JP6799933B2 - Manufacturing method of copper alloy plate and connector and copper alloy plate - Google Patents

Description

The present invention relates to a copper alloy plate material and a connector, and a method for manufacturing the copper alloy plate material, and particularly applies to a copper alloy applied to in-vehicle parts and parts for electric / electronic devices such as lead frames, connectors, terminal materials, relays, switches, sockets, and the like. Regarding the improvement of plate materials.

The characteristic items required for copper alloy plate materials used in in-vehicle parts and parts for electrical and electronic equipment, such as lead frames, connectors, terminal materials, relays, switches, and sockets, are tensile strength and proof stress (yield stress). Has bending workability, conductivity, and fatigue resistance. In recent years, this required characteristic has been increasing with the miniaturization, weight reduction, high functionality, and high-density mounting of parts for electric / electronic devices and in-vehicle parts.

In particular, copper alloy plate materials for terminals are being studied for weight reduction and material usage reduction by making the material thinner and narrower. At this time, in order to secure the contact pressure (contact pressure) of the leaf spring portion of the terminal, high strength is required for the material. Further, since electrical and electronic parts are generally formed by press working and bending, excellent press punching workability and bending workability are required.

Further, in the large current connector, there is a problem that the material itself generates heat due to Joule heat generated by the flow of current, and a stress relaxation phenomenon occurs. Further, when a copper alloy plate material is used as a terminal, there is a problem that the initial contact pressure cannot be maintained due to the settling of the spring during use, the conductivity is lowered, and contact failure occurs. Therefore, it is also required to have excellent conductivity and stress relaxation resistance.

Further, when it is used as a part used in an electronic device or an automobile, vibration may be applied depending on the usage condition, and repeated stress may be applied to the material constituting the part. Further, if a constant load stress continues to act on the material within the elastic deformation region, cracks are likely to occur in the material, and in some cases, it is assumed that the material will break due to the extension of the cracks.

Conventionally, copper-based materials such as phosphor bronze and brass are widely used in addition to iron-based materials as materials used as parts for electric / electronic devices and parts for automobiles. As these copper-based materials, copper alloy materials whose strength is improved by a combination of solid solution strengthening of Sn and Zn and work hardening by cold working such as rolling and drawing are known. However, the copper alloy material whose strength has been improved by such a strengthening method tends to have insufficient conductivity, and in addition, the strength is obtained by performing cold rolling or the like at a high cold working rate. In addition, there is a tendency that sufficient bending workability cannot be obtained. Therefore, as an alternative strengthening method to solid solution strengthening or work hardening, there is precipitation strengthening in which the second phase is precipitated in the copper alloy material. This strengthening method is used for many copper alloy materials because it can not only increase the strength but also the conductivity at the same time.

Under these circumstances, examples of copper alloy materials used for parts for electric / electronic devices and parts for automobiles include Cu—Ni—Si based alloys (Corson alloys). Cu-Ni-Si alloys are alloys that are mainly strengthened by precipitation strengthening and work hardening. Therefore, Cu—Ni—Si alloys used for parts for electrical and electronic equipment and parts for automobiles have sufficient precipitation strengthening, high conductivity, excellent stress relaxation resistance, and fatigue resistance. Is required.

As a means for satisfying the required characteristics of the copper alloy plate material used for these parts for electric / electronic devices and parts for automobiles (for example, terminals), the applicant has, for example, in Patent Documents 1 and 2, Cu-Ni-Si. We proposed a copper alloy plate material that satisfied the required performance by controlling the second phase particles in the system alloy. More specifically, in Patent Document 1, Cr is contained to control the crystal grain size and improve the precipitation effect, and is present on the grain boundaries of the crystal grains of the Cu—Ni—Si alloy. By setting the density of the second phase particles to 10 ⁴ to 10 ⁸ grains / mm ² and controlling the average crystal grain size of the crystal grains to 10 μm or less, the strength, bending workability and stress resistance relaxation characteristics are improved. ing. Further, in Patent Document 2, the precipitate is made finer by containing Co, and the density of the second phase of the Cu—Ni—Si and Cu—Co—Si alloys is reduced to 10 ⁸ to 10 ¹² pieces / mm ² . By controlling, strength, bending workability and stress relaxation characteristics are improved.

Japanese Patent No. 4785092 JP-A-2007-169765

So far, Cu—Ni—Si alloy materials have been solution heat treated during the manufacturing process as a means to obtain the strength required for use as parts for electrical and electronic equipment and automobile in-vehicle parts (for example, terminals). A method has been adopted in which the additive element is sufficiently solid-solved in the above step, and then the precipitation is strengthened by finely and densely precipitation by the aging precipitation heat treatment in the next step. However, in such a method, since it is necessary to carry out solution heat treatment at a high temperature in order to dissolve the added element, solid solution of the second phase (precipitate, crystallized product) of Ni, Si and other elements. Not only progresses, but also crystal grain growth tends to proceed at the same time. In addition, if the solution temperature is raised to increase the amount of precipitation hardening, abnormal grain growth of crystal grains is likely to occur, and it is difficult to satisfy all of the strength, bending workability, and fatigue resistance in a well-balanced manner. There was a problem.

The copper alloy plate material described in Patent Document 1 defines the number of second-phase particles of a Cu—Ni—Si-based alloy per fixed area, but the size (diameter) and existence (distribution) of the second-phase particles ) The state is not specified, and the fatigue resistance characteristics when a constant load stress continues to act on the copper alloy plate material within the elastic deformation region were not paid attention to. Therefore, depending on the copper alloy plate material, The fatigue resistance may be particularly inferior due to the presence of the second phase particles in the copper alloy plate, and there is room for further improvement such as improving the product yield. Further, in the copper alloy described in Patent Document 2, the number of the second phase per unit area (10 ⁸ to 10 ¹² pieces / mm ² ) is specified, and the strength, conductivity and the like are improved. Since the existence (distribution) state of the two phases was not specified, and the fatigue resistance characteristics when a constant load stress continued to act in the elastic deformation region on the copper alloy plate material were not paid attention to. As in the case of Patent Document 1, there was room for further improvement.

Therefore, an object of the present invention is a copper alloy plate material having high strength and excellent bending workability and fatigue resistance, particularly in-vehicle parts and parts for electric / electronic devices such as lead frames, connectors, terminal materials, relays, switches, and the like. It is an object of the present invention to provide a copper alloy plate material and a connector applied to a socket and the like, and a method for manufacturing the copper alloy plate material.

As a result of diligent studies on copper alloy plate materials suitable for use in parts for electrical and electronic equipment and parts for automobiles (for example, terminals), the present inventor has made Cu-Ni-Si alloys stronger than before. It was found that it is important to optimize the size and dispersion state of dispersions (for example, crystallization), which greatly improve bending workability and fatigue resistance characteristics. In addition, if solution heat treatment is performed at a high temperature for the solid solution of solute elements required for precipitation strengthening, grain growth tends to proceed at the same time, but the average diameter is 0.1 to 3.0 μm, which is a relatively large size. By evenly dispersing the dispersion in the copper alloy plate material, grain growth is suppressed even if it is held at a high temperature, and both high solid solubility required for precipitation and fine crystal grains (for example, 30 μm or less) can be achieved at the same time. As a result of being possible, it was found that the characteristics were significantly improved. We also found a manufacturing method to realize these distribution states. Here, the crystal grain size of a general copper alloy is usually about 0.05 mm (50 μm) in the case of a copper alloy for an electronic device connector.

That is, the gist structure of the present invention is as follows.
(1) Contains 2.5 to 6.0% by mass Ni and 0.5 to 2.0% by mass Si, and 0 to 0.2% by mass Mg, 0 to 0.01% by mass P, 0 to 0. .2 mass% Cr, 0-0.2 mass% Mn, 0-1.5 mass% Co, 0-1.5 mass% Zn, 0-0.01 mass% Zr, 0-0.17 mass% Ag A copper alloy plate material containing at least one component selected from the group consisting of 0 to 0.5% by mass Sn and 0 to 2.0% by mass in total, and having an alloy composition in which the balance is Cu and unavoidable impurities. the copper alloy sheet in, there is a dispersion comprising a plurality of elements, the dispersion has an average diameter of 0.1 to 3.0 m, 10 ⁵ pieces 10 ³ or more to 300μm square in the measurement field of view Each dispersion present below and having a diameter of 0.1 to 3.0 μm is characterized in that the number of other dispersions present in the surrounding region within a radius of 10.0 μm is one or less. Alloy plate material.

(2) 0.01 to 0.20 mass% Mg, 0 to 0.01 mass% P, 0.01 to 0.20 mass% Cr, 0.01 to 0.20 mass% Mn, 0 to 1.5 At least selected from the group consisting of mass% Co, 0.5 to 1.5 mass% Zn, 0 to 0.01 mass% Zr, 0 to 0.17 mass% Ag and 0.01 to 0.50 mass% Sn. The copper alloy plate material according to (1) above, which contains one component in a total amount of 0.05 to 2.00% by mass.

(3) In the plate spring fatigue test of the copper alloy sheet, the number of repetitions of when repeated until rupture by applied stress 500MPa is more than 10 ⁶ times, the copper alloy sheet according to (1) or (2) ..

(4) In the 90 ° W bending test of the copper alloy plate material, the ratio (R) of the bending radius R and the plate thickness t of the 90 ° W bending in the vertical direction of rolling when the plate thickness is 0.1 mm and the width is 1.0 mm. The copper alloy plate material according to any one of (1) to (3) above, wherein / t) is 2.0 or less.

(5) The connector made of the copper alloy plate material according to any one of (1) to (4) above.

(6) The method for producing a copper alloy plate according to any one of (1) to (4) above, which is dissolved in a copper alloy material having an alloy component composition that gives the copper alloy plate [step 1]. ], Casting [step 2], homogenizing heat treatment [step 3], hot rolling [step 4], water cooling [step 5], face milling [step 6], cold rolling 1 [step 7], slit [step 8] ], Annealing [Step 9], Recrystallized solution heat treatment [Step 10], Aging precipitation heat treatment [Step 11], Pickling [Step 12], Surface polishing [Step 13], Cold rolling 2 [Step 14] and final Annealing [step 15] is performed in this order, and in the casting [step 2], cooling during casting is performed by primary cooling at 1 to 100 ° C./sec, secondary cooling at 50 to 250 ° C./sec, and 100 to 350 ° C. The annealing [step 9] is performed by three-step cooling of tertiary cooling of / sec, and the annealing [step 9] is performed by heating to a heating temperature of 400 to 800 ° C. and holding at this heating temperature for 1 second to 60 minutes. Manufacturing method.

According to the present invention, it contains 2.5 to 6.0% by mass Ni and 0.5 to 2.0% by mass Si, and 0 to 0.2% by mass Mg, 0 to 0.01% by mass P, 0 to 0.2% by mass Cr, 0 to 0.2% by mass Mn, 0 to 1.5% by mass Co, 0 to 1.5% by mass Zn, 0 to 0.01% by mass Zr, 0 to 0.17 A copper alloy plate containing at least one component selected from the group consisting of mass% Ag and 0 to 0.5 mass% Sn in a total of 0 to 2.0 mass% and having an alloy composition in which the balance is Cu and unavoidable impurities. there, in the copper alloy sheet, there is a dispersion comprising a plurality of elements, the dispersion has an average diameter of 0.1 to 3.0 m, 10 ³ or more to 300μm square in the measurement field of view 10 ⁵ exists less and a diameter of each dispersion 0.1~3.0μm, by the number of other dispersion present in the surrounding area within a radius 10.0μm is 1 or less, It has become possible to provide a copper alloy plate material having high strength, bending workability and fatigue resistance, and a connector made of this copper alloy plate material. In particular, this copper alloy plate material is suitable for use in parts for electrical and electronic equipment and parts for automobiles, such as connectors, lead frames, actuators, heat radiating members, relays, switches, and sockets. Further, according to the method for producing a copper alloy plate material according to the present invention, the copper alloy plate material can be suitably produced.

FIG. 1 is a conceptual diagram for explaining a fatigue characteristic test method for evaluating fatigue resistance characteristics of a copper alloy plate material. FIG. 2 is a conceptual diagram for explaining a test method of stress relaxation characteristics, in which (a) is a state (before heat treatment) when an initial stress of 80% of the proof stress is applied to the test piece. b) shows a state in which stress relaxation occurs after the test piece in the state of (a) is subjected to a predetermined heat treatment.

Hereinafter, preferred embodiments of the copper alloy plate material of the present invention will be described in detail.
The copper alloy plate material according to the present invention contains 2.5 to 6.0% by mass Ni and 0.5 to 2.0% by mass Si, and further, as optional additive components, 0 to 0.2% by mass Mg, 0. ~ 0.01% by mass P, 0 to 0.2% by mass Cr, 0 to 0.2% by mass Mn, 0 to 1.5% by mass Co, 0 to 1.5% by mass Zn, 0 to 0.01 mass It contains a total of 0 to 2.0% by mass of at least one component selected from the group consisting of% Zr, 0 to 0.17% by mass Ag and 0 to 0.5% by mass Sn, and the balance consists of Cu and unavoidable impurities. It is a copper alloy plate material having an alloy composition, and a dispersion composed of a plurality of elements is present in the copper alloy plate material, and the dispersion has an average diameter of 0.1 to 3.0 μm and is 300 μm square. each dispersion present in the measurement field 10 ³ or more 10 ⁵ or less, and a diameter 0.1~3.0μm, it the number of other dispersion present in the surrounding area within a radius 10.0μm No more than one.

Here, the "copper alloy plate material" as used in the present invention means that a copper alloy material (before processing and having a predetermined alloy composition) has a predetermined shape (for example, a plate, a strip, a foil, a rod, a wire, etc.). It refers to a processed material that has a specific thickness, is stable in shape, and spreads in the plane direction, and in a broad sense, it means that it includes a strip material. In the present invention, the thickness of the plate material is not particularly limited, but is preferably 0.03 to 1.0 mm, more preferably 0.05 to 0.8 mm.

<Ingredient composition>
The component composition of the copper alloy plate material of the present invention and its action are shown.

(Indispensable additive component)
The copper alloy plate material of the present invention contains 2.5 to 6.0% by mass Ni and 0.5 to 2.0% by mass Si.

[2.5 to 6.0% by mass Ni]
Ni is an element that forms a compound with Si to form a precipitate, which is an effective element for strengthening precipitation. By setting the Ni content in the range of 2.5 to 6.0% by mass, a Ni-Si system is used. The compound (Ni ₂ Si phase) can be precipitated in the Cu matrix to have the effect of improving the strength and conductivity. On the other hand, if the Ni content is less than 2.5% by mass, there is a problem that sufficient tensile strength cannot be obtained, and if it exceeds 6.0% by mass, it contributes to the improvement of strength during casting and hot working. There is a problem that a compound that does not exist is produced and the strength corresponding to the added amount cannot be obtained. Therefore, the Ni content was in the range of 2.5 to 6.0% by mass, preferably 2.6 to 5.5% by mass, and more preferably 2.7 to 5.0% by mass.

[0.5 to 2.0% by mass Si]
Si is an element contained together with Ni and added to form a Ni ₂ Si phase precipitated by aging precipitation heat treatment, and the Si content is set in the range of 0.5 to 2.0% by mass. As a result, the strength of the copper alloy plate can be improved by appropriately forming the Ni ₂ Si phase. On the other hand, if the Si content is less than 0.5% by mass, there is a problem that the precipitation of the Ni ₂ Si phase is insufficient and sufficient strength cannot be obtained, and if it exceeds 2.0% by mass, it is excessive. There is a problem that the Si is dissolved in the copper matrix to reduce the conductivity of the copper alloy plate material. Therefore, the Si content was set in the range of 0.5 to 2.0% by mass, preferably 0.55 to 1.9% by mass, and more preferably 0.6 to 1.8% by mass.

(Optional additive component)
In the copper alloy plate material of the present invention, in addition to the essential additive components of Ni and Si, as optional additive elements, 0.01 to 0.20 mass% Mg, 0 to 0.01 mass% P, 0.01. ~ 0.2% by mass Cr, 0.01 to 0.20% by mass Mn, 0 to 1.5% by mass Co, 0.5 to 1.5% by mass Zn, 0 to 0.01% by mass Zr, 0 to 0 At least one component selected from the group consisting of 0.17% by mass Ag and 0.01 to 0.50% by mass Sn can be contained in a total of 0.05 to 2.0% by mass.

[0.01 to 0.20% by mass Mg]
Like Sn and Zn, Mg is an element having an action of improving stress relaxation resistance and remarkably improving embrittlement of solder. However, if the Mg content is less than 0.01% by mass, such an action may not be sufficiently exerted, and if it exceeds 0.2% by mass, Mg is solidified in the base material of the copper alloy. It may melt and cause a problem of significantly deteriorating the conductivity. Therefore, the Mg content was set to 0.01 to 0.20% by mass. It is preferable to add Mg together with Sn or Zn because the stress relaxation resistance can be remarkably improved by synergistic action when it is added together with Sn or Zn rather than being added alone.

[0 to 0.01 mass% P]
P is an element having an action of improving hot workability and strength. However, if the P content exceeds 0.01% by mass, the conductivity may be significantly deteriorated. Therefore, the P content was set to 0 to 0.01% by mass.

[0.01 to 0.20% by mass Cr]
Cr finely precipitates as a compound or a simple substance and contributes to precipitation hardening, and also has the effect of precipitating as a compound in a size of 50 to 500 nm and suppressing grain growth to make the crystal grain size finer. It is an element effective for improving bending workability. However, if the Cr content is less than 0.01% by mass, such an effect cannot be sufficiently exerted, and if it exceeds 0.20% by mass, the conductivity is lowered and eutectic Cr is formed. Problems may occur. Therefore, the Cr content was set to 0.01 to 0.20% by mass. Even in a state where Cr is not added, coarsening of crystal grains can be suppressed by adjusting other elements.

[0.01 to 0.20% by mass Mn]
Mn is an element that has the effect of improving hot workability and strength. However, if the Mn content is less than 0.01% by mass, such an action cannot be sufficiently exerted, and if it exceeds 0.20% by mass, Mn-based inclusions that do not contribute to the strength are formed. Problems may occur. Therefore, the Mn content was set to 0.01 to 0.20% by mass.

[0 to 1.5% by mass Co]
Co is an element that combines with Si to form Co—Si-based precipitates and has the effect of improving precipitation strengthening. However, if the Co content exceeds 1.5% by mass, it becomes difficult to dissolve Co in the solution heat treatment, which may cause a problem that sufficient precipitation strength cannot be obtained. Therefore, the Co content was set to 0 to 1.5% by mass. When Co is not added, NiSi precipitates are responsible for strengthening the precipitation. By adding Co and adjusting the amount of Ni, the amount of precipitation strengthening increases.

[0.5 to 1.5% by mass Zn]
Similar to Mg and Sn, Zn is an element having an action of improving stress relaxation resistance and remarkably improving embrittlement of solder. However, if the Zn content is less than 0.5% by mass, such an effect cannot be sufficiently exerted, and if it exceeds 1.5% by mass, there may be a problem that the conductivity deteriorates. .. Therefore, the Zn content was set to 0.5 to 1.5% by mass. It is preferable to add Zn together with Mg and Sn because the stress relaxation resistance can be remarkably improved by synergistic action when it is added together with Mg and Sn rather than added alone.

[0 to 0.01 mass% Zr]
Zr finely precipitates as a compound or a simple substance and contributes to precipitation hardening, and also has the effect of precipitating as a compound in a size of 50 to 500 nm and suppressing grain growth to make the crystal grain size finer. It is an element effective for improving bending workability. However, if the Zr content exceeds 0.01% by mass, defects may occur in the formation of coarse Zr-based compounds. Therefore, the Zr content was set to 0 to 0.01% by mass. Even when Zr is not added, the effects of precipitation hardening and grain refinement can be obtained by controlling other elements.

[0 to 0.17% by mass Ag]
Ag is an element that has the effect of improving hot workability and strength. However, if the Ag content exceeds 0.17% by mass, the problem of deterioration of cold workability may occur. Therefore, the Ag content was set to 0 to 0.17% by mass.

[0.01 to 0.50% by mass Sn]
Similar to Mg and Zn, Sn is an element having an action of improving stress relaxation resistance and remarkably improving embrittlement of solder. However, if the Sn content is less than 0.01% by mass, such an effect cannot be sufficiently exerted, and if it exceeds 0.50% by mass, the hot workability and the conductivity are deteriorated. May occur. Therefore, the Sn content was set to 0.01 to 0.50% by mass. It is preferable to add Sn together with Mg or Zn because the stress relaxation resistance can be remarkably improved by synergistic action when it is added together with Mg or Zn rather than added alone.

[A total of 0.05 to 2.00% by mass of at least one component selected from the group consisting of Mg, P, Cr, Mn, Co, Zn, Zr, Ag and Sn]
The content of at least one component selected from the group consisting of Mg, P, Cr, Mn, Co, Zn, Zr, Ag and Sn is preferably 0.05 to 2.00% by mass in total. When the content of at least one component of the optional additive component is 0.05% by mass or more in total, the effect when the optional additive component is added can be exhibited, and when the content is 2.0% by mass or less. If so, the harmful effect of lowering the conductivity is unlikely to occur. Therefore, the total content of the optional additive components is 0.05 to 2.00% by mass, preferably 0.10 to 1.90% by mass, and more preferably 0.12 to 1.80% by mass. did.

<Dispersion in copper alloy plate>
The present invention relates to a copper alloy sheet in, there is a dispersion comprising a plurality of elements, the dispersion has an average diameter of 0.1 to 3.0 m, 10 ³ or more to 300μm square in the measurement field of view 10 ⁵ exists less and a diameter of each dispersion 0.1~3.0μm, the number of other dispersion present in the surrounding area within a radius 10.0μm is 1 or less. The "dispersion" referred to here is, for example, a crystallized product generated during solidification from a liquid phase to a solid phase in a casting process, a precipitate formed by forming an intermetallic compound in a heat treatment process, and other substances generated in a melting and casting process. Refers to inclusions and second phase particles.

[Diameter of dispersion and presence (dispersion) state]
In the copper alloy plate material of the present invention, it is necessary to control the dispersion, and more specifically, the dispersion has an average diameter of 0.1 to 3.0 μm and is within a measurement field of 300 μm square. ³ or more 10 ⁵ is present below and the dispersion of the diameter 0.1~3.0μm has a number of other dispersion present in the surrounding area within a radius 10.0μm to 1 or less ..

The effect of the controlled dispersion present in the copper alloy plate material of the present invention is mainly the suppression of grain growth during the recrystallization solution heat treatment. The mechanism by which the controlled dispersion suppresses grain growth is not clear, but for example, in a Cu—Ni—Si based alloy, Ni, Si, Mg, P, Cr, Mn, Co, Zn, Zr, A dispersion that forms a binary or ternary compound (dispersion) composed of Ag and Sn elements, and the grain boundaries pass through the dispersion (second phase particles) during grain growth of the crystal grains. It is considered that a difference in energy occurs between the grain boundaries and the grain boundaries, and as a result of this energy difference making it difficult for grain boundary movement to occur, grain growth is suppressed.

The average crystal grain size of the copper alloy plate material is preferably as fine as 30 μm or less, and more preferably 20 μm or less. The lower limit of the average crystal grain size is not particularly limited, but is preferably 2.0 μm or more, for example. The crystal grain size is measured based on the crystal grain size measurement method (cutting method) specified in JIS H0501-1986, and the average crystal grain size is obtained by sampling a plurality of points in the width direction at the front and rear ends of the plate material. This is done by observing multiple points on the surface and inside of the plate thickness. The sample is an average value of crystal grain size calculated from a mirror-polished surface (n ≧ 5) cut into a size of 20 mm × 20 mm from a copper alloy plate material.

In addition, the present inventor investigated the tissue state that contributes to the fatigue resistance of the leaf spring in order to improve the fatigue resistance of the copper alloy plate material. First, when a fatigue characteristic test in which a predetermined vibration is repeatedly applied to a plate material under a constant load stress action within the elastic deformation region (during measurement of fatigue characteristics), stress within the elastic range acts on the plate material macroscopically. Even if it was, it was found that some atoms may behave inelastically microscopically. As a result, minute slip zones are generated at the grain boundaries and inside the crystal grains, and after slip deformation occurs, minute cracks are generated along the grain boundaries, which propagate with the repetition of the above vibration. It was found that this may lead to breakage of the material.

Therefore, in the copper alloy sheet of the present invention, the metal an average diameter of (copper alloy) dispersion present in the tissue and 0.1 to 3.0 m, 10 ³ or more in the dispersion of 300μm square in the measurement field of view 10 ⁵ is present below, and a diameter of each dispersion 0.1~3.0μm is by a one less number of other dispersion present in the surrounding area within a radius of 10.0 [mu] m, The effect of significantly improving the fatigue life can be obtained. The reason why each dispersion having a diameter of 0.1 to 3.0 μm has one or less other dispersions existing in the surrounding region within a radius of 10.0 μm is configured in this manner. As a result, the dispersion can be distributed (equally dispersed) in the metal (copper alloy) structure at equal intervals, and as a result, there is an effect of suppressing the movement of dislocations around the dispersion, whereby individual crystal grains are produced. This is because slip deformation is less likely to occur, the frequency of occurrence of microscopic inelastic behavior of atoms in polycrystals is reduced, and the occurrence of cracks can be suppressed. The reason for limiting the average diameter of the dispersion to 0.1 to 3.0 μm is that if the average diameter is smaller than 0.1 μm, the additive elements will be dissolved even if they are evenly dispersed in the copper alloy plate. When the solution heat treatment is performed at a high temperature, the growth of crystal grains cannot be suppressed, it is difficult to satisfy all of the strength, bending workability and fatigue resistance in a well-balanced manner, and if it is larger than 3.0 μm, This is because there is a problem that a defect occurs during the press processing of the material and the accuracy of the press processing is significantly lowered. Further, dispersions of an average diameter 0.1~3.0μm is when only 10 less than ³ do not exist in the 300μm square in the measurement field of view, to reduce the effect of pinning the grain boundaries, the grain size There is a problem that control becomes difficult and, when present at greater than 10 ^5, there is a problem that adverse effects on press processing accuracy, the plate breakage in the occurrence of defects during cold working occur. Further, each dispersion having a diameter of 0.1 to 3.0 μm is regarded as a crack starting point during bending when the number of other dispersions existing in the surrounding region within a radius of 10.0 μm is larger than one. This is because there is a problem that it becomes.

The dispersion is composed of a plurality of elements, and examples of the plurality of elements constituting the dispersion include Ni, Si, Cr, and Co.

Further, the diameter and the existence (dispersion) state of the dispersion are measured by sampling a plurality of points in the front and rear ends of the plate material and in the width direction, and observing the surface layer of the plate thickness and a plurality of points inside. The sample is cut out from a copper alloy plate to a size of 20 mm × 20 mm, and the surface is mirror-polished and electrolytically polished, and then observed with a scanning electron microscope (SEM). At this time, the magnification is 1000 times or more, and in some cases, a plurality of points are observed so as to have a field of view of 300 μm square. The size of the dispersion shall be the diameter measured at the time of SEM observation. Further, in some cases, the measurement of the number of other dispersions existing in the surrounding region within a radius of 10.0 μm of each dispersion having a diameter of 0.1 to 3.0 μm is observed at a high magnification of 1000 times or more. The method was performed by counting the size and number of the dispersions.

[Manufacturing method of copper alloy plate]
Next, a preferable manufacturing method of the copper alloy plate material of the present invention will be described.
First, 2.5 to 6.0% by mass Ni and 0.5 to 2.0% by mass Si are contained, and if necessary, optional additive components Mg, P, Cr, Mn, Co, Zn, A copper alloy material having an alloy composition in which Zr, Ag and Sn are appropriately contained and the balance is composed of Cu and unavoidable impurities is prepared, and this copper alloy material is melted in a high-frequency melting furnace [step 1] and then cast [step 1]. 2] is performed.

In this casting [step 2], the primary, secondary, and tertiary cooling are finely adjusted to perform three-stage cooling, the dumb shape is controlled, the ingot thickness is 150 mm or more, and the size (diameter) of the dispersion and the dispersion It controls the existence (dispersion) state and the like. For example, the cooling rate in the three-stage cooling is preferably 1 to 100 ° C./sec for the primary cooling, 50 to 250 ° C./sec for the secondary cooling, and 100 to 350 ° C./sec for the tertiary cooling. As the cooling method for secondary cooling, it is preferable to select one of two types: water cooling of the mold and direct injection of water into the ingot.

Next, the homogenizing heat treatment [step 3] is performed by heating to a heating temperature of 800 to 1050 ° C. and holding at this heating temperature for 1 to 30 hours. By this homogenization heat treatment, among the dispersions existing in the copper alloy structure, fine dispersions (second phase) having a diameter smaller than 0.1 μm are dissolved.

After that, hot rolling [step 4] with a total processing rate of 80% or more is performed at 1000 ° C. or lower, and after the hot rolling is completed, water cooling [step 5] is started at a temperature of 600 ° C. or higher to rapidly cool (quenching). ).

Next, the surface of the hot-rolled copper alloy plate is face-cut [step 6] of 0.5 mm or more to remove the oxide film on the surface. If the surface scraping amount is less than 0.5 mm, an oxide film may remain on the surface layer.

After that, cold rolling 1 [step 7] is performed so that the number of rolling passes is 4 or more and the total processing rate is 80% or more, and then the end portion in the plate width direction generated by cold rolling 1 is performed. A slit [step 8] for cutting the off-gauge portion is performed.

Next, annealing [step 9] is performed by heating to a heating temperature of 400 to 800 ° C. and holding at this heating temperature for 1 second to 60 minutes. By performing this annealing [step 9], fine dispersions smaller than 0.1 μm generated in the steps before annealing are solid-solved, and the solute element is solid-solved in the solution heat treatment [step 10] of the next step. The degree can be increased. By this annealing [step 9], the dispersion of 0.1 to 3.0 μm slightly diffuses, but does not reach a solid solution.

Then, a recrystallization solution heat treatment [step 10] is performed in which the mixture is heated to a solution temperature of 750 to 980 ° C., which is a high temperature range, held at this solution temperature for 5 seconds to 2 hours, and then rapidly cooled (quenched). The solute element is dissolved by this recrystallization solution heat treatment [step 10]. The grain growth in the recrystallization solution heat treatment [step 10] is carried out by a dispersion of 0.1 to 3.0 μm controlled by casting.

Next, aging precipitation heat treatment [step 11] is performed, in which the mixture is heated to a temperature reached at 300 to 600 ° C., held at this heating temperature for 5 minutes to 10 hours, and then air-cooled. By this aging precipitation heat treatment, the solute element dissolved in the recrystallization solution heat treatment is precipitated as an intermetallic compound.

After that, pickling [step 12] for removing the oxide film generated in the recrystallization solution heat treatment [step 10] and the aging precipitation heat treatment [step 11], transfer of minute roll scratches generated in the rolling process, and transfer of minute roll scratches generated in the rolling process. In order to remove the indentation of fine foreign matter (contamination), the surface polishing [step 13] is sequentially performed with a buff of No. 1000 to 3000. As a result, a smooth copper alloy plate material can be obtained.

In addition, when fine adjustment of the material strength is required, it is preferable to further perform cold rolling 2 [step 14] of 2 passes or more at a rolling processing rate of 5 to 50%, but it is constant by the previous step. If the strength of is obtained, it may be omitted. When strain removal is required, it is preferable to perform final annealing [step 15] of heating to a temperature of 300 to 600 ° C. and then rapidly cooling (quenching), but cold rolling 2 [step 14] is performed. If not, it may be omitted.

<Characteristics of copper alloy plate material>
The copper alloy plate material of the present invention can satisfy the characteristics required when used as a component for electric / electronic devices and a component for automobiles, particularly as a terminal, and examples thereof are as follows.
(I) The tensile strength is 700 to 1050 MPa, preferably 740 to 960 MPa, and more preferably 780 to 940 MPa.
(II) The bending workability is preferably such that the ratio R / t of the bending radius R and the plate thickness t of 90 ° W bending in the vertical direction of rolling is 2.0 or less, with a plate thickness of 0.1 mm and a width of 1.0 mm. It is 1.75 or less, more preferably 1.5 or less.
(III) fatigue resistance, due fatigue test method shown in FIG. 1, the number of repetitions of when measured at a load stress 500MPa is at least 10 ⁶ times, more preferably not less than 10 ⁷ times.
(IV) The conductivity is 26% IACS or higher, preferably 28% IACS or higher, and more preferably 30% IACS or higher. The above% IACS represents the conductivity when the resistivity of 1.7241 × ^10-8 Ωm of International Annealed Copper Standard is 100% IACS.

Further, the measurement conditions for the characteristics of (I) to (III) above are all as described in Examples unless otherwise specified, and the measurement conditions for the characteristics of (IV) above are 20 ° C. (± 0). The conductivity (% IACS) was calculated by measuring the specific resistance by the four-terminal method (distance between terminals: 100 mm) in a constant temperature bath kept at (5.5 ° C.).

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

(Examples 1 to 16 of the present invention and Comparative Examples 1 to 9)
Examples 1 to 16 of the present invention and Comparative Examples 1 to 9 contain a copper alloy material containing Ni, Si and necessary optional additive components, respectively, and the balance is Cu and unavoidable impurities so as to have the compositions shown in Table 1. It was melted in a high-frequency melting furnace [step 1], and this was cast by cooling under the conditions shown in Table 2 [step 2] to obtain an ingot. Of these, as shown in Table 2, the cooling method for the secondary cooling was one of two methods: water cooling of the mold and direct injection of water into the ingot. Thereby, the shape of the boundary line between the liquid phase and the solid phase was adjusted, and the diameter (μm) of the dispersion (second phase) composed of each element and the existence (dispersion) state of them were controlled. In Comparative Example 9, the cooling in the casting [step 2] is not controlled.

In Examples 1 to 16 of the present invention, the obtained ingot was homogenized at 800 to 1050 ° C. for 1 minute to 30 hours [step 3], and then at 1000 ° C. or lower, the total processing rate was 80. Hot working [step 4] was performed so as to be% or more. Then, it was water-quenched (corresponding to water cooling [step 5]), and surface milling of 0.5 mm or more [step 6] was performed to remove the oxide scale. Then, cold rolling 1 [step 7] was performed so that the total processing rate was 80% or more. Next, after performing a slit [step 8] to remove the off-gauge in the width direction generated by rolling, 0.1 μm generated up to this step in order to increase the solid solubility of the solute element in the solution heat treatment. In order to dissolve the following dispersion as a solid solution, annealing [step 9] is performed at the reaching temperature and holding time shown in Table 2. Here, the dispersion of 0.1 to 3.0 μm slightly diffuses but does not dissolve in solid solution. Next, a recrystallization solution heat treatment [step 10] is performed at an ultimate temperature of 750 to 980 ° C. for the purpose of solid solution of the solute element. Next, in order to precipitate solute elements dissolved in the recrystallization solution heat treatment [step 10], an aging precipitation heat treatment [step 11] is performed. Then, in order to remove the oxide film and remove surface scratches, pickling [step 12] and surface polishing [step 13] are performed, and cold rolling 2 [step 14] of 2 passes or more at 5 to 50% and final. Annealing [step 15] is performed. Through the above steps, a copper alloy plate material was used as a test material. Here, the final plate thickness of the test material was 0.1 mm. Table 3 shows the metallographic structure and evaluation characteristics of each example.

On the other hand, for each Comparative Example, a test material was produced in the same manner as in each Example except that the above-mentioned production conditions were changed as shown in Table 2. Table 3 shows the metallographic structure and evaluation characteristics of each comparative example.

The following characteristics were evaluated for each test material.

a. Measurement of dispersion The diameter and presence (dispersion) state of the dispersion are measured by sampling multiple points in the width direction at the front and rear ends of the plate material and observing multiple points on the surface layer and inside of the plate thickness. The sample is cut out from a copper alloy plate to a size of 20 mm × 20 mm, and the surface is mirror-polished and electrolytically polished, and then observed with a scanning electron microscope (SEM). At this time, the magnification is 1000 times or more, and in some cases, a plurality of points are observed so as to have a field of view of 300 μm square. The size of the dispersion shall be the diameter measured at the time of SEM observation. Further, in some cases, the measurement of the number of other dispersions existing in the surrounding region within a radius of 10.0 μm of each dispersion having a diameter of 0.1 to 3.0 μm is observed at a high magnification of 1000 times or more. The method was performed by counting the size and number of the dispersions.

b. Fatigue resistance The fatigue characteristics were measured in the parallel and vertical directions of rolling in accordance with JCBA T308: 2001 (Fatigue characteristics test method for copper and copper alloy thin sheet strips). An explanatory diagram is shown in FIG. 1 (leaf spring fatigue test). One end of the test piece 1 is sandwiched and fixed by the fixing portion 2, and the other end is sandwiched and bent by the knife edge 2 vibrating in the vertical direction. The width of the test piece 1 is 10 mm ± 0.2 mm, and the fixing torque of the test piece 1 is 2 N ・ m at the lower part and 3 N ・ m at the upper part of the fixed portion 3. The load stress value of the test piece 1 was calculated by the following formula (a).
A repeated test of double swing with a single amplitude of 2.0 mm was performed under a load stress of 500 MPa, and the number of repetitions (times) until the material broke was determined. Number of repetitions until fracture, a shows the above both 10 ⁶ times parallel to the rolling direction (RD) and the rolling direction perpendicular (TD) to a acceptable level, parallel to the rolling direction (RD) and rolling vertical (TD) at least 1 hand has rejected those of less than 10 ⁶ times. As the fatigue tester, a thin plate fatigue tester (model AST52B) manufactured by Akashi Seisakusho was used.

σ = (3 × E × t × δ) / (2 × l ² ) ・ ・ ・ (a)
Here, in the reference numerals in the formula (a), "σ" is the maximum bending stress (N / mm ² ), "E" is the deflection coefficient (N / mm ² ), and "t" is the test piece thickness (mm). “Δ” is the amount of deflection (one piece amplitude given to the test piece) (mm), and “l” is the test piece set length (mm).

c. 90 ° W bending test It was punched by a press so that the width was 1.0 mm and the length was 25.0 mm perpendicular to the rolling direction. W-bent so that the bending axis is perpendicular to the rolling direction is called GW (Good Way), and W-bent so that it is parallel to the rolling direction is called BW (Bad Way), and 90 ° W bending is performed. After that, 180 ° close contact bending was performed with a compression tester. The bent surface was observed with a scanning electron microscope (magnification: 100 times) to investigate the presence or absence of cracks. Those without cracks were judged as "○", and those with cracks were judged as "x".

d. Tensile strength Three test pieces of JIS Z2201-13B cut out from the direction parallel to rolling were measured according to JIS Z2241, and the average value was shown. In this example, the case where the tensile strength TS was 700 MPa or more was regarded as acceptable.

e. Conductivity [EC]
The conductivity was calculated by measuring the specific resistance by the four-terminal method in a constant temperature bath kept at 20 ° C. (± 0.5 ° C.). The distance between the terminals was set to 100 mm. The conductivity was 26% IACS or higher.

f. Stress Relaxation Characteristics According to JCBA T309: 2001 (provisional: former Japan Electronic Materials Industry Association standard EMAS-3003), measurements were taken under the conditions after holding at 150 ° C for 1000 hours as shown below. An initial stress of 80% of the yield strength was applied by the cantilever method. The stress relaxation resistance was 20% or less.

2A and 2B are explanatory views of a test method for stress relaxation characteristics, in which FIG. 2A shows a state before heat treatment and FIG. 2B shows a state after heat treatment. As shown in FIG. 2A, the position of the test piece 1 when the initial stress of 80% of the proof stress is applied to the test piece 1 held cantilevered on the test table 4 is a distance of δ0 from the reference. .. After holding this in a constant temperature bath at 150 ° C. for 1000 hours (heat treatment in the state of the test piece 1) and removing the load, the position of the test piece 2 is Ht from the reference as shown in FIG. 2 (b). The distance. Reference numeral 3 denotes a test piece when no stress is applied, and the position thereof is the distance of H1 from the reference. From this relationship, the stress relaxation rate (%) was calculated as {(Ht−H1) / δ0} × 100. In the formula, δ0 is the distance from the reference to the test piece 1, H1 is the distance from the reference to the test piece 3, and Ht is the distance from the reference to the test piece 2.

Table 3 shows the evaluation results.

From the results shown in Table 3, Examples 2, 4, 6 to 9, 11 to 16 of the present invention all have an alloy composition range, an average diameter of the dispersion, the number of dispersions present in the measurement field of 300 μm square, and Since all of the number of other dispersions present in the peripheral region within a radius of 10.0 μm of each dispersion having a diameter of 0.1 to 3.0 μm is within the appropriate range of the present invention, the strength is high. It had excellent fatigue resistance, bending workability, and stress relaxation resistance, and its conductivity was at the acceptable level.
On the other hand, in Comparative Examples 1 to 4, 7 to 9, the alloy composition range, the average diameter of the dispersions, the number of dispersions existing in the measurement field of 300 μm square, and the dispersions having a diameter of 0.1 to 3.0 μm are shown. Since at least one of the number of other dispersions existing in the peripheral region within a radius of 10.0 μm of the object is outside the appropriate range of the present invention, the bending workability is inferior, and in addition, the strength and fatigue resistance characteristics It can be seen that at least one property of stress relaxation resistance and conductivity is also inferior.

According to the present invention, it has become possible to provide a copper alloy plate material and a connector having high strength, excellent bending workability and fatigue resistance. In particular, this copper alloy plate material is suitable for use in parts for electrical and electronic equipment and parts for automobiles, such as connectors, lead frames, actuators, heat radiating members, relays, switches, and sockets. Further, according to the method for producing a copper alloy plate material according to the present invention, the copper alloy plate material can be suitably produced.

1 Test piece 2 Knife edge 3 Fixed part 10 Test piece under stress load 20 Test piece after stress application and heat treatment 30 Test piece without stress load 40 Test stand

Claims (5)

Contains 2.5-6.0 mass% Ni and 0.5-2.0 mass% Si, and 0-0.2 mass% Mg, 0-0.01 mass% P, 0-0.2 mass % Cr, 0 to 0.2% by mass Mn, 0 to 1.5% by mass Co, 0 to 1.5% by mass Zn, 0 to 0.01% by mass Zr, 0 to 0.17% by mass Ag and 0 to 0 A copper alloy plate material containing at least one component selected from the group consisting of 0.5% by mass Sn in a total of 0 to 2.0% by mass and having an alloy composition in which the balance is Cu and unavoidable impurities.
In the copper alloy plate material, a dispersion composed of a plurality of elements is present.
The dispersion has an average diameter of 0.1 to 3.0 m, there 10 ³ or more 10 ⁵ or less to 300μm square in the measurement field of view, and a diameter of each dispersion 0.1 to 3.0 m the state, and are the number is not more than one other dispersion existing around the area within a radius 10.0μm in diameter each dispersion 0.1 to 3.0 m,
Copper alloy sheet having an average crystal grain size of the copper alloy sheet is characterized in der Rukoto below 30 [mu] m. 0.01 to 0.2 mass% Mg, 0 to 0.01 mass% P, 0.01 to 0.2 mass% Cr, 0.01 to 0.2 mass% Mn, 0 to 1.5 mass% Co , 0.5-1.5 mass% Zn, 0-0.01 mass% Zr, 0-0.17 mass% Ag and 0.01-0.5 mass% Sn at least one component selected from the group. The copper alloy plate material according to claim 1, which contains 0.05 to 2.00% by mass in total. Wherein the leaf spring fatigue test of the copper alloy sheet, the number of repetitions is at least 10 ⁶ times when repeated until rupture by applied stress 500 MPa, the copper alloy sheet according to claim 1 or claim 2. In the 90 ° W bending test of the copper alloy plate material, the ratio (R / t) of the bending radius R of the 90 ° W bending in the vertical direction of rolling and the plate thickness t when the plate thickness is 0.1 mm and the width is 1.0 mm. The copper alloy plate material according to any one of claims 1 to 3, wherein the value is 2.0 or less. The connector made of the copper alloy plate material according to any one of claims 1 to 4.