KR101612186B1 - Cu-co-si-based copper alloy strip and method of manufacturing the same - Google Patents

Abstract

A Cu-Co-Si-based copper alloy tank having excellent workability while maintaining conductivity and strength, and a method of manufacturing the same.
The steel sheet is characterized by containing 0.5 to 3.0% by weight of Co, 0.1 to 1.0% by weight of Si, a mass ratio of Co / Si of 3.0 to 5.0, the balance being copper and inevitable impurities, The r values of 0 degree, 45 degrees, and 90 degrees with respect to the rolling parallel direction are represented by r = (r0 + r90-2 x r45) / 2, where r0, r45 and r90 are absolute values of the anisotropy in plate? Cu-Co-Si-based copper alloy bath.

Description

TECHNICAL FIELD The present invention relates to a Cu-Co-Si-based copper alloy tank and a method of manufacturing the same. BACKGROUND ART [0002]

TECHNICAL FIELD The present invention relates to a Cu-Co-Si type copper alloy tank which can be suitably used for the production of electronic parts such as electronic materials, and electronic parts for exclusive use or heat dissipation. Particularly, Cu-Co-Si type copper alloy tanks used as materials for electronic parts such as connectors, relays, switches, sockets, bus bars, lead frames and heat sinks, and electronic parts using the copper alloy tanks. Among them, Cu-Co-Co-based alloys 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 use as electronic components for heat dissipation such as liquid crystal frames used in smart phones and tablet PCs, Si based copper alloy tanks and copper alloy tanks.

BACKGROUND ART [0002] Copper alloy tanks having excellent strength and electrical conductivity are widely used as materials for electric or heat conduction of electronic devices such as terminals, connectors, switches, sockets, relays, bus bars, lead frames, and heat sinks. Here, the electrical conductivity and the thermal conductivity are in a proportional relationship. However, it has been considered that it is necessary to have an electric conductivity of 55% IACS or more and a proof stress of 550 MPa or more, with good bendability, with the recent trend toward higher currents in connectors of electronic apparatuses. In order to ensure solderability, the connector material is required to have good plating ability and solder wettability.

On the other hand, for example, a heat dissipation component called a liquid crystal frame is used for a liquid crystal of a smartphone or a tablet PC. In such a copper alloy bath for heat radiation, too, the high thermal conductivity is on the increase, and it is considered that it is necessary to have good bendability and high strength. Therefore, it is considered that it is necessary to have a conductivity of 55% IACS or more and a proof stress of 550 MPa or more even in a copper alloy bath for heat radiation.

However, since it is difficult to achieve a conductivity of 60% IACS or more with a Ni-Si-based copper alloy, development of a Co-Si-based copper alloy has been proceeding. Since the Co-Si-containing copper alloy has a small amount of Co ₂ Si, the conductivity can be higher than that of the Ni-Si-based copper alloy.

A copper alloy excellent in plating adhesion is disclosed by reducing coarse precipitates by setting the size of the inclusions to 2 m or less as the Co-Si based copper alloy (Patent Document 1).

Patent Document 1: JP-A-2008-056977

However, the Co-Si-based copper alloy is excellent in conductivity and strength, but is not suitable for processing such as drawing or extrusion, and cracks and shape defects tend to occur at the time of processing. For this reason, when the processing design is difficult or difficult when the Co-Si-based copper alloy is applied to a connector or a heat sink of an electronic device or the like, it is difficult to obtain a necessary function due to the use of another alloy having a low conductivity (thermal conductivity) There was a problem.

That is, the present invention has been made to solve the above problems, and an object of the present invention is to provide a Cu-Co-Si based copper alloy tanks having excellent workability while maintaining electrical conductivity and strength, and a manufacturing method thereof. Further, it is an object of the present invention to provide a method for producing the copper alloy bath, and an electronic component suitable for use in a large current or for heat radiation.

The Cu-Co-Si based copper alloy set of the present invention contains 0.5 to 3.0% by weight of Co, 0.1 to 1.0% by weight of Si, a mass ratio of Co / Si of 3.0 to 5.0 and the balance of copper and inevitable impurities And the absolute value of the anisotropy Δr of the rank pod value r is 0.2 or less (where? R = (r0 + r90-2 x r45) / 2 and the r value of 0 degree, 45 degrees, and 90 degrees with respect to the rolling parallel direction is R0, r45, and r90, respectively).

In the Cu-Co-Si based copper alloy bath of the present invention, the work hardening coefficient (n value) is preferably 0.04 or more.

It is preferable that the crystal grain diameter observed on the rolled surface is 20 mu m or less.

At least one selected from the group consisting of Ni, Cr, Mg, Mn, Ag, P, Sn, Zn, As, Sb, Be, B, Ti, Zr, Al and Fe in a total amount of 0.001 to 2.5 mass% desirable.

The method for producing a Cu-Co-Si-based copper alloy bath of the present invention is a method for producing the Cu-Co-Si-based copper alloy bath by hot rolling, first annealing, , Aging treatment is performed in this order, and the first annealing and the first cold rolling are repeated twice or more, and the first annealing is performed under the condition that tensile strength is reduced by 10 to 40% before and after annealing.

According to still another aspect of the present invention, there is provided an electronic component for a large current using the Cu-Co-Si-based copper alloy bath.

According to another aspect of the present invention, there is provided a heat dissipation electronic component using the Cu-Co-Si based copper alloy bath.

According to the present invention, it is possible to provide a Cu-Co-Si-based copper alloy tank having excellent workability while maintaining conductivity and strength, a method for producing the same, and an electronic part suitable for use in a large current or heat radiation. This copper alloy plate can be preferably used as an electronic component material such as a terminal, a connector, a switch, a socket, a relay, a bus bar and a lead frame. Particularly, . ≪ / RTI >

Hereinafter, a Cu-Co-Si based copper alloy bath according to an embodiment of the present invention will be described. In the present invention, "%" means% by mass unless otherwise specified.

First, the reason for limiting the composition of the copper alloy bath will be described.

≪ Co and Si &

Co and Si are aged to form precipitation particles of an intermetallic compound in which Co and Si are made of fine Co ₂ Si, thereby remarkably increasing the strength of the alloy. Also, the conductivity is improved with the precipitation of Co ₂ Si by the aging treatment. However, when the Co concentration is less than 0.5% or when the Si concentration is less than 0.1 (1/5 of Co%)%, desired strength can not be obtained even if the other components are added. When the Co concentration exceeds 3.0% or when the Si concentration exceeds 1.0 (1/3 of Co%), sufficient strength is obtained, but the conductivity is lowered, and further, the strength is improved. Coarse Co-Si based particles (crystals and precipitates) are generated in the mother phase, resulting in lowering of bending workability, etching property and plating ability. Therefore, the content of Co is set to 0.5 to 3.0 mass%. The content of Co is preferably 1.0 to 2.0% by mass. Similarly, the content of Si is set to 0.1 to 1.0% by mass. Preferably, the content of Si is set to 0.2 to 0.7 mass%.

When the mass ratio of Co / Si is set to 3.0 to 5.0, both strength and conductivity after precipitation hardening can be improved. If the mass ratio of Co / Si is less than 3.0, the concentration of Si not precipitated as Co ₂ Si increases and the conductivity is lowered. If the mass ratio of Co / Si is more than 5, the concentration of Co which is not precipitated as Co ₂ Si increases and the conductivity decreases.

In addition, 0.001 to 2.5 mass% of a total of at least one element selected from the group consisting of Ni, Cr, Mg, Mn, Ag, P, Sn, Zn, As, Sb, Be, B, Ti, Zr, . These elements contribute to the strength increase by strengthening of solid solution or precipitation strengthening. If the total amount of these elements is less than 0.001 mass%, the above effect may not be obtained. When the total amount of these elements exceeds 2.5% by mass, the conductivity may be lowered or cracked in the hot rolling.

The thickness of the Cu-Co-Si-based copper alloy bath of the present invention is not particularly limited, but may be 0.03 to 0.6 mm, for example.

≪ In-plane anisotropy? R of the rank-pod value r>

Next, the specification that characterizes the copper alloy bath will be described. The present inventors have found that an alloy having an in-plane anisotropy? R of a rank-pod value r of 0.2 or less can be obtained by producing a Cu-Co-Si-based copper alloy bath under predetermined conditions. This is considered to be because the annealing and rolling are repeated under the following conditions so that the shape of the crystal grains in the rolling direction and the thickness direction and the introduction method of the distortion become uniform and the decrease in the plate thickness direction at the time of deformation is suppressed.

Here, r represents a plastic deformation value such as which of the plate thickness direction and plate width direction is liable to be deformed, and the degree of deep drawability is excellent when r is high.

Theoretically, r is obtained by the following equation.

r = ln (Wo / W) / ln (to / t)

Here, Wo and W are plate widths before and after deformation, and to and t are plate thicknesses before and after deformation. However, depending on the point at which the test piece is extracted, r may change, and the deep drawability may decrease depending on the sheet surface direction. Therefore, in the present invention, paying attention to the in-plane anisotropy? R of the r value, the smaller the value is, the better the deep drawability in any direction, and the workability is greatly improved. Further, when the ease of shrinkage of the material changes in accordance with the direction during deep drawing forming, the height of the wall (ear) of the flange portion becomes uneven, and as? R is smaller, the height of the ear becomes smaller and workability is improved.

? R = (r0 + r90-2? R45) / 2

Lt; / RTI > Here, r values obtained by tensile test of the specimen in the directions of 0 degree, 45 degrees and 90 degrees with respect to the rolling parallel direction are r0, r45 and r90, respectively, and? R is calculated from these values.

As a condition for producing the Cu-Co-Si-based copper alloy bath, the ingot is subjected to hot rolling, first annealing, first cold rolling of not less than 10%, solution treatment and aging treatment in this order, 1 annealing and the first cold rolling are repeated twice or more, and the first annealing is performed under the condition that the tensile strength is reduced by 10 to 40% before and after the annealing, and an alloy trough of |? R |? 0.2 is obtained.

In addition, final cold rolling may be performed between the solution treatment and the aging treatment.

By performing the first annealing and the first cold rolling under the above conditions, the shape of the crystal grains in the rolling direction, the plate thickness direction and the plate width direction, and the manner of introduction of the distortion become uniform as described above, Is suppressed, it is considered that? R becomes 0.2 or less.

If the number of repetitions of the first annealing and the first cold rolling is less than 2, the above effect can not be obtained and | Δr |> 0.2.

In the first annealing, when the tensile strength is reduced by only less than 10% before and after annealing, the above effect is not obtained and |? R |> 0.2. On the other hand, when the tensile strength is reduced by more than 40% before and after annealing, the crystal grain diameter becomes too large and the surface becomes rough during drawing. The first annealing is preferably performed under the condition that the tensile strength is reduced by 15 to 30% before and after the annealing.

If the processing degree of the first cold rolling is less than 10%, the above effect can not be obtained and | Δr |> 0.2. The upper limit of the degree of processing of the first cold rolling is, for example, 97%. When the degree of processing exceeds 97%, the processing degree of the second cold rolling becomes less than 10%. It is preferable that the processing degree of the first cold rolling is 15 to 50%.

Cold rolling (initial cold rolling) may be performed between the hot rolling and the first annealing, and the working degree may be 0 to 98%.

The other conditions may be the same as the conditions for producing a typical Cu-Co-Si-based copper alloy bath.

When the work hardening coefficient (n value) is 0.04 or more, the absolute value of DELTA r can be reliably made to be 0.2 or less and the workability of the copper alloy tanks is improved.

Here, when the test piece is tensioned in the tensile test and the load is applied, each part of the test piece is uniformly stretched in the plastic deformation range until the maximum load point is reached beyond the elastic limit (uniform stretching). In the plastic deformation region where this uniform elongation occurs, between the true stress σ _t and the true strain ε _t , Equation 1

σ _t = Kε _t ⁿ

And this is called the n-th hardening rule. "N" is used as the work hardening coefficient (Sudohage: Material Testing, Uchida Kakuhosha, (1976), p. 34). n takes a value of 0? n? 1, and the larger the value of n, the greater the degree of work hardening, and when the portion subjected to local deformation is subjected to work hardening, the deformation shifts to other portions. For this reason, a material having a large n value exhibits uniform stretching, which improves workability such as deep drawability and prevents the surface from being roughened after processing.

When the crystal grain diameter observed on the rolled surface is not more than 20 탆, the workability of the copper alloy tanks is improved, and the surface roughness after processing can be suppressed, which is preferable.

Example

The copper alloy having the composition shown in Tables 1 and 2 was melted using electric copper as a raw material and using an atmospheric melting furnace to cast it as an ingot. The ingot was hot-rolled at 850 to 1000 ° C and appropriately subjected to machining or the like to have a thickness of 10 mm. Thereafter, the initial cold rolling was carried out under the conditions shown in Tables 1 and 2 (some samples were not subjected to the initial cold rolling).

Next, the first annealing and the first cold rolling were repeated twice or three times under the conditions shown in Tables 1 and 2, respectively. Further, the solution treatment is carried out at 850 to 1000 ° C. for 5 to 100 seconds, and then the final cold rolling is carried out at 0 to 20% in the degree of processing. Further, aging treatment (at a temperature at which the strength becomes maximum) To prepare a sample having a thickness of 0.2 mm.

The following evaluations were carried out for each sample.

≪ Tensile Strength (TS) >

The tensile strength (TS) in a direction parallel to the rolling direction was measured by a tensile tester in accordance with JIS-Z2241.

<R value>

The sheet width was measured by a tensile tester in accordance with JIS-Z2241 in the directions of 0 degree, 45 degrees and 90 degrees with respect to the rolling parallel direction, and the sheet width at 5% (2.5% when the elongation at break was 5% (Wo / W) / ln (W0 / W) / ln (WL / WoLo), where W0 and W are the widths before and after the tensile test and Lo and L are the lengths before and after the tensile test, respectively. Value. The r values of 0 degree, 45 degree and 90 degree with respect to the rolling parallel direction were r0, r45 and r90, respectively.

<? R value>

? R = (r0 + r90-2 x r45) / 2

<N value>

When the tensile test was conducted by a tensile tester in the direction parallel to the rolling direction according to JIS-Z2241, the true stress? _T and the true strain? _T were determined in the plastic deformation region,

σ _t = Kε _t ⁿ

Respectively.

<Grain diameter observed on the rolling surface (average crystal diameter (GS))>

The average grain diameter of the rolled surface of the obtained sample was measured by the cutting method of JIS H0501.

&Lt; Conductivity (% IACS) &gt;

The conductivity (% IACS) of the obtained sample was measured by the four-terminal method.

<Drawing processability>

A cup was manufactured under the conditions of a blank diameter:? 64 mm, a punch diameter:? 33 mm, a sheet pressure: 3.0 kN, and a lubricant: grease.

This cup was placed on a glass plate with its open end side down and the gap between the ears and the glass plate was measured by a reading microscope to obtain the average value of the gap between the four recesses generated in the cup to obtain the ear height .

In addition, the appearance of the cup was visually observed to determine the surface roughness.

Drawing processability was evaluated based on the following criteria.

○: The surface of the ear is not roughly 0.5 mm or less in height

X: Surface roughness exceeding 0.5 mm in ear height

The obtained results are shown in Table 1. In each of the examples, the TS was 550 MPa or more and the electric conductivity was 55% IACS or more.

As is clear from Tables 1 and 2, the first annealing and the working were also repeated by repeating the first cold rolling more than 10% at least twice, and the first annealing was performed under the condition that the tensile strength was reduced by 10 to 40% In each of the embodiments, |? R |? 0.2, and the drawing processability was improved.

On the other hand, in the case of Comparative Examples 1 to 4 in which the first annealing was reduced to a tensile strength of more than 40% before and after the annealing, | DELTA r | &gt; 0.2, and the drawing processability was inferior.

In the case of Comparative Example 5 in which the first annealing and the first cold rolling were repeated only once, | DELTA r | &gt; 0.2 was obtained and the drawing processability was inferior.

In the case of Comparative Example 6 in which the first annealing and the first cold rolling were not performed, |? R | &gt; 0.2 was obtained and the drawing processability was inferior.

In the case of Comparative Example 7 in which the degree of processing of the first cold rolling was set to less than 10%, |? R |> 0.2 was obtained and the drawing processability was inferior.

Claims (7)

0.5 to 3.0 mass% of Co, 0.1 to 1.0 mass% of Si, a mass ratio of Co / Si of 3.0 to 5.0, the balance being copper and inevitable impurities,
The r value of 0 degree, 45 degree, and 90 degree with respect to the rolling parallel direction is expressed by r0 (r0 + r90-2 x r45) / 2 where r is the absolute value of the anisotropy in plate r of the rank pod value r is 0.2 or less r45, and r90, respectively). The method according to claim 1,
A Cu-Co-Si type copper alloy bath having a work hardening coefficient (n value) of 0.04 or more. The method according to claim 1,
A Cu-Co-Si-based copper alloy bath having a crystal grain diameter of 20 占 퐉 or less as observed on the rolled surface. The method according to claim 1,
Containing 0.001 to 2.5% by mass in total of at least one selected from the group consisting of Ni, Cr, Mg, Mn, Ag, P, Sn, Zn, As, Sb, Be, B, Ti, Zr, -Co-Si type copper alloy tank. A method for producing a Cu-Co-Si-based copper alloy bath according to any one of claims 1 to 4,
Hot rolling, first annealing, first cold rolling of not less than 10%, solution treatment and aging treatment are performed in this order, and the first annealing and the first cold rolling are repeated twice or more,
Wherein the first annealing is performed under the condition that the tensile strength is reduced by 10 to 40% before and after the annealing. An electronic component for a large current using the Cu-Co-Si based copper alloy bath according to any one of claims 1 to 4. A heat-dissipating electronic component using the Cu-Co-Si based copper alloy bath according to any one of claims 1 to 4.