JP2021046590A - Copper alloys, copper products and electronic equipment parts - Google Patents

Abstract

To provide a copper alloy satisfying all of high strength, high conductivity and annealing softening resistance, a drawn copper article and an electronic apparatus component.SOLUTION: A copper alloy has Ni of 1.0-4.0 mass% and Si of 0.2-1.5 mass% with the balance being copper and inevitable impurities, and the copper alloy having second phase particles with a particle size of 1.0 μm or more and less than 5.0 μm of 1000-20000/mm 2.SELECTED DRAWING: None

Description

The present invention provides excellent strength, conductivity, shrinkage and softening characteristics, etc., which are suitable as lead frame materials for conductive spring materials such as connectors, terminals, relays, and switches, and semiconductor devices such as transistors and integrated circuits (ICs). Regarding copper alloys, copper products and electronic device parts provided.

In recent years, the miniaturization of electrical and electronic parts has progressed, and the copper alloys used for these parts are required to have good strength, conductivity, and annealing softening characteristics. In response to this demand, the demand for precipitation-hardened copper alloys such as Corson alloys having high strength and conductivity is increasing in place of the conventional solid-melt reinforced copper alloys such as phosphor bronze and brass. A Cu-Ni-Si alloy, which is one of the Corson alloys, is an alloy in which compound particles of Ni and Si are precipitated in a Cu matrix, and has high strength, high conductivity, and annealing softening properties. .. It is desired to further improve the annealing softening resistance of the Cu—Ni—Si alloy so that the strength before annealing can be maintained by strain removal annealing after pressing.

In recent years, as a technique for improving the annealing softening resistance of Cu—Ni—Si alloys, a measure for adjusting the amount of low temperature annealing hardening has been proposed. For example, in Patent Document 1, ingots are hot-rolled, cold-rolled, solution-treated, aged, low-temperature solution-treated under conditions where the conductivity is 2 to 4% IACS lower, and after aging with a processing rate of 50% or more. By sequentially performing cold rolling and strain relief annealing at 200 to 500 ° C. for 1 to 1000 seconds, the amount of decrease in strength due to atmospheric heating at 500 ° C. for 60 seconds is controlled to 30 to 140 MPa.

JP-A-2017-179512

However, the invention described in Patent Document 1 targets only the annealing softening resistance before press working, and the annealing softening property deteriorates due to the strain generated by the deformation during press working, and the strain after pressing. It may not be able to withstand annealing.

Therefore, it is an object of the present invention to provide a copper alloy, a copper wrought product, and an electronic device component having high strength, high conductivity, and annealing softening resistance.

As a result of diligent studies by the present inventor, in order to obtain a Cu—Ni—Si alloy having high strength and high conductivity, which has annealing softening resistance to the extent that it can withstand strain removal annealing after press working, particles are required. It was found that the improvement can be achieved by controlling the number density of the second phase particles having a diameter of 1.0 μm or more and less than 5.0 μm.

The copper alloy according to the embodiment of the present invention completed based on the above findings contains 1.0 to 4.0% by mass of Ni and 0.2 to 1.5% by mass of Si on one side. The balance is a copper alloy composed of copper and unavoidable impurities, and containing 1000 to 20000 second-phase particles having a particle size of 1.0 μm or more and less than 5.0 μm / mm ^2.

In one embodiment, the copper alloy according to the embodiment of the present invention contains 3000 to 150,000 second-phase particles having a particle size of 0.2 μm or more and less than 1.0 μm / mm ^2.

In another embodiment, the copper alloy according to the embodiment of the present invention contains 0.0 to 0.5% by mass of Co.

In still another embodiment, the copper alloy according to the embodiment of the present invention contains one or more of Sn, Zn, Mg, Fe, Ti, Zr, Al, P, Mn, Cr and Ag in a total amount of 0. Contains 005 to 3.0% by mass.

In still another embodiment, the copper alloy according to the embodiment of the present invention has a tensile strength of 700 MPa or more, a conductivity of 40% IACS or more, and is annealed at a temperature of 500 ° C. for 1 minute. In addition, the tensile strength after the annealing treatment is 85% or more of the tensile strength before the annealing treatment.

In another aspect, the present invention is a copper product provided with the above-mentioned copper alloy.

In yet another aspect, the present invention is an electronic device component comprising the copper alloy.

According to the present invention, it is possible to provide a copper alloy, a copper wrought product, and an electronic device component having high strength, high conductivity, and annealing softening resistance.

(Amount of Ni and Si added)
Ni and Si are precipitated as fine intermetallic compounds of 50 nm or less, such as _{Ni 2} Si, by performing an appropriate aging treatment. The strength is improved by the action of this precipitate, and Ni and Si dissolved in the Cu matrix are reduced by the precipitation, so that the conductivity is improved. However, if Ni is less than 1.0% by mass or Si is less than 0.2% by mass, the desired strength cannot be obtained, and conversely, if Ni exceeds 4.0% by mass or Si is 1.5% by mass. If it exceeds, processing becomes difficult. Therefore, in the Cu—Ni—Si alloy according to the present invention, the amount of Ni added is 1.0 to 4.0% by mass, and the amount of Si added is 0.2 to 1.5% by mass. Further, the addition amount of Ni is preferably 1.5 to 3.0% by mass, and the addition amount of Si is preferably 0.3 to 0.80% by mass.

(Other additive elements)
Co contributes to an increase in conductivity. When Co exceeds 0.5% by mass, the strength decreases. Therefore, the Cu—Ni—Si based alloy according to the present embodiment preferably contains 0.0 to 0.5% by mass, preferably 0.005 to 0.5% by mass of Co.

Sn, Zn, Mg, Fe, Ti, Zr, Al, P, Mn, Cr and Ag contribute to the increase in strength. Further, Zn is effective in improving the heat-resistant peeling property of Sn plating, Mg is effective in improving stress relaxation characteristics, and Zr, Cr, and Mn are effective in improving hot workability. When the total amount of Sn, Zn, Mg, Fe, Ti, Zr, Al, P, Mn, Cr and Ag exceeds 3.0% by mass, the conductivity is significantly lowered. Therefore, the Cu—Ni—Si alloy according to the present invention preferably contains one or more of these elements in a total amount of 0.005 to 3.0% by mass, preferably 0.01 to 2.0% by mass. % Is more preferable.

(Second phase particles)
The second phase particles in the present embodiment refer to particles that are formed when copper contains other elements and form a phase different from that of the copper matrix. The number density of the second phase particles is the cross section perpendicular to the processing direction of the copper alloy after mirror finishing by mechanical polishing and then electrolytic polishing and / or pickling etching, that is, for the rolled copper alloy. The number of particles in the corresponding particle size range from the one-field scanning electron micrograph obtained by arbitrarily selecting five cross sections perpendicular to the rolling direction and the wire drawing direction of the drawn copper alloy. Is measured and divided by the evaluation area. Here, the particle size means the average value of the minor axis and the major axis of each particle. Most of the second phase particles of the copper alloy according to this embodiment are Ni ₂ Si, but other intermetallic compounds are also included in the measurement of the number density if the particle size is within the range. The elements constituting the second phase particles can be confirmed by using, for example, EDX attached to FE-SEM (Japan FEI Co., Ltd. model XL30SFEG).

The copper alloy according to the present embodiment contains 1000 second-phase particles having a particle size of 1.0 μm or more and less than 5.0 μm in the microstructure observation using an electron microscope having a cross section perpendicular to the processing direction of the copper alloy. ^It contains 2 or more, preferably 2000 pieces / mm ² or more, and more preferably 3000 pieces / mm ² or more. The number density of the second phase particles having a particle size of 1.0 μm or more and less than 5.0 μm can be adjusted by slowing the cooling rate after hot working to precipitate the particles, and if necessary, heat-treating after hot working. When the number of second-phase particles having a particle size of 1.0 μm or more and less than 5.0 μm is 1000 particles / mm ² or more, the annealing softening resistance is improved. On the other hand, if the number of second-phase particles having a particle size of 1.0 μm or more and less than 5.0 μm exceeds 20,000, fine precipitates having a particle size of 50 nm or less, which are necessary for strengthening precipitation, are insufficient, resulting in insufficient strength.

The copper alloy according to the present embodiment preferably has 3000 second-phase particles having a particle size of 0.2 μm or more and less than 1.0 μm in the microstructure observation using an electron microscope having a cross section perpendicular to the processing direction of the copper alloy. / mm ² or more, more preferably 5000 / mm ² or more, even more preferably contained 10000 / mm ² or more. The second-phase particles having a particle size of 0.2 μm or more and less than 1.0 μm can be adjusted by slowing the cooling rate after hot working and precipitating them, and if necessary, heat-treating after hot working. When the number of second-phase particles having a particle size of 0.2 μm or more and less than 1.0 μm is 3000 particles / mm ² or more, the effect is less than that of the second-phase particles having a particle size of 1.0 μm or more and less than 5.0 μm, but annealing resistance It has the effect of improving the softening characteristics. On the other hand, if the number of second-phase particles having a particle size of 0.2 μm or more and less than 1.0 μm ^{exceeds 150,000 particles / mm 2} , the fine precipitates of 50 nm or less required for precipitation strengthening are insufficient, so that the strength is insufficient.

(Tensile strength)
The copper alloy according to this embodiment has a tensile strength (TS) of 700 MPa or more, more preferably 750 MPa or more, and even more preferably 800 MPa or more. The tensile strength of the copper alloy conforms to JIS Z 2241, and the result of measuring the tensile strength in the direction parallel to the rolling direction using a tensile tester is shown. In the present embodiment, the upper limit of the tensile strength is not limited to the following, but can be typically 1600 MPa or less.

(conductivity)
The copper alloy according to this embodiment has a conductivity (EC) of 40% IACS or more, more preferably 45% IACS or more, and even more preferably 48% IACS or more. The conductivity of the copper alloy conforms to JIS H 0505, and shows the result of measuring the conductivity in the direction parallel to the rolling direction. In the present embodiment, the upper limit of conductivity is not limited to the following, but can typically be 70% IACS or less.

(Softening characteristics)
When the copper alloy according to the present embodiment is annealed at a temperature of 500 ° C. for 1 minute, the tensile strength after the annealing treatment is 85% or more of the tensile strength before the annealing treatment. Excellent softening characteristics can be obtained. More typically, the softening properties of the copper alloy according to this embodiment are more typically 88% or more, and even more typically 90% or more.

(Use)
The Cu-Ni-Si alloy can be processed into various copper products such as plates, strips, rods, wires and foils, and the Cu-Ni—Si alloy of the present invention can be used for lead frames, connectors, and so on. It can be used for electronic device parts such as pins, terminals, relays, switches, wire rods, stranded wires, and foil materials for secondary batteries.

(Production method)
An example of a method for producing a copper alloy according to an embodiment of the present invention will be described below. In a general manufacturing process for Cu—Ni—Si alloys, raw materials such as electrolytic copper, Ni, and Si are first melted in a melting furnace to obtain a molten metal having a desired composition. Then, this molten metal is cast into an ingot. After that, hot working, cold working, solution treatment, aging treatment, and cold working are performed in this order to finish a plate, strip, rod, wire, foil, or the like having a desired thickness, diameter, and characteristics. After the heat treatment, the surface may be pickled, polished, or the like in order to remove the surface oxide film formed by the heat treatment. Further, in order to increase the strength, cold working may be performed between the solution treatment and the aging or after the aging.

In the present embodiment, the cooling rate after hot working is adjusted in order to obtain a copper alloy having ^{a number density of 1000 to 20000 particles / mm 2} of the second phase particles having a particle size of 1.0 μm or more and less than 5.0 μm. If necessary, heat treatment is performed after hot working.

The hot working is a method of processing a heated ingot by rolling or extrusion, and preferably includes heating to a material temperature of 900 to 1000 ° C. and ending the hot working at 700 ° C. or higher. By adjusting the cooling rate from 700 ° C. to 500 ° C. after the completion of hot working to an average of 0.01 to 0.1 ° C./s, Ni ₂ Si and the like are precipitated during cooling, and the desired second phase particles are formed. It becomes the number density of. After hot working, heat treatment is performed at 500 to 700 ° C. for 1 to 60 minutes _{to coarsen the precipitates such as Ni 2} Si, and the particle size is 1.0 μm or more and less than 5.0 μm. The number density of the second phase particles of 0.2 μm or more and less than 1.0 μm can be further increased. When the cooling rate from 700 ° C. to 500 ° C. is lower than 0.01 ° C./s, the amount of precipitation during cooling becomes too large, and the number density of the second phase particles having a particle size of 1.0 μm or more and less than 5.0 μm becomes 20000. exceed pieces / mm ^2, the tensile strength is insufficient, the second-phase particles size of less than 0.2μm or 1.0μm exceeds 150,000 / mm ^2, the strength becomes insufficient.

The manufacturing methods in the case of the copper alloy plate material according to the present embodiment are listed in the order of processes as follows.
(1) Casting of ingot (2) Hot rolling (heating temperature 900 to 1000 ° C, thickness to about 5 to 20 mm, cooling rate of 700 ° C to 500 ° C after rolling 0.01 to 0.1 ° C / s)
(3) Heat treatment (1 to 60 minutes at 500 to 700 ° C)
(4) Cold rolling (working degree 1-99%)
(5) Solution treatment (500 to 1050 ° C. for 5 to 300 seconds)
(6) Cold rolling (working degree 1-60%)
(7) Aging treatment (2 to 20 hours at 400 to 600 ° C)
(8) Cold rolling (working degree 1-99.9%)
(9) Strain removal annealing (5 seconds to 10 hours at 300 to 700 ° C)

Here, in the hot rolling (2), it is preferable to heat to 900 to 1000 ° C. and finish the rolling at 700 ° C. or higher, and the cooling rate from 700 ° C. to 500 ° C. after the processing is finished is 0.01 to 0 on average. It is preferably adjusted to 1 ° C./s, and more preferably 0.01 to 0.08 ° C./s.

The heat treatment (3) can further increase the number density of the second phase particles, but it does not have to be performed. The workability of cold rolling (4) is preferably 1 to 99%, but it is not necessary. Cold rolling (6) and (8) are arbitrarily performed for high strength, and while the strength increases as the rolling degree increases, the conductivity decreases. The effect of the present embodiment that the annealing softening resistance is improved can be obtained regardless of the presence or absence of cold rolling (6) and (8) and the degree of processing of each. Cold rolling (6) and (8) may or may not be performed.

The strain removing annealing (9) is arbitrarily performed in order to improve the annealing softening resistance. While the annealing softening resistance is improved, the strength is lowered, so this is carried out as necessary. If the number density of the second phase particles is controlled, the desired annealing softening resistance can be obtained without performing strain relief annealing (9).

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

(Manufacturing of copper alloy 1)
The amount and type of added elements were changed and added to the molten metal made of electrolytic copper, Ni, and Si, and an ingot having a thickness of 30 mm was cast. This ingot was heated at 1000 ° C. for 3 hours and hot-rolled to a plate having a thickness of 10 mm so that the end temperature was 700 ° C. or higher. The cooling rate of 700 ° C. to 500 ° C. after hot rolling was carried out under the conditions shown in Table 1. Next, the oxide scale on the surface was ground and removed, and then cold rolling, solution treatment, aging, and cold rolling were performed in this order to finish a final product having a final thickness of 0.1 mm.

The following evaluations were performed on the product samples.
(Measurement of strength (tensile strength) and evaluation of annealing softening characteristics)
The tensile strength was measured in parallel with the rolling direction according to JIS Z 2241 using a tensile tester. In addition, a sample was annealed at 500 ° C. for 1 minute in this final product, and the tensile strength was measured in the same manner in parallel with the rolling direction. The annealing softening characteristics (TS after annealing / TS before annealing) were determined from the TS before annealing and the TS after annealing.

(Conductivity (EC) measurement)
The conductivity was measured according to JIS H 0505. The energization in the measurement was performed parallel to the rolling direction.

(Measurement of second phase particle density)
The particle size and density of the second phase particles are determined by mechanically polishing the rolled rectangular cross section of the final product to give a mirror surface, and then performing electrolytic polishing and / or pickling etching to reveal the rolled rectangular cross section, and scanning electron microscope. Was measured using. For second-phase particles with a particle size of 1.0 μm or more and less than 5.0 μm, five 1000-fold micrographs, and for second-phase particles with a particle size of 0.2 to 1.0 μm, five 5000-fold micrographs. And used as the average value. Table 1 shows the evaluation results.

In Examples 1 to 11, the cooling rate after hot rolling was controlled under the conditions specified in the present embodiment, and the tensile strength was 700 MPa or more and the conductivity was 40% IACS or more. The number density of the second phase particles having high strength and high conductivity and a particle size of 1.0 μm or more and less than 5.0 μm was within the range of the present embodiment, and a softening property of 85% or more was obtained.

In Comparative Example 1, the Ni concentration was high, cracks occurred during hot rolling, and subsequent processing became difficult. In Comparative Examples 2, 4 and 5, the cooling rate after hot rolling is high, the number density of the second phase particles having a particle size of 1.0 μm or more and less than 5.0 μm is less than 1000 particles / mm ² , and the softening characteristics are low. became. In Comparative Example 3, the Ni concentration was low and the strength was low. In Comparative Example 6, since the cooling rate after hot rolling was too slow, the number density of the second phase particles having a particle size of 1.0 μm or more and less than 5.0 μm ^{exceeded 20000 particles / mm 2} and the strength decreased. In Comparative Example 7, the concentration of other added elements exceeded 3%, and the conductivity was low.

(Manufacturing of copper alloy 2)
Billets were cast by adding different amounts and types of added elements to molten metal made from electrolytic copper, Ni, and Si. This billet was heated at 1000 ° C. for 3 hours and hot-extruded to a rod having a diameter of 10 mm so that the end temperature was 700 ° C. or higher. The cooling rate of 700 ° C. to 500 ° C. after hot extrusion was carried out under the conditions shown in the table. Next, the oxide scale on the surface was ground and removed, and then cold wire drawing, solution treatment, aging treatment, and cold wire drawing were performed in this order to finish a final product having a final diameter of 0.1 mm.

The following evaluations were performed on the product samples.
(Strength (TS) measurement and evaluation of annealing softening characteristics)
Tensile strength was measured using a tensile tester in accordance with JIS Z 2241. In addition, a sample was annealed at 500 ° C. for 1 minute in this final product, and the tensile strength was measured in the same manner. The annealing softening characteristics (TS after annealing / TS before annealing) were determined from the TS before annealing and the TS after annealing.

(Conductivity (EC) measurement)
The conductivity was measured according to JIS H 0505. The energization in the measurement was performed parallel to the wire drawing direction.

(Measurement of second phase particle density)
The particle size and density of the second phase particles are determined by mechanically polishing the right-angled cross section of the final product to make it mirror-finished, and then performing electrolytic polishing and / or pickling etching to reveal the right-angled cross section of the final product. It was measured using an electron microscope. For second-phase particles with a particle size of 1.0 μm or more and less than 5.0 μm, five 1000-fold micrographs, and for second-phase particles with a particle size of 0.2 to 1.0 μm, five 5000-fold micrographs. And used as the average value. Table 2 shows the evaluation results.

In Examples 1 to 11, the cooling rate after hot extrusion was controlled under the conditions specified in the present embodiment, and the tensile strength was 700 MPa or more and the conductivity was 40% IACS or more. The number density of the second phase particles having high strength and high conductivity and a particle size of 1.0 μm or more and less than 5.0 μm was within the range of this embodiment, and a softening property of 85% or more was obtained.

In Comparative Example 1, the Ni concentration was high, cracks were generated during hot extrusion, and subsequent processing became difficult. In Comparative Examples 2, 4 and 5, the cooling rate after hot extrusion is high, the number density of the second phase particles having a particle size of 1.0 μm or more and less than 5.0 μm is less than 1000 particles / mm ² , and the softening characteristics are low. became. In Comparative Example 3, the Ni concentration was low and the strength was insufficient. In Comparative Example 6, since the cooling rate after hot extrusion was too slow, the number density of the second phase particles having a particle size of 1.0 μm or more and less than 5.0 μm ^{exceeded 20000 particles / mm 2} and the strength was insufficient. In Comparative Example 7, the concentration of the added element exceeded 3%, and the conductivity was low.

Claims (7)

The second phase contains 1.0 to 4.0% by mass of Ni and 0.2 to 1.5% by mass of Si, and the balance is composed of copper and unavoidable impurities, and the particle size is 1.0 μm or more and less than 5.0 μm. A copper alloy containing 1000 to 20000 particles / mm ^2. The copper alloy according to claim 1, which contains ^{3000 to 150,000 particles / mm 2 of} second-phase particles having a particle size of 0.2 μm or more and less than 1.0 μm. The copper alloy according to claim 1 or 2, which contains 0.0 to 0.5% by mass of Co. Any one of claims 1 to 3 containing one or more of Sn, Zn, Mg, Fe, Ti, Zr, Al, P, Mn, Cr and Ag in a total amount of 0.005 to 3.0% by mass. The copper alloy described in. When the tensile strength is 700 MPa or more, the conductivity is 40% IACS or more, and the annealing treatment is performed at a temperature of 500 ° C. for 1 minute, the tensile strength after the annealing treatment is the tensile strength before the annealing treatment. The copper alloy according to any one of claims 1 to 4, which has a temperature of 85% or more. A copper product comprising the copper alloy according to any one of claims 1 to 5. An electronic device component comprising the copper alloy according to any one of claims 1 to 5.