 1 shows the evaluation results. In Table 1, the notation of “<10 μm” in the crystal grain size after the final recrystallization annealing means that all of the rolled structure was recrystallized and the average crystal grain size was less than 10 μm, and the rolling It includes both cases where only a part of the structure is recrystallized.

  As shown in Table 1, Invention Examples 1 to 23 all contain 0.01 to 0.5 mass% Fe and 0.01 to 0.3 mass% P. The ratio (% Fe /% P) of the mass% concentration (% Fe) of Fe to the mass% concentration (% P) of the steel is 1.0 to 6.0, and the crystal grain size of the final recrystallization annealing is 50 μm or less. In addition, since the total workability of final rolling is 40 to 99% and the tension in strain relief annealing is 1 to 5 MPa, the 0.2% proof stress after strain relief annealing is 400 MPa or more, and the conductivity is 65. % And a plate thickness anisotropy r of 1.2 or more, a material having good heat dissipation, strength and workability is obtained. Further, except for Invention Examples 13 and 23, the difference between the 0.2% proof stress after final rolling and the 0.2% proof stress after strain relief annealing is 10 to 50 MPa, so that the bending workability is 2. Good at 0 or less.

  On the other hand, in Comparative Examples 1 and 2, strain relief annealing was performed, but the tension exceeded the upper limit of the specified range, the plate thickness anisotropy was less than 1.2, and the drawability was poor. In Comparative Example 3, the amount of decrease in 0.2% yield strength in strain relief annealing is excessive, the yield strength after strain relief annealing is less than 400 MPa, and the strength is insufficient. In Comparative Example 4, since the Fe concentration is too low, the yield strength is less than 400 MPa and the strength is insufficient.

  In Comparative Example 5, the Fe concentration is excessive, the conductivity is less than 65%, and the heat dissipation is poor. In Comparative Examples 6 and 7, since the addition concentration of P with respect to the mass% concentration of Fe is outside the specified range, the conductivity is less than 65% and the heat dissipation is poor. In Comparative Example 8, since the crystal grain size in recrystallization annealing exceeds 50 μm, the strength is insufficient. In Comparative Example 9, the total degree of processing in the final rolling is less than 40%, so that the strength is insufficient.

Claims (6)

The ratio of the mass% concentration (% Fe) of Fe to the mass% concentration (% P) of P containing 0.01 to 0.5% by mass of Fe and further containing P (% Fe /% P) 1.0 to 6.0, the balance is made of copper and its inevitable impurities, has a conductivity of 65% IACS or more, a 0.2% proof stress of 400 MPa or more, and parallel to the rolling direction. (R ₀ + r ₉₀ + 2 × r ₄₅ ) / 4, where the rankford values in the right direction, the right angle direction, and the 45 ° direction are r ₀ , r ₉₀ , and r ₄₅ , respectively. A copper alloy plate having a plate thickness anisotropy r of 1.2 or more.   The ratio of the minimum bending radius (MBR) in the rolling parallel direction (GW direction) and the rolling perpendicular direction (BW direction) in the W bending test to the sheet thickness (t) is given by MBR / t ≦ 2.0. The copper alloy plate described in 1.   The copper alloy plate according to claim 1 or 2, further containing 0.5 mass% or less of Sn.   The copper alloy plate according to any one of claims 1 to 3, further containing 1.0% by mass or less of Zn.   5. The composition according to claim 1, further containing at least 2.0% by mass of one or more elements selected from the group consisting of Ag, Co, Ni, Cr, Mn, Mg, Si and B. Copper alloy plate.   A heat dissipating electronic component comprising the copper alloy plate according to any one of claims 1 to 5.