JP7046032B2 - Copper alloys for electronic materials, manufacturing methods and electronic parts for copper alloys for electronic materials - Google Patents

Description

The present invention relates to a copper alloy for electronic materials, a method for producing a copper alloy for electronic materials, and electronic parts, and more particularly to a Cu—Co—Si based alloy, which is a precipitation-curable copper alloy suitable for application to various electronic parts.

Copper alloys for electronic materials used in various electronic components such as connectors, switches, relays, pins, terminals, and lead frames are required to have both high strength and high conductivity (or thermal conductivity) as basic characteristics. Will be done. In recent years, with the miniaturization of electronic devices such as smartphones and tablet PCs, the boards, connectors, and the like mounted on them have become thinner and shorter. The copper alloy used is also required to have high strength and bendability so that the terminal holding strength can be maintained when the connector or the like is miniaturized and it can withstand complicated bending.

Further, as the capacity of batteries of electronic devices increases and the needs for quick charging increase, copper alloys used as power supply terminals tend to be required to have high conductivity from the viewpoint of suppressing heat generation.

Further, stress relaxation characteristics are required for electrical connection connectors of electronic devices. The connectors are electrically connected to each other by elastic contact of materials, but the contact pressure gradually decreases due to the stress relaxation phenomenon in a high temperature environment. When a material having low stress relaxation characteristics is used for the connector, contact failure may occur in a high temperature environment, and the heat generation amount of the connector increases as the contact resistance of the contact portion increases. In particular, as for connectors for in-vehicle use, since the number of connectors mounted around the engine room, exhaust system, etc. is increasing, a copper alloy having good stress relaxation characteristics in a harsher high temperature environment is desired.

Cu—Co—Si alloys and Cu—Co—Ni—Si alloys are examples of copper alloys having high strength, conductivity, bending workability and good stress relaxation characteristics. In these alloys, fine Co—Si and Co—Ni—Si intermetallic compound particles are precipitated in the copper matrix to improve the strength and conductivity.

For example, Patent Document 1 (Japanese Patent No. 5117602) contains 0.5 to 5.0 mass% of any one or two of Ni and Co in total, and 0.2 to 1.5 mass% of Si. , The balance has an alloy composition consisting of copper and unavoidable impurities, and the area ratio of the Cube orientation {100} <001> is 5% or more in the crystal orientation analysis in EBSD (Electron Backscatter Diffraction) measurement. Moreover, the copper alloy plate material characterized in that the area ratio of the NDRDW direction {012} <221> is 10% or less is described. As a result, the copper alloy plate has a low deflection coefficient in the direction perpendicular to the rolling direction, has excellent bending workability, has excellent strength, and has the effect of improving the yield in the manufacturing process of connectors and the like. ..

Further, in Patent Document 2 (Japanese Patent No. 5448763), the total of either one or both of Ni or Co is 0.5 to 5.0% by mass, and Si is 0.2 to 1.5% by mass, respectively. It is a copper alloy material contained and the balance is composed of Cu and unavoidable impurities, and is characterized in that the area ratio of crystal grains in the Cube orientation is 10% or more and the area ratio of crystal grains in the RDW orientation is 10% or more. A copper alloy material for electrical and electronic parts, which has high strength and excellent bending workability, is described. The reason for doing so is that by increasing the Cube direction and the RDW direction, the shear band on the plate surface that causes cracking during bending is reduced.

Further, Patent Document 3 (Japanese Patent No. 5534610) contains 0.7 to 3.0% by mass of Co and 0.1 to 1.0% by mass of Si, and the balance is composed of copper and unavoidable impurities. A Cu—Co—Si alloy strip having a twin boundary frequency of 40 to 70% and an aspect ratio of crystal grain size in the direction perpendicular to rolling of 0.45 to 0.88 is described. The reason why the twinning boundary frequency is set to 40 to 70% is that by controlling the twinning boundary with good atomic consistency between the boundaries to a predetermined ratio, non-uniform deformation is less likely to occur near the boundary, and bending deformation occurs. This is because cracks and wrinkles starting from the vicinity of the boundary are less likely to occur.

Further, Patent Document 4 (Japanese Patent No. 4875768) contains 0.5 to 5.0 mass% of any one or two of Ni and Co in total and 0.3 to 1.5 mass% of Si. The balance is composed of copper and unavoidable impurities, 0.2% proof stress is 600 MPa or more, conductivity is 35% IACS or more, the inner bending radius is the same as the plate thickness, and it is parallel to the rolling direction. And when 90 ° W bending is performed in the vertical direction, cracking does not occur, the stress relaxation rate after applying a stress of 80% of the yield strength and holding at 150 ° C for 1000 hours is within 30%, and EBSD. A copper alloy plate material characterized in that the area ratio of the Cube orientation {001} <100> is 7 to 47% in the crystal orientation analysis in the measurement is described. The reason for doing this is that the plastic deformation develops locally to form a shear deformation zone, and local work hardening causes the formation and connection of microvoids, reaching the molding limit, which is the cause of cracks. This is because, as a countermeasure, it is effective to increase the ratio of the crystal orientation in which work hardening is unlikely to occur in bending deformation.

Japanese Patent No. 5117602 Japanese Patent No. 5448763 Japanese Patent No. 5534610 Japanese Patent No. 4875768

However, electronic components are becoming thinner and shorter, and along with this, the 0.2% proof stress, conductivity, and bending workability required for metal components for electronic materials are also on the rise. It is also expected that the demand for stress relaxation characteristics will increase.

The inventions described in Patent Documents 1 to 3 show improvements in strength and bending workability, but it seems that they cannot sufficiently cope with the case where both higher strength and bending workability are required. Moreover, the stress relaxation characteristics have not been examined.

In the invention described in Patent Document 4, stress relaxation characteristics have been an issue, but the solution thereof is to add sub-additive elements such as Mg, Sn, and Zn, and the effect is limited. , It is considered that it cannot be sufficiently dealt with when there are restrictions on copper alloy materials.

The present disclosure solves the above problems, and is for highly reliable electronic materials having 0.2% proof stress and conductivity suitable for electronic material applications and having improved bending workability and stress relaxation characteristics. The subject is to provide a copper alloy.

As a result of diligent studies, the inventor contained 0.5 to 3.0% by mass of Co and Si in a mass ratio of Co / Si to 3.0 to 5.0, and the balance was copper. In the copper alloy for electronic materials consisting of unavoidable impurities, the ratio of the number of crystal grains in which twins are present among the crystal grains confirmed by EBSD measurement on the rolled surface is 30% or more, and the direction perpendicular to the rolling direction (rolling perpendicular direction ( By setting the ratio of the twin boundary with the TD) to 20 ° or less to the total twin boundary of 40% or more, bending processing is performed while maintaining the 0.2% resistance and conductivity at a high level. It has been found that a highly reliable copper alloy for electronic materials with improved properties and stress relaxation characteristics can be obtained. Then, we have obtained new knowledge that such a copper alloy for electronic materials can be obtained by adding prestraining with a tension leveler at a specific stage of the manufacturing process.

The method for producing a copper alloy for electronic materials, electronic components, and a copper alloy for electronic materials according to an embodiment of the present invention is specified as follows.
(1) Co is contained in an amount of 0.5 to 3.0% by mass, Si is contained in a mass ratio of Co / Si of 3.0 to 5.0, and the balance is composed of copper and unavoidable impurities. Of the crystal grains confirmed by EBSD measurement on the rolled surface, the ratio of the number of crystal grains in which twins are present is 30% or more, and the angle θ with the rolling perpendicular direction (TD) is 20 ° or less. A copper alloy for electronic materials in which a certain twin boundary occupies 40% or more of all twin boundaries.
(2) Further, according to (1), the total of at least one selected from Cr, Mn, Sn, P, B, Zr, Ti, Mg, Al, Fe and Zn is 1.0% by mass or less. Copper alloy for electronic materials.
(3) The copper alloy for electronic materials according to (1) or (2), which further contains Ni in an amount of less than 0.1% by mass.
(3) An electronic component provided with the copper alloy for electronic materials according to any one of (1) to (3).
(4) Co is contained in an amount of 0.5 to 3.0% by mass, Si is contained in a mass ratio of Co / Si of 3.0 to 5.0, and the balance is composed of copper and unavoidable impurities. A method for producing a copper alloy for electronic materials, in which a copper alloy ingot is hot-rolled and then a cold rolling step and a subsequent solution treatment step are performed. In the solution treatment step, the solution treatment is made into a first solution. The treatment and the second solution treatment are performed separately, and the treatment temperature in the first solution treatment is 750 to 900 ° C, the cooling rate is 20 ° C / sec or more, and the treatment temperature in the second solution treatment is 850 to 1000 ° C. The value of the in-core tension is set to 5 to 10 MPa, and a prestrain of 1.5 to 3.0% is added by a tension leveler between the first solution treatment and the second solution treatment. A method for manufacturing copper alloys for electronic materials.

According to the present disclosure, a highly reliable copper alloy for electronic materials having 0.2% proof stress and conductivity suitable for electronic material applications and having improved bending workability and stress relaxation characteristics can be obtained.

FIG. 1 shows a schematic diagram of a crystal grain and a twin interface.

Hereinafter, embodiments of the present invention will be described in detail.
The copper alloy for electronic materials according to the embodiment of the present invention contains 0.5 to 3.0% by mass of Co and has a Co / Si content of 3.0 to 5.0 in a mass ratio of Si. The ratio of the number of crystal grains in which twins are present is 30% or more among the crystal grains contained and the balance is composed of copper and unavoidable impurities and confirmed by EBSD measurement on the rolled surface, and the direction perpendicular to the rolling direction. The ratio of the twin boundary having an angle θ with (TD) of 20 ° or less to the total twin boundary is 40% or more.

(Amount of Co added)
By applying an appropriate heat treatment, Co and Si are precipitated as Co ₂ Si in the matrix phase, and the strength can be increased without deteriorating the conductivity. However, if the Co concentration is less than 0.5%, precipitation hardening becomes insufficient, and even if the other component is added, the desired strength cannot be obtained. Further, when the Co concentration exceeds 3.0% by mass, sufficient strength is obtained, but conductivity, bending workability, and hot workability are deteriorated.

(Amount of Si added)
Si is adjusted so that Co / Si is 3.0 to 5.0 in terms of mass ratio. With the above ratio, both the strength and conductivity after precipitation hardening can be improved. If the above ratio exceeds 5.0, the precipitation of Co ₂ Si in the aging treatment becomes insufficient, and the strength decreases. When the above ratio is less than 3.0, Si that does not precipitate as Co ₂ Si dissolves in the matrix phase, and the conductivity decreases.

(Twin boundary frequency and twin grain boundary angle)
It is necessary that the ratio of the number of crystal grains in which twins are present to the crystal grains confirmed by EBSD measurement on the rolled surface of the copper alloy is 30% or more. It is preferably 35% or more, more preferably 40% or more. At the same time, the ratio of the twin boundary having an angle θ with the rolling perpendicular direction (TD) of 20 ° or less to the total twin boundary is set to 40% or more. It is preferably 45% or more, more preferably 50% or more.

Grain boundaries are classified into large-angle grain boundaries and small-angle grain boundaries according to the orientation difference between adjacent crystal grains. Generally, a crystal grain boundary having an orientation difference of 15 ° or more is called a large angle grain boundary, and a crystal grain boundary having an orientation difference of less than 15 ° is called a small angle grain boundary. Among the large-angle grain boundaries, the grain boundaries with extremely high consistency are called corresponding grain boundaries, and the Σ value is used as an index to indicate the consistency. This Σ value is the reciprocal of the volume ratio of the unit cell of the corresponding lattice to the unit cell of the crystal, and the grain boundary with a low Σ value is a stable grain boundary with a low grain boundary energy. Of these, the Σ3 grain boundaries are twin grain boundaries, which correspond to the annealed twins generated when the Cu—Co—Si alloy is subjected to solution treatment.

FIG. 1 shows a schematic diagram of the interface between crystal grains and twins. Twin grain boundaries occur within one crystal grain shown by the solid line, as shown by the dotted line. Here, the angle formed by the rolling perpendicular direction (TD) and the twin grain boundaries is defined as θ. By increasing the proportion of crystal grains in which twin grain boundaries, which are low-energy grain boundaries with high atomic consistency, are present, bending workability and high-temperature creep characteristics are improved. Furthermore, by increasing the twin boundary where the angle θ between the rolling perpendicular direction (TD) and the twin boundary is 20 ° or less, the strength, bending workability and stress relaxation characteristics are higher than those of conventional copper alloys. Can be compatible.

(Amount of Cr, Mn, Sn, P, B, Zr, Ti, Mg, Al, Fe and Zn added)
Cr, Mn, Sn, Zr, Ti, Mg, Al, Fe and Zn are added in a small amount to improve product characteristics such as strength and stress relaxation characteristics without impairing conductivity. P has a deoxidizing effect, B has an effect of miniaturizing the cast structure, and has an effect of improving hot workability. The effect of the addition is mainly exerted by solid solution to the parent phase, but further effect can be exerted by being contained in the second phase particles. However, if the total concentration of Cr, Mn, Sn, P, B, Zr, Ti, Mg, Al, Fe and Zn exceeds 1.0% by mass, the bending characteristics and stress relaxation characteristics are deteriorated, and the manufacturability is also impaired. Is done.

Therefore, in this embodiment, it is preferable to add Cr, Mn, Sn, P, B, Zr, Ti, Mg, Al, Fe and Zn in a total amount of 1.0% by mass or less. Further, the total of Cr, Mn, Sn, P, B, Zr, Ti, Mg, Al, Fe and Zn is more preferably 0.7% by mass or less, still more preferably 0.5% by mass or less. However, if the total of Cr, Mn, Sn, P, B, Zr, Ti, Mg, Al, Fe and Zn is less than 0.01% by mass, the effect is small, so that Cr, Mn, Sn, P, B and Zr , Ti, Mg, Al, Fe and Zn are preferably 0.01% by mass or more. Further, 0.05% by mass or more is more preferable, and 0.1% by mass or more is further preferable.

(Amount of Ni added)
Ni is precipitated in the matrix phase as Ni ₂ Si by applying an appropriate heat treatment to improve the strength of the alloy. However, since the conductivity is impaired when the concentration of Ni is 0.1% by mass or more, the amount of Ni added is less than 0.1% by mass, preferably 0.02 to 0.08% by mass.

(0.2% proof stress)
In order to satisfy the characteristics required for a predetermined electronic material such as a connector, the 0.2% proof stress in the rolling parallel direction is preferably 575 MPa or more, more preferably 590 MPa or more. The upper limit of the 0.2% proof stress is not particularly limited, but is typically 850 MPa or less for a conductivity of 55% IACS or more. 0.2% proof stress is measured according to JIS Z2241 using a tensile tester.

(conductivity)
The conductivity is preferably 55% IACS or higher. Thereby, it can be effectively used as an electronic material. The conductivity can be measured by the 4-terminal method according to JIS H0505. The conductivity is preferably 60% IACS or higher.

(Production method)
In the Cu—Co—Si alloy as described above, raw materials such as electrolytic copper, Co, and Si are first melted using an atmospheric melting furnace or the like to obtain a molten metal having a desired composition, which is then cast into an ingot. After that, homogenization annealing, hot rolling, first intermediate cold rolling, first solution treatment, second intermediate cold rolling, tension leveler treatment, second solution treatment, aging treatment, final cold rolling, strain relief annealing In this order, a Cu—Co—Si based alloy as described above can be produced. After hot rolling, face cutting can be performed as needed. Further, between each of the above steps, grinding, polishing, shot blast pickling and the like for removing the oxide scale on the surface are appropriately performed.

Here, in the solution treatment step, it is important to perform the solution treatment in two steps and to add prestrain by a tension leveler between the first solution treatment and the second solution treatment. Is. In the prior art, the solution treatment is usually performed only once, and the prestrain is not added by the tension leveler at this stage.

<Manufacturing ingots>
Melting casting is generally carried out in an atmospheric melting furnace, but it can also be carried out in vacuum or in an inert gas atmosphere. After dissolving the electrolytic copper, raw materials are added according to the composition of each sample such as Co and Si, and the mixture is kept for a certain period of time after stirring to obtain a molten metal having a desired composition. Then, after adjusting this molten metal to 1250 ° C. or higher, it is cast into an ingot. In addition to Co and Si, at least one selected from Cr, Mn, Sn, P, B, Zr, Ti, Mg, Al, Fe and Zn may be added so as to have a total of 1.0% by mass or less. can. Further, Ni may be added in an amount of less than 0.1% by mass.

<Homogenization annealing / hot rolling>
Coarse crystals are formed in the solidification process during casting, and coarse precipitates are formed in the cooling process. By performing homogenization annealing at an appropriate temperature and time and then hot rolling, these second-phase particles are re-dissolved in the parent phase. If the homogenization annealing temperature is too low, the coarse second-phase particles cannot be re-dissolved in the parent phase, and the product strength and bending workability are impaired. If the homogenization annealing temperature is too high, the material may dissolve, which is not preferable. Specifically, the homogenization temperature is preferably 950 to 1025 ° C., and the time is preferably 1 to 24 hours.

Since the material may crack when hot rolling is performed at a high temperature, it is preferable to start hot rolling in a temperature range of 960 ° C. or lower. It is also desirable to cool quickly after hot rolling. If the cooling rate is slow, coarse second-phase particles will precipitate. Precipitation of the second phase particles can be suppressed by quenching (= water cooling) to 400 ° C. or lower after the completion of hot rolling. Specifically, the cooling rate up to 400 ° C. is preferably 10 ° C./sec or more.

<First intermediate cold rolling>
Intermediate cold rolling is performed on the ingot after hot rolling. Here, in order to accumulate sufficient machining strain, it is desirable that the workability of the first intermediate cold rolling is 95% or more.

<First solution treatment>
In the first solution treatment, Co and Si are solid-solved in the matrix phase to reduce the stacking defect energy of the alloy. By performing this first solution treatment under predetermined conditions, the formation of annealed twins in the second solution treatment after the subsequent intermediate rolling and tension leveler treatment is promoted. The treatment temperature of the first solution treatment is 750 to 900 ° C. If the temperature is too low, the solid solution amounts of Co and Si are insufficient, and the ratio of crystal grains in which twins are present in the product cannot be controlled within a predetermined range. If the temperature is too high, the solid solution of Co and Si will proceed too much, and the ratio of crystal grains with twins will increase, but the ratio of twin boundaries with θ ≤ 20 ° will be set to a predetermined ratio. I can't control it.

The first solution treatment can be performed at 15 to 300 ° C./sec. If this time is too long or too short, it will be difficult to control the twin state of the product.

Further, from the viewpoint of preventing the precipitation of the second phase particles, it is preferable that the cooling rate after the solution treatment is as high as possible, and specifically, the cooling rate after the first solution treatment is 20 ° C./sec or more. If not controlled in this way, the proportion of crystal grains in which twins are present in the product will decrease.

<Second intermediate cold rolling>
After the first solution treatment, a second intermediate cold rolling is subsequently performed. Here, by setting the workability of the second intermediate cold rolling to 15 to 50%, it becomes easy to control the ratio and direction of twins in the product within a predetermined range.

<Tension leveler processing>
By passing the material through the tension leveler, further strain is applied to the material, which serves as a driving force for generating annealed twins in a predetermined state in the subsequent second solution treatment. It is possible to apply the same degree of strain as the tension leveler processing by rolling processing, but in this case, it is not possible to obtain annealed twins in a predetermined state in the product. Although the reason is not clear, when the tension leveler is used, the material is repeatedly bent and bent back, so that compressive strain is concentrated on the surface layer of the material, resulting in a strain distribution different from that during rolling. This strain distribution is considered to be convenient for the formation of annealed twins.

Normally, the elongation rate of the material when passing the material through the tension leveler for the purpose of shape correction is about 0.1 to 1.0%, but in this manufacturing method, the elongation rate is 1.5 to 3.0%. A high tension is applied so that the plate is passed through. If the elongation rate at the time of passing the tension leveler plate is too high, the ratio of crystal grains in which twins are present in the product decreases. If the elongation is too low, the proportion of twin boundaries of θ ≦ 20 ° in the product will decrease.

<Second solution treatment>
After the tension leveler treatment, a second solution treatment is performed. The purpose of the second solution treatment is to improve the aging hardening ability by dissolving Co and Si in the matrix phase and to form annealed twins. The treatment temperature of the second solution treatment is 850 to 1000 ° C. If it is out of this range, annealed twins in a predetermined state cannot be obtained. In addition, if the temperature is too low, a sufficient amount of aging hardening cannot be obtained, resulting in insufficient product strength. The strength decreases. In addition, it is also important to control the in-core tension during the second solution treatment, and by setting the in-core tension value to 5 to 10 MPa, annealed twins in a predetermined state can be obtained.

<Aging process>
The desired strength and conductivity can be obtained by performing the second aging treatment so that the precipitates of an appropriate size are uniformly distributed. The temperature of the second aging treatment is preferably 450 to 550 ° C. because the conductivity is lowered when the temperature is lower than 450 ° C. and the strength is lowered when the temperature is higher than 550 ° C. The aging treatment time is preferably 1 to 24 hours. The second aging treatment is preferably carried out in an inert atmosphere such as Ar, N ₂ or H ₂ in order to suppress the formation of an oxide film.

<Final cold rolling>
After the aging treatment, the final cold rolling is carried out to introduce dislocations and increase the strength. The higher the degree of rolling, the higher the strength of the material, but if the degree of rolling is too high, the bending workability is impaired. In order to obtain a good balance between strength and bending workability, the rolling workability is set to 10 to 50%, preferably 20 to 40%.

<Strain removal annealing>
After the final cold rolling, strain relaxation annealing is performed to obtain the stress relaxation properties required for application to electronic components. The conditions for strain removal annealing may be conventional conditions, but specifically, it is 0.5 to 60 min at 350 to 550 ° C.

The copper alloy for electronic materials of the present invention can be processed into various copper products such as plates, strips, pipes, rods and wires, and further, the copper alloy for electronic materials can be used for lead frames, connectors, pins and terminals. , Relays, switches, electronic parts such as foil materials for secondary batteries, etc.

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

The copper alloy having the composition shown in Table 1 was melted at 1300 ° C. using a high-frequency melting furnace and cast into an ingot having a thickness of 30 mm. Next, the ingot was homogenized and annealed at 950 ° C. for 3 hours, then hot-rolled to a plate thickness of 10 mm, and quickly cooled in water. Then, after performing the first intermediate cold rolling with a processing degree of 97%, the first solution treatment is performed under the conditions shown in Table 1, the second intermediate cold rolling is performed with a processing degree of 40%, and a predetermined elongation rate is further performed. After the tension leveler treatment, the second solution treatment was performed as shown in Table 1, the aging treatment was performed at 500 ° C. for 12 hours, and then the final cold rolling was performed to obtain a plate having a thickness of 0.1 mm. Finally, strain removal annealing was performed at 500 ° C. under the condition of 10 min.

The following characteristic evaluations were performed on each of the test pieces thus obtained. The results are shown in Table 2.

<Strength (0.2% proof stress)>
A JIS 13B test piece was prepared so that the tensile direction was parallel to the rolling direction, and a tensile test was conducted in parallel with the rolling direction with a tensile tester in accordance with JIS Z 2241 to measure 0.2% strength.

<Conductivity>
The test piece was collected so that the longitudinal direction of the test piece was parallel to the rolling direction, and the conductivity (EC:% IACS) was measured by the 4-terminal method according to JIS H0505.

<Twin boundary frequency and twin grain boundary angle>
The ratio of crystal grains in which twins are present and the ratio of twin boundaries at θ≤20 ° were calculated using EBSD (Electron Backscatter Diffraction) measurement. First, the test piece was cut into 20 mm squares, and the surface of the rolled surface was electropolished for 60 sec at a voltage of 15 V in a solution of 67% phosphoric acid + 10% sulfuric acid. JXA8500F manufactured by JEOL Ltd. is used for the measurement, the rolling surface normal direction (ND: Normal Direction) of the test piece is tilted by 70 ° with respect to the incident electron beam, and the rolling parallel direction (RD: Rolling Direction) of the sample holder is set. It was installed in the direction of inclination, and the inclined surface was irradiated with an electron beam focused on it. The acceleration voltage was 20 kV, the irradiation current amount was 5 × 10 ^-8 A, the working distance was 25 mm, and the measurement was performed at n = 5 with an observation field of view of 500 μm × 500 μm (step width 1 μm). Here, a region where the orientation difference between adjacent measurement points obtained by EBSD is 15 ° or more is defined as a grain boundary, and the Σ3 corresponding grain boundary of each corresponding grain boundary is defined as a twin grain boundary. The ratio of crystal grains in which twins were present and the ratio of twin boundaries with θ ≦ 20 ° to all twin boundaries were determined. The measurement program used was TSL OIM data collection, and the analysis program used was TSL OIM Analysis.

式中、y₀：初期そり（ｍｍ）、y₁：試料高さ（ｍｍ）、y：永久変形量（ｍｍ）である。
温度１５０℃における１０００ｈ後の応力緩和率が２５％以下であり、かつ２５０℃における１０００ｈ後の応力緩和率が６０％以下の時、電子材料として有効に用いることができる。 <Stress relaxation characteristics>
The stress relaxation rate was measured according to JIS-B2712 (2006). A test piece having a width of 10 mm and a length of 100 mm was cut out, and the sample height y ₁ was determined so that a load stress of 80% of the 0.2 proof stress was applied at a gauge point distance of 25 mm. This was heated at temperatures of 150 ° C. and 250 ° C. for 1000 hours and then unloaded, and the stress relaxation rate was calculated from the permanent deformation amount y. Here, the stress relaxation rate is given by the following equation.

In the formula, y ₀ : initial warp (mm), y ₁ : sample height (mm), y: permanent deformation amount (mm).
When the stress relaxation rate after 1000 hours at a temperature of 150 ° C. is 25% or less and the stress relaxation rate after 1000 hours at 250 ° C. is 60% or less, it can be effectively used as an electronic material.

<Bending workability>
A W bending test was carried out in Badway (the bending axis is orthogonal to the rolling direction) and R / t = 1.0 (t = 0.1 mm) according to JIS H3130 (2012), and the outer peripheral surface of the bent portion of this test piece was observed. did. As an observation method, the outer peripheral surface of the bent portion was photographed using a lasertec confocal microscope HD100, and the average roughness Ra (based on JIS-B0601: 2013) was measured and compared using the attached software. When the surface of the sample before bending was observed using a confocal microscope, no unevenness could be confirmed, and the average roughness Ra was 0.2 μm or less. The case where the surface average roughness Ra after bending was 1.0 μm or less was evaluated as ◯, and the case where Ra exceeded 1.0 μm was evaluated as ×.

As shown in Tables 1 and 2, all of Invention Examples 1 to 20 are suitable 0.2 because the first solution treatment, the tension leveler treatment and the second solution treatment under predetermined conditions are appropriately performed. It has% proof stress and conductivity, and bending workability and stress relaxation characteristics can be obtained.

Comparative Examples 1 to 3 are examples in which the first solution treatment temperature or cooling rate does not satisfy the production conditions according to the present embodiment, Comparative Example 4 is an example in which tension leveler processing is not performed, and Comparative Examples 5 and 6 are tension levelers. Examples in which the elongation rate in processing did not satisfy the conditions according to the present embodiment, and Comparative Examples 7 to 10 are examples in which the processing temperature of the second solution treatment or the tension in the furnace did not satisfy the conditions according to the present embodiment. In each case, any of 0.2% proof stress, conductivity, bending workability and stress relaxation characteristics deteriorated.
Since Comparative Examples 11 to 15 do not satisfy the composition of the copper alloy according to the present embodiment, any one of 0.2% proof stress, conductivity, bending workability and stress relaxation characteristics deteriorated.

As described above, according to the present disclosure, a highly reliable copper alloy for electronic materials having 0.2% proof stress and conductivity suitable for use in electronic materials and having improved bending workability and stress relaxation characteristics is provided. It turns out that it can be obtained.

Claims (5)

It contains 0.5 to 3.0% by mass of Co and contains Si in a mass ratio of 3.0 to 5.0, and the balance is composed of copper and unavoidable impurities, and the rolled surface. Of the crystal grains confirmed by EBSD measurement, the ratio of the number of crystal grains in which twins are present is 30% or more, and the angle θ with the rolling perpendicular direction (TD) is 20 ° or less. The ratio of the boundary length to the total twin boundary is 40% or more , 0.2% proof stress is 575 MPa or more, conductivity is 55% IACS or more, and stress relaxation characteristics after 1000 hours at a temperature of 150 ° C are 25% or less . A copper alloy for electronic materials having 0.2% proof stress, conductivity, bending workability, and stress relaxation characteristics required for electronic material applications. The first aspect of claim 1, further comprising at least one selected from Cr, Mn, Sn, P, B, Zr, Ti, Mg, Al, Fe and Zn, the total of which is 1.0% by mass or less. Copper alloy for electronic materials. The copper alloy for electronic materials according to claim 1 or 2, further containing Ni in an amount of less than 0.1% by mass. An electronic component comprising the copper alloy for an electronic material according to any one of claims 1 to 3 . A copper alloy containing 0.5 to 3.0% by mass of Co, containing Si in a mass ratio of 3.0 to 5.0, and the balance being copper and unavoidable impurities. The method for producing a copper alloy for an electronic material according to claim 1, wherein a cold rolling step and a subsequent solution treatment step are performed after hot rolling the ingot.
In the solution treatment step, the solution treatment is divided into a first solution treatment and a second solution treatment, and the treatment temperature in the first solution treatment is 750 to 900 ° C. and the cooling rate is 20 ° C./sec or more. The treatment temperature in the second solution treatment was set to 850 to 1000 ° C, the value of the in-core tension was set to 5 to 10 MPa, and the tension leveler was used between the first solution treatment and the second solution treatment. A prestrain of 1.5 to 3.0% is added, and the ratio of the number of crystal grains in which twins are present to the crystal grains confirmed by EBSD measurement on the rolled surface is 30% or more, and A copper alloy for electronic materials, characterized in that a copper alloy having a ratio of the boundary length of the twin boundary having an angle θ with the rolling perpendicular direction (TD) of 20 ° or less to the total twin boundary is 40% or more. Manufacturing method.

Images