CN102666890B - Cu-Co-Si-based alloy sheet, and process for production thereof - Google Patents

Abstract

The present invention provides a Cu-Co-Si-based alloy plate which is suitable for use in various electronic components, and in particular has excellent uniform adhesion for plating. The copper alloy sheet for electronic materials is a copper alloy sheet for electronic materials that contains Co: 0.5 to 3.0% by mass, Si: 0.1 to 1.0% by mass, and the remainder is composed of Cu and unavoidable impurities. The average crystal grain size at the center of the plate thickness 20 μm or less, and 5 or less crystal grains with a major axis of 45 μm or more in contact with the surface relative to a length of 1 mm in the rolling direction.

Description

Cu-Co-Si alloy plate and its manufacturing method

technical field

The present invention relates to a Cu—Co—Si based alloy sheet that is a precipitation hardening type copper alloy preferably used in various electronic components, and particularly relates to a Cu—Co—Si based alloy sheet excellent in uniform adhesion of plating.

Background technique

Copper alloys for electronic materials used in various electronic components such as connectors, switches, relays, pins, terminals, and lead frames require both high strength and high electrical conductivity (or thermal conductivity) as basic characteristics. In recent years, high integration and miniaturization and thinning of electronic components have been rapidly advanced, and correspondingly, the level of demand for copper alloys used in electronic equipment components has also increased.

From the standpoint of high strength and high conductivity, precipitation-hardening copper alloys are increasingly used as copper alloys for electronic materials instead of solid-solution-strengthened copper alloys such as conventional phosphor bronze and brass. In the precipitation hardening copper alloy, by aging the solution-treated supersaturated solid solution, the fine precipitates are uniformly dispersed, and the strength of the alloy is increased while the amount of solid solution elements in the copper is reduced and the conductivity is improved. Therefore, a material having excellent mechanical properties such as strength and elasticity and good electrical and thermal conductivity can be obtained.

Among precipitation-hardening copper alloys, Ni-Si-based copper alloys generally called Corson alloys are representative copper alloys with high electrical conductivity, strength, and bending workability, and are currently being actively developed in the industry. one of the alloys. In this copper alloy, the strength and electrical conductivity can be improved by precipitating fine Ni—Si-based intermetallic compound particles in the copper matrix.

For the purpose of further improving the properties of Corson alloys, various technological developments have been carried out: addition of alloy components other than Ni and Si, exclusion of components that adversely affect properties, optimization of crystal structure, and optimization of precipitated particles. optimization etc. For example, it is known that the properties are improved by adding Co or controlling the second phase particles precipitated into the matrix, and the following technologies are mentioned as recent improvement technologies of Ni-Si-Co-based copper alloys.

In Japanese National Publication No. 2005-532477 (Patent Document 1), in order to obtain a Ni-Si-Co-based copper alloy excellent in bending workability, electrical conductivity, strength and stress relaxation resistance, the amount of Ni, Si, Co and its The relationship between them is controlled, and the average crystal grain size of 20 μm or less is also described. Furthermore, it is characterized in that in the manufacturing process, the first aging annealing temperature is higher than the second aging annealing temperature (paragraphs 0045 to 0047).

In JP-A-2007-169765 (Patent Document 2), for the purpose of improving the bending workability of a Ni—Si—Co-based copper alloy, the distribution state of the second phase particles is controlled to suppress the coarsening of crystal grains. In this patent document, for a copper alloy in which cobalt is added to a Corson alloy, the relationship between precipitates having the effect of suppressing grain coarsening during high-temperature heat treatment and their distribution state is clarified, and the strength, strength, and Electrical conductivity, stress relaxation properties, bendability (paragraph 0016). The smaller the crystal grain size is, the more preferable it is, and bending workability is improved by being 10 μm or less (paragraph 0021).

Japanese Unexamined Patent Publication No. 2008-248333 (Patent Document 3) discloses a copper alloy for electronic materials that suppresses the generation of coarse second-phase particles in a Ni—Si—Co-based copper alloy. In this patent document, when the generation of coarse second-phase particles is suppressed by performing hot rolling and solution treatment under specific conditions, the desired excellent characteristics can be achieved (paragraph 0012).

prior art literature

patent documents

Patent Document 1: Japanese PCT Publication No. 2005-532477

Patent Document 2: Japanese Patent Laid-Open No. 2007-169765

Patent Document 3: Japanese Unexamined Patent Publication No. 2008-248333.

Contents of the invention

The technical problem to be solved by the invention

Copper alloy boards for electronic materials used in various electronic components such as connectors, switches, relays, pins, terminals, and lead frames are usually plated with Au, but in this case, Ni plating is usually applied as a base. This Ni-based plating is also further thinned along with weight reduction and thinning of parts in recent years.

Therefore, the poor condition of Ni plating, which was not a problem until now, specifically, the poor condition of the Ni-plating portion becoming non-uniform, becomes apparent.

The copper alloys described in the aforementioned Patent Documents 1 to 3 all describe the crystal grain size, but they are completely unaware of the unevenness of the crystal grain size in the depth direction, especially the adhesion between the coarse crystals formed on the surface and the plating. Relationship.

An object of the present invention is to provide a Cu—Co—Si alloy plate to which base plating, particularly Ni plating, can be uniformly adhered.

Methods used to solve technical problems

In order to solve the above-mentioned technical problems, the inventors of the present invention have repeatedly conducted studies, and as a result, found that by substituting Ni for Co in a Cu-Ni-Si alloy plate to make a Cu-Co-Si alloy, it is possible to further improve the relationship with the substrate plating. tightness. Furthermore, it has been found that the surface layer of the Cu-Co-Si alloy sheet is more prone to locally coarsened crystal grains than the interior (thickness center), and coarsened crystals exist on the surface. Coverage (uniform adhesion) will also be reduced. The present invention has the following constitutions.

(1) A copper alloy sheet for electronic materials, which is a copper alloy sheet for electronic materials containing Co: 0.5 to 3.0% by mass, Si: 0.1 to 1.0% by mass, and the remainder consisting of Cu and unavoidable impurities, wherein It is characterized in that the average crystal grain size at the thickness center is 20 μm or less, the length with respect to the rolling direction is 1 mm, and the number of crystal grains in contact with the surface with a major diameter of 45 μm or more is 5 or less.

(2) The copper alloy sheet for electronic materials as described in (1), which further contains a maximum of 0.5% by mass of Cr.

(3) The copper alloy sheet for electronic materials described in (1) or (2), which further contains a total of up to 2.0% by mass of Mg, P, As, Sb, Be, B, Mn, Sn, Ti, Zr , Al, Fe, Zn and Ag in one or two or more.

(4) The method for producing a copper alloy sheet for electronic materials according to any one of (1) to (3), comprising sequentially performing the following steps:

The process of melting and casting ingots;

The process of heating the material at a temperature of not less than 950°C and not more than 1050°C for more than 1 hour, then hot rolling, and ending the hot rolling at a temperature of not less than 700°C;

The intermediate rolling process before solid solution is carried out with the processing degree of the final pass being 8% or more;

Intermediate solid solution process of heating the material at a temperature above 850°C and below 1050°C for 0.5 minutes to 1 hour;

Aging process with heating at 400°C or more and 600°C or less; and

The final rolling process with a working degree of 10-50%.

Description of drawings

[ Fig. 1 ] is a micrograph (magnification: × 200) of a plated surface of a copper alloy sheet of the present invention (invention example 1) subjected to Ni plating.

[ Fig. 2] Fig. 2 is a photomicrograph (magnification: × 200) of a plated surface of a comparative example copper alloy plate (Comparative Example 11) subjected to Ni plating.

[ Fig. 3 ] is an enlarged micrograph (magnification: × 2500) of the plated surface of Fig. 2 .

Detailed ways

(1) The amount of Co and Si added

The added Co and Si form an intermetallic compound in the copper alloy by performing appropriate heat treatment, and even if there are additive elements other than copper, the electrical conductivity is not deteriorated, and high strength can be achieved by the precipitation strengthening effect.

When the addition amounts of Co and Si are respectively Co: less than 0.5% by mass and Si: less than 0.1% by mass, desired strength cannot be obtained. Conversely, when Co: exceeds 3.0% by mass and Si: exceeds 1.0% by mass, although high strength can be achieved, electrical conductivity significantly decreases and hot workability deteriorates. Therefore, the addition amount of Co and Si is Co: 0.5-3.0 mass %, Si: 0.1-1.0 mass %. The amounts of Co and Si added are preferably Co: 0.5 to 2.0% by mass and Si: 0.1 to 0.5% by mass.

(2) The amount of Cr added

During the cooling process of smelting and casting, Cr is preferentially precipitated at the grain boundaries, so that the grain boundaries can be strengthened, cracks are less likely to occur during hot working, and the decrease in yield during manufacturing can be suppressed. That is, Cr that precipitated at the grain boundary during smelting and casting is re-dissolved by solution treatment or the like, and then precipitated particles with a bcc structure containing Cr as the main component or a compound (silicide) with Si are generated during aging precipitation. Among the amounts of Si added to ordinary Ni—Si-based copper alloys, Si that does not contribute to aging precipitation remains in a solid-solution state in the matrix phase, causing a decrease in electrical conductivity. Therefore, by adding Cr as a silicide-forming element and further precipitating Si that does not contribute to aging precipitation as silicide, the amount of solid-solution Si can be reduced, and a decrease in electrical conductivity can be prevented without impairing strength. However, when the Cr concentration exceeds 0.5% by mass, coarse second-phase particles tend to be formed, thereby deteriorating product characteristics. Therefore, a maximum of 0.5% by mass of Cr can be added to the Cu—Co—Si alloy according to the present invention. However, since the effect is small when it is less than 0.01% by mass, it is preferably added in an amount of 0.01 to 0.5% by mass, more preferably 0.09 to 0.3% by mass.

(3) Addition amount of the third element

a) Addition of Mg, Mn, Ag and P

Mg, Mn, Ag, and P are added in small amounts to improve product characteristics such as strength and stress relaxation characteristics without compromising electrical conductivity. The effect of addition is mainly exhibited by solid solution in the matrix phase, but further effects can be exhibited by being contained in the second phase particles. However, when the total concentration of Mg, Mn, Ag, and P exceeds 2.0% by mass, not only the property improvement effect is saturated, but also manufacturability is impaired. Therefore, in the Cu—Co—Si alloy sheet according to the present invention, it is preferable to add one or two or more kinds selected from Mg, Mn, Ag, and P in a total of up to 2.0% by mass. However, since the effect is small when it is less than 0.01% by mass, it is more preferable to add 0.01 to 2.0% by mass in total, further preferably to add 0.02 to 0.5% by mass in total, and typically to add 0.04 to 0.2% by mass in total.

b) Addition amount of Sn and Zn

Sn and Zn are also added in small amounts to improve product properties such as strength, stress relaxation properties, and platability without impairing electrical conductivity. The addition effect is mainly exerted by solid solution in the parent phase. However, when the total of Sn and Zn exceeds 2.0% by mass, not only the property improvement effect is saturated, but also the manufacturability is impaired. Therefore, in the Cu—Co—Si alloy sheet according to the present invention, it is preferable to add one or two selected from Sn and Zn at a maximum of 2.0% by mass in total. However, since the effect is small when it is less than 0.05% by mass, it is preferable to add 0.05 to 2.0% by mass in total, more preferably 0.5 to 1.0% by mass in total.

c) Addition amount of As, Sb, Be, B, Ti, Zr, Al and Fe

Among As, Sb, Be, B, Ti, Zr, Al, and Fe, the addition amount is adjusted according to the required product characteristics to improve product characteristics such as electrical conductivity, strength, stress relaxation characteristics, and platability. The addition effect is mainly exhibited by solid solution in the matrix, and further effects can be exhibited by being contained in the second phase particles or by forming second phase particles of a completely new composition. However, when the total of these elements exceeds 2.0% by mass, not only the property improvement effect is saturated, but also manufacturability is impaired. Therefore, in the Cu-Co-Si alloy sheet according to the present invention, one or more kinds selected from As, Sb, Be, B, Ti, Zr, Al, and Fe may be added in a total of up to 2.0% by mass. . However, since the effect is small when it is less than 0.001% by mass, it is preferable to add 0.001 to 2.0% by mass in total, more preferably 0.05 to 1.0% by mass in total.

When the total addition amount of the above-mentioned Mg, P, As, Sb, Be, B, Mn, Sn, Ti, Zr, Al, Fe, Zn and Ag exceeds 2.0% by mass, since manufacturability is liable to be impaired, it is preferable to make them total 2.0 mass % or less, more preferably 1.5 mass % or less, still more preferably 1.0 mass % or less.

(4) Crystal particle size

It is conventionally known that high strength is obtained when the crystal grain size is small, and in the present invention, the average crystal grain size at the thickness center of the cross-section in the rolling direction is also 20 μm or less. Here, the average grain size at the thickness center is based on JIS H 0501 (truncation method) for determination. The average crystal grain size at the thickness center of the copper alloy sheet of the present invention does not undergo significant relative changes before and after final rolling with a working degree of 10 to 50%. Therefore, as long as the average crystal grain size is 20 μm or less before final rolling, the crystal structure is still finer than that of the sample copper alloy with an average crystal grain size of 20 μm after final rolling. Therefore, even if the crystal structure is too fine to numerically and accurately measure the average grain size after final rolling, by performing final rolling on a sample with an average grain size of 20 μm before final rolling under the same conditions, The product is used as a standard for comparison, and it can also be judged whether the average crystal grain size exceeds 20 μm. In the present invention, "the average crystal grain size at the thickness center of 20 μm or less" is a regulation for confirming the same high strength as in the prior art, and "thickness center" is a term used to indicate the measurement position.

In the prior art, the non-uniformity of crystal grain size, especially the coarsening of crystals on the surface has not been paid special attention, and the adverse effect of the coarsening of crystal grains on the surface on the uniform adhesion of plating is completely unknown. However, the surface layer is the most likely to accumulate strain energy during the rolling process, and the crystals are more likely to be locally coarsened than the inside (thickness center) under normal manufacturing conditions. In addition, in the heat treatment process, the heat histories of the surface layer and the inside may be different, and the crystals may be locally coarsened compared to the inside (thickness center). At this time, it should be noted that the "surface layer" referred to here refers to the range of 25 μm from the surface.

The inventors of the present invention have found that by reducing the coarsened crystal grains on the surface of the Cu—Co—Si alloy sheet, it is possible to obtain a copper alloy sheet for electronic materials in which plating uniformly adheres.

Specifically, the number of crystal grains in contact with the surface and having a major diameter of 45 μm or more after final rolling is 5 or less, preferably 4 or less, more preferably 2 or less, with respect to a length of 1 mm in the rolling direction. When the number exceeds 5, the plating does not adhere uniformly and becomes a defective product in which the plating surface is blurred when observed with the naked eye.

In addition, the number of crystal grains is measured by measuring the number of crystal grains of 45 μm or more in contact with the surface of the cross-section in the rolling direction in a microscopic photograph (magnification: ×400), and dividing the number of crystal grains by the number (10 b) Measure the total length of the surface in the field of view in the range of 2000 μm, and take it as a unit of 1 mm.

Since the copper alloy sheet of the present invention has five or less crystal grains having a major diameter of 45 μm or more on the surface, it is excellent in uniform adhesion of plating. Various plating materials can be applied to the copper alloy sheet of the present invention, and examples thereof include Ni-based plating, Cu-based plating, and Sn-based plating that are generally used for Au-plated substrates.

The plating thickness of the present invention is of course generally used at a thickness of 2 to 5 μm, and shows sufficient uniform adhesion even at a thickness of 0.5 to 2.0 μm.

(5) Manufacturing method

The manufacturing method of the copper alloy sheet of the present invention uses the usual manufacturing process for copper alloy sheets (smelting and casting→hot rolling→intermediate cold rolling→intermediate solid solution→final cold rolling→aging), but the following conditions are adjusted in the process To manufacture target copper alloy plates. In addition, intermediate rolling and intermediate solid solution may be repeated several times as needed.

In the present invention, it is important to strictly control the conditions of hot rolling, intermediate cold rolling, and intermediate solution treatment. The reason for this is that when Co, which is easy to coarsen the second phase particles, is added to the copper alloy sheet of the present invention, the formation and growth rate of the second phase particles greatly affect the holding temperature and cooling rate during heat treatment.

In the smelting/casting process, raw materials such as electrolytic copper, Si, and Co are melted to obtain a molten solution with a desired composition. The melt is then cast into an ingot. In subsequent hot rolling, it is necessary to perform a uniform heat treatment to remove crystallized substances such as Co-Si generated during casting as much as possible. For example, hot rolling is performed after holding at 950° C. to 1050° C. for 1 hour or more. When the holding temperature before hot rolling is less than 950°C, the solid solution is insufficient; and when it exceeds 1050°C, the material may melt.

In addition, when the temperature at the end of hot rolling is less than 700°C, it means that the last pass of hot rolling or the processing of several passes including the last pass is performed at less than 700°C. When the temperature at the end of the hot rolling is lower than 700° C., the inside is in a recrystallized state, and the surface layer ends in a state of receiving working strain. In this state, after cold rolling and solid solution under normal conditions, the inside becomes a normal recrystallized structure, and the surface layer forms coarse grains. Therefore, in order to prevent the formation of coarse crystals in the surface layer, it is desirable to finish hot rolling at 700°C or higher, preferably 850°C or higher, and it is desirable to perform rapid cooling after hot rolling. Quenching can be achieved by water cooling.

After hot rolling, intermediate rolling and intermediate solution are performed by appropriately selecting the number of times and order within the target range. When the processing degree of the final pass of intermediate rolling is less than 5%, since the processing deformation energy is only accumulated on the surface of the material, coarse grains will be generated on the surface layer. In particular, it is preferable to set the intermediate rolling working degree of the final pass to be 8% or more. In addition, controlling the viscosity of rolling oil used for intermediate rolling and the speed of intermediate rolling is also effective for uniformly applying processing deformation energy.

The intermediate solid solution is performed sufficiently to dissolve the crystallized particles during smelting and casting or the precipitated particles after hot rolling, and to remove as much coarse Co-Si and other precipitates as possible. For example, when the solution treatment temperature is lower than 850° C., the solution is insufficient, and desired strength cannot be obtained. When the solution treatment temperature exceeds 1050°C, there is a possibility that the material will melt. Therefore, it is preferable to perform solution treatment in which the temperature of the material is heated to 850°C to 1050°C. The time for solution treatment is preferably 0.5 minutes to 1 hour.

It should be noted that, as a relationship between temperature and time, in order to obtain the same heat treatment effect (for example, the same crystal grain size), it is common knowledge that the time must be shortened at high temperatures and extended at low temperatures. For example, in the present invention, it is preferably 1 to 2 minutes at 950°C, and preferably 0.5 to 1 minute at 1000°C.

Regarding the cooling rate after solution treatment, rapid cooling is generally performed in order to prevent the precipitation of solid-solved second-phase particles.

Next, aging treatment is performed at a temperature of 400° C. to 600° C. to uniformly precipitate fine second-phase particles. When the aging temperature is lower than 400°C, the precipitation of the second phase particles is insufficient, and there is a problem that the desired strength and electrical conductivity cannot be obtained; while when the aging temperature exceeds 600°C, the precipitated second phase particles are coarsened, and there is a problem that the desired strength and electrical conductivity cannot be obtained. A question of strength. The aging temperature is preferably not less than 450°C and not more than 550°C.

The working degree of the final rolling is preferably 10 to 50%, more preferably 30 to 50%. When it is less than 10%, desired strength cannot be obtained. On the other hand, when it exceeds 50%, bending workability will deteriorate.

The copper alloy sheet of the present invention has excellent uniform adhesion of plating since there are no coarse crystal particles on the surface, and can be suitably used for lead frames, connectors, pins, terminals, relays, switches, foil materials for secondary batteries, etc. electronic components.

Example

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

(1) Measurement method

(a) Grain diameter at center of plate thickness: After solution treatment, a standard sample (Co: 1.0% by mass, Si: 0.66% by mass, the remainder being copper). Average grain size according to JIS H 0501 (cutting method) determination. The standard sample was subjected to final cold rolling (processing ratio 15%), and an optical microscope photograph (magnification: ×400) of the plate thickness center of the section in the rolling direction was taken as a reference. Then, visually compare the size of the optical microscope photos (same magnification as the standard) and the standard size of the thickness center after the final cold rolling of each Example (inventive example and comparative example), and when it is large, it is indicated as greater than 20 μm (> 20 μm), Equivalent or hour is expressed as 20 μm or less (≤20 μm).

(b) Observation of grains near the surface

For the surface layer, use the microscope photograph of the cross section of the surface layer in the rolling direction, draw a line parallel to the surface at a position 10 μm deep from the surface layer, find the length of the line, and obtain at least 45 μm in contact with the surface by the line segment method The number of grains with a diameter of 45 μm or more was divided in 10 fields of view by the total number of grains with a grain size of 45 μm or more to obtain the number of grains with a grain size of 45 μm or more relative to 1 mm.

(c) Uniformity of plating adhesion

(Electrolytic Degreasing Sequence)

Electrolytic degreasing is carried out in alkaline aqueous solution with the sample as the negative electrode.

Pickling was performed using a 10% by mass sulfuric acid aqueous solution.

(Ni base plating conditions)

・Composition of plating bath: nickel sulfate 250g/L, nickel chloride 45g/L, boric acid 30g/L

・Coating bath temperature: 50°C

・Current density: 5A/dm ²

・Ni plating thickness is adjusted by electrodeposition time and set to 1.0μm. The plating thickness was measured using a CT-1 electrolytic film thickness meter (manufactured by Densek Co., Ltd.) using electrolyte solution R-54 manufactured by Kokull Corporation.

(Plating adhesion uniformity evaluation)

Take an optical microscope photo of the plated surface (magnification: ×200, field of view: 0.1 mm ² ), and measure and observe the number and distribution state of the plated islands. Evaluations are as follows.

S: None,

A: The number of island-shaped plating is 50 pieces/mm ² or less,

B: The number of island-shaped plating is 100 pieces/mm ² or less,

C: The number of plated islands exceeds 100/mm ² .

In addition, FIG. 1 is an optical micrograph of the plated surface of Example 1 of the present invention, corresponding to "S" class, and Fig. 2 is an optical micrograph of the plated surface of Comparative Example 11, corresponding to "C" class. FIG. 3 is an enlarged photograph (magnification: ×2500) of “island-like plating” observed on the plated surface, and the number of island-like plating in the field of view was measured by counting such an island shape as one.

(d) Strength

A tensile test in the rolling direction was performed to measure the 0.2% yield strength (YS: MPa).

(e) Conductivity (EC; %IACS)

It can be obtained by measuring the volume resistance using a double bridge.

(f) Bending workability

According to JIS H 3130, the W bending test of Badway (the bending axis is in the same direction as the rolling direction) is carried out, and the ratio MBR/t value of the minimum radius (MBR) without fracture to the plate thickness (t) is measured. Bending workability was evaluated by the following criteria.

MBR/t≤2.0 Good

2.0＜MBR/t Poor

(2) Manufacturing method

Copper alloys having the compositions listed in Table 1 were smelted at 1300° C. in a high-frequency melting furnace, and cast into ingots with a thickness of 30 mm. Next, after heating the ingot for 3 hours under the conditions described in Table 1, it was hot-rolled to a plate thickness of 10 mm at the hot-rolling finish temperature (finish temperature), and water-cooled to room temperature immediately after the hot-rolling was finished. Next, in order to remove the scale on the surface, after performing flat cutting to a thickness of 9 mm, the cold rolling of the final pass with a processing degree of 5 to 15%, and the intermediate solid solution process at a material temperature of 900°C for 0.5 minutes to 1 hour are appropriately carried out. A plate with a thickness of 0.15 mm was produced. After the solution treatment, it was quickly cooled to room temperature by water cooling. Next, an aging treatment was performed at 520° C. for 3 hours in an inert atmosphere. Thereafter, each test piece was produced by final cold rolling with a working degree of 15%. Table 1 shows the measurement results of each test piece.

[Table 1]

Compared with the 15% working degree of intermediate rolling in the final pass of Invention Example 1, Invention Example 2 with the same composition was as low as 10%, resulting in the generation of coarse particles on the surface and slightly poor plating uniformity and adhesion. The relationship between Invention Examples 4 and 5 is also the same.

Compared with the finish temperature (temperature at the end of hot rolling) of 750° C. in Invention Example 1, Invention Example 3 having the same composition was as low as 700° C., so the plating uniform adhesion was poor. The relationship between Invention Examples 4 and 6 is also the same.

Compared with the hot rolling start temperature of 950°C and finish temperature of 750°C in Invention Example 1, Comparative Example 11 with the same composition was as low as 800°C and 500°C, resulting in coarse particles on the surface and poor plating uniformity. In addition, when Ni plating was performed on the surface of the copper alloy of Comparative Example 11 with a thickness of 3.0 μm, island-like plating on the plated surface became inconspicuous and was in a state close to “S” class.

The relationship between Inventive Example 4 and Comparative Example 14 is also the same.

In Comparative Example 11, the working degree of intermediate rolling in the final pass was 15%, but in Comparative Example 12 with the same composition, it was as low as 5%, so coarse particles were generated on the surface, and the plating uniformity was poor.

Compared to Inventive Example 7, which had a hot rolling start temperature of 950°C, an end temperature of 750°C, and a working degree of intermediate rolling in the final pass of 15%, Comparative Example 17 with the same composition was lower at 800°C and 500°C. And 5%, so coarse particles are produced on the surface, and the uniform adhesion of plating is poor. The relationship between Inventive Example 8 and Comparative Example 18 is also the same.

Claims (4)

1. a copper alloy for electronic material plate, it is to contain Co:0.5～3.0 quality %, Si:0.1～1.0 quality %, remainder by Cu and copper alloy for electronic material plate that inevitably impurity forms, it is characterized in that, the average crystallite particle diameter at thickness of slab center is below 20 μ m, with respect to rolling direction length 1mm, join with surface and major diameter is that more than 45 μ m crystal grain is below 5.

2. copper alloy for electronic material plate according to claim 1, it also contains the Cr of maximum 0.5 quality %.

3. copper alloy for electronic material plate according to claim 1 and 2, it also contains one kind or two or more in Mg, P, As, Sb, Be, B, Mn, Sn, Ti, Zr, Al, Fe, Zn and Ag of being selected from that amounts to maximum 2.0 quality %.

4. according to the manufacture method of the copper alloy for electronic material plate described in claim 1～3 any one, it comprises and carries out successively following operation:

By the operation of ingot casting melting and casting;

Making material temperature is that 950 ℃ of above and 1050 ℃ of following heating 1 hour are carried out hot rolling after above, and hot rolling end temp is 700 ℃ of above operations;

Intermediate rolling operation take final passage before the solid solution that more than 8% degree of finish carries out;

Making material temperature is 850 ℃ of above and 1050 ℃ of following heating middle solid solution operations of 0.5 minute～1 hour;

More than 400 ℃ and 600 ℃ of timeliness operations that heat below; With

The final rolling process of degree of finish 10～50%.

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