WO2016047175A1

WO2016047175A1 - Copper alloy sheet and process for producing copper alloy sheet

Info

Publication number: WO2016047175A1
Application number: PCT/JP2015/059359
Authority: WO
Inventors: 恵一郎大石; 孝一須崎; 教男高崎; 孝外薗
Original assignee: 三菱伸銅株式会社
Priority date: 2014-09-26
Filing date: 2015-03-26
Publication date: 2016-03-31
Also published as: TW201612326A; CN106460097B; KR20160146943A; CN106460097A; KR101777987B1; TWI540213B

Abstract

Provided is a copper alloy sheet which is excellent in terms of resistance to stress corrosion cracking, stress relaxation property, tensile strength, proof stress, electrical conductivity, bendability, and solder wettability. The copper alloy sheet contains 4-14 mass% Zn, 0.1-1 mass% Sn, 0.005-0.08 mass% P, and 1.0-2.4 mass% Ni, with the remainder comprising Cu and unavoidable impurities, and satisfies the relational expressions 7≤[Zn]+3×[Sn]+2×[Ni]≤18, 0≤[Zn]-0.3×[Sn]-1.8×[Ni]≤11, 0.3≤(3×[Ni]+0.5×[Sn])/[Zn]≤1.6, 1.8≤[Ni]/[Sn]≤10, and 16≤[Ni]/[P]≤250. The copper alloy sheet has an average crystal grain diameter of 2-9 μm and contains circular or elliptic precipitates which have an average grain diameter of 3-75 nm or in which precipitate grains each having a grain diameter of 3-75 nm account for 70% by number or more of all the circular or elliptic precipitates. The copper alloy sheet has an electrical conductivity of 24% IACS or greater and a degree of stress relaxation, measured at 150°C for 1,000 hours as an index to resistance to stress relaxation, of 25% or less.

Description

Copper alloy plate and method for producing copper alloy plate

The present invention is a copper alloy plate excellent in stress corrosion cracking resistance, stress relaxation characteristics, tensile strength, proof stress, electrical conductivity, bending workability, and solder wettability, particularly for terminals / connectors and electrical / electronic components. It is related with the copper alloy plate used for a use, and the manufacturing method of this copper alloy plate.
This application claims priority based on Japanese Patent Application No. 2014-196430 filed in Japan on September 26, 2014, the contents of which are incorporated herein by reference.

Conventionally, it has high conductivity and high strength as a component of connectors, terminals, relays, springs, switches, semiconductors, lead frames, etc. used in automobile parts, electrical parts, electronic parts, communication equipment, electronic / electrical equipment, etc. A copper alloy plate is used. However, with recent downsizing, weight reduction, and high performance of such devices, extremely strict characteristic improvements are required for the constituent materials used for them. For example, an ultra-thin plate is used for the spring contact portion of the connector, but the high-strength copper alloy that constitutes such an ultra-thin plate has a high strength and a high balance between elongation and strength in order to reduce the thickness. It is required to have. Furthermore, there are problems in terms of productivity, economic efficiency, conductivity, corrosion resistance (stress corrosion cracking resistance, dezincification corrosion resistance, migration resistance), stress relaxation characteristics, solder wettability, etc. that suppress deterioration of the material during use. It is required that there is no.

However, strength and electrical conductivity are contradictory properties, and as the strength increases, the electrical conductivity generally decreases. For example, in places where the operating environment temperature is high, such as near the engine room of an automobile, there are parts that may rise to, for example, 100 ° C. to 150 ° C., and are required to have further excellent stress relaxation characteristics and heat resistance. Furthermore, in recent years, with the evolution of automobile engine electronic control technology, the number of parts used at high temperatures has increased, and a copper alloy material that can ensure high reliability in high temperature environments is required. Of course, automobile parts and electrical / electronic equipment parts are exposed to severe competition, and low-cost copper alloy materials are required. From the viewpoint of global procurement, a copper alloy material that is easy to manufacture is desired.

Here, as the high-conductivity high-strength copper alloy, beryllium copper, phosphor bronze, white, brass, or brass added with Sn is generally known.
Further, as an alloy for satisfying the demand for high conductivity and high strength, for example, a Cu—Zn—Sn alloy as disclosed in Patent Document 1 is known.

JP 2007-056365 A

However, general high-strength copper alloys such as the above-mentioned beryllium copper, phosphor bronze, white and brass have the following problems, and have not been able to meet the above requirements.
Beryllium copper has the highest strength among copper alloys, but beryllium is very harmful to the human body (particularly in the molten state, even a very small amount of beryllium vapor is very dangerous). For this reason, it is difficult to dispose (especially incineration) a beryllium copper member or a product including the member, and the initial cost required for the melting equipment used for manufacturing becomes extremely high. Accordingly, there is a problem in economic efficiency including manufacturing cost, in combination with the necessity of solution treatment at the final stage of manufacturing in order to obtain predetermined characteristics.

Phosphor bronze and western white are generally manufactured by horizontal continuous casting because they have poor hot workability and are difficult to manufacture by hot rolling. Therefore, productivity is poor, energy costs are high, and yield is poor.
Moreover, since the phosphor bronze for springs and the white for springs, which are representative varieties of high-strength copper alloys, contain a large amount of expensive Sn and Ni, they are poor in conductivity and have a problem in economical efficiency.

Zn, which is the main element of brass, is cheaper than Cu, and by adding Zn to Cu, the density decreases, and the strength, that is, tensile strength, yield strength or yield stress, spring limit value, and fatigue strength are high. Become. However, in brass, as the Zn content increases, the stress corrosion cracking sensitivity becomes very high, and the reliability as a material is impaired. On the other hand, brass has poor stress relaxation characteristics as is well known, and cannot be used for parts that reach high temperatures such as around the engine room. Further, as the Zn content increases, the strength improves, but the ductility and bending workability deteriorate, and the balance between strength and ductility deteriorates.
As described above, brass and brass with simple addition of Sn are inexpensive, but are not satisfactory in strength, have poor stress relaxation characteristics, poor conductivity, and have problems with corrosion resistance (stress corrosion and dezincification corrosion) Therefore, it is unsuitable as a product component for achieving the above-mentioned miniaturization and high performance.

Therefore, such a general high-conductivity and high-strength copper alloy is not completely satisfactory as a component material for various devices that tend to be reduced in size, weight, and performance as described above. There is a strong demand for the development of conductive and high-strength copper alloys.
In addition, the Cu—Zn—Sn alloy described in Patent Document 1 does not have sufficient properties including conductivity and strength.

The present invention has been made to solve the above-mentioned problems of the prior art, and is excellent in stress corrosion cracking resistance, stress relaxation characteristics, tensile strength, proof stress, conductivity, bending workability, and solder wettability. It is an object of the present invention to provide an alloy plate, in particular, a highly reliable terminal / connector that can withstand harsh use environments, a copper alloy plate suitable for electric / electronic components, and a method of manufacturing the copper alloy plate.

In order to solve the above problems, the present inventor has repeatedly studied from various angles and conducted various studies and experiments. As a result, first, Ni and Sn were added to a Cu—Zn alloy containing 4 to 14 mass% of Zn. In order to optimize the interaction between Ni and Sn at the same time, the total content of Ni and Sn and the ratio of the content are within the proper range, and further, the interaction between Zn, Ni and Sn In view of the above, three compositional relational expressions, f1 = [Zn] + 3 × [Sn] + 2 × [Ni], f2 = [Zn] −0.3 × [Sn] −1.8 × [Ni], and f3 = Adjust Zn, Ni, and Sn so that (3 × [Ni] + 0.5 × [Sn]) / [Zn] is set to appropriate values at the same time, and set the appropriate amounts of Ni and Sn, and P and Ni. To adjust the content ratio within the appropriate range and appropriately adjust the size of the precipitates formed and the crystal grain size. We found a copper alloy that has excellent cost performance, low density, high strength, elongation / bending workability and electrical conductivity, excellent stress corrosion cracking resistance, and stress relaxation characteristics, and can be used in various usage environments. The present invention has been accomplished.

Specifically, high strength is obtained without impairing ductility and bending workability by dissolving appropriate amounts of Zn, Ni, and Sn in a matrix and containing P. Further, Sn having a valence (or the number of valence electrons, the same shall apply hereinafter) of Sn (divalent valence number of 4), divalent Zn, Ni and pentavalent P can be added, thereby causing stress corrosion cracking resistance, Improves stress relaxation characteristics, simultaneously lowers stacking fault energy, and makes crystal grains finer during recrystallization. Further, by forming a fine compound mainly composed of Ni and P, crystal grain growth is suppressed and fine crystal grains are maintained.

Further, by refining crystal grains (recrystallized grains), the strength mainly including tensile strength and proof stress can be remarkably improved. That is, the strength increases as the average crystal grain size decreases. Specifically, the addition of Zn, Sn, and Ni to Cu has an effect of increasing the nucleation sites of recrystallization nuclei. Addition of P and Ni to the Cu—Zn—Sn—Ni alloy has an effect of suppressing grain growth. Therefore, by using these effects, it is possible to obtain a Cu—Zn—Sn—Ni—P-based alloy having fine crystal grains. The increase in the nucleation sites of recrystallized nuclei is thought to be one of the main reasons that the stacking fault energy is lowered by adding Zn, Ni, and Sn, each having a valence of 2, 2, or 4. It is done. Suppression of crystal grain growth that maintains the fine recrystallized grains thus produced is considered to be caused by the production of fine precipitates by the addition of P and Ni. However, the balance of strength, elongation, and bending workability cannot be achieved simply by aiming at ultrafine recrystallized grains. In order to maintain the balance, it has been found that a crystal grain refinement region having a certain range of sizes is good by providing a margin for refinement of recrystallized grains. Regarding the refinement or ultrafine refinement of crystal grains, the minimum crystal grain size in the standard photograph described in JIS H 0501 is 0.010 mm. From this, it can be said that those having an average crystal grain of less than 0.010 mm may be referred to as crystal grains being refined.

In order to improve the strength and improve the stress relaxation characteristics and stress corrosion cracking resistance without impairing the ductility and bending workability by dissolving each element of Zn, Ni, and Sn in Cu, It is necessary to consider the interaction between elements from various viewpoints including the properties of each element of Ni and Sn. In other words, simply defining the content of each element of Zn, Ni, and Sn improves stress relaxation characteristics and stress corrosion cracking resistance, and does not necessarily reduce high ductility and bending workability. I can't get it.
Therefore, the composition relational expression f1 = [Zn] + 3 × [Sn] + 2 × [Ni], the composition relational expression f2 = [Zn] −0.3 × [Sn] −1.8 × [Ni], and f3 = The three compositional relational expressions of (3 × [Ni] + 0.5 × [Sn]) / [Zn] need to be within a predetermined range.

The lower limit values of the compositional relational expressions f1 and f2 are the minimum necessary values for obtaining high strength even when the interaction of each element of Zn, Ni, and Sn is taken into consideration. When f1 and f2 exceed the upper limit value or lower than the lower limit value of the compositional relational expression f3, although the strength is increased, the stress relaxation property or the stress corrosion cracking resistance is impaired.
The upper limit value of the compositional relational expression f1 = [Zn] + 3 × [Sn] + 2 × [Ni] is a value indicating whether the conductivity of the alloy of the present invention exceeds 24% IACS.
The upper limit value of the compositional relational expression f2 = [Zn] −0.3 × [Sn] −1.8 × [Ni] is excellent stress relaxation characteristics, stress corrosion cracking resistance, good ductility, bending workability It is also a boundary value for obtaining solder wettability. As described above, the critical drawbacks of Cu—Zn alloys are high sensitivity to stress corrosion cracking and poor stress relaxation characteristics.
The lower limit value of the compositional relational expression f3 = (3 × [Ni] + 0.5 × [Sn]) / [Zn] is a boundary value for obtaining good stress relaxation properties. As described above, the Cu—Zn alloy is an alloy having excellent cost performance. However, the stress relaxation property is poor, and even if it has a high strength, the high strength cannot be utilized. In general, brass alloys have poor stress relaxation properties, but by optimizing the balance of (3 × [Ni] + 0.5 × [Sn]) and [Zn], that is, the compounding ratio, higher stress Relaxation characteristics can be realized. The upper limit value increases the amount of Ni and Sn, increases the cost, or deteriorates the electrical conductivity, and saturates the stress relaxation characteristics.

Further, in the present application, it is important to set the Ni content and the Sn content, and the P content and the Ni content to an appropriate content ratio, so that excellent stress relaxation characteristics, strength, and bending workability can be realized. In particular, in order to improve the stress relaxation of the Cu—Zn alloy, the first condition is to co-add 1 to 2.4% by mass of Ni and 0.1 to 1% by mass of Sn. The content ratio of Ni and Sn is important, and the compositional relational expression f4 = [Ni] / [Sn] needs to be within a predetermined range. Although details will be described later, at least 3.5 Ni atoms are required for one Sn atom. For Ni and P, which are important for stress relaxation characteristics, crystal grain size, strength, and bending workability, the compositional relational expression f5 is obtained from the relationship between Ni and P that are dissolved and the compound of Ni and P that is precipitated. = [Ni] / [P] must be within a predetermined range.

Moreover, in the above-mentioned copper alloy sheet, it is desirable to carry out a recovery heat treatment step and a heat treatment according thereto after the finish cold rolling step. In this case, since the recovery heat treatment is performed, the stress relaxation rate, Young's modulus, spring limit value, and elongation are improved.

As a method of manufacturing the above-described copper alloy sheet, an ingot manufacturing process and a hot rolling process blended with predetermined components, a continuous casting process in which a hot rolling process is omitted in some cases, a cold rolling process, A crystallization heat treatment step and a finish cold rolling step. The hot rolling start temperature of the hot rolling step is 800 to 950 ° C., the final rolling is finished at 750 ° C. to 500 ° C., and then air cooling Or it cools to normal temperature by the forced cooling by water cooling. As the recrystallization heat treatment step, there are a batch method in which heating is performed for a long time and a continuous heat treatment method in which short-time heating is continuously performed at high temperature. After final finish rolling, a tension leveler may be used to improve the distortion of the material. In addition, recovery heat treatment may be performed by a continuous heat treatment method, or when used in terminals / connectors, electrical / electronic parts, molten Sn plating, reflow Sn plating, regardless of the presence or absence of the recovery heat treatment step. In some cases, a plating process such as
Depending on the thickness of the copper alloy plate, the cold rolling step and the annealing step that are paired between the hot rolling step and the cold rolling step may be performed once or a plurality of times.

And especially the manufacturing method of the copper alloy plate used for a terminal, a connector material, etc., Preferably, the cold work rate in the said cold rolling process is 55% or more, The said recrystallization heat treatment process is a continuous heat treatment furnace. A heating step for heating the copper alloy material to a predetermined temperature, a holding step for holding the copper alloy material at a predetermined temperature for a predetermined time after the heating step, and a predetermined step for holding the copper alloy material after the holding step. A cooling step for cooling to a temperature of 5 ° C., and in the recrystallization heat treatment step, the maximum reached temperature of the copper alloy material is Tmax (° C.), and the maximum reached temperature is 50 ° C. lower than the maximum reached temperature of the copper alloy material. in a temperature range up to the time to be heated maintained when the tm (min), 560 ≦ Tmax ≦ 790,0.04 ≦ tm ≦ 1.0,520 ≦ It1 = (Tmax-30 × tm ^1/2) is ≦ 690, and further, after the finish cold rolling step, a heating step of heating the copper alloy material to a predetermined temperature for a predetermined time the copper alloy material to a predetermined temperature after the heating step is kept And a cooling step for cooling the copper alloy material to a predetermined temperature after the holding step, wherein the maximum reached temperature of the copper alloy material is Tmax2 (° C.), and from the maximum reached temperature of the copper alloy material In the temperature range from the temperature lower by 50 ° C. to the highest temperature, the time for heating and holding is tm2 (min), 150 ≦ Tmax2 ≦ 580, 0.02 ≦ tm2 ≦ 100, 120 ≦ It2 = (Tmax2-25 × tm2 ^−1/2 ) ≦ 390, a recovery heat treatment step, or a method including Sn plating. By carrying out a high-temperature short-time recrystallization heat treatment and a recovery heat treatment step, the stress relaxation rate, Young's modulus, spring limit value, bending workability and elongation can be improved.

The present invention has been made on the basis of the above-mentioned knowledge, and the copper alloy plate according to the first aspect of the present invention is composed of 4 to 14% by mass of Zn, 0.1 to 1% by mass of Sn. 0.005 to 0.08 mass% P and 1.0 to 2.4 mass% Ni, the balance being made of Cu and inevitable impurities, Zn content [Zn] mass%, Between the Sn content [Sn] mass%, the P content [P] mass%, and the Ni content [Ni] mass%,
7 ≦ [Zn] + 3 × [Sn] + 2 × [Ni] ≦ 18,
0 ≦ [Zn] −0.3 × [Sn] −1.8 × [Ni] ≦ 11,
0.3 ≦ (3 × [Ni] + 0.5 × [Sn]) / [Zn] ≦ 1.6,
1.8 ≦ [Ni] / [Sn] ≦ 10,
16 ≦ [Ni] / [P] ≦ 250,
And the average crystal grain size is 2 to 9 μm, the average particle size of the circular or elliptical precipitate is 3 to 75 nm, or the particle size is 3 to The ratio of the number of precipitates of 75 nm is 70% or more, the conductivity is 24% IACS or more, and the stress relaxation rate is 150% at 1000 ° C. and the stress relaxation rate is 25% or less at 1000 hours. To do.

The copper alloy sheet according to the second aspect of the present invention comprises 4 to 12% by mass of Zn, 0.1 to 0.9% by mass of Sn, 0.008 to 0.07% by mass of P, 1 0.05 to 2.2% by mass of Ni, the balance being Cu and inevitable impurities, Zn content [Zn]% by mass, Sn content [Sn]% by mass, and P content Between [P] mass% and Ni content [Ni] mass%,
7 ≦ [Zn] + 3 × [Sn] + 2 × [Ni] ≦ 16,
0 ≦ [Zn] −0.3 × [Sn] −1.8 × [Ni] ≦ 9,
0.3 ≦ (3 × [Ni] + 0.5 × [Sn]) / [Zn] ≦ 1.3,
2 ≦ [Ni] / [Sn] ≦ 8,
18 ≦ [Ni] / [P] ≦ 180,
The average crystal grain size is 2 to 9 μm, and the average particle size of the circular or elliptical precipitate is 3 to 60 nm, or the particle size of 3 to The ratio of the number of precipitates of 60 nm is 70% or more, the conductivity is 26% IACS or more, and the stress relaxation rate is 23% or less at 150 ° C. for 1000 hours as stress relaxation characteristics. To do.

The copper alloy plate according to the third aspect of the present invention is the above-described copper alloy plate, further comprising Al, Fe, Co, Mg, Mn, Ti, Zr, Cr, Si, Sb, As, Pb, and a rare earth element. It is characterized by containing at least one or two or more selected from 0.0005% by mass to 0.05% by mass, and a total of 0.0005% by mass to 0.2% by mass.

The copper alloy sheet according to the fourth aspect of the present invention is implemented after the finish cold rolling step in which the copper alloy material is cold-rolled in the above-described copper alloy plate and, if necessary, the finish cold rolling step. And a recovery heat treatment step, wherein the electrical conductivity is C (% IACS), 150 ° C., and the effective stress at 1000 hours is Pw (N / mm ² ),
Pw ≧ 300,
Pw × (C / 100) ^1/2 ≧ 190
The ratio of the yield strength YS _{90 in the} direction forming 90 degrees with respect to the rolling direction and the yield strength YS _{0 in the} direction forming 0 degrees with respect to the rolling direction, YS ₉₀ / YS ₀ is 0.95. ≦ YS ₉₀ / YS ₀ ≦ 1.07 is set.

The copper alloy plate according to the fifth aspect of the present invention is used for electronic / electric equipment parts such as connectors, terminals, relays, switches, and semiconductors.

The manufacturing method of the copper alloy plate which is the 6th aspect of this invention is a manufacturing method of the copper alloy plate which manufactures the above-mentioned copper alloy plate, Comprising: A hot rolling process, a cold rolling process, and a recrystallization heat processing Process and finish cold rolling process in this order, the cold working rate in the cold rolling process is 55% or more, the recrystallization heat treatment process using a continuous heat treatment furnace, after cold rolling A heating step for heating the copper alloy material to a predetermined temperature, a holding step for holding the copper alloy material at a predetermined temperature for a predetermined time after the heating step, and the copper alloy material to a predetermined temperature after the holding step. A cooling step for cooling, wherein in the recrystallization heat treatment step, a maximum temperature of the copper alloy material is Tmax (° C.), and a temperature from a temperature that is 50 ° C. lower than the maximum temperature of the copper alloy material to a maximum temperature When heated The when and tm (min),
560 ≦ Tmax ≦ 790,
0.04 ≦ tm ≦ 1.0,
520 ≦ It1 = (Tmax−30 × tm ^−1/2 ) ≦ 690 and, in the recrystallization heat treatment step, 5 ° C./second in a temperature range from a temperature 50 ° C. lower than the highest temperature to 400 ° C. Cooling is performed under the above conditions. Depending on the thickness of the copper alloy plate, the paired cold rolling step and annealing step may be performed once or a plurality of times between the hot rolling step and the cold rolling step.

The method for producing a copper alloy sheet according to the seventh aspect of the present invention includes a recovery heat treatment step that is performed after the finish cold rolling step, and the recovery heat treatment step uses a predetermined copper alloy material after finish cold rolling. A heating step for heating to a predetermined temperature; a holding step for holding the copper alloy material at a predetermined temperature for a predetermined time after the heating step; and a cooling step for cooling the copper alloy material to a predetermined temperature after the holding step. The maximum temperature of the copper alloy material is defined as Tmax2 (° C.), and the time during which the copper alloy material is heated and held in the temperature range from a temperature 50 ° C. lower than the maximum temperature of the copper alloy material to the maximum temperature is tm2 (min) And when
150 ≦ Tmax2 ≦ 580,
0.02 ≦ tm2 ≦ 100,
120 ≦ It2 = (Tmax2−25 × tm2 ^−1/2 ) ≦ 390
It is said that it is said.

The manufacturing method of the copper alloy plate which is the 8th aspect of this invention is a manufacturing method of the copper alloy plate which manufactures the above-mentioned copper alloy plate, Comprising: The cold rolling process and annealing process used as a pair, Cold rolling Including a process, a recrystallization heat treatment process, a finish cold rolling process, a recovery heat treatment process, and after performing the cold rolling process and the annealing process to be paired one or more times without performing hot working A combination of the cold rolling step and the recrystallization treatment step, and a combination of the finish cold rolling step and the recovery heat treatment step, or both, and the cold The cold working rate in the rolling process is 55% or more, and the recrystallization heat treatment step uses a continuous heat treatment furnace to heat the copper alloy material after cold rolling to a predetermined temperature, and the heating step Later, the copper alloy material is set to a predetermined temperature. A holding step for holding for a time, and a cooling step for cooling the copper alloy material to a predetermined temperature after the holding step, and in the recrystallization heat treatment step, the maximum temperature of the copper alloy material is Tmax (° C.), In the temperature range from a temperature 50 ° C. lower than the maximum temperature of the copper alloy material to the maximum temperature, when the heating and holding time is tm (min),
560 ≦ Tmax ≦ 790,
0.04 ≦ tm ≦ 1.0,
520 ≦ It1 = (Tmax−30 × tm ^−1/2 ) ≦ 690 and, in the recrystallization heat treatment step, 5 ° C./second in a temperature range from a temperature 50 ° C. lower than the highest temperature to 400 ° C. Cool under the above conditions. The recovery heat treatment step includes a heating step for heating the copper alloy material after finish cold rolling to a predetermined temperature, a holding step for holding the copper alloy material at a predetermined temperature for a predetermined time after the heating step, and the holding A cooling step of cooling the copper alloy material to a predetermined temperature after the step, wherein the maximum reached temperature of the copper alloy material is Tmax2 (° C.), and the maximum reached from a temperature that is 50 ° C. lower than the maximum reached temperature of the copper alloy material When the heating and holding time is tm2 (min) in the temperature range up to the temperature,
150 ≦ Tmax2 ≦ 580,
0.02 ≦ tm2 ≦ 100,
120 ≦ It2 = (Tmax2−25 × tm2 ^−1/2 ) ≦ 390
It is said that it is said.

According to the present invention, a copper alloy plate excellent in stress corrosion cracking resistance, stress relaxation characteristics, tensile strength, proof stress, conductivity, bending workability, and solder wettability, in particular, capable of withstanding harsh use environments. Terminal, connector, copper alloy plate suitable for electric / electronic parts, and a method for producing the copper alloy plate can be provided.

Below, the manufacturing method of the copper alloy plate and copper alloy plate which concern on embodiment of this invention is demonstrated. The copper alloy plate according to the present embodiment is used as a constituent material for connectors, terminals, relays, springs, switches, semiconductors, lead frames, etc. used for automobile parts, electrical parts, electronic parts, communication equipment, electronic / electric equipment, etc. It is used.
Here, in this specification, an element symbol in parentheses such as [Zn] indicates the content (% by mass) of the element.
And in this embodiment, using this content display method, a plurality of compositional relational expressions are defined as follows. Note that effective additive elements such as Co and Fe and unavoidable impurities are not included in the respective calculation formulas described later because the contents specified in the present embodiment have little influence on the properties of the copper alloy sheet. Furthermore, for example, Cr less than 0.005% by mass is an inevitable impurity.

Composition relation f1 = [Zn] + 3 × [Sn] + 2 × [Ni]
Compositional relation f2 = [Zn] −0.3 × [Sn] −1.8 × [Ni]
Compositional relation f3 = (3 × [Ni] + 0.5 × [Sn]) / [Zn]
Composition relation f4 = [Ni] / [Sn]
Compositional relation f5 = [Ni] / [P]

The copper alloy sheet according to the first embodiment of the present invention has 4 to 14% by mass of Zn, 0.1 to 1% by mass of Sn, 0.005 to 0.08% by mass of P, and 1. It contains 0 to 2.4% by mass of Ni, the balance is made of Cu and inevitable impurities, the composition relational expression f1 is in the range of 7 ≦ f1 ≦ 18, and the compositional relational expression f2 is in the range of 0 ≦ f2 ≦ 11. The composition relational expression f3 is in the range of 0.3 ≦ f3 ≦ 1.6, the compositional relational expression f4 is in the range of 1.8 ≦ f4 ≦ 10, and the compositional relational expression f5 is in the range of 16 ≦ f5 ≦ 250. ing.

The copper alloy sheet according to the second embodiment of the present invention comprises 4 to 12% by mass of Zn, 0.1 to 0.9% by mass of Sn, 0.008 to 0.07% by mass of P, 1.05 to 2.2% by mass of Ni, the balance being made of Cu and inevitable impurities, the compositional relational expression f1 being in the range of 7 ≦ f1 ≦ 16, and the compositional relational expression f2 being 0 ≦ f2 ≦ 9 Within the range, the composition relational expression f3 is within the range of 0.3 ≦ f3 ≦ 1.3, the compositional relational expression f4 is within the range of 2 ≦ f4 ≦ 8, and the compositional relational expression f5 is within the range of 18 ≦ f5 ≦ 180. ing.

The copper alloy plate according to the third embodiment of the present invention has 4 to 14% by mass of Zn, 0.1 to 1% by mass of Sn, 0.005 to 0.08% by mass of P, and 1. 0 to 2.4% by mass of Ni and at least one or more selected from Al, Fe, Co, Mg, Mn, Ti, Zr, Cr, Si, Sb, As, Pb and rare earth elements, respectively 0.0005% by mass or more and 0.05% by mass or less and a total of 0.0005% by mass or more and 0.2% by mass or less, with the balance being Cu and inevitable impurities, and the compositional relational expression f1 is 7 ≦ f1 ≦ 18, composition relational expression f2 is in the range of 0 ≦ f2 ≦ 11, composition relational expression f3 is in the range of 0.3 ≦ f3 ≦ 1.6, and composition relational expression f4 is 1.8 ≦ f4 ≦ 10. In this range, the compositional relational expression f5 is in the range of 16 ≦ f5 ≦ 250.

The copper alloy sheet according to the fourth embodiment of the present invention comprises 4 to 12% by mass of Zn, 0.1 to 0.9% by mass of Sn, 0.008 to 0.07% by mass of P, 1.05 to 2.2% by mass of Ni and at least one or more selected from Al, Fe, Co, Mg, Mn, Ti, Zr, Cr, Si, Sb, As, Pb and rare earth elements 0.0005 mass% or more and 0.05 mass% or less in total and 0.0005 mass% or more and 0.2 mass% or less in total, and the balance is made of Cu and inevitable impurities, and the compositional relational formula f1 is 7 ≦ f1 ≦ 16, composition relational expression f2 is in the range of 0 ≦ f2 ≦ 9, composition relational expression f3 is in the range of 0.3 ≦ f3 ≦ 1.3, and compositional relational expression f4 is 2 ≦ f4 ≦ 8 In this range, the compositional relational expression f5 is in the range of 18 ≦ f5 ≦ 180.

In the copper alloy plates according to the first to fourth embodiments of the present invention described above, the average crystal grain size is 2 to 9 μm.
In the copper alloy plates according to the first and third embodiments of the present invention, the average particle diameter of the circular or elliptical precipitate is 3 to 75 nm, or the particle diameter is within the precipitate. The ratio of the number of precipitates of 3 to 75 nm is 70% or more.
In the copper alloy plates according to the second and fourth embodiments of the present invention, the average particle diameter of the circular or elliptical precipitate is 3 to 60 nm, or the particle diameter is 3 in the precipitate. The ratio of the number of precipitates of ˜60 nm is 70% or more.
Furthermore, in the above-described copper alloy plates according to the first to fourth embodiments of the present invention, the conductivity is 24% IACS or more, or the conductivity is 26% IACS or more, and the stress relaxation resistance is 150 ° C. The stress relaxation rate is 25% or less at 1000 hours, or 23% or less at 150 ° C. and 1000 hours.

In the copper alloy sheets according to the first to fourth embodiments of the present invention, the balance index f6 is defined as follows as an index representing the balance between the conductivity and the stress relaxation characteristics. The balance index f6 is defined as f6 = Pw × (C / 100) ^1/2 when the electrical conductivity is C (% IACS), the effective stress at 150 ° C. and 1000 ° C. is Pw (N / mm ² ). The That is, the balance index f6 is a product of Pw and (C / 100) ^1/2 . In the present embodiment, it is preferable that Pw ≧ 300 and f6 ≧ 190.
Furthermore, in the copper alloy sheets according to the first to fourth embodiments of the present invention, the yield strength YS _{90 in the} direction forming 90 degrees with respect to the rolling direction and the yield strength YS _{0 in the} direction forming 0 degrees with respect to the rolling direction. The ratio YS ₉₀ / YS ₀ is preferably in the range of 0.95 ≦ YS ₉₀ / YS ₀ ≦ 1.07.

The reasons why the component composition, the composition relational expressions f1, f2, f3, f4, f5, the metal structure, and various characteristics are defined as described above will be described below.

(Zn)
Zn is a main element constituting the copper alloy plate of the present embodiment, the valence is bivalent, the stacking fault energy is lowered, the number of recrystallized nucleus generation sites is increased during annealing, and the recrystallized grains are refined. Ultra-fine. In addition, the solid solution of Zn improves the tensile strength, proof stress, spring characteristics, etc. without impairing the bending workability, improves the heat resistance and stress relaxation characteristics of the matrix, and improves the solder wettability and migration resistance. Improve. Zn is inexpensive, lowers the specific gravity of the copper alloy, and has economic advantages. Although depending on the relationship with other additive elements such as Sn, Zn needs to be contained in an amount of at least 4% by mass in order to exhibit the above effects. For this reason, the lower limit of the Zn content is 4% by mass or more, preferably 4.5% by mass or more, and optimally 5% by mass or more. On the other hand, although depending on the relationship with other additive elements such as Sn, a remarkable effect commensurate with the content with regard to the refinement of crystal grains and the improvement of strength even when Zn is contained in an amount exceeding 14 mass%. Begins to disappear, conductivity decreases, sensitivity to stress corrosion cracking increases, Young's modulus decreases, elongation and bending workability deteriorate, stress relaxation characteristics decrease, and solder wettability also deteriorates. Therefore, the upper limit of the Zn content is 14% by mass, preferably 12% by mass or less, 11% by mass or less, and optimally 9% by mass or less. When Zn is in a suitable composition range, the heat resistance of the matrix is improved, the stress relaxation characteristics are improved by the interaction with Ni, Sn, and P. Excellent bending workability, high strength, Young's modulus, desired It has conductivity.

Even if the content of Zn having a valence of 2 is within the above range, it is difficult to make crystal grains fine if Zn alone is added. In order to make the crystal grains finer to a predetermined grain size, it is necessary to consider the value of the compositional relational expression f1 along with co-addition with Sn, Ni, and P described later. Similarly, in order to improve heat resistance, stress relaxation characteristics, strength, and spring characteristics, it is necessary to consider the values of the compositional relational expressions f1, f2, and f3 together with co-addition with Sn, Ni, and P described later. .
In addition, when Zn is 9 mass% or more, high tensile strength and yield strength can be obtained. However, as described above, bending workability, stress corrosion cracking resistance, and stress relaxation characteristics are worse with increasing amount of Zn. And the Young's modulus is low. In order to further improve these characteristics, the interaction with Ni or Sn and the values of the compositional relational expressions f1, f2, and f3 are more important.

(Sn)
Sn is a main element constituting the copper alloy plate according to the present embodiment, has a valence of 4 and lowers stacking fault energy, and combined with Zn and Ni, increases the number of recrystallization nucleus generation sites during annealing. The recrystallized grains are made finer and ultrafine. In particular, by co-addition with 4% by mass or more of divalent Zn and divalent Ni, the effect appears remarkably even when Sn is contained in a small amount. Sn dissolves in the matrix and improves tensile strength, yield strength, spring characteristics, etc., improves heat resistance of the matrix, improves stress relaxation characteristics, and improves stress corrosion cracking resistance. In order to exert the above effects, Sn needs to be contained at least 0.1% by mass or more. For this reason, the minimum of content of Sn is 0.1 mass% or more, and is 0.2 mass% or more optimally. On the other hand, the inclusion of a large amount of Sn deteriorates the conductivity, deteriorates the bending workability, Young's modulus, and solder wettability, and on the other hand decreases the stress relaxation characteristics and stress corrosion cracking resistance. In particular, the stress relaxation characteristics are greatly affected by the compounding ratio with Ni. For this reason, the upper limit of the content of Sn is 1% by mass or less, preferably 0.9% by mass or less, and optimally 0.8% by mass or less.

(Cu)
Since Cu is a main element constituting the copper alloy plate according to the present embodiment, it is the remainder. However, in order to secure conductivity and stress corrosion cracking resistance depending on the Cu concentration, and to maintain stress relaxation characteristics, elongation, Young's modulus, and solder wettability, the lower limit of the Cu content is 84% by mass or more. Furthermore, 86 mass% or more is preferable. On the other hand, in order to obtain high strength, the upper limit of the Cu content is preferably 94.5% by mass or less, and more preferably 94% by mass or less.

(P)
P has a valence of pentavalent and an effect of refining crystal grains and an effect of suppressing the growth of recrystallized grains, but the latter effect is large because of its low content. Moreover, although it is trace amount, it has the effect | action which improves a stress relaxation characteristic to the precipitate which combines with the solid solution P and P and Ni in P. Part of P forms precipitates by combining with Ni, which will be described later, and in some cases, Ni is mainly used to form precipitates by combining with Co or Fe, etc., further strengthening the effect of suppressing grain growth can do. In order to suppress the growth of crystal grains, there are circular or elliptical precipitates, and the average particle diameter of the precipitates is 3 to 75 nm, or of the precipitated particles having a particle diameter of 3 to 75 nm. It is necessary that the ratio of the number occupied is 70% or more. This precipitate has a larger action and effect of suppressing the growth of recrystallized grains during annealing than precipitation strengthening, and is distinguished from a strengthening action caused simply by precipitation. And P has the effect of remarkably improving the stress relaxation characteristic, which is one of the subjects of the present application, by the interaction with Ni under the inclusion of Zn and Sn within the above-mentioned range.
In order to exhibit these effects, the lower limit of the P content is 0.005% by mass or more, preferably 0.008% by mass or more, and optimally 0.01% by mass or more. On the other hand, even if the content exceeds 0.08% by mass, the effect of suppressing recrystallized grain growth due to precipitates is saturated. On the other hand, if excessive precipitates are present, elongation, bending workability, and stress relaxation characteristics are degraded. . For this reason, the upper limit of content of P is 0.08 mass%, Preferably it is 0.07 mass% or less.

(Ni)
A part of Ni is combined with P to form a compound, and the other is in solid solution. Ni improves the stress relaxation characteristics, increases the Young's modulus of the alloy, interacts with P, Zn, Sn contained in the concentration range specified as described above, and improves solder wettability and stress corrosion cracking resistance. And the growth of recrystallized grains is suppressed by the formed compound. In order to exert these effects remarkably, it is necessary to contain 1% by mass or more. Therefore, the lower limit of the Ni content is 1% by mass or more, preferably 1.05% by mass or more, and optimally 1.1% by mass or more. On the other hand, increasing the amount of Ni inhibits the electrical conductivity and saturates the stress relaxation characteristics, so the upper limit of the Ni content is 2.4% by mass or less, preferably 2.2% by mass or less. Is 2% by mass or less. In addition, in order to satisfy the compositional relational expression described later in relation to Sn, and at the same time, in order to improve stress relaxation characteristics, Young's modulus, and bending workability in particular, the Ni content is 1.8% of the Sn content. It is preferably contained more than twice, and more preferably twice or more. This is because the stress relaxation characteristics are particularly improved by containing divalent Ni in an atomic concentration of 3.5 times or more, particularly 4 times or more of tetravalent Sn. On the other hand, the Ni content is preferably 10 times or less, more preferably 8 times or less, and most preferably 6 times or less of the Sn content from the relationship between strength and electrical conductivity and stress relaxation characteristics.

(At least one or more selected from Al, Fe, Co, Mg, Mn, Ti, Zr, Cr, Si, Sb, As, Pb and rare earth elements)
Elements such as Al, Fe, Co, Mg, Mn, Ti, Zr, Cr, Si, Sb, As, Pb, and rare earth elements have the effect of improving various characteristics. Therefore, the copper alloy plate of the third embodiment and the copper alloy plate of the fourth embodiment contain at least one or more selected from these elements.
Here, Al, Fe, Co, Mg, Mn, Ti, Zr, Cr, Si, Sb, As, Pb, and rare earth elements make the crystal grains of the alloy fine. Al, Fe, Co, Mg, Mn, Ti, and Zr form a compound together with P or Ni, suppress the growth of recrystallized grains during annealing, and have a large effect of crystal grain refinement. In particular, Fe and Co have a large effect, and form a compound of Ni and P containing Fe or Co, thereby reducing the particle size of the compound. The fine compound further refines the size of recrystallized grains during annealing and improves the strength. However, if the effect becomes excessive, bending workability and stress relaxation characteristics are impaired. Furthermore, Al, Sb and As have the effect of improving the stress corrosion cracking resistance and corrosion resistance of the copper alloy, Sb having a valence of 5 improves stress relaxation characteristics, and Pb improves press formability. Has the effect of
In order to exert these effects, at least one element selected from Al, Fe, Co, Mg, Mn, Ti, Zr, Cr, Si, Sb, As, Pb, and rare earth elements, or any two or more elements However, it is necessary to contain 0.0005 mass% or more of each. On the other hand, if any of the selected elements exceeds 0.05% by mass, the effect is saturated. In particular, when Fe, Co, etc., which easily form a compound with P, exceed 0.05 mass%, the stress relaxation characteristics also deteriorate. Preferably, any element selected is 0.03% by weight or less. Furthermore, if the total content of these elements is more than 0.2% by mass, the effect is not saturated but the bending workability is inhibited. Therefore, the upper limit of the total content of these elements is 0.2% by mass or less, preferably 0.15% by mass or less, and more preferably 0.1% by mass or less.

(Inevitable impurities)
Copper alloy sheets contain unavoidable elements such as oxygen, hydrogen, carbon, sulfur, and water vapor in the production process including the raw material including the return material and mainly when dissolved in the atmosphere. Of course, these inevitable impurities are included.
Here, in the copper alloy of the present embodiment, elements other than the specified component elements may be treated as inevitable impurities, and the total content of inevitable impurities is preferably 0.2% by mass or less, more Preferably it is 0.1 mass% or less. Moreover, elements other than Zn, Ni, Sn, P, and Cu among the elements defined in the copper alloy plate of the present embodiment may be contained as impurities in a range less than the lower limit defined above.

(Composition relational expression f1)
When the compositional relational expression f1 = [Zn] + 3 × [Sn] + 2 × [Ni] is 7, the alloy of the present embodiment is a boundary value at which high strength is obtained, and is also a boundary value that improves stress relaxation characteristics. Therefore, the lower limit of the compositional relational expression f1 is 7 or more, preferably 7.5 or more. On the other hand, if the value of f1 exceeds 18, desired conductivity cannot be obtained, and the stress relaxation property, stress corrosion cracking resistance, bending workability, and solder wettability are also adversely affected. Therefore, the upper limit of the compositional relational expression f1 is 18 or less, preferably 16 or less, and optimally 14 or less.

(Composition relational expression f2)
When the compositional relational expression f2 = [Zn] −0.3 × [Sn] −1.8 × [Ni] is 11 or 10, the boundary of whether or not cracking occurs in a severe stress corrosion cracking environment Value. At the same time, it is a boundary value for obtaining excellent ductility, bending workability, good solder wettability, and good stress relaxation characteristics. As described above, a critical defect of the Cu—Zn alloy is high sensitivity to stress corrosion cracking. In the case of Cu—Zn alloy, the sensitivity of stress corrosion cracking depends on the Zn content, Sensitivity of stress corrosion cracking is increased at a Zn content of about 10% by mass. For this reason, the upper limit of the compositional relational expression f2 is 11, preferably 9 or less, and optimally 8 or less. Further, the compositional relational expression f2 = 10 corresponds to a Zn content of 10% by mass or 9% by mass in the case of a Cu—Zn binary alloy. Within the composition range in which Ni and Sn of the present application are co-added, in the compositional relational expression f2, the coefficient of Ni is large, and the stress corrosion cracking sensitivity can be particularly lowered by the inclusion of Ni. On the other hand, if f2 is less than 0, the strength is low, so the lower limit of the compositional relational expression f2 is 0 or more, preferably 0.5 or more, and more preferably 1 or more.

(Composition relational expression f3)
The compositional relational expression f3 = (3 × [Ni] + 0.5 × [Sn]) / [Zn], that is, the blending ratio of (3 × [Ni] + 0.5 × [Sn]) and [Zn] is appropriately set As a result, excellent stress relaxation characteristics are exhibited despite containing Zn in an amount of 4 to 14% by mass. When the value of f3 is 0.3 or more, that is, the value of (3 × [Ni] + 0.5 × [Sn]) is 0.3 or more with respect to [Zn], good stress relaxation characteristics are exhibited. become. Preferably, it is 0.35 or more, more preferably 0.4 or more. At the same time, solder wettability and stress corrosion cracking resistance are improved. On the other hand, even if the value of f3 exceeds 1.6, rather than the effect being saturated, the conductivity and stress relaxation characteristics are worsened, and more expensive Sn and Ni are contained compared to Zn. This is also an economic problem. Therefore, the upper limit value of the compositional relational expression f3 is 1.6 or less, preferably 1.3 or less, and optimally 1.2 or less.

(Composition relational expression f4)
In order to improve the stress relaxation characteristics in the Cu—Zn—Ni—Sn—P alloy, the compositional relational expression f4 = [Ni] / [Sn] indicating the mixing ratio of Ni and Sn is important. When the mass concentration ratio of Ni with a valence of 2 is 1.8 times and the atomic concentration ratio is 3.5 times or more with respect to Sn with an valence of 4, the stress relaxation characteristics are remarkably improved. If the value of f4 is 2 or more, that is, if there are 4 or more divalent Ni atoms per 1 tetravalent Sn atom, the stress relaxation characteristics are further improved, and the bending workability and stress corrosion resistance are improved. The cracking property is also improved. On the other hand, when there are too many Ni atoms, the stress relaxation characteristics are saturated, and in some cases, it becomes worse and the strength is lowered. The upper limit of the compositional relational expression f4 is 10 or less, preferably 8 or less, and optimally 6 or less. When in this range, the effects of Ni and Sn can be maximized.

(Composition relational expression f5)
Furthermore, the stress relaxation property is affected by Ni, P, and a compound of Ni and P in a solid solution state. Here, if the compositional relational expression f5 = [Ni] / [P] is less than 16, the ratio of the Ni and P compounds to Ni in the solid solution state increases, so that the stress relaxation characteristics are deteriorated and bending work is performed. Also worse. That is, when the compositional relational expression f5 = [Ni] / [P] is 16 or more, preferably 18 or more, and optimally 20 or more, stress relaxation characteristics and bending workability are improved. On the other hand, when the compositional relational expression f5 = [Ni] / [P] exceeds 250, the amount of the compound formed by Ni and P and the amount of P in solid solution are reduced, so that the stress relaxation property is deteriorated. In addition, the effect of making the crystal grains finer is reduced, and the strength of the alloy is reduced. For this reason, the upper limit of f5 is 250 or less, preferably 180 or less, and optimally 120 or less.

(Average crystal grain size)
In the copper alloy plate of the present embodiment, although depending on the process, the average crystal grain size can be about 1.5 μm. However, when the average crystal grain size of the copper alloy plate according to this embodiment is refined to 1.5 μm, the proportion of crystal grain boundaries formed with a width of several atoms increases, and the elongation, bending workability, stress The relaxation characteristics are deteriorated. Therefore, in order to provide high strength, high elongation, and good stress relaxation characteristics, the average crystal grain size needs to be 2.0 μm or more. The lower limit of the average crystal grain size is preferably 3 μm or more, and optimally 4 μm or more. On the other hand, as the crystal grains become larger, good elongation and bending workability are exhibited, but desired tensile strength and yield strength cannot be obtained. At least, the average crystal grain size needs to be reduced to 9 μm or less. The upper limit of the average crystal grain size is preferably 8 μm or less, particularly 7 μm or less when the strength is important. Thus, by setting the average crystal grain size in a narrower range, it is possible to obtain a highly excellent balance among bending workability, elongation, strength, conductivity, or stress relaxation characteristics.

(Precipitate)
For example, when annealing a rolled material that has been cold-rolled at a cold working rate of 50% or more, there is a relationship with time, but if a certain critical temperature is exceeded, the grain boundary where machining strain is accumulated is the center. Recrystallization nuclei are formed in Although it depends on the alloy composition, in the case of the copper alloy plate of this embodiment, the grain size of the recrystallized grains formed after nucleation is 1 μm, 2 μm, or smaller recrystallized grains. In addition, the processed structure is not replaced with recrystallized grains all at once. In order to replace all or, for example, 95% or more with recrystallized grains, a temperature higher than the temperature at which recrystallization nucleation starts or a time longer than the time at which recrystallization nucleation starts is required. is there. During this annealing, the first recrystallized grains grow with temperature and time, and the crystal grain size increases. In order to maintain a fine recrystallized grain size, it is necessary to suppress the growth of the recrystallized grains. In this embodiment, P and Ni are contained in order to suppress the growth of recrystallized grains. A compound produced by P and Ni (precipitate containing P and Ni) acts like a pin that suppresses the growth of recrystallized grains. In order for a compound produced by P and Ni (a precipitate containing P and Ni) to serve as a pin as described above, the properties of the compound itself and the particle size of the compound are important. That is, from the research results, in the composition range of the copper alloy plate according to the present embodiment, the compound produced by P and Ni (precipitate containing P and Ni) basically hardly inhibits the elongation. It was found that when the grain size of 3 to 75 nm is 3 to 75 nm, the growth of crystal grains is effectively suppressed with little inhibition of elongation.

The precipitate containing P and Ni that suppresses the growth of recrystallized grains has a circular or elliptical precipitate at the stage of the recrystallization heat treatment step, and the average particle diameter of the precipitate is 3 to 75 nm, or The proportion of the number of particles having a particle diameter of 3 to 75 nm in the precipitated particles may be 70% or more. When the average grain size of the precipitates is reduced, the precipitation strengthening of the precipitates and the effect of suppressing the growth of crystal grains are too effective, the recrystallized grains are reduced, the strength of the rolled material is increased, but the bending workability is deteriorated. Further, when the precipitate reaches, for example, 100 nm, the effect of suppressing the crystal grain growth is almost lost and the bending workability is deteriorated. Incidentally, the circular or elliptical precipitate includes not only a perfect circular or elliptical shape but also a shape approximated to a circular or elliptical shape.
In order to ensure that the above-described effects are achieved, the average particle diameter of the circular or elliptical precipitates is 3 to 60 nm, or the ratio of the number of the particle diameters of 3 to 60 nm in the precipitated particles is 70. % Or more is preferable. Optimally, the average particle size is 5 to 20 nm.

(conductivity)
In the copper alloy plate according to the present embodiment, current-carrying members such as connectors, terminals, relays, springs, switches, semiconductors, lead frames, etc. used in automobile parts, electrical parts, electronic parts, communication equipment, electronic / electric equipment, etc. Therefore, it is necessary to secure a conductivity of 24% IACS or more, preferably 26% IACS or more, and more preferably 28% IACS or more.

(Stress relaxation characteristics)
For example, when the terminal and connector are used in a place close to the engine room of an automobile, the temperature rises to about 100 ° C. Therefore, the stress is applied at 80 ° C. for 1000 hours at 80 ° C. The relaxation rate should be 25% or less, preferably 23% or less, and optimally 20% or less. This is because when the stress relaxation rate increases, the strength (contact pressure, spring pressure) corresponding to the stress relaxation rate is substantially impaired. Alternatively, evaluation can be performed with the maximum effective contact pressure and spring pressure. That is, the effective maximum contact pressure, spring pressure (effective stress) Pw is expressed by Pw = proof stress × 80% × (100% −stress relaxation rate (%)), and is simply proof stress at normal temperature or 1000 at 150 ° C. In addition to high stress relaxation characteristics over time, it is desirable that the value of the previous equation be high. If the proof stress × 80% × (100% −stress relaxation rate (%)) is 270 N / mm ² or more in a test at 150 ° C. for 1000 hours, it is the lowest level that can withstand use in a high temperature state, 300 N / If it is mm ² or more, it is suitable for use in a high temperature state, and if it is 330 N / mm ² or more, it is optimal. Incidentally, for example, in the case of Cu-30 mass% Zn which is a typical alloy of brass having a proof stress of 500 N / mm ² , the proof stress × 80% × (100% −stress relaxation rate) in a test at 150 ° C. for 1000 hours. (%)) values of phosphor bronze of about 70N / mm ^2, likewise yield strength is 550N / mm ² Cu-6 wt% Sn, and about 180 N / mm ^2, in the current practical alloys, far from satisfactory Can not.

(Balance index f6)
In the rolled material after finish cold rolling, the rolled material subjected to recovery heat treatment after finish cold rolling, or the rolled material subjected to reflow Sn plating or hot Sn plating, R / t = 1 in the W bending test. 0.0 (where R is the radius of curvature of the bent portion and t is the thickness of the rolled material), preferably no cracking occurs, preferably on the premise that no cracking occurs at R / t = 0.5. The balance index f6 = Pw × (C / 100) ^1/2 is important as an index representing the balance of If this balance index f6 is a high value, it can be a suitable material for terminals and connectors in an environment close to a severe engine room. In other words, (C / 100) ^1/2 , which is an index of electrical characteristics, can be a criterion for terminal / connector evaluation in an environment close to a severe engine room where the product of effective stress is severe. The balance index f6 needs to be at least 180, preferably 190 or more, more preferably 200 or more, and optimally 210 or more.

(Yield ratio YS ₉₀ / YS ₀ )
In general, when observing the metal structure of the finished cold-rolled material, it appears that the crystal grains are stretched in the rolling direction and compressed in the thickness direction, and the specimen taken in the rolling direction and the sample taken in the vertical direction are collected. Test specimens have differences in tensile strength, proof stress, and bending workability. The specific metal structure is that if the crystal grain is a cross section parallel to the rolling surface, it is an elongated crystal grain, and if it is viewed in the cross section, it becomes a crystal grain compressed in the thickness direction and sampled perpendicular to the rolling direction. The tensile strength TS ₉₀ and the proof strength YS ₉₀ of the rolled material obtained are higher than the tensile strength TS ₀ and the proof strength YS _{0 of} the rolled material collected in the parallel direction, and the strength ratio TS ₉₀ / TS ₀ and the proof strength ratio YS ₉₀ / YS. ₀ exceeds 1.05, further exceeds 1.07, and may reach 1.1 in some cases. As these strength ratio TS ₉₀ / TS ₀ and proof stress ratio YS ₉₀ / YS ₀ become higher than 1.05, the bending workability of specimens taken perpendicular to the rolling direction deteriorates. Conversely, depending on the manufacturing process, the strength ratio TS ₉₀ / TS ₀ and the yield strength ratio YS ₉₀ / YS ₀ may be 0.97, and in some cases, less than 0.95. In the anisotropy of the strength surface, the proof stress ratio YS ₉₀ / YS ₀ and the tensile strength ratio TS ₉₀ / TS ₀ are both preferably 1.07 or less, more preferably 1.05 or less, optimally Is 1.03 or less, or preferably 0.95 or more, more preferably 0.97 or more, and most preferably 0.99 or more. Various members such as terminals and connectors targeted by the copper alloy plate according to the present embodiment are in the rolling direction, the vertical direction, that is, the direction parallel to the rolling direction during actual use and processing from the rolled material to the product. Both vertical directions are often used, and it is desired that there is no difference in properties such as tensile strength, proof stress, and bending workability in the rolling direction and the vertical direction from the actual use surface and the product processing surface.

In the copper alloy plates according to the first to fourth embodiments of the present invention, the interaction of Zn, Sn, P, and Ni, the compositional relational expressions f1 to f5 are satisfied, the average crystal grain size is 2 to 9 μm, and P The size of precipitates formed of Ni and Ni and the ratio between these elements are controlled to predetermined values, and a rolled material is produced by the manufacturing process described below, whereby a direction that forms 0 degrees with respect to the rolling direction The difference in the tensile strength and proof stress of the rolled material collected in the direction of the degree is eliminated. Thus, in the copper alloy sheets according to the first to fourth embodiments of the present invention, the proof stress YS _{90 in the} direction forming 90 degrees with respect to the rolling direction and the proof stress in the direction forming 0 degrees with respect to the rolling direction. the ratio _YS 90 / YS ₀ and YS ₀ becomes in the range of _{_{0.95 ≦ YS 90 / YS 0 ≦}} 1.07. In this embodiment, the ratio TS ₉₀ / TS ₀ of the tensile strength TS _{90 in the} direction forming 90 degrees with respect to the rolling direction and the tensile strength TS _{0 in the} direction forming 0 degrees with respect to the rolling direction is It is in the range of 0.95 ≦ TS ₉₀ / TS ₀ ≦ 1.07.

(Other characteristics)
In the copper alloy plate according to the present embodiment, it is preferable to define the characteristics other than the above-described conductivity and stress relaxation resistance as follows.
In the copper alloy plate of the present embodiment, in many applications, it has high strength, and the bending workability when evaluated by W bending is preferably R / t ≦ 1.0, more preferably R / t ≦ 0.5. In particular, in terminals, connectors, and electric / electronic component applications, the bending workability is R / t ≦ 1.0 in W bending with respect to bending in both directions parallel and perpendicular to the rolling direction. It is preferable that R / t ≦ 0.5.

Also, terminals, connectors, and the like are usually subjected to Sn plating on the surface in terms of corrosion resistance, contact resistance, and bonding. In this case, in the state of the coil (strip), the Sn plating is performed after the molten Sn plating, the reflow Sn plating, or the terminal or connector shape. Therefore, it is necessary to have good Sn plating property, that is, solder wettability, for terminal / connector material use or for electric / electronic parts. The Sn plating property is not particularly problematic in the state of the coil. However, when Sn plating, particularly Pb-free solder plating is performed after forming the terminals and connectors, due to production, it is not immediately after forming but for a certain period. There is a case where plating is performed after being left standing, and there is a possibility that plating property and solder wettability may deteriorate due to surface oxidation during the standing time. There is a need for a copper alloy that has good solder wettability, and has good surface wettability after being left in the atmosphere, even if there is some surface oxidation or hardly surface oxidation. There are various evaluations of solder wettability, but from the viewpoint of industrial production, it is appropriate to evaluate the solder wettability quickly.

Next, a method for manufacturing a copper alloy plate according to the first to fourth embodiments of the present invention will be described.
In this specification, processing performed at a temperature lower than the recrystallization temperature of the copper alloy material to be processed is referred to as cold processing, and processing performed at a temperature higher than the recrystallization temperature is referred to as hot processing. The forming processes are defined as cold rolling and hot rolling, respectively. In addition, recrystallization is defined as a change from one crystal structure to another crystal structure or the formation of a strain having a strain caused by processing into a new, unstrained crystal structure.

First, an ingot having the above-described component composition is prepared, and hot working (typically hot rolling) is performed on the ingot. The hot rolling start temperature is 800 ° C. or higher, preferably 840 ° C. or higher, so that each element is in a solid solution state, and 950 ° C. or lower, preferably 920 ° C. or lower, from the viewpoint of energy cost and hot ductility. . And in order to make P and Ni into a more solid solution state, the temperature at the end of the final rolling or a temperature range from 650 ° C. to 350 ° C. so that at least these precipitates do not become coarse precipitates that hinder elongation. Is preferably cooled at a cooling rate of 1 ° C./second or more. If the precipitates become coarse in the hot rolling stage, it is difficult to be eliminated by a heat treatment such as a subsequent annealing step, which hinders the elongation of the final rolled product.
When a plate-shaped ingot having a thickness of about 15 to 20 mm is manufactured by a continuous casting method, hot working (hot rolling) can be omitted. In this case, homogenization heat treatment may be performed at 650 ° C. to 850 ° C. after casting. When hot rolling is not performed, heat treatment is performed at about 700 ° C. or about 800 ° C. for 1 hour or longer, and a coarse compound of Ni and P generated at the casting stage is once made into a solid solution state, Sn having a low melting point, It is preferable to make the concentration distribution of Ni or the like having a high content uniform.

And it cold-rolls with respect to a copper alloy material, it is set as predetermined thickness, and recrystallization heat processing is performed following cold rolling. The cold rolling step, the annealing step, or the recrystallization heat treatment step is performed once or a plurality of times depending on the final product thickness.
As an annealing method and a recrystallization heat treatment method, there are a batch-type heat treatment method in which heat is maintained for a long time and a method in which heat treatment is continuously performed at a high temperature for a short time. As the final recrystallization heat treatment method, the high temperature-short time heat treatment has particularly improved stress relaxation characteristics. This is because P does not completely precipitate with Ni, and a certain concentration of P exists in a solid solution state. In the recrystallization heat treatment step by high-temperature-short-time continuous heat treatment, a continuous heat treatment furnace is used to heat the copper alloy material to a predetermined temperature, and after the heating step, the copper alloy material is heated to a predetermined temperature. A holding step for holding for a period of time, and a cooling step for cooling the copper alloy material to a predetermined temperature after the holding step. In the recrystallization heat treatment step, the maximum temperature of the copper alloy material is Tmax (° C.), In a temperature range from a temperature that is 50 ° C. lower than the highest temperature of the copper alloy material to the highest temperature, when the heating and holding time is tm (min),
560 ≦ Tmax ≦ 790,
0.04 ≦ tm ≦ 1.0,
520 ≦ It1 = (Tmax−30 × tm ^−1/2 ) ≦ 690
And

When the final recrystallization heat treatment conditions are below the maximum temperature, holding time, or lower limit of the range of the heat treatment index It1 of the high temperature-short time continuous heat treatment conditions, unrecrystallized portions remain or average grain size It becomes a state of ultrafine crystal grains whose diameter is smaller than 2 μm. Further, if the annealing is performed exceeding the upper limit of the range of the maximum temperature reached, the holding time, or the heat treatment index It1, a fine metal structure having an average crystal grain size of 9 μm or less cannot be obtained. And if it carries out on the conditions outside a range, the balance of the amount of Ni which dissolves, the amount of P, and the precipitate of Ni and P will collapse, and a stress relaxation characteristic will worsen.
Further, at the time of cooling in the recrystallization heat treatment step, it is preferable to cool under the condition of 5 ° C./second or more, more preferably 10 ° C./second or more in the temperature range from “maximum reached temperature −50 ° C.” to 400 ° C. Cooling under the above conditions, and optimally, cooling at 15 ° C./second or more improves the stress relaxation characteristics. When the cooling rate is slow, coarse precipitates appear, the ratio of P and Ni precipitates increases, the amount of P that dissolves decreases, and stress relaxation characteristics and bending workability deteriorate.

In order to obtain uniform and fine recrystallized grains without mixed grains in the recrystallization heat treatment process, it is not enough to lower the stacking fault energy. Strain, specifically, the accumulation of strain at the grain boundaries is necessary. Therefore, the cold working rate in the cold rolling before the recrystallization heat treatment step needs to be 55% or more, and preferably 60% or more. On the other hand, if the cold work rate of the cold rolling before the recrystallization heat treatment process is increased too much, problems such as distortion occur, so 98% or less is desirable and optimally 96% or less. In other words, in order to increase the number of recrystallization nucleation production sites due to physical action, it is effective to increase the cold work rate, and by adding a high work rate within a range that can tolerate distortion of the product, Finer recrystallized grains can be obtained.

The recrystallization heat treatment step can be heat-treated even by batch annealing, and is maintained at a temperature in the range of 400 ° C. to 650 ° C. for 1 to 24 hours. However, the average crystal grain size and the grain size of the precipitates are within the predetermined range in the final heat treatment step, whether it is a high temperature-short time continuous heat treatment or batch annealing. It is necessary to adjust the conditions so that The final heat treatment process is preferably a high-temperature-short-time continuous heat treatment that can bring a certain concentration of P into a solid solution state, and the intermediate recrystallization heat treatment performed as necessary, that is, the annealing process is a batch type. Even if it is a high-temperature-short-time continuous heat treatment, it does not significantly affect the properties of the final rolled material.

Next, finish rolling is performed on the copper alloy material subjected to the final recrystallization heat treatment step. After the finish cold rolling, the maximum temperature reached 150 to 580 ° C., and the holding time in the temperature range from the “maximum temperature reached −50 ° C.” to the maximum temperature was 0.02 to 100 minutes, It is preferable to perform a recovery heat treatment step in which a heat treatment index It2 defined below satisfies a relationship of 120 ≦ It2 ≦ 390.
Specifically, after the finish cold rolling process, a heating step for heating the copper alloy material to a predetermined temperature, a holding step for holding the copper alloy material at a predetermined temperature for a predetermined time after the heating step, and the holding A cooling step of cooling the copper alloy material to a predetermined temperature after the step, wherein the maximum reached temperature of the copper alloy material is Tmax2 (° C.), and the maximum reached from a temperature that is 50 ° C. lower than the maximum reached temperature of the copper alloy material In the temperature range up to the temperature, the heating and holding time is tm2 (min),
150 ≦ Tmax2 ≦ 580,
0.02 ≦ tm2 ≦ 100,
120 ≦ It2 = (Tmax2−25 × tm2 ^−1/2 ) ≦ 390
It is preferable to manufacture by the recovery heat treatment process which is.

This recovery heat treatment process does not involve recrystallization, improves the stress relaxation rate, spring limit value, bending workability and elongation of the rolled material by low-temperature or short-time recovery heat treatment, and reduces the conductivity reduced by cold rolling. It is a heat treatment for recovering the rate. In the heat treatment index It2, the lower limit is preferably 200 or more, and the upper limit is preferably 380 or less. By performing the recovery heat treatment step, the stress relaxation rate is reduced to about 1/2 compared to before the heat treatment, the stress relaxation characteristics are improved, and the spring limit value is improved by 1.5 to 2 times. The rate is improved by 0.5-2% IACS.
In an Sn plating process such as hot-dip Sn plating or reflow Sn plating, it is heated at about 150 ° C. to about 300 ° C. for a short time, after being formed into a rolled material, and in some cases terminals and connectors. Even if this Sn plating step is performed after the recovery heat treatment, the properties after the recovery heat treatment are hardly affected. On the other hand, the heating step of the Sn plating step is an alternative to the recovery heat treatment step, and improves the stress relaxation characteristics, spring strength, and bending workability of the rolled material.

Through the manufacturing process as described above, the copper alloy sheets according to the first to fourth embodiments of the present invention are manufactured.

As described above, the copper alloy sheets according to the first to fourth embodiments of the present invention have excellent stress corrosion cracking resistance and stress relaxation characteristics, high strength, and good bending workability. From these characteristics, it becomes a suitable material for electronic / electric equipment parts such as connectors, terminals, relays, switches, and automobile parts with excellent cost performance.
Furthermore, the average crystal grain size is 2 to 9 μm, the conductivity is 24% IACS or more, preferably 26% IACS or more, and the upper limit is not particularly specified. If a precipitate having a shape is present and the average particle size of the precipitate is 3 to 75 nm, the balance of strength, strength and bending workability is further improved, and stress relaxation characteristics, stress relaxation characteristics and electrical conductivity Since the effective stress at 150 ° C. is increased, it is a suitable material for electronic / electric equipment parts such as connectors, terminals, relays, switches, and automobile parts used in harsh environments.

As mentioned above, although embodiment of this invention was described, this invention is not limited to this, It is possible to change suitably in the range which does not deviate from the technical idea of the invention.

Hereinafter, the result of the confirmation experiment conducted to confirm the effect of the present invention will be shown. The following examples are for explaining the effects of the present invention, and the configurations, processes, and conditions described in the examples do not limit the technical scope of the present invention.
Using the copper alloy plate according to the first to fourth embodiments of the present invention described above and the copper alloy plate having a comparative composition, samples were produced by changing the manufacturing process. The compositions of the copper alloy are shown in Tables 1-3. Tables 1 to 3 show the values of the composition relational expressions f1, f2, f3, f4, and f5 shown in the above-described embodiment.

The sample manufacturing process was performed in three types A, B, and C, and the manufacturing conditions were further changed in each manufacturing process. Manufacturing process A was performed with actual mass production equipment, and manufacturing processes B and C were performed with experimental equipment. Table 4 shows the manufacturing conditions of each manufacturing process. In addition, in the manufacturing process A8 and the manufacturing process A9, the heat treatment index is out of the set condition range of the present invention.

In the manufacturing process A (A1 to A33), the raw material was melted in a medium frequency melting furnace having an internal volume of 10 tons, and an ingot having a thickness of 190 mm and a width of 630 mm was manufactured by semi-continuous casting. The ingots are each cut to a length of 1.5 m, and then in the processes A1 to A9 and A31 to A33, hot rolling process (sheet thickness 13 mm) -cooling process-milling process (sheet thickness 12 mm) -first cold Cold rolling step (sheet thickness 1.5 mm)-Annealing step (540 ° C, hold for 4 hours) or (670 ° C, 0.24 minutes))-Second cold rolling step (plate thickness 0.5 mm, cold working) 67%)-Final annealing step (recrystallization heat treatment step)-Finish cold rolling step (sheet thickness 0.3 mm, cold working rate 40%)-Recovery heat treatment step. In the manufacturing process A10, the first cold rolling process and the annealing process were omitted. The above holding time is the time for holding in the high temperature range from the highest temperature to the highest temperature of -50 ° C.

The hot rolling start temperature in the hot rolling process was set to 860 ° C., and after hot rolling to a plate thickness of 13 mm, shower water cooling was performed in the cooling process. In this specification, the hot rolling start temperature and the ingot heating temperature have the same meaning. The average cooling rate in the cooling step is the rolling material temperature after the final hot rolling, or the average cooling rate in the temperature region from when the rolled material temperature is 650 ° C. to 350 ° C. Measured at the edge. The measured average cooling rate was 4 ° C./second.

In the recrystallization heat treatment step, the maximum achieved temperature Tmax (° C.) of the rolled material and the holding time tm (min) in the temperature region from the temperature 50 ° C. lower than the maximum achieved temperature of the rolled material to the maximum achieved temperature are (690 C, 0.09 min), (660 ° C., 0.07 min), (710 ° C., 0.16 min), (770 ° C., 0.25 min), (620 ° C., 0.06 min). In the production step A1, the recrystallization heat treatment was performed using batch annealing at 470 ° C. for 4 hours. Of the steps in which high-temperature-short-time recrystallization heat treatment was performed, steps A31 and A32 had an average cooling rate in the range of 50 ° C. to 400 ° C. lower than the maximum temperature of the rolled material during cooling. The cooling was performed at 20 to 30 ° C./second in the other steps.

And as mentioned above, the cold working rate of the finish cold rolling process was set to 40%.
In the recovery heat treatment step, the maximum achieved temperature Tmax (° C.) of the rolled material is set to 450 (° C.), and the holding time tm (min) in the temperature region from the temperature 50 ° C. lower than the maximum achieved temperature of the rolled material to the maximum achieved temperature is set. 0.05 minutes. However, the recovery heat treatment process was not performed in the manufacturing process A6. In production step A5, the obtained sample was heated in an electric furnace at 300 ° C. for 30 minutes and air-cooled. In the production step A4, the obtained sample was completely immersed in an oil bath at 350 ° C. for 0.07 minutes and air-cooled. This heat treatment is a heat treatment condition corresponding to the hot Sn plating treatment.

The production process B (B1 to B4) was performed as follows.
A laboratory test ingot having a thickness of 40 mm, a width of 120 mm, and a length of 190 mm is cut out from the ingot of the manufacturing process A, and then a hot rolling process (sheet thickness 6 mm) -cooling process (shower water cooling) -pickling process -Cold rolling step (thickness 0.5 mm)-Recrystallization heat treatment step-Finish cold rolling step (plate thickness 0.3 mm, processing rate 40%)-Recovery heat treatment step was performed.
In the hot rolling step, the ingot was heated to 860 ° C. and hot rolled to a thickness of 6 mm. The cooling rate in the cooling step (the temperature of the rolled material after hot rolling or the cooling rate from when the temperature of the rolled material is 650 ° C. to 350 ° C.) was 3 ° C./second.

After cold rolling to a sheet thickness of 0.5 mm, the recrystallization heat treatment step is performed at a Tmax of 690 (° C.), a holding time tm of 0.09 minutes, and an average cooling rate of 640 ° C. to 400 ° C. at 25 ° C./second. went. Manufacturing process B1 performed recrystallization heat processing on the conditions hold | maintained at 480 degreeC for 4 hours using batch annealing. And it cold-rolled to 0.3 mm at the finish cold rolling process. The recovery heat treatment step was carried out under the conditions of Tmax of 450 (° C.) and holding time tm of 0.05 minutes for manufacturing step B1 and manufacturing step B2. In manufacturing process B4, it heated to the 300 degreeC electric furnace for 30 minutes, and air-cooled. In the production process B3, the obtained sample was completely immersed in an oil bath at 250 ° C. for 0.15 minutes and air-cooled. This heat treatment is also a heat treatment condition corresponding to the hot Sn plating treatment.

In addition, in the manufacturing process B5 and the manufacturing process B5A, hot rolling is omitted, the plate thickness is 6 mm by cold rolling after homogeneous annealing at 700 ° C. for 4 hours, and annealing is performed again at 620 ° C. for 4 hours. By cold rolling, the plate thickness is 0.5 mm, and in manufacturing step B5, Tmax is 690 (° C.), holding time tm is 0.09 minutes, and an average cooling rate from 640 ° C. to 400 ° C. is 25 ° C./second. In the manufacturing process B5A, recrystallization heat treatment was performed using batch annealing under the condition of holding at 480 ° C. for 4 hours. And it cold-rolled to 0.3 mm by the finish cold rolling process, and the recovery heat treatment process was implemented on the conditions of heating for 30 minutes to a 300 degreeC electric furnace.

In addition, in the manufacturing process B and the manufacturing process C to be described later, the process corresponding to the short-time heat treatment performed in the manufacturing process A in a continuous annealing line or the like is substituted by immersing the rolled material in a salt bath, and reaches the maximum. The temperature was the salt bath liquid temperature, the time during which the rolled material was completely immersed was the holding time, and air cooling was performed after the immersion. As a salt (solution), a mixture of BaCl, KCl, and NaCl was used.

Furthermore, as a laboratory test, the manufacturing process C (C1, C1A, C2) was performed as follows. It melt | dissolved and cast so that it might become a predetermined component with the electric furnace of a laboratory, and the ingot for a test in a laboratory of thickness 40mm, width 120mm, and length 190mm was obtained. Thereafter, it was manufactured by the same process as the manufacturing process B described above. That is, the ingot is heated to 860 ° C., hot-rolled to a thickness of 6 mm, and after hot rolling, the temperature of the rolled material is the rolled material temperature after hot rolling, or from 650 ° C. to 350 ° C. The temperature range was cooled at a cooling rate of 3 ° C./second. After cooling, the surface was pickled and the plate thickness was reduced to 0.5 mm by cold rolling. In the recrystallization heat treatment process, the production process C1 has a Tmax of 690 (° C.), a holding time tm of 0.09 minutes, an average cooling rate of 640 ° C. to 400 ° C., conditions of 25 ° C./second, and the production process C1A The conditions of 470 ° C. for 4 hours and the production process C2 were performed under the conditions of 380 ° C. for 4 hours. And it cold-rolls to 0.3 mm by a finish cold rolling process, and the recovery heat treatment process hold | maintains for 30 minutes at 300 degreeC using the electric furnace of a laboratory in manufacturing process C1 and manufacturing process C1A, and in manufacturing process C2. , At a temperature of 230 ° C. for 30 minutes.

As an evaluation of the copper alloy plate prepared by the method described above, metal structure observation (average crystal grain size and average grain size of precipitates), conductivity, stress relaxation characteristics, stress corrosion cracking resistance, solder wettability, tensile strength, Yield strength, elongation, and bending workability were evaluated. The evaluation results are shown in Tables 5-20.

(Average crystal grain size)
The average grain size of the recrystallized grains is determined by appropriately selecting a magnification according to the size of the crystal grains in metal microscope photographs such as 600 times, 300 times, and 150 times, and a copper grain size test in JIS H 0501. The measurement was performed according to the quadrature method. Twins are not regarded as crystal grains. What was difficult to judge from a metallographic microscope was determined by the FE-SEM-EBSP (Electron Back Scattering Diffraction Pattern) method. That is, FE-SEM is JSM-7000F manufactured by JEOL Ltd., and TSL Solutions OIM-Ver. 5.1 was used, and the average crystal grain size was determined from a grain size map (Grain map) with an analysis magnification of 200 times and 500 times. The calculation method of the average crystal grain size is based on the quadrature method (JIS H 0501).
One crystal grain is elongated by rolling, but the volume of the crystal grain hardly changes by rolling. In the cross section obtained by cutting the plate material in parallel with the rolling direction, it is possible to estimate the average crystal grain size in the recrystallization stage from the average crystal grain size measured by the quadrature method.

(Precipitate particle size)
The average particle size of the precipitate was determined as follows. The transmission electron image by TEM of 500,000 times and 100,000 times (detection limits are 1.0 nm and 5 nm, respectively) is elliptically approximated to the precipitate contrast using image analysis software “Win ROOF”. The geometrical average value of the short axes was obtained for all the precipitated particles in the field of view, and the average value was taken as the average particle diameter. In addition, in the measurement of 500,000 times and 100,000 times, the detection limits of the particle diameter were 1.0 nm and 5 nm, respectively, and those smaller than that were treated as noise and were not included in the calculation of the average particle diameter. In addition, the average particle diameter was measured at 500,000 times when the average particle size was approximately 10 nm or less, and 100,000 times when the average particle size was more than 100,000 nm. In the case of a transmission electron microscope, it is difficult to accurately grasp the information of precipitates because the dislocation density is high in a cold-worked material. In addition, since the size of the precipitate does not change depending on the cold working, the observation this time was the recrystallization portion after the recrystallization heat treatment step before the finish cold rolling step. The measurement positions were two places where the length of the plate thickness was ¼ from both the front and back surfaces of the rolled material, and the measured values at the two places were averaged.

(conductivity)
The conductivity was measured using a conductivity measuring device (SIGMATEST D2.068) manufactured by Nippon Felster Co., Ltd. In the present specification, the terms “electric conduction” and “conduction” are used in the same meaning. Further, since there is a strong correlation between thermal conductivity and electrical conductivity, the higher the conductivity, the better the thermal conductivity.

(Stress relaxation characteristics)
The measurement of the stress relaxation rate was performed as follows according to JCBA T309: 2004. A cantilever screw type jig was used for the stress relaxation test of the specimen. The test piece was taken from the direction of 0 degrees (parallel) and 90 degrees (vertical) in the rolling direction, and the shape of the test piece was set to plate thickness t × width 10 mm × length 60 mm. The stress applied to the specimen was 80% of the 0.2% proof stress, and the specimen was exposed to an atmosphere at 150 ° C. and 120 ° C. for 1000 hours. The stress relaxation rate is
Stress relaxation rate = (displacement after opening / displacement under stress load) × 100 (%)
As sought. In the present invention, the stress relaxation rate is preferably small.
In the evaluation at 120 ° C., a stress relaxation rate of 8% or less was evaluated as A (excellent), 8% and 13% or less was evaluated as B (good), and those exceeding 13% were evaluated as evaluation C (impossible). The stress relaxation characteristics required in the present application assume high reliability and severe cases.
Also, the effective stress Pw under the condition of 1000 hours at 150 ° C.
Pw = yield strength {(YS ₀ + YS ₉₀ ) / 2} × 80% × (100% −stress relaxation rate (%))
It was calculated by the following formula. Yield strength and stress relaxation characteristics may not be collected from the relationship between the slitter width after slitting, that is, when the width is smaller than 60 mm, the direction is 90 degrees (perpendicular) to the rolling direction. In this case, the test piece is evaluated only in the direction of 0 degree (parallel) to the rolling direction, and stress relaxation characteristics and Pw are evaluated.
In addition, Test No. In T3 and T36 (alloys No. 1 and 3), the effective stress Pw calculated from the results of the stress relaxation test in the direction of 90 degrees (perpendicular) in the rolling direction and in the direction of 0 degrees (parallel) in the rolling direction, and rolling The effective stress Pw calculated from the result of the stress relaxation test in only the 0 degree (parallel) direction in the direction and the effective stress Pw calculated from the result of the stress relaxation test in only the 90 degree (perpendicular) direction in the rolling direction are large. It was confirmed that there was no difference.

(Balance index f6)
From the measured conductivity C (% IACS) and effective stress Pw (N / mm ² ), the balance index f6 was calculated by the following equation.
f6 = Pw × (C / 100) ^1/2

(Stress corrosion cracking resistance)
The stress corrosion cracking resistance was measured using a test container and a test liquid defined in JIS H 3250, and using a liquid in which an equal amount of ammonia water and water were mixed.
In the stress corrosion cracking test, in order to investigate the sensitivity of the stress corrosion cracking to the load stress, a rolled material with a bending stress of 80% of the proof stress was applied in the above ammonia atmosphere using a resin cantilever screw type jig. The stress corrosion cracking resistance was evaluated from the stress relaxation rate. That is, if fine cracks are generated, they do not return to their original state, and the stress relaxation rate increases as the degree of cracks increases, so that the stress corrosion cracking resistance can be evaluated. A material having a stress relaxation rate of 25% or less after 48 hours exposure is evaluated as A with excellent stress corrosion cracking resistance, and even if the stress relaxation rate exceeds 25% for 48 hours exposure, it is 25% or less for 24 hours exposure. Those having good corrosion cracking resistance (no problem in practical use) were evaluated as B, and those having a stress relaxation rate exceeding 25% after 24 hours exposure were inferior in stress corrosion cracking resistance (practical) Evaluation C was assigned as a problem). In addition, the stress corrosion cracking resistance calculated | required by this application assumes high reliability and a severe case.

(Solder wettability)
Solder wettability was carried out by the meniscograph method. The test equipment is PHESCA (Reska) model: SAT-5200. A test piece was taken from the rolling direction and cut into a thickness: 0.3 mm × width: 10 mm × length: 25 mm. The used solder is Sn-3.5 mass% Ag-0.7 mass% Cu and pure Sn. As pretreatment, acetone degreasing → 15% sulfuric acid washing → water washing → acetone degreasing was performed. A standard rosin flux (NA200 manufactured by Tamura Corporation) was used as the flux. An evaluation test was performed under the conditions of a solder bath temperature of 270 ° C., an immersion depth of 2 mm, an immersion speed of 15 mm / sec, and an immersion time of 15 sec.

The evaluation of solder wettability was performed with zero cross time. That is, it is the time required for the solder to completely get wet after being immersed in the bath, and if the zero cross time is within 5 seconds, that is, within 5 seconds after being immersed in the solder bath, the solder wettability has a practical problem. Evaluation B was given as no evaluation, and evaluation A was given as being particularly excellent when the zero crossing time was within 2 seconds. When the zero crossing time exceeds 5 seconds, there is a problem in practical use, and thus the evaluation is C. The sample was washed with sulfuric acid after the final step of finish rolling or recovery heat treatment, and the surface was polished with No. 800 abrasive paper to obtain a non-oxidized surface for 3 days or 10 days. What was left in was used. In the table, “−1” and “−2” indicate the results of tests using a solder of Sn-3.5 mass% Ag-0.7 mass% Cu and left for 3 days and 10 days, respectively. "Is a test result for 3 days using pure Sn.

(Mechanical properties)
The tensile strength, proof stress, and elongation were measured according to the methods specified in JIS Z 2201 and JIS Z 2241, and the shape of the test piece was a No. 5 test piece. The test was performed in a direction of 0 ° with respect to the rolling direction and a direction of 90 ° with respect to the rolling direction.

(Bending workability)
The bending workability was evaluated by W bending with a bending angle of 90 degrees defined by JIS H 3110. The bending test (W-bending) was performed as follows. The bending radius (R) at the tip of the bending jig is 1 times the thickness (t) of the material (bending radius = 0.3 mm, R / t = 1.0) and 0.5 times (bending radius = 0.0). 15 mm, R / t = 0.5). Samples were taken from a direction called 90 ° with respect to the rolling direction in a so-called bad way and a direction called 0 ° in the rolling direction called a good way. Judgment of bending workability is determined by the presence or absence of cracks observed with a 50-fold stereomicroscope. Cracks occur when the bending radius is 0.5 times the thickness of the material (R / t = 0.5). No evaluation was A, the bending radius was 1.0 times the thickness of the material, and no cracks were evaluated B, and the thickness of the material was 1 time (R / t = 1.0). A crack was evaluated as C. The bending workability of R / t ≦ 0.5 means that no cracks are generated in a bending test in which the bending radius is 0.5 times or less the thickness of the material (R / t = 0.5). .

From the above evaluation results, the following was confirmed with respect to the composition and the compositional relational expression and characteristics.

Regarding the composition of the copper alloy plate, the following results were obtained. The comparative alloys are as follows.
Alloy No. 100 and 121 contain less Zn than the composition range of the alloys according to the invention.
Alloy No. No. 101 has a Sn content smaller than the composition range of the inventive alloy.
Alloy No. 102 has more P content than the composition range of an alloy according to the invention.
Alloy No. 103 has more Zn content than the composition range of an alloy according to the invention.
Alloy No. 104 has less P content than the composition range of the alloy according to the invention.
Alloy No. No. 105 has a Sn content higher than the composition range of the inventive alloy.
Alloy No. 106 and 122 have less Ni content than the composition range of the alloys according to the invention.
Alloy No. No. 107 does not satisfy the range of the compositional relational expressions f2 and f3 of the invention alloy.
Alloy No. 108 and 109 do not satisfy the range of the compositional relational expression f1 of the invention alloy.
Alloy No. 110 to 113 do not satisfy the range of the compositional relational expression f4 of the invention alloy.
Alloy No. 114 does not satisfy the range of the compositional relational expression f3 of the alloy according to the invention.
Alloy No. 115 and 116 do not satisfy the range of the compositional relational expression f5 of the alloy according to the invention.
Alloy No. Reference numerals 118 to 120 are general brass.
Alloy No. 117 and 123 have a large content of Fe and Co.

(1) If the P content is larger than the range of the alloy of the present invention, the average particle size of the precipitated particles after the recrystallization heat treatment step is small, the average crystal particle size is small, and the bending workability and the stress relaxation rate are deteriorated. (Refer to Alloy No. 102 etc.). When the content of P is less than the range of the alloy of the present invention, or when Ni / P in the compositional relational expression f5 is set, more than 250, the average grain size and average crystal of the precipitated particles after the recrystallization heat treatment step The particle size increases, the tensile strength and proof stress decrease, and the stress relaxation rate deteriorates. When Ni / P is 180 or less, and further 120 or less, the tensile strength and the proof stress are increased, and the stress relaxation rate is improved. When Ni / P of f5 is smaller than the set range, bending workability and stress relaxation rate deteriorate (see Alloy Nos. 104, 116, 115, 13, 18, etc.).

(2) If the Zn content is less than the range of the alloy of the present invention, the average crystal grain size after the recrystallization heat treatment step becomes large and the tensile strength becomes low. Moreover, the effect corresponding to Ni content is not acquired, but a stress relaxation rate deteriorates (refer alloy No. 100 grade | etc.,). The amount of Zn: around 4% by mass is a boundary value for satisfying the tensile strength, stress relaxation characteristics, and effective stress Pw (see Alloy Nos. 1, 10, 100, etc.). If the Zn content exceeds the condition range of the alloy according to the invention, the electrical conductivity, tensile strength, proof stress, stress relaxation rate, bending workability, stress corrosion cracking resistance, and solder wettability will deteriorate. When the Zn content is 12% by mass or less, and further 10% by mass or less, the above characteristics are improved (see Alloy Nos. 103, 12, 15, 18, etc.).

(3) If the content of Sn is larger than the range of the present invention, bending workability and stress relaxation characteristics are also deteriorated, and the conductivity is also lowered. The tensile strength and proof stress in the vertical direction increase with respect to the rolling direction. On the other hand, if the Sn content is less than the range of the present invention, the strength is low and the stress relaxation characteristics are deteriorated. When the Ni content is low, excellent stress relaxation characteristics cannot be obtained, but when the Ni content exceeds 1.0 mass%, the stress relaxation characteristics are improved (Alloy Nos. 101, 105, 106, 122, 17). , 19 etc.).

(4) When the compositional relational expression f1 is smaller than the condition range of the alloy according to the invention, the average crystal grain size after the recrystallization heat treatment step is large, the tensile strength and the proof stress are low, and the stress relaxation property is the Ni content. A reasonable effect is not obtained and it is bad. When the compositional relational expression f1 is larger than the condition range of the alloy according to the invention, the stress corrosion cracking resistance, bending workability, solder wettability are poor, and the conductivity is also low. Moreover, an effect commensurate with the Ni content cannot be obtained, and the stress relaxation characteristics are poor. The value of f1 corresponds to the boundary value of these characteristics, about 7 on the lower limit side and about 18 or about 16 on the upper limit side. When the value of f1 is smaller than 14, the characteristics are slightly improved (see Alloy Nos. 108, 109, 12, 1, 15, 18, etc.).

(5) When the compositional relational expression f2 is larger than the condition range of the invention alloy, the stress corrosion cracking resistance is deteriorated, and the stress relaxation characteristics and bending workability are also deteriorated. The values of the composition relational expression f2, 9 to 11, correspond to the boundary values regarding the quality of these characteristics. When the value of f2 is smaller than 8, stress corrosion cracking resistance, stress relaxation characteristics, and bending workability are improved (see Alloy Nos. 107, 103, 12, 15, 18, etc.).
(6) When the compositional relational expression f3 is smaller than the condition range of the alloy according to the invention, the stress corrosion cracking resistance, stress relaxation characteristics, and bending workability deteriorate. The value of the boundary of f3 is around 0.3 to 0.35. When the value of f3 is larger than 0.4, the stress corrosion cracking resistance, the stress relaxation property, and the bending workability are improved (see Alloy Nos. 107, 114, 2, 15, etc.).

(7) When the compositional relational expression f4 is smaller than the condition range of the alloy according to the invention, the stress relaxation characteristics are deteriorated, and the bending workability and the stress corrosion cracking resistance are also lowered. The tensile strength and proof stress in the vertical direction increase with respect to the rolling direction. When the compositional relational expression f4 is larger than the condition range of the alloy according to the invention, the stress relaxation characteristics are deteriorated (see Alloy Nos. 110 to 113, 14, 17, etc.).
As described above, even if the concentrations of Zn, Sn, Ni, and P are within a predetermined concentration range, if the values of the composition relational expressions f1, f2, f3, f4, and f5 are out of the predetermined range, the stress corrosion resistance Does not satisfy any of crackability, stress relaxation characteristics, strength, bending workability, solder wettability, and conductivity.

(8) When one or more selected from Al, Fe, Co, Mg, Mn, Ti, Zr, Cr, Si, Sb, As, and Pb are contained, the strength is improved by the refinement of crystal grains, and the stress is relaxed Improvements in characteristics and resistance to stress corrosion cracking are observed (see Alloy Nos. 20 to 32, etc.).
(9) When 0.08% by mass of Fe or 0.07% by mass of Co is contained, the average crystal grain size becomes small, and bending workability and stress relaxation characteristics deteriorate (see Alloy Nos. 117 and 123).

Further, when the copper alloy plate of the present invention was used, it was as follows.
(1) In the example alloys of the manufacturing process A using mass production equipment and the manufacturing process B using experimental equipment, if the manufacturing conditions are the same, the metallographic structure after the recrystallization heat treatment in both processes is the average crystal grains and precipitates Their average particle diameters are almost the same, almost the same mechanical properties, stress relaxation characteristics (stress relaxation rate, effective stress relaxation characteristics, product of effective stress and conductivity to the power of 1/2) Stress corrosion cracking resistance and solder wettability are obtained (see Test Nos. T10, T12, T26, T28, etc.).

(2) Even if the number of annealing (recrystallization heat treatment process) is one or two, there is no difference in the average crystal grain size, and almost the same mechanical properties, stress relaxation characteristics, stress corrosion resistance Crackability and solder wettability can be obtained (see Test Nos. T2, T3, T10, T18, T19, T26, etc.).
(3) In the final recrystallization heat treatment step, high temperature-short time heat treatment has better stress relaxation characteristics than batch annealing (Test Nos. T1, T2, T3, T17, T18, T19, T102, (See T103 etc.). Further, in the high temperature-short time heat treatment, the stress relaxation is slightly improved at the cooling rate of 5 ° C./second. When it is 10 ° C./second or more, or 15 ° C./second or more, it becomes a little better. Further, when the average grain size is 5 to 7 μm than 3 to 4 μm, the proof stress is slightly lower, but the stress relaxation characteristics are slightly better (Test Nos. T18, T23, T34, T39, T50, T55, T3A, See T3B, T3, etc.).

(4) Even in a process that does not undergo hot rolling, the particle size of the precipitate is slightly larger than in the process that passes through the hot rolling process, but almost the same mechanical properties, stress relaxation characteristics, and stress corrosion cracking resistance. And solder wettability (see Test Nos. T14, T15, T46, T47, etc.).
(5) When the coefficient It1 of the recrystallization heat treatment is large within the set range, the average crystal grain size, precipitates, and the size increase, and the yield strength is slightly low, but the stress relaxation characteristics are slightly good. If the coefficient It1 of the recrystallization heat treatment is small within the set range, the average crystal grain size and precipitates become small, and the proof stress is a little high, but the stress relaxation characteristics are a little bad. If the It1 is lower than the set condition, the recrystallized structure is not completely obtained, and the bending workability is deteriorated. If It1 is too large, the average crystal grain size becomes large, the grain size of the precipitates becomes large, the proof stress is low, and the stress relaxation property is low (see Test Nos. T3, T3C, T7, T8, T9, etc.). .

(6) When the value of f1 is about 16, which is close to the upper limit, bending workability and solder wettability are slightly deteriorated, and the resistance to stress corrosion cracking is slightly increased (see Alloy Nos. 12, 27, etc.).
(7) When the value of f2 is about 9, the susceptibility to stress corrosion cracking is slightly increased (see Alloy Nos. 15, 20, 22, etc.).

(8) If the value of f3 is about 0.35, which is a lower setting range, the stress relaxation characteristics are a little worse and the susceptibility to stress corrosion cracking is a little higher (see Alloy Nos. 20, 27, 31, etc.). .
(9) When the value of f4 is 1.8 to 2, which is a little lower than the set range, the stress relaxation characteristics are slightly deteriorated (see alloy No. 14 and the like).
(10) When the value of f5 is about 19 which is a lower setting range, and is about 250 which is close to the upper limit, the stress relaxation characteristics are slightly deteriorated (see alloy Nos. 13 and 15, etc.).

(11) When Co and Fe are contained, the average crystal grain size becomes small and the tensile strength and proof stress are increased, but the elongation is low and the bending workability is slightly deteriorated (see Alloy Nos. 22, 123, etc.).
(12) Even if the heat treatment is performed under the conditions corresponding to Sn plating, the tensile strength, proof stress and stress are almost the same as those of the copper alloy material manufactured under other heat treatment conditions before the heat treatment. Relaxation characteristics, bending workability, elongation, electrical conductivity, stress corrosion cracking resistance, and solder wettability can be obtained (see Test Nos. T3 to T6, T12 to T14, T19 to T22, T28 to 30).
(13) Even if the final heat treatment is performed by batch annealing at 470 ° C. × 4 hours or 480 ° C. × 4 hours, the stress relaxation properties are slightly deteriorated as compared with high-temperature short-time annealing, but the tensile strength It has good characteristics with respect to proof stress, bending workability, elongation and stress corrosion cracking resistance (see Test Nos. T1, T2, T11, T12, T15, T16, T102, T103, etc.).

The copper alloy sheet of the present invention has excellent stress corrosion cracking resistance and stress relaxation properties, high strength, good solder wettability, and balance between strength, bending workability, effective stress relaxation properties and conductivity. Excellent. For this reason, the copper alloy plate of the present invention can be suitably applied as a component for electrical and electronic parts such as relays, springs, switches, semiconductors, and lead frames as well as connectors and terminals.

Claims

4 to 14% by mass of Zn, 0.1 to 1% by mass of Sn, 0.005 to 0.08% by mass of P, and 1.0 to 2.4% by mass of Ni, and the balance Consists of Cu and inevitable impurities,
Between Zn content [Zn] mass%, Sn content [Sn] mass%, P content [P] mass%, and Ni content [Ni] mass%,
7 ≦ [Zn] + 3 × [Sn] + 2 × [Ni] ≦ 18,
0 ≦ [Zn] −0.3 × [Sn] −1.8 × [Ni] ≦ 11,
0.3 ≦ (3 × [Ni] + 0.5 × [Sn]) / [Zn] ≦ 1.6,
1.8 ≦ [Ni] / [Sn] ≦ 10,
16 ≦ [Ni] / [P] ≦ 250,
Have the relationship
The average grain size is 2-9 μm,
The average particle diameter of the circular or elliptical precipitates is 3 to 75 nm, or the ratio of the number of the precipitates having a particle diameter of 3 to 75 nm in the precipitates is 70% or more,
Conductivity is 24% IACS or higher,
A copper alloy sheet having a stress relaxation rate of 25% or less at 150 ° C. for 1000 hours as stress relaxation resistance.
4-12% by mass of Zn, 0.1-0.9% by mass of Sn, 0.008-0.07% by mass of P, and 1.05-2.2% by mass of Ni. The balance consists of Cu and inevitable impurities,
Between Zn content [Zn] mass%, Sn content [Sn] mass%, P content [P] mass%, and Ni content [Ni] mass%,
7 ≦ [Zn] + 3 × [Sn] + 2 × [Ni] ≦ 16,
0 ≦ [Zn] −0.3 × [Sn] −1.8 × [Ni] ≦ 9,
0.3 ≦ (3 × [Ni] + 0.5 × [Sn]) / [Zn] ≦ 1.3,
2 ≦ [Ni] / [Sn] ≦ 8,
18 ≦ [Ni] / [P] ≦ 180,
Have the relationship
The average grain size is 2-9 μm,
The average particle diameter of the circular or elliptical precipitates is 3 to 60 nm, or the ratio of the number of the precipitates having a particle diameter of 3 to 60 nm in the precipitates is 70% or more,
Conductivity is 26% IACS or higher,
A copper alloy sheet having a stress relaxation resistance of 23% or less at 150 ° C. for 1000 hours as stress relaxation resistance.
Furthermore, at least one or two or more selected from Al, Fe, Co, Mg, Mn, Ti, Zr, Cr, Si, Sb, As, Pb, and rare earth elements are each 0.0005% by mass or more and 0.0. The copper alloy sheet according to claim 1, wherein the copper alloy sheet is contained in an amount of 05 mass% or less and a total of 0.0005 mass% or more and 0.2 mass% or less.
Manufactured by a manufacturing process including a finish cold rolling process in which the copper alloy material is cold-rolled, and a recovery heat treatment process performed after the finish cold-rolling process as necessary,
When the electrical conductivity is C (% IACS), the effective stress at 150 ° C. and 1000 hours is Pw (N / mm 2 ),
Pw ≧ 300,
Pw × (C / 100) 1/2 ≧ 190
Have the relationship
The ratio of the yield strength YS 90 in the direction forming 90 degrees to the rolling direction and the yield strength YS 0 in the direction forming 0 degrees relative to the rolling direction, YS 90 / YS 0 is 0.95 ≦ YS 90 / YS 0 The copper alloy sheet according to any one of claims 1 to 3, wherein the copper alloy sheet is within a range of ≦ 1.07.
The copper alloy plate according to any one of claims 1 to 4, wherein the copper alloy plate is used for electronic / electric equipment parts such as connectors, terminals, relays, switches, and semiconductors.
It is a manufacturing method of the copper alloy plate which manufactures the copper alloy plate according to any one of claims 1 to 5,
Including a hot rolling step, a cold rolling step, a recrystallization heat treatment step, and a finish cold rolling step in this order,
The cold working rate in the cold rolling step is 55% or more,
The recrystallization heat treatment step uses a continuous heat treatment furnace to heat the copper alloy material after cold rolling to a predetermined temperature, and hold the copper alloy material at the predetermined temperature for a predetermined time after the heating step. A holding step, and a cooling step for cooling the copper alloy material to a predetermined temperature after the holding step, wherein the maximum temperature of the copper alloy material is Tmax (° C.) in the recrystallization heat treatment step, and the copper alloy When the heating and holding time is tm (min) in the temperature range from the temperature 50 ° C. lower than the highest temperature of the material to the highest temperature,
560 ≦ Tmax ≦ 790,
0.04 ≦ tm ≦ 1.0,
520 ≦ It1 = (Tmax−30 × tm −1/2 ) ≦ 690
And in the recrystallization heat treatment step, cooling is performed under a condition of 5 ° C./second or more in a temperature range from a temperature 50 ° C. lower than the highest temperature to 400 ° C. .
A recovery heat treatment step performed after the finish cold rolling step;
The recovery heat treatment step includes a heating step for heating the copper alloy material after finish cold rolling to a predetermined temperature, a holding step for holding the copper alloy material at a predetermined temperature for a predetermined time after the heating step, and the holding A cooling step of cooling the copper alloy material to a predetermined temperature after the step, wherein the maximum reached temperature of the copper alloy material is Tmax2 (° C.), and the maximum reached from a temperature that is 50 ° C. lower than the maximum reached temperature of the copper alloy material When the heating and holding time is tm2 (min) in the temperature range up to the temperature,
150 ≦ Tmax2 ≦ 580,
0.02 ≦ tm2 ≦ 100,
120 ≦ It2 = (Tmax2−25 × tm2 −1/2 ) ≦ 390
The method for producing a copper alloy sheet according to claim 6, wherein:
It is a manufacturing method of the copper alloy plate according to any one of claims 1 to 5,
Including a cold rolling process and an annealing process, a cold rolling process, a recrystallization heat treatment process, a finish cold rolling process, and a recovery heat treatment process, and a pair of cold rolling processes without performing hot working. After performing the cold rolling step and the annealing step one or more times, any one of the combination of the cold rolling step and the recrystallization treatment step, and the combination of the finish cold rolling step and the recovery heat treatment step It is configured to do either or both,
The cold working rate in the cold rolling step is 55% or more,
The recrystallization heat treatment step uses a continuous heat treatment furnace to heat the copper alloy material after cold rolling to a predetermined temperature, and hold the copper alloy material at the predetermined temperature for a predetermined time after the heating step. A holding step, and a cooling step for cooling the copper alloy material to a predetermined temperature after the holding step, wherein the maximum temperature of the copper alloy material is Tmax (° C.) in the recrystallization heat treatment step, and the copper alloy When the heating and holding time is tm (min) in the temperature range from the temperature 50 ° C. lower than the highest temperature of the material to the highest temperature,
560 ≦ Tmax ≦ 790,
0.04 ≦ tm ≦ 1.0,
520 ≦ It1 = (Tmax−30 × tm −1/2 ) ≦ 690
And in the recrystallization heat treatment step, in a temperature range from 50 ° C. lower than the highest temperature to 400 ° C., cooling is performed at a condition of 5 ° C./second or more,
The recovery heat treatment step includes a heating step for heating the copper alloy material after finish cold rolling to a predetermined temperature, a holding step for holding the copper alloy material at a predetermined temperature for a predetermined time after the heating step, and the holding A cooling step of cooling the copper alloy material to a predetermined temperature after the step, wherein the maximum reached temperature of the copper alloy material is Tmax2 (° C.), and the maximum reached from a temperature that is 50 ° C. lower than the maximum reached temperature of the copper alloy material When the heating and holding time is tm2 (min) in the temperature range up to the temperature,
150 ≦ Tmax2 ≦ 580,
0.02 ≦ tm2 ≦ 100,
120 ≦ It2 = (Tmax2−25 × tm2 −1/2 ) ≦ 390
The manufacturing method of the copper alloy board characterized by the above-mentioned.