JP2006283059A - High strength copper alloy sheet with excellent bendability, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a Corson (Cu-Ni-Si based) copper alloy sheet having ≥700 N/mm<SP>2</SP>proof stress, ≥35% IACS electric conductivity and excellent bendability. <P>SOLUTION: The copper alloy sheet has a composition containing 2.5 to <6.0% (by mass, the same applies to the following) Ni and 0.5 to <1.5% Si under the condition that the mass ratio between Ni and Si, Ni/Si, ranges from 4 to 5, further containing 0.01 to <4% Sn and having the balance Cu with inevitable impurities and also has a crystalline texture having ≤10μm average grain size and containing ≥50% crystals with a cubic orientation ä001}<100> by ratio when measured by the SEM-EBSP method. The copper alloy sheet can be manufactured by performing continuous annealing to form a solution heat treated recrystallized structure, carrying out cold rolling at ≤20% draft and aging treatment at 400 to 600°C for 1 to 8 h, successively applying final cold rolling at 1 to 20% draft, and then carrying out short-time annealing at 400 to 500°C for ≤30 sec. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a high-strength copper alloy plate excellent in bending workability used for electrical / electronic parts such as terminals, connectors, wire harnesses, terminals, relays, switches, and spring materials, and a method for producing the same.

Conventionally, a Be copper alloy (CDA17410: Cu-0.3Be) has been used for the above applications. This alloy tensile strength: 800 N / mm ² or more, proof stress: 700 N / mm ² or more, conductivity: is utilized as fine spring material for excellent in bending workability in 30% IACS about. However, while this field has expanded rapidly due to the recent spread of mobile phones and personal computers, it is dissolved due to environmental problems of Be (Be is easy to oxidize and the generated oxide is harmful to the human body). Manufacturing processes such as casting and heat treatment require careful attention, and in particular, the amount of production is limited because special equipment is required for melt casting, and supply shortages are a problem as demand increases. It has become to. There is also the problem of high prices.

For this reason, a Corson alloy (Cu—Ni—Si series) having high strength, excellent bending workability, high conductivity, and low cost has come to be used for this kind of electric / electronic parts. This Corson alloy is an alloy in which the solubility limit of nickel silicide compound (Ni ₂ Si) in copper changes significantly with temperature. It is a kind of precipitation hardening type alloy that hardens by quenching and tempering. So far, it has been widely used for various conductive springs and high tensile strength electric wires.

  However, also in this Corson alloy, when the strength of the copper alloy material (especially the proof stress necessary for the spring property) is improved, the conductivity and bending workability are also lowered. For example, in Patent Documents 1 to 3 below, a high-strength copper alloy plate made of a Corson alloy and excellent in bending workability has been proposed, but even in these improved Corson alloys, the strength of the copper alloy material is improved. After all, conductivity and bending workability are lowered. As for the bending workability, it is not possible to cope with severe bending work (so-called BW) performed particularly with a bending line parallel to the rolling direction. That is, in a high-strength Corson alloy, it is a very difficult task to simultaneously realize high conductivity, high strength, and bending workability.

On the other hand, in the Cu—Fe—P copper alloy for lead frames, B. W. It has been proposed to improve the bending workability by controlling the texture for severe bending processes such as the above. For example, in Patent Documents 4 and 5, in the texture of the Cu-Fe-P-based copper alloy, by controlling the orientation density of the Cube orientation that is too strongly developed by a normal manufacturing method, and controlling it to an appropriate range, We are trying to achieve improved bending workability and stabilization. This is because it aims at uniform deformation during deformation during bending such as stamping in semiconductor lead frame applications.
However, Cu-Fe-P-based copper alloy lead frame disclosed in Patent Document 4 and 5, yield strength only 400~500N / mm ² level, alternative proof stress 700 N / mm ² or more Be copper alloy Compared with Corson alloy aiming for the strength, the strength level is remarkably low, and the alloy system is completely different.

Japanese Patent No. 049137 JP-A-6-184680 JP 2002-266042 A JP 2002-339028 A JP 2000-328157 A

The present inventors previously described in Japanese Patent Application No. 2004-346766, Ni: 2.0 to 6.0%, and Corson containing Si in a mass ratio Ni / Si of Ni / Si in the range of 4-5. For the alloy, cold rolling before the final solution treatment is performed at a processing rate of 95% or more, and after the final solution treatment, the cold rolling is performed at a processing rate of 20% or less, and then an aging treatment is performed. A copper alloy plate having a texture in which the ratio of the orientation {001} <100> is 50% or more, whereby a tensile strength of 700 N / mm ² or more, a high conductivity of 35% IACS or more, and excellent bending workability. It was shown that a copper alloy plate having

However, in the copper alloy plate obtained by the above-mentioned prior application method, there was a problem that bending workability deteriorated when it was attempted to secure a proof stress of 700 N / mm ² or more.
Therefore, the present invention further improves the copper alloy plate of the prior application and the method for producing the same, has a proof stress of 700 N / mm ² or more, an electrical conductivity of 35% IACS or more, and excellent bending workability (Cu— The object is to obtain a (Ni-Si) copper alloy sheet.

The high-strength copper alloy sheet excellent in bending workability according to the present invention is obtained by adding Ni: 2.5% or more and less than 6.0%, and Si: 0.5% or more and less than 1.5% by mass of Ni and Si. The ratio Ni / Si is included in the range of 4 to 5, and Sn: 0.01% or more and less than 4%, and the balance is composed of Cu and inevitable impurities, and the proof stress is 700 N / mm ^2. As described above, it has a texture with a conductivity of 35% IACS or more, an average crystal grain size of 10 μm or less, and a Cube orientation {001} <100> ratio of 50% or more as a result of measurement by SEM-EBSP method. And
The copper alloy preferably further contains Zn: 0.01% or more and less than 3% or / and Mg: 0.001% or more and less than 1%. Further, if necessary, Mn: 0.01% or more and less than 0.1%, Ag: 0.001% or more and less than 1%, Cr: 0.001% or more and less than 1%, Zr: 0.001% One or more of 0.5% or less, Co: 0.01% or more and less than 0.5%, and P: 0.01% or more and less than 0.1% can be contained.

  Moreover, the manufacturing method of the said copper alloy board is hot-rolling and quenching as needed with respect to the copper alloy ingot of the said composition, and then performing cold rolling, performing continuous annealing, and forming a solution recrystallized structure. After obtaining, cold rolling with a processing rate of 20% or less and aging treatment at 400 to 600 ° C. for 1 to 8 hours, followed by final cold rolling with a processing rate of 1 to 20%, followed by 400 to 550 ° C. × 30 It is characterized by performing a short time annealing for less than a second.

According to the present invention, it is possible to obtain a Cu—Ni—Si based copper alloy plate having high strength (particularly yield strength) and electrical conductivity and having excellent bending workability.
Although this copper alloy plate has a proof stress of 700 N / mm ² or more, B.I. W. In the 90 ° W bending process in the direction, cracks do not occur even when R / t = 1 (R: bending radius, t: plate thickness), and the conductivity is 35% IACS or more, and further 500 N / mm ² or more. As a high-grade spring material used for next-generation terminals, connectors, mobile phones, personal computers, etc., it has characteristics that can be substituted for the conventional Be copper alloy plate.

The copper alloy plate according to the present invention will be described in detail below.
First, the reason for adding each additive element and the reason for limiting the composition will be described.
(Ni)
Ni is an element that imparts strength by precipitates (Ni ₂ Si) produced by co-addition with Si. When the content is less than 2.5%, Si is 0.5% or more and less than 1.5%. Even if it is contained, the strength is not improved, and even if it is contained in an amount of 6.0% or more, the strength is not obtained and the conductivity is lowered and it is uneconomical. Therefore, the Ni content is 2.5% or more and less than 6.0%, more preferably 4.01% or more and less than 5.0%.

(Si)
Si, like Ni, is an element that improves strength. If the content is less than 0.5% by weight, no improvement in strength is observed. Reduce. Therefore, the Si content is 0.5% or more and less than 1.5%, more preferably 0.8% or more and less than 1.25%.

(Mass ratio of Ni / Si)
Ni and Si are elements that are co-added to form a precipitate of Ni ₂ Si and contribute to improvement in strength and conductivity. However, in order to improve both the electrical conductivity and strength characteristics, it is necessary to include the equivalents necessary for forming Ni ₂ Si within the range of the respective contents of Ni and Si. When this is expressed in terms of mass ratio Ni / Si, the range is 4-5. If the Ni and Si are excessively contained outside this range, the excess Ni or Si is dissolved in the copper matrix, so that the conductivity is lowered. Moreover, when Si is contained excessively, castability and hot workability will deteriorate, and a casting crack or a rolling crack will arise. On the other hand, when the Si content is small, Ni ₂ Si precipitates are insufficient and the strength cannot be satisfied.

(Sn)
Sn brings about an effect in improving the tensile strength, proof stress, spring limit value, etc., but the effect is not obtained if it is 0.01% or less, and conversely if 4% or more is contained, the anisotropy becomes strong and the bending workability. The electrical conductivity is lowered and is not economical. Therefore, the addition amount of Sn is set to 0.01% or more and less than 4%.
(Zn)
In the alloy of the present invention, Zn is an element effective in improving the migration resistance and the weather resistance of the solder and suppressing the occurrence of whiskers in the Sn plating material. If the Zn content is less than 0.01%, the effect is small, and if the Zn content is 3% or more, the electrical conductivity is lowered and stress corrosion cracking is likely to occur. Therefore, the Zn content is 0.01% or more and less than 3%.

(Mg)
Mg, like Mn, fixes S in the matrix in the form of a stable compound and improves hot workability. Furthermore, even if Mg is a trace amount, it has the effect of improving strength (especially spring limit value) and heat resistance. If the Mg content is less than 0.01%, the effect is not sufficient. Moreover, when the content is 1% or more, the crack becomes a base point at the time of bending, and the crack propagates to deteriorate the formability. Therefore, the Mg content is 0.001% or more and less than 1%.

(Mn)
S and O easily intrude from the raw material, atmosphere, etc. in the melt casting process. In the alloy of the present invention, Mn fixes S and O in the form of a stable compound in the matrix, and then deoxidizes and desulfurizes. , Improve hot workability. Furthermore, Mn has the effect of improving heat resistance. If the Mn content is less than 0.01%, the effect is not sufficient. Moreover, when the content is 0.1% or more, conductivity, bending workability, and solder weather resistance deteriorate. Therefore, the Mn content is 0.01% or more and less than 0.1%.

(Cr)
Cr mainly refines crystal grains to improve the strength and bending workability of the copper alloy sheet. The effect is not recognized if the Cr content is less than 0.001%. On the other hand, if it is 1% or more, cracks occur during hot working, and workability is lowered. Therefore, when it contains, it is made into 0.001% or more and less than 1%.
(Zr)
Zr mainly refines the crystal grains to improve the strength and bending workability of the copper alloy sheet. The effect is not recognized if the content of Zr is less than 0.001%. On the other hand, if the content is 0.5% or more, a compound is formed and cracks occur during hot working, thereby reducing workability. Therefore, when it contains, it is made into 0.001% or more and less than 0.5%.

(Co) Co also mainly refines the crystal grains to improve the strength and bending workability of the copper alloy sheet. The effect is not recognized when the Co content is less than 0.01%. On the other hand, if the content is 0.5% or more, a compound is formed and cracks occur during hot working, thereby reducing workability. Therefore, when it contains, it is 0.01 or more and less than 0.5 weight%.
(Ag)
Ag mainly improves conductivity. Therefore, when it is desired to improve the electrical conductivity, it is selectively contained, but if the content is less than 0.01%, the effect is not recognized. On the other hand, even if it is contained in an amount of 1% or more, the cost is significantly increased and an effect commensurate with the amount added cannot be obtained. Therefore, when it contains, it is made into 0.001% or more and less than 1%.

(P)
P is an element that mainly contributes to improving the soundness of the ingot (deoxidation, hot water flow, etc.). Therefore, if it is desired to improve the soundness of the ingot, it is included. However, when 0.1% or more is added, Ni-P intermetallic compounds are easily precipitated, agglomerated and coarsened, and cracks are generated during hot working. Reduce. Therefore, if included, the content is less than 0.1% by weight.
(Other elements)
Ca, Be, Al, Fe, Ti, V, Nb, Mo, In, Hf, Ta, and B are impurities that deteriorate the characteristics of any element, but the total amount is less than 0.1%. The properties of the alloy plate are not impaired. Accordingly, the total content of one or more of these elements is allowed to be 0.1% or less.

Next, the structure of the copper alloy sheet according to the present invention will be described.
(Average crystal grain size)
In order to achieve the target strength (particularly yield strength) in the copper alloy of the present invention, the average measured in the sheet width direction is measured by the cutting method defined in JIS-H0501 on the rolled surface of the sheet or strip. The crystal grain size is desirably 10 μm or less. If the average crystal grain size exceeds 10 μm, the strength decreases. Therefore, the average crystal grain size is 10 μm or less.

(Gathering organization)
In particular, the alloy plate of the present invention is B.I. W. In order to suppress cracking in the bending process in the direction, it is assumed that the measurement result by the SEM-EBSP method has a texture in which the ratio of the Cube orientation {001} <100> is 50% or more and the Cube orientation is the main orientation. .
In the case of a copper alloy plate, it mainly has a texture called Cube orientation, Goss orientation, Brass orientation, etc. shown below. The formation of these textures varies depending on the processing rate and heat treatment conditions even in the same crystal system. In the case of a texture of a plate material by rolling, the surface and direction are represented by {ABC}, and the direction is represented by <DEF>.

Cube orientation {001} <100>
Goss orientation {011} <100>
Rotated-Goss orientation {011} <011>
Brass orientation (B orientation) {011} <211>
Copper orientation (Cu orientation) {112} <111>
S orientation {123} <634>
B / G direction {011} <511>
B / S orientation {168} <211>
P direction {011} <111>

When the composition ratio of these textures changes, the plastic anisotropy of the plate material changes, and the workability such as bending changes. When the texture of the conventional Corson-based copper alloy is produced by a normal method, the S orientation {123} <634> or the Brass orientation {011} <211> other than the Cube orientation {001} <100> is mainly used. The ratio of the Cube orientation is less than 50%. W. Cracks occurred during bending.
Therefore, in order to prevent the deterioration of the bending workability of the texture of the alloy plate of the present invention, the ratio of the Cube orientation {001} <100> is 50% or more in the measurement result by the SEM-EBSP method, and the Cube orientation is the main orientation. It has a texture that is In the present invention, if the ratio of the Cube orientation {001} <100> is 50% or more, the other Goss orientation {011} <100>, the Rotated-Goss orientation {011} <011>, the Brass orientation {011} <211>, Copper azimuth {112} <111>, S azimuth {123} <634> etc. are allowed to exist as sub-azimuths.

The degree of integration of the Cube orientation {001} <100> is measured by analyzing the orientation using a crystal orientation distribution function (ODF) based on data obtained by measuring an electron microscope structure of 10,000 times using SEM using EBSP. can get. Since these orientation distributions change in the plate thickness direction, it is desirable to take an average of some points in the plate thickness direction.
This SEM-EBSP method is an abbreviation for Scanning Electron Microscopy-Electron Back Scattering Diffraction Pattern Method, which irradiates individual crystal grains appearing on the SEM screen and identifies individual crystal orientations from the diffracted electrons. It is. In the present invention, basically, the deviations within ± 10 ° from these crystal planes belong to the same crystal plane. The crystal orientation identified by the SEM-EBSP method is obtained by analyzing the Cube orientation {001} <100>, {123} (<634>) plane, {110} ({110}) in the orientation analysis using the crystal orientation distribution function (ODF). <112>) The area occupied by each orientation, such as a plane, is obtained, and the ratio of the Cube orientation {001} <100> to the total area, which is the total area occupied by each orientation, is defined as the Cube orientation {001} <100>. The ratio (%).

Next, the manufacturing method of the copper alloy plate which concerns on this invention is demonstrated.
The outline of the manufacturing process is as follows. Casting → hot rolling → cold rolling 1 → solution treatment → cold rolling 2 → aging treatment → cold rolling 3 → short time annealing. If necessary, the cold rolling 1 and solution treatment steps can be repeated (double solution treatment).
Among these, the process of casting to solution treatment is not different from the conventional general method, and after hot rolling, it is rapidly cooled as usual. When a plate-shaped ingot is obtained by horizontal continuous casting, hot rolling can be omitted. Hereinafter, each process after hot rolling is demonstrated concretely.

(Solution)
The solution treatment is a heat treatment for forming a structure formed by the cold rolling 1 into a solution and a recrystallized structure, and it is desirable to perform in a continuous annealing furnace. As conditions, it is desirable to hold at an actual temperature of 800 to 950 ° C. for 30 seconds or less and to cool at a cooling rate of 10 ° C./second or more after holding.

(Cold rolling 1, 2)
Cold rolling 2 is performed at a processing rate of 20% or less. When it exceeds 20%, bending workability is lowered. In the case of many conventional high-strength materials, the processing rate of cold rolling (cold rolling 2) after solution treatment is increased as much as possible for the purpose of improving the strength. When the processing rate is increased here, the texture becomes Cube. The S orientation {123} <634> and the B orientation {011} <211> other than the orientation {001} <100> are mainly used, and the ratio of the Cube orientation is inevitably less than 50%, so that the bending workability is deteriorated.
In the present invention, in order to set the ratio of the Cube orientation to 50% or more, the strength is improved by lowering the processing rate of cold rolling (cold rolling 2) after solution, and continuing aging treatment, contrary to the conventional case. Specifically, the processing rate of cold rolling 1 before solution treatment (final solution formation when solution treatment is performed twice or more) is set to 95% or more, and solution treatment (when solution treatment is performed twice or more is final) It is desirable that the processing rate of the cold rolling 2 after solution treatment is 20% or less. If the processing rate of cold rolling 1 is less than 95%, there is a high possibility that the Cube orientation ratio cannot be secured at 50% or more, and even if the processing rate of cold rolling 2 exceeds 20%, the Cube orientation cannot be secured at 50% or more. High nature.

(Aging)
The aging treatment is a heat treatment for improving strength, elongation characteristics, conductivity, bending workability and the like by recrystallization and age hardening. It is desirable to hold at a body temperature of 400 to 600 ° C. for 1 to 8 hours using a batch furnace and to cool the furnace at a cooling rate of less than 10 ° C./second after the holding. When the holding temperature is lower than this condition or for a short time, recrystallization does not occur and the ratio of the Cube orientation is lowered and the bending workability is not improved, and when the holding temperature is high or for a long time, the crystal grains are coarsened. Yield decreases.
In addition, since the rolling rate of cold rolling 2 is low, the proof stress value is low under this aging condition, and the target value (700 N / mm ² or more) cannot be achieved (Japanese Patent Application No. 2004-346766). Accordingly, the cold rolling 3 and the short annealing process are added to improve the proof stress and the bending workability.

(Cold rolling 3)
The cold rolling 3 is rolling for improving the yield strength, and the processing rate is desirably 1 to 20%. If it is less than 1%, the effect is small, and if it exceeds 20%, high strength (yield strength) and excellent bending workability cannot be achieved at the same time even if annealing is performed for a short time.
(Short time annealing)
The purpose of this short-time annealing is to rearrange the dislocations introduced into the structure in the cold rolling 3 to maintain the yield strength and to recover the elongation and improve the bending workability. It is desirable to carry out in a continuous annealing furnace without recrystallization. It is desirable to hold at an actual temperature of 400 to 550 ° C. for 30 seconds or less and to cool at a cooling rate of 10 ° C./second or more after holding. When the holding temperature is lower than this condition, the elongation is not recovered and bending workability is inferior, and when the holding temperature is high or for a long time, recrystallization occurs and the proof stress and spring property become inferior.
In addition, in this short-time annealing, the present inventors have found that maintenance of yield strength and improvement of bending workability are closely related to conductivity. That is, high proof stress and excellent bending workability are ensured in a state where the electrical conductivity after the short time annealing is lowered in the range of 0.5 to 3% IACS with respect to the electrical conductivity before the short time annealing. Conductivity: Good bending workability cannot be ensured if the decrease is less than 0.5% IACS, and if the decrease is 3% IACS or more, the yield strength is less than the target 700 N / mm ² . Therefore, it is desirable to perform the short-time annealing so that the range of decrease in conductivity is 0.5 to 3% IACS, which is realized within the range of the holding temperature and holding time.

Examples of the present invention and comparative examples will be described below. Here, it will be demonstrated about whether the plate material can be produced and the effect of the additive element.
The copper alloys having the compositions shown in Tables 1 and 2 were melted under the charcoal coating in the atmosphere by an electric furnace, and castability was judged. The molten ingot was hot-rolled and finished to a thickness of 15 mm, and it was visually determined whether cracks occurred during hot-rolling.
As a result, No. in the composition range prescribed | regulated to this invention. Nos. 1 to 6 were all castable, and no cracks occurred during hot rolling.
No. outside the composition range defined in the present invention. 7-22, no. 10, 19, 20, 21 and 22 have Si content, Cr content, Zr content, Co content, and P content exceeding specifications, respectively, so that cracks occur during hot rolling, and hot rolling is performed. Canceled and canceled the subsequent steps. No. In No. 11, the Ni / Si ratio was less than specified and excessive Si was dissolved, so that cracking occurred during casting, and the subsequent steps were canceled.

  Subsequently, no. For the hot rolled materials 1-6, 7-9, 12-18, cold rolling and heat treatment under the conditions defined in the present invention (cold rolling 1 → solution annealing continuous → cold rolling 2 → aging treatment → Cold rolling 3 → short-time annealing) was performed to produce a 0.25 mm thick copper alloy sheet. Various material properties of this copper alloy plate were measured and evaluated in the following manner. Moreover, the average crystal grain size and the ratio of the Cube orientation were measured as described above. The results are shown in Table 3.

(Mechanical strength)
Yield strength, tensile strength and elongation were measured with a JIS No. 5 test piece in which the longitudinal direction of the test piece was parallel to the rolling direction.
(Spring limit value)
This was determined by a moment type test using a spring limit value testing machine (MODEL: APT) manufactured by Akashi. The test direction of the material was parallel (LD) to the rolling direction.
(Solder weather resistance)
After soldering based on MIL-STD-202F METHOD 208D, it was bent back at 180 ° with 1 mmφ after 150 ° C. × 1000 Hr in the air, and the presence or absence of peeling of the solder was visually confirmed.
(conductivity)
Conductivity was measured based on JISH0505.

(Migration resistance)
A test piece having a width of 3.0 mm and a length of 80 mm was collected from the plate material. This test piece was used as a set of two sheets.
1 and 2 show a test apparatus for measuring leakage current using the above test piece. 1 and 2, reference numerals 2a and 2b denote test pieces, 3 denotes an ABS resin having a thickness of 1 mm, and 4 denotes a press plate for the ABS resin 3. Reference numeral 5 denotes a clip whose surface is coated with an insulating paint for pressing and fixing the presser plate 4, 6 is a battery, and 7 is an electric wire. The test piece 2a, 2b has an electric wire 7 connected to the end.
A direct current of 14V is applied from the battery 6 to the two test pieces 2a and 2b shown in FIGS. 1 and 2 and immersed in tap water for 5 minutes, followed by drying for 10 minutes, followed by 50 drying tests. The maximum leakage current during that time was measured with a high sensitivity recorder (not shown). If the maximum leakage current is 1 A or less, there is no practical problem.

(Stress corrosion cracking resistance)
A test piece of 0.25 mmt × 12.7 mmw × 150 mml was cut out from the plate material, and a stress corrosion cracking test was performed according to the Thompson method (Materials Research & Standards (1961) 1081). That is, after making the test piece into a loop as shown in FIG. 3, it is exposed to a desiccator filled with 14 wt% ammonia water and filled with saturated vapor at a temperature of 40 ° C. until the test piece breaks. Was measured. If the life until breakage is 40 hours or more, there is no problem.

(Bending workability)
With a B-type bending jig specified in the CESM0002 metal material W bending test, the bending line is set parallel to the rolling direction (BW), and the test material processed to a width of 10 mm and a length of 35 mm is sandwiched between Using a Shimadzu universal testing machine RH-30, bending at 90 ° W with a load of 1 t at R / t = 1 (R: bending radius, t: plate thickness), The presence or absence was evaluated. The evaluation level is ◯ when there is no crack in the bent part, and there is no micro-dent or wrinkle, but there is no crack, but there is a micro-dent or wrinkle that is the starting point of the crack. Those that cannot be bent are marked with x.

(Heat-resistant)
The hardness after heating for 5 minutes at each temperature was measured using a glass furnace, and the temperature at which the hardness decreased to 80% of the hardness before heating was determined. When the temperature is 550 ° C. or higher, the heat resistance is good, and when the temperature is less than 550 ° C., the heat resistance is poor.
(Whisker resistance)
The strip-shaped test piece was bent, and a compressive stress of about 400 N / mm ² was applied and held at room temperature for 3 months. Then, the occurrence of whiskers on the compressed surface was observed with a stereomicroscope.

No. 1 to 6, the proof stress (700 N / mm ² or more), spring limit value (500 N / mm ² or more), bending workability and conductivity (35% IACS or more) are good, and the maximum leakage current value in migration resistance is Low solder resistance, solder weather resistance, stress corrosion cracking resistance, and whisker resistance are also excellent. The average crystal grain size was all 10 μm or less, and the ratios of Cube orientation {001} <100> were all 50% or more.

On the other hand, no. No. 7 is inferior in proof stress and spring limit because the Ni content is below the specified value. No. In No. 8, since the Ni content exceeds the specified value, the conductivity is lowered.
No. No. 9 is inferior in yield strength and spring limit because the Si content is below the specified value.
No. In No. 12, the Ni / Si content ratio exceeded the specified value, so the conductivity was low, the elongation characteristics were inferior, and cracking occurred in bending.
No. Since the Sn content of No. 13 is less than the specified value, sufficient yield strength and spring limit values are not obtained. No. No. 14 had a Sn content exceeding the specified range, so the conductivity was low, the elongation characteristics were inferior, and cracking occurred in bending.
No. No. 15 has good proof stress, electrical conductivity, and bending workability, but the Zn content is less than the specified value, so it is inferior in migration resistance, and in solder weather resistance, solder peeling occurs. Furthermore, whisker generation is observed. No. No. 16 has a Zn content exceeding the specified value, so that the electrical conductivity is lowered, and the stress corrosion cracking property is damaged in a short time.
No. No. 17 has good yield strength, electrical conductivity, and bending workability, but since the Mg content is below the specified value, a sufficient spring limit value cannot be obtained, and the heat resistance is also poor. No. No. 18 has inferior elongation characteristics because the Mg content exceeds the specified value, and cracks are generated in the bending test.

Here, the effect of the process conditions will be verified.
No. in Table 1 The hot rolled material (15 mm thick) having the composition 1 was subjected to cold rolling and heat treatment under the conditions shown in Table 4 to produce a 0.25 mm thick copper alloy sheet. In Table 4, the time for solution annealing, the time for aging treatment, and the time for short-time annealing were the same except those specifically described. No. 1-1 to 1-9 were subjected to cold rolling and heat treatment under the conditions specified in the present invention. For 1-10 to 1-23, any process is different from the prescribed or desirable conditions of the present invention.
Various characteristics of the copper alloy sheet were evaluated in the above manner. The results are shown in Table 5.

No. In 1-1 to 1-9, the ratio between the average crystal grain size and the Cube orientation is within the specified range of the present invention, the proof stress (700 N / mm ² or more), the spring limit value (500 N / mm ² or more), bending work. Property and electrical conductivity (35% IACS or more) are good, and both strength and bending properties conflict with each other.
In addition, No. The electrical conductivity of 1-1, 1-8, and 1-9 before short-time annealing is 42.8% IACS (see No. 1-17), and the electrical conductivity after short-time annealing is 0.7%, respectively. IACS, 0.6% IACS, 2.9% IACS decreased.

On the other hand, no. Since 1-10 has a high solution temperature, the crystal grains are coarsened and the yield strength is lowered.
No. No. 1-11 was performed under conditions where the working rate of the cold rolling 2 exceeded the specified range, so that the ratio of the Cube orientation was lowered and the bending workability was inferior.
No. 1-12 does not recrystallize because the temperature of the aging treatment is below the specified value (average crystal grain size is not measurable), the ratio of the Cube orientation is lowered, bending workability is inferior, and the conductivity is also deteriorated. No. In No. 1-13, since the temperature of the aging treatment exceeded the specified value, the crystal grains became coarse and the proof stress was lowered. No. 1-14 is not recrystallized because the retention time of the aging treatment is less than specified (the average crystal grain size cannot be measured), the ratio of the Cube orientation is lowered, the bending workability is inferior, and the conductivity is also deteriorated.
No. 1-15 is inferior in yield strength since cold rolling 3 is not performed. No. In No. 1-16, since the processing rate of the cold rolling 3 exceeded the regulation, the yield strength was improved but the bending workability was inferior.
No. Since No. 1-17 was not subjected to final short-time annealing, bending workability was inferior, and no improvement in the spring limit value was observed. No. In 1-18, since the temperature for short-term annealing was lower than the specified value, the spring limit value was not sufficiently recovered, the bending workability was not improved, and wrinkles were generated. No. Since 1-19 was a condition in which the temperature of short-time annealing exceeded the specified value, the conductivity was reduced by about 20% compared to before annealing (No. 1-17), the crystal grains were coarsened and the proof stress was also reduced. Yes. No. In 1-20, since the holding time for short-time annealing was longer than specified, the conductivity was reduced by about 20% compared to that before annealing (No. 1-17), the crystal grains were coarsened, and the yield strength was also reduced. ing. No. For 1-21, cold rolling 3 and short-time annealing were not performed, so the yield strength was not improved, the bending workability was not improved, and wrinkles occurred. No. No. 22 is performed under the condition that the processing rate of the cold rolling 2 exceeds the specified value, and since the annealing is not performed for a short time, the ratio of the Cube orientation is lowered and the bending workability is inferior. No. No. 23 was performed under conditions where the processing rate of the cold rolling 2 exceeded the specified value and the temperature of the short-time annealing exceeded the specified value. Therefore, the ratio of the Cube orientation was low, the conductivity decreased, and the crystal grains were coarse. The yield strength is reduced.

It is a top view explaining the test method of migration resistance of an Example. It is the front sectional drawing. It is a side view explaining the test method of the stress corrosion cracking resistance of an Example.

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2a, 2b Test piece 3 ABS resin 4 Holding plate 5 Clip

Claims (5)

Ni: 2.5% (mass%, hereinafter the same) or more and less than 6.0%, and Si: 0.5% or more and less than 1.5%, the mass ratio of Ni to Si, Ni / Si is in the range of 4-5 In addition, Sn: 0.01% or more and less than 4%, the balance is composed of Cu and inevitable impurities, the proof stress is 700 N / mm ² or more, the conductivity is 35% IACS or more, High strength excellent in bending workability characterized by having a texture with an average crystal grain size of 10 μm or less and a Cube orientation {001} <100> ratio of 50% or more as measured by SEM-EBSP method Copper alloy plate. Furthermore, Zn: 0.01% or more and less than 3% are contained, The high-strength copper alloy plate excellent in the bending workability described in Claim 1 characterized by the above-mentioned. Furthermore, Mg: 0.001% or more and less than 1% is contained, The high-strength copper alloy plate excellent in the bending workability described in Claim 1 or 2 characterized by the above-mentioned. Furthermore, Mn: 0.01% or more and less than 0.1%, Ag: 0.001% or more and less than 1%, Cr: 0.001% or more and less than 1%, Zr: 0.001% or more and less than 0.5%, Co: 0.01% or more and less than 0.5%, P: 0.01% or more and less than 0.1% of one kind or two kinds or more are contained. High strength copper alloy sheet with excellent bending workability. The copper alloy ingot having the composition described in any one of claims 1 to 4, after being hot-rolled and rapidly cooled as necessary, cold-rolled and continuously annealed to form a solution recrystallized structure After performing cold rolling at a processing rate of 20% or less and aging treatment at 400 to 600 ° C. for 1 to 8 hours, followed by final cold rolling at a processing rate of 1 to 20%, 400 to 550 ° C. The method for producing a high-strength copper alloy plate excellent in bending workability according to any one of claims 1 to 4, wherein the annealing is performed for a short time of 30 seconds or less.

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