WO2010016429A1

WO2010016429A1 - Copper alloy material for electrical/electronic component

Info

Publication number: WO2010016429A1
Application number: PCT/JP2009/063615
Authority: WO
Inventors: 邦照三原; 亮佑松尾; 立彦江口
Original assignee: 古河電気工業株式会社
Priority date: 2008-08-05
Filing date: 2009-07-30
Publication date: 2010-02-11
Also published as: CN102112640B; KR20110039371A; EP2333128A1; CN102112640A; KR101570556B1; US20110200479A1; JPWO2010016429A1; JP4913902B2; EP2333128A4

Abstract

A copper alloy material for electrical/electronic components containing Co and Si as additional elements, wherein a compound A composed of Co and Si and having an average particle diameter of not less than 5 nm but less than 50 nm is dispersed, and at least one compound selected from the group consisting of a compound B containing one or neither of Co and Si and having an average particle diameter of not less than 50 nm but not more than 500 nm, a compound C containing both of Co and Si and an additional element and having an average particle diameter of not less than 50 nm but not more than 500 nm, and a compound D composed of Co and Si and having an average particle diameter of not less than 50 nm but not more than 500 nm, is also dispersed. The copper alloy material for electrical/electronic components is also characterized in that the matrix copper alloy has a crystal grain size of 3-35 μm, and that the copper alloy material has a conductivity of not less than 50% IACS.

Description

Copper alloy materials for electrical and electronic parts

INDUSTRIAL APPLICABILITY The present invention is applied to connectors and terminal materials for electrical and electronic equipment, particularly high frequency relays and switches for which high conductivity is desired, or electrical and electronic parts such as connectors, terminal materials and lead frames for automobiles. The present invention relates to a copper alloy material.

Up to now, connectors (terminals, relays, switches, etc.) for electronic and electrical equipment include brass (C26000), phosphor bronze (C51910, C52120, C52100), beryllium copper (C17200, C17530), and corson copper alloys (hereinafter simply referred to as “copper alloys”). For example, C70250) has been used.

In recent years, the frequency of currents used in electronic and electrical equipment in which these are used has increased, and high conductivity has been demanded for materials. Therefore, originally, brass and phosphor bronze have low conductivity, and Corson copper shows medium conductivity (EC≈40% IACS) as a connector material, but higher conductivity is required. It is also well known that beryllium copper is expensive. On the other hand, pure copper (C11000) and Sn-filled copper (C14410), which are highly conductive, have a drawback of low strength. Therefore, there is a demand for a copper alloy having tensile strength and bending workability equivalent to those of electrical conductivity exceeding conventional Corson copper.
Here, CXXXXXX is a type of copper alloy defined by CDA (Copper Development Association). Further,% IACS is a unit indicating the conductivity of a material, and “IACS” is an abbreviation of “internationally annealed copper standard”.

In particular, in recent electronic device parts, there are many connectors and terminals that have been subjected to complicated and severe bending as the devices are downsized. This is because the size of the connector is downsized as the size is reduced, but in order to maintain the reliability of the contact, it is desired to have a contact length as long as possible. Connectors and terminals having such a design concept are often referred to as bellows (bellows) bent connectors or terminals. In other words, there is a high demand for installing and installing terminals and connectors bent in a complicated manner in small parts. On the other hand, the material of the connector and terminal used with size reduction becomes thinner. This is also progressing from the viewpoint of weight reduction and resource saving. A thin material is required to have a higher strength than a thick material in order to maintain the same contact pressure.

There are various strengthening methods such as solid solution strengthening, work strengthening, and precipitation strengthening as methods for increasing the strength of copper alloy materials, but generally conductivity and strength are contradictory properties. Among these, it is known that precipitation strengthening is promising as a method for increasing the strength of copper alloys without lowering the conductivity. This precipitation strengthening involves heat-treating an alloy to which elements that cause precipitation are added at a high temperature so that these elements are dissolved in the copper matrix, and then heat-treating at a temperature lower than the temperature at which the element is dissolved. This is a technique for precipitating dissolved elements. For example, beryllium copper, corson copper, etc. employ the strengthening method.

By the way, the above-described bending workability and strength are contradictory properties. Generally, a material having high strength has poor bending workability, and a material having good bending workability has low strength. It is said that increasing the cold rolling rate is effective for increasing the strength, but if the cold rolling rate is increased, the bending workability tends to deteriorate significantly. Until now, beryllium copper, corson copper, titanium copper and the like have been considered to have a good balance between bending workability and strength as precipitation-type copper alloys. However, for beryllium copper, beryllium, which is an additive element, is regarded as an environmentally hazardous substance, and an alternative material is required. Corson copper and titanium copper generally do not have a conductivity of 50% IACS or higher. Applications requiring high conductivity of 50% IACS or higher include, for example, battery terminals and relay contacts to which a high current is applied. In general, a material having high conductivity has excellent heat conduction characteristics, so that a material such as a CPU (integrated arithmetic element) socket or heat sink that requires heat dissipation also has high conductivity. Particularly in recent hybrid vehicles and CPUs that perform high-speed processing, materials having high conductivity and high strength are required.

From such a background, a copper alloy using an intermetallic compound composed of cobalt (Co) and silicon (Si) in consideration of strength, bending workability, and conductivity (thermal conductivity) is attracting attention. A copper alloy that essentially contains Co and Si and related techniques are known as follows.

First, the prior art of a copper alloy that essentially contains Co and Si will be described.
Patent Document 1 describes an alloy that essentially contains Co, Si, Zn (zinc), Mg (magnesium), and S (sulfur). The object in Patent Document 1 is to improve hot workability.
Patent Document 2 describes an alloy containing Co, Si, Mg, Zn, and Sn (tin). Patent Document 3 describes an alloy containing Co, Si, Sn, and Zn as essential components. Incidentally, Patent Document 2 and Patent Document 3, precipitates of Co and Si for (compound) is described with _Co 2 Si compound.
Patent Document 4 describes a Cu—Co—Si alloy. The use of the alloy of Patent Document 4 is a lead frame, and it is described that the type of alloy is a precipitation strengthening type alloy.
Patent Document 5 describes that the size of inclusions precipitated in a Cu—Co—Si alloy is 2 μm or less.
Patent Document 6 describes that a Co ₂ Si compound is precipitated in a Cu—Co—Si alloy.

Patent Documents 1 to 6 all describe only one type (or one size) of an intermetallic compound composed of Co and Si. By the way, with respect to other alloy systems, in particular, so-called Corson copper containing Ni and Si as essential additive elements, there is a knowledge that when two or more kinds of intermetallic compounds are dispersed in a copper alloy, bending characteristics and the like are improved. . As this technique, Patent Documents 7 to 11 are known.

JP-A-61-87838 JP-A 63-307232 Japanese Patent Laid-Open No. 02-129326 Japanese Patent Laid-Open No. 02-277735 JP 2008-88512 A JP 2008-55977 A JP 2006-161148 A JP 2006-265731 A JP 2007-314847 A JP 2008-75151 A JP 2008-75152 A

However, none of the techniques described in each patent document satisfies all of strength, bending workability, and conductivity (thermal conductivity) at a high level.
Patent Document 1 aims to improve hot workability, and there is no description of precipitates (compounds) of Co and Si, and there is no description of strength and conductivity.
In Patent Document 2, there is no description that recrystallization treatment is performed, and it is considered that bending workability is poor.
Patent Document 3 shows a comparatively low value of conductivity of 30% IACS or less in the embodiment.
Patent Document 4 describes a precipitation strengthened alloy, but does not describe a specific compound or its size. Moreover, there is no description that the recrystallization process is performed, and the bending workability is considered to be poor.
In Patent Document 5 and Patent Document 6, there is an example in which bending workability is evaluated under the condition of R / t = 1 where R is the inner bending radius of the material and t is the plate thickness. Therefore, it may be impossible to meet the bending workability required in the future.

Also, the techniques described in Patent Documents 7 to 11 are so-called Corson coppers having Ni and Si as main elements. Since Corson copper and Cu—Co—Si alloy have different components, there are differences such as different temperatures for solution treatment. For example, in the case of Corson copper, when the Ni content is 3 mass% or more, a solution treatment temperature of about 900 ° C. is required, but in the case of a Cu—Co—Si alloy, the amount of Co is about 900 ° C. However, it has been found that only about 1.0 to 1.2 mass% can be sufficiently subjected to a solution treatment. Corson copper with an Ni content of 3 mass% or higher is practically difficult to have a conductivity of 20% IACS or higher when it is desired to obtain high strength and bending properties, and a copper alloy with high conductivity can be obtained. Can not. In other words, Corson copper and Cu—Co—Si alloy have a large difference in solution treatment temperature and characteristics as an alloy, and a new technology that is not an extension of the prior art is required.

Accordingly, the present inventors have added two or more kinds of precipitates (compounds) in a Cu—Co—Si based copper alloy in order to satisfy simultaneously high conductivity, high strength, and good bending workability in the copper alloy material. A specific suitable relationship with the crystal grain size was found by dispersing and controlling the size of the precipitates (and the density if necessary), and further studies were made to complete the present invention.
According to the present invention, the following means are provided:
(1) A copper alloy material for electrical and electronic parts containing Co and Si as additive elements,
Compound A composed of Co and Si having an average particle size of 5 nm or more and less than 50 nm is dispersed, and further, Compound B having an average particle size of 50 nm or more and 500 nm or less that does not contain one or both of Co and Si, and both Co and Si And at least one compound selected from the group consisting of Compound C having an average particle size of 50 to 500 nm and further containing Compound D and Co and Si having an average particle size of 50 to 500 nm. A copper alloy material for electrical and electronic parts, wherein the copper alloy material is dispersed and has a crystal grain size of 3 to 35 μm and a conductivity of 50% IACS or more.
(2) A copper alloy material for electrical and electronic parts containing Co and Si as additive elements,
Compound A composed of Co and Si having an average particle diameter of 5 nm or more and less than 50 nm, Compound B having an average particle diameter of 50 nm or more and 500 nm or less that does not contain one or both of Co and Si, both Co and Si, and other Compound C having an average particle size of 50 nm or more and 500 nm or less containing compound and Compound D having an average particle size of 50 nm to 500 nm composed of Co and Si are dispersed,
The ratio of the dispersion densities of the compounds A to D is 0.0001 ≦ {(dispersion density of compound B + dispersion density of compound C + dispersion density of compound D) / dispersion density of compound A} ≦ 0.1,
A copper alloy material for electrical and electronic parts, characterized in that the crystal grain size of the base copper alloy is 3 to 35 μm and the electrical conductivity is 50% or more.
(3) Furthermore, it contains 0.05 to 1.0 mass% in total of at least one selected from Al, Ag, Sn, Zn, Mg, Mn, and In, and the balance is made of Cu and inevitable impurities. ) Or the copper alloy material for electric and electronic parts according to (2).
(4) Further, at least one selected from Fe, Cr, Ni, Zr, Ti is contained in a total of 0.05 to 1.0 mass%, and the balance is made of Cu and inevitable impurities. (1) to (3 The copper alloy material for electrical and electronic parts according to any one of items 1).
(5) The copper alloy material for electric and electronic parts according to (1) or (2), which contains Co and Si as additive elements, and the balance is made of Cu and inevitable impurities.
(6) The electrical and electronic device according to any one of (1) to (5), wherein the Co content is 0.4 to 2.0 mass% and the Si content is 0.1 to 0.5 mass%. Copper alloy material for parts.
(7) The electric / electronic device according to any one of (1) to (6), wherein an average cooling rate from a solid phase temperature to 500 ° C. during ingot production is 5 to 100 ° C./sec Copper alloy material for parts.
Here, the “average particle diameter (size) of the precipitate (compound)” is the average particle diameter of the precipitate determined by the method described later. The “crystal grain size” is a value measured based on JIS-H0501 (cutting method) described later.

The present invention optimizes the crystal grain size by controlling two or more types of precipitates (compounds) in a Cu—Co—Si alloy exhibiting high conductivity, and has high conductivity, high strength, bending work It is possible to provide a copper alloy material suitable for use in electrical and electronic parts having excellent properties.

The above and other features and advantages of the present invention will become more apparent from the following description.

A preferred embodiment of the copper alloy material of the present invention will be described in detail. Here, the “copper alloy material” means a copper alloy material (which means a mixture of each component element of a copper alloy having no concept of shape) having a predetermined shape (for example, plate, strip, foil, rod, It means something processed into a line). Further, the “base copper alloy” means a copper alloy not including the concept of shape.
In addition, although a board | plate material and a strip are demonstrated as a preferable specific example of copper alloy material, the shape of a copper alloy material is not restricted to a board | plate material or a strip.

First, the technical idea of the present invention will be described. According to the study by the present inventors, in order to obtain a copper alloy material having high strength, high conductivity, and good bending workability, two or more kinds of sizes are different in the Cu—Co—Si alloy. It was found that precipitates (compounds) are necessary, and it is important to adjust the crystal grain size of the base copper alloy to 3 to 35 μm. Further, it was found that controlling the density of the precipitate (compound) is preferable in order to adjust the crystal grain size of the base copper alloy to 3 to 35 μm. Further, among the two types of precipitates having different sizes, a coarse compound having an average particle diameter of 50 nm or more and 500 nm or less can be preferably obtained by appropriately setting a cooling rate at the time of manufacturing the ingot. all right.

In addition, as a copper alloy material suitable for electrical and electronic component applications, the electrical conductivity is 50% IACS or more, and the relationship between the tensile strength and the bending workability is bending when the tensile strength is 550 MPa or more and less than 650 MPa. R / t ≦ 0.5, which is a guideline for workability, R / t ≦ 1 when the tensile strength is 650 MPa or more and less than 700 MPa, R / t ≦ 2 when the tensile strength is 700 MPa or more and less than 750 MPa, and tensile strength Is preferably 750 MPa or more and less than 800 MPa, it is preferable that R / t ≦ 3.
Here, R / t means the result of a W-bending test at a bending angle of 90 ° in accordance with the Japan Copper and Brass Association technical standard “Evaluation method for bending workability of copper and copper alloy sheet strip (JBMA T307)”. Then, the plate material cut in the vertical direction of rolling is subjected to a bending test at a predetermined bending radius (R), and the limit R at which the crack does not occur at the apex is obtained, and normalized by the thickness (t) at that time It is the value. In general, the smaller the R / t, the better the bending workability.
In the copper alloy material for electrical and electronic parts of the present invention, the electrical conductivity is 50% IACS or more. The conductivity is more preferably 55% IACS or more, and even more preferably 60% IACS or more. The higher the conductivity, the better, but the upper limit is usually about 75% IACS. Moreover, in the copper alloy material for electrical and electronic parts of the present invention, it is preferable that the tensile strength and the bending workability (R / t) have the above relationship. Further, the lower limit of the bending workability (R / t) is zero.

In order to obtain a material with high conductivity, high strength, and excellent bending workability as a copper alloy material suitable for electrical and electronic parts, two or more types of intermetallic compounds with different sizes are made of Cu-Co-Si. A technique of dispersing in the alloy is useful.

First, the background of this technology will be described. The copper alloy described here is an example in which the intermetallic compound is one kind of compound containing Co and Si. When Co and Si are added to copper and subjected to an appropriate heat treatment, a so-called precipitation-type copper alloy is formed in which an intermetallic compound composed of Co and Si is precipitated.
In general, the following two heat treatments are always performed as a heat treatment method for exerting the function of the precipitation type copper alloy. The first heat treatment is called a solution (or recrystallization) treatment or a homogenization treatment, and a heat treatment is performed at a relatively high temperature for a short time. The second heat treatment is called aging heat treatment or precipitation treatment, and is performed at a temperature lower than the solution treatment temperature and for a long time.

First, the first heat treatment is performed using a continuous annealing furnace in which a rolled copper alloy sheet is passed through a heat treatment furnace. This is because adhesion occurs when heat treatment is performed at a high temperature while the thin plate is wound in a coil shape, and if the subsequent cooling rate is slow, the dissolved element causes precipitation without control, resulting in precipitation that does not contribute to strength. It is. In addition, since a high temperature furnace is passed through the plate, there is a concern that the plate may be cut. Therefore, heat treatment is performed for a short time.
On the other hand, in the second heat treatment, in order to disperse precipitates (compounds) that contribute to strength uniformly and finely in the copper alloy, the temperature of the heat treatment furnace in which the copper alloy thin plate is wound in a coil shape is controlled. In this, heat treatment is carried out for a relatively long time (specifically, several minutes to several tens of hours), and the optimum precipitate (compound) is sufficiently dispersed by solid phase diffusion treatment.

Therefore, in precipitation-type copper alloys, the temperature during the solution treatment (first heat treatment) is increased as much as possible to increase the amount of solute elements to be dissolved in the copper matrix phase, and the subsequent aging heat treatment (second heat treatment) The copper alloy is strengthened by depositing precipitates (compounds) using the difference in temperature between the two. The higher the temperature of this solution treatment (first heat treatment), the more the amount of solute element dissolved (this increases the amount of precipitation that precipitates during the subsequent second heat treatment). Heat treatment is advantageous, but conversely, coarsening of the recrystallization structure that occurs at the same time adversely affects bending workability. If the crystal grain size is coarse with a copper alloy with high strength, when bending is performed, cracks (cracks) occur in the part, wrinkles (rough skin) unevenness becomes large, and the necessary contact pressure is It cannot be obtained, or the contact portion becomes unstable, so that it is not a copper alloy material suitable for applications such as connectors and terminals. In addition, the grain size at the time of recrystallization becomes coarser as the temperature increases, and as described above, if a high temperature heat treatment is performed in the first heat treatment when trying to increase the solute element, the bending workability deteriorates conversely. . Thus, it can be said that it is extremely difficult to satisfy all of high conductivity, high strength, and good bending workability in a copper alloy material in which the intermetallic compound is one kind of compound containing Co and Si.

Therefore, in the present invention, in order to satisfy all of high conductivity, high strength, and good bending workability, a technique for dispersing two or more types of intermetallic compounds having different sizes in a Cu—Co—Si based alloy is developed. did. A fine compound of 5 nm or more and less than 50 nm made of Co and Si is a compound that contributes to precipitation strengthening. On the other hand, a coarse compound of 50 nm or more and 500 nm or less does not contribute to precipitation strengthening and is a compound that exhibits an effect during the high-temperature solution treatment. This coarse compound cannot be dissolved in the copper matrix even during the high-temperature solution treatment and exists in the copper matrix. Therefore, even if grain growth occurs, the coarse compound becomes an obstacle, causing a state in which grain boundary migration is difficult to occur, and as a result, coarsening of the crystal grain size is suppressed.

In the case of copper alloy, after the raw material is melted (melted), the solidified ingot is used as the starting material, and hot rolling, cold rolling, and various heat treatments are performed to complete the copper alloy material that has the desired characteristics. To do. Various sizes of intermetallic compounds are formed during solidification and hot rolling of the ingot, during its cooling, and during various heat treatments and during its cooling. It is processing. The solution treatment is performed before the aging heat treatment, but only the coarse compound remains during the solution treatment, and the others are dissolved in the copper matrix. That is, only coarse compounds remain in the copper matrix after the solution treatment.
Fine precipitates (compounds) are precipitated by the aging heat treatment in the next step. At this temperature, the size and density of the coarse compound that has been exposed to a high temperature in the pre-heat treatment does not change. In addition, there is a case where a solution heat treatment and an aging heat treatment are continuously performed, and a case where a cold rolling process is sandwiched between them, but in any of these heat treatment processes, there is a change in the size and density of the coarse compound. No.

Compound A having an average particle size of 5 nm or more and less than 50 nm, which is a compound that contributes to precipitation strengthening, is a compound that precipitates by aging heat treatment and improves strength. The compound A is preferably Co ₂ Si, but may contain a compound that does not have a composition ratio of Co ₂ Si (for example, CoSi, CoSi _2, etc.). If the average particle size of compound A is 5 nm or more, the precipitation hardening amount is sufficient, and if the average particle size is less than 50 nm, the strength is sufficient without the disappearance of matching strain. Therefore, the size of the compound A is defined as 5 nm or more and less than 50 nm, and a desirable size is 10 nm or more and 30 nm or less. However, since this compound A varies depending on the observation method, the details are shown in “Examples” below.

Next, compound B is a compound that does not contain one or both of Co and Si, and this contributes little to the strength. Examples of the composition of compound B include Co-x, Si-x, and xy. Here, x and y are elements other than Co and other than Si. If this compound B dissolves and disappears in the copper matrix at the solution treatment temperature, it cannot be used to control the crystal grain size of the base copper alloy. Therefore, this compound B is a compound having a melting point higher than the solid solution temperature (that is, the melting point) of Co ₂ Si which is the main element of the compound A.
When the average particle size of Compound B is 50 nm or more and 500 nm or less, the effect of suppressing (pinning) grain boundary migration at a high temperature is exhibited. Compound B is an inconsistent compound because it has an average particle diameter of 50 nm or more. In order to suppress grain boundary migration of the base copper alloy, Compound B preferably has an average particle diameter of 50 nm to 500 nm. The average particle size of compound B is more preferably 100 nm or more and 300 nm or less. By observation of the structure after the solution treatment, it was confirmed that the grain growth was most suppressed when Compound B was dispersed.

Next, the compound C is a compound containing both Co and Si and other elements, and this also contributes little to the strength. The difference from the compound B is a compound having a composition such as Co—Si—x or Co—Si—xy. Here, x and y are elements other than Co and other than Si. Compound C is also a compound having a melting point higher than the solid solution temperature of Co ₂ Si (that is, the melting point) because it is desired that the compound C is dissolved in the copper matrix during the high-temperature solution treatment and does not disappear. The average particle size of Compound C is preferably 50 nm or more and 500 nm or less in order to obtain the same effect as Compound B. In addition, the average particle diameter of the compound C is more preferably 100 nm or more and 300 nm or less.

Here, the compound B or the compound C may exist in a size of 5 nm or more and less than 50 nm, which is the same average particle diameter as the compound A. Compounds having the same composition as compound B or compound C having an average particle diameter of 5 nm or more and less than 50 nm are substituted with Co as the main element when the element once dissolved in the solution treatment is precipitated. Forms a compound with Si and contributes to strength improvement. For example, Fe, Ni, and Cr among the additive elements are replaced with a part of Co in the main precipitation phase to form a (Co, x) ₂ Si compound (x = Fe, Ni, Cr) to improve the strength. There is a work to make.

Finally, the compound D is a compound composed only of Co and Si, and the component A is the same as that of the compound A. However, there are compounds that are different in size and do not have a composition ratio of Co ₂ Si (for example, CoSi, CoSi ₂ ). Compound D is different from Compound A because of its coarse size, so solution treatment at high temperature and short time does not have enough time for solid solution in the parent phase, and as a result, it remains in the copper parent phase and suppresses grain growth. Demonstrate the function to do. The compound D often has an angular shape, but its particle size is defined as an average particle size.
Therefore, the average particle size of compound D is preferably 50 nm or more and 500 nm or less because compound D seeks the same effect as compound B or compound C. In addition, the average particle diameter of the compound D is more preferably 100 nm or more and 300 nm or less.
The compound B, compound C, and compound D are identified by analyzing their components using an EDS (energy dispersive detector) attached to a transmission electron microscope to determine which compound (precipitate) is. Its size can be measured.

The reason for setting the crystal grain size of the base copper alloy in the present invention to 3 to 35 μm is that if the crystal grain size is 3 μm or more, recrystallization is sufficient and an insufficient recrystallization portion is observed. This is because there is no fear of mixed grains containing crystals and bending workability is improved. Further, if the crystal grain size is 35 μm or less, the grain boundary density is high, bending stress (strain applied) can be sufficiently absorbed, and workability is improved. The crystal grain size of the copper alloy is preferably 10 nm or more and 30 μm or less.
Furthermore, in the present invention, the electrical conductivity of the material is 50% IACS or more. This characteristic is preferably achieved by, for example, setting the Co content to 0.4 to 2.0 mass%, the Si content to 0.1 to 0.5 mass%, and precipitating a Co ₂ Si intermetallic compound. It is a characteristic obtained.

Here, the ratio of the dispersion density of each compound is preferably 0.0001 ≦ {(dispersion density of compound B + dispersion density of compound C + dispersion density of compound D) / dispersion density of compound A} ≦ 0.1. Give the reason. First, coarse compound B, compound C, and compound D that suppress the grain boundary migration of the base copper alloy may be present in combination with compound A, but the ratio of the dispersion density is preferably 0.0001 ≦ {(dispersion density of compound B + dispersion density of compound C + dispersion density of compound D) / dispersion density of compound A} ≦ 0.1. Within this range, the effect of suppressing grain boundary migration is large, and the ratio of coarse precipitates (compounds) that do not contribute to the strength to inhibit migration decreases, so that the purpose of high strength can be sufficiently achieved. The ratio of the dispersion density of each compound is preferably 0.0001 ≦ {(dispersion density of compound B + dispersion density of compound C + dispersion density of compound D) / dispersion density of compound A} ≦ 0.01, More preferably, 0.0001 ≦ {(dispersion density of compound B + dispersion density of compound C + dispersion density of compound D) / dispersion density of compound A} ≦ 0.001.
If the number of the compound B, the compound C, and the compound D (particularly the total number thereof) is too small, deterioration of the bendability of the copper alloy material obtained by crystal grain coarsening may occur.
In the copper alloy material of the present invention, the greater the number of precipitates of compound A, that is, the higher the dispersion density of compound A in the copper alloy material, the higher the strength. Further, the larger the number of precipitates of compound B, compound C and compound D (particularly the total number thereof), that is, (dispersion density of compound B + dispersion density of compound C + dispersion density of compound D) in the copper alloy material. ) Is higher, a copper alloy material having better bendability with respect to strength improvement can be obtained. Regarding the number of these compounds (its dispersion density), it is generally considered that the more the added alloy element component is, the more compounds are obtained if the conditions in the solution treatment and the aging treatment are appropriately adjusted.

Regarding the addition amount of Co and Si in the copper alloy material of the present invention, the reason why Co is set to 0.4 to 2.0 mass% is that a desired strength can be obtained as long as it is 0.4 mass% or more. This is because the solution treatment temperature falls within an appropriate range at less than%, and an extremely difficult manufacturing technique is not required. On the other hand, for Si, the stoichiometric ratio of Co ₂ Si, which is the precipitation strengthening phase of this Cu—Co—Si alloy, is Co / Si≈4.2, and the Si addition range is set accordingly. If the value of Co / Si is 3.5 or more and 4.8 or less, there is no practical problem. When each element of Fe, Ni, and Cr is replaced with a part of Co in the main precipitation phase to form a (Co, x) ₂ Si compound (x = Fe, Ni, Cr), the calculation of the ratio is , (Co + x) /Si≈4.2 (x = Fe, Ni, Cr). Even in that case, there is no practical problem if (Co + x) /Si≈3.5 to 4.8.

The copper alloy material of the present invention may contain elements other than Co and Si.
Al, Ag, Sn, Zn, Mg, Mn, and In are characterized by solid solution in the copper matrix and strengthening. If the added amount is 0.05 mass% or more in total, the effect is obtained, and if it is 1.0 mass% or less, the conductivity is not hindered. A preferable addition amount is 0.2 to 0.4 mass% in total of at least one of these elements.

Zn has the effect of improving solder adhesion, and Mn has the effect of improving hot workability. Addition of Sn and Mg is effective in improving the stress relaxation resistance. Although the effect can be seen even when individual Sn and Mg are added, it is an element that exhibits the effect synergistically when added simultaneously. If the added amount is 0.1 mass% or more in total, the effect is obtained, and if it is 1.0 mass% or less, conductivity is not hindered and conductivity of 50% IACS or more is ensured. On the other hand, the addition ratio of Sn and Mg is also known. In the case of Sn / Mg ≧ 1, the stress relaxation resistance is more excellent. Moreover, since each element of Zn, Mn, Sn, and Mg has the function which becomes x and y of the compound B and the compound C, the grain boundary movement inhibitory effect as the compound B and the compound C is exhibited.

Fe, Cr, Ni, Zr, and Ti are elements that contribute to strength improvement by forming a compound with Si by substitution with Co. That is, each element of Fe, Ni, Cr, Zr, and Ti is substituted with a part of Co of the main precipitation phase, and (Co, z) ₂ Si compound (z = Fe, Ni, Cr, Zr, Ti) Has the effect of improving the strength by forming. If the total amount of these elements is 0.05 mass% or more, the effect of adding at least one of these elements is exhibited. If the amount is 1.0 mass% or less, crystallization occurs during casting or contributes to strength. No intermetallic compound is formed. In addition, since each element of Fe, Cr, Ni, Zr, and Ti also has the function which becomes x and y of the compound B and the compound C, the grain boundary movement inhibitory effect as the compound B and the compound C is exhibited. Even if these elements are added in combination or added alone, substantially the same effect is observed. Desirable addition amount is 0.5 to 0.8 mass% in total of at least one of these elements.
Even if each element of the group consisting of Al, Ag, Sn, Zn, Mg, Mn, In and each element of the group consisting of Fe, Cr, Ni, Zr, Ti are added in combination, the above-mentioned range If it is within, individual properties will not be disturbed.
Examples of inevitable impurities in the copper alloy material for electric and electronic parts of the present invention include H, C, O, and S.

Next, the copper alloy material of the present invention will be described from the viewpoint of the production method.
The copper alloy material of the present invention can be produced, for example, by the following process. The outline of the main production process of the copper alloy material of the present invention is melting → casting → homogenization treatment → hot rolling → face milling → cold rolling → solution heat treatment → aging heat treatment → final cold rolling → low temperature annealing. . Aging heat treatment and final cold rolling may be performed in reverse order. Further, the final low-temperature annealing (strain relief annealing) may be omitted. As conditions for each step, the steps other than those specifically mentioned here can be carried out by a conventional method.
In the present invention, the average cooling rate from the solid phase temperature to 500 ° C. during the production of the copper alloy ingot is 5 to 100 ° C./second. It contributes to precipitation. If this average cooling rate is 5 ° C./second or more and 100 ° C./second or less, Compound B, Compound C, and Compound D are appropriately formed, and as a result, the crystal grain size of the base copper alloy should be in an appropriate range. Can do. Here, the solid phase temperature is a temperature at which solidification starts, and since it becomes a temperature zone in which compound A precipitates at a temperature lower than 500 ° C., the lower limit of the temperature range was set to 500 ° C.
In addition, when the cooling rate after the casting is too slow, the strength may decrease due to an increase in coarse precipitates.

The solution heat treatment temperature is preferably 800 to 950 ° C. when the Co content is 0.4 to 1.2 mass%, 900 to 950 ° C. when 1.3 to 1.5 mass%, and 1.3 to 2%. If it is 0 mass%, sufficient solution and recrystallization can be performed at 900 to 1000 ° C., respectively. The crystal grain size of the base copper alloy is determined by the heat treatment at this temperature. Moreover, it is preferable that the cooling rate from the temperature is rapid cooling of about 50 ° C./second. If this rapid cooling is not carried out, the elements dissolved at the high temperature may cause precipitation. The particles (compounds) that cause precipitation during this cooling are inconsistent precipitates that do not contribute to the strength, and are also formed in the next (or next cold rolling) aging heat treatment step. Sometimes it contributes as a nucleation site, accelerates the precipitation of that part, and adversely affects the properties. This cooling rate means the average rate from the solution heat treatment temperature at high temperature to 300 ° C. Since a large tissue change does not occur at a temperature of 300 ° C. or lower, the cooling rate up to this temperature may be set to a predetermined cooling rate.

In the present invention, an aging heat treatment is performed after the solution heat treatment (recrystallization is also performed together with the solution heat treatment) to form a Co and Si compound in the copper alloy. This heat treatment may be performed after the solution heat treatment or after a predetermined cold rolling. The aging heat treatment is preferably performed at a temperature of 500 to 600 ° C. for 1 to 4 hours after the solution heat treatment and after the final cold rolling after the solution heat treatment. In some cases, a temperature of 450 to 550 ° C. and 1 to 4 hours are preferable. Moreover, there exists a preferable range in the cooling rate after this aging heat processing. When the cooling rate is in the range of 20 to 100 ° C./hour, the increase in conductivity is sufficient. In addition, if the cooling rate is faster than 100 ° C./hour, the increase in conductivity is not sufficient, and even if the cooling rate is slower than 20 ° C./hour, the intended characteristic change does not occur and the heat treatment time is long. It ’s not just economic. On the other hand, the temperature range for the cooling rate is a cooling range from each heat treatment temperature to 300 ° C. If the lower limit of the temperature range is higher than 300 ° C, desired high conductivity cannot be obtained, and the obtained conductivity does not change even if the lower limit of the temperature range is lower than 300 ° C.
The cooling rate after the aging heat treatment can be adjusted by controlling the temperature in a heat treatment furnace. In addition, when it wants to cool rapidly, a sample can be taken out from the heating zone of a heat treatment furnace, and it can respond by forced air cooling or water quenching.

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

Example 1
Alloys containing the components shown in Tables 1 and 2 and the balance of Cu and inevitable impurities (Invention Examples No. 1 to 35, Comparative Examples No. 101 to 128) were melted in a high frequency melting furnace, Casting was performed at a cooling rate of 5 to 100 ° C./second to obtain an ingot having a thickness of 30 mm, a width of 100 mm, and a length of 150 mm. At this time, a thermocouple was set in the vicinity of the casting wall of the mold, and casting and melting were performed while measuring to create an ingot.
The obtained ingot is held at a temperature of 930 to 1050 ° C. for 0.5 to 1.0 hour, and then hot-rolled to produce a hot rolled sheet having a thickness t = 12 mm. Then, the plate thickness t was set to 10 mm, and then the plate thickness t was set to 0.3 mm by cold rolling, followed by solution heat treatment at a temperature of 700 to 950 ° C. The prepared material was subjected to one of the following two steps to prepare a final product specimen.
Step A: (Solution heat treatment) -Aging heat treatment (at a temperature of 500 to 600 ° C. for 2 to 4 hours) -Cold working (working rate 5 to 25%)
* After this, strain relief annealing was performed at a temperature of 300 to 400 ° C. for 1 to 2 hours as necessary.
Step B: (Solution heat treatment)-Cold rolling (working rate 5 to 25%)-Aging heat treatment (at a temperature of 450 to 550 ° C for 2 to 4 hours)

The following property investigation was conducted on this specimen. Table 1 shows the results of Examples of the present invention, and Table 2 shows the results of Comparative Examples. In Tables 1 and 2, “E + 08” or the like in the item of compound density represents a power of 10 (“× 10 ⁸ ” in the case of “E + 08”).
a. Tensile strength:
Three test pieces of JIS Z2201-13B cut out from the direction parallel to the rolling of the specimen (test piece) were measured according to JIS Z2241, and the average value was shown.
b. Conductivity measurement:
Using the four-terminal method, the conductivity of two test pieces was measured in a thermostatic chamber controlled at 20 ° C. (± 1 ° C.), and the average value (% IACS) is shown in Tables 1-2. It was. At this time, the distance between terminals was set to 100 mm.
c. Bendability:
A test piece was cut out from the test material to a width of 10 mm and a length of 35 mm perpendicular to the rolling direction, and the bending axis was 0.1 mm between the bending radius R = 0 to 0.5 (mm) parallel to the rolling direction. W-bending (Bad-way bending) of 90 ° was performed at 6 levels of increments, and the presence or absence of cracks in the bent portion was observed to investigate the presence or absence of cracks. Observation of the presence or absence of cracks in the bent portion was performed by visual observation with a 50 × optical microscope and observation of a bent portion with a scanning electron microscope (SEM). In Table 1, R of R / t is a bending radius, t indicates a plate thickness, and a smaller value indicates better bending workability.
d. Crystal grain size:
After a cross section perpendicular to the rolling direction of the specimen (test piece) is polished to a mirror surface by wet polishing and buffing, the polished surface is corroded with a solution of chromic acid: water = 1: 1 for several seconds, and then 200 by an optical microscope. A photograph was taken at a magnification of up to 400 times or a magnification of 500 to 2000 using a secondary electron image of a scanning electron microscope (SEM), and the crystal grain size of the cross section was measured according to the cutting method of JIS H0501. . The magnification of the photograph was changed depending on the size of the observed crystal grain. The “mixed grain” in the table is a structure in which both the recrystallized region and the non-recrystallized region (the state in which the rolled structure remains), and in the case of mixed particles, the particle size was not measured. . It is said that bending workability deteriorates when unrecrystallized exists. Therefore, mixed grains are undesirable structures.
e. Cooling rate after aging heat treatment The cooling rate was adjusted by changing the weight of the material to be heat-treated or by controlling the temperature in the heat treatment furnace used. For example, by using the same heat treatment furnace (batch type), in order to obtain a faster cooling rate, the amount of heat treatment is reduced at the same time, while to obtain a slower cooling rate, a dummy test The amount of heat treatment that was performed at the same time after putting the pieces was increased, and each was heat-treated. In addition, when it wanted to cool rapidly, the sample was taken out from the heating zone of the heat treatment furnace, and it responded by forced air cooling or water quenching. The cooling rate was also adjusted by controlling the temperature in a heat treatment furnace. When the number of samples was particularly small or the cooling rate was very slow, the cooling rate was adjusted by controlling the temperature in a heat treatment furnace.
f. Compound size, number and dispersion density The size (average particle size) of the precipitate (compound) was measured using a transmission electron microscope. In the final product, the structure of the material after aging heat treatment was observed because it was difficult to observe due to the influence of processing strain. Test specimen for observation by cutting out TEM test piece from any place of heat-treated material and performing electrolytic polishing (with twin jet type electrolytic polishing apparatus) at a temperature of -20 to -25 ° C with methanol solution of nitric acid (20%) Completed the piece.
Thereafter, observation was performed at an accelerating voltage of 300 kV, and three photographs having a magnification of 100000 times were arbitrarily taken with the incident direction of the electron beam being set in the vicinity of (001). Using the photograph, the number of compounds A (about 100) corresponding to the specified size was determined.
Compound B, Compound C, and Compound D were subjected to component analysis using an EDS (energy dispersive detector) attached to a transmission electron microscope, and three photographs were arbitrarily taken at a magnification of 1000 to 5000 times. Then, the number corresponding to the desired specified size was determined using the photograph. The number is 10 to 100.
From these values, the dispersion density (pieces / mm ² ) of each compound A, B, C and D was determined. In the following table, the dispersion density is simply abbreviated as density. Further, “compound B, C, D density (pieces / mm ² )” indicates the total of the dispersion density (pieces / mm ² ) of each compound, B, C, and D, but if there is a certain compound. Needless to say, it is the total of the dispersion density of the remaining compound alone or the dispersion density of the remaining two compounds. Furthermore, “(B + C + D) / A” is an abbreviation of “{(dispersion density of compound B + dispersion density of compound C + dispersion density of compound D) / dispersion density of compound A}”.

As shown in Table 1, the examples (examples of the present invention) satisfy all of strength, conductivity, and bending workability at a high level in a well-balanced manner. Specifically, when the electrical conductivity (EC) is 50% IACS or more and the relationship between the tensile strength (TS) and the bending workability (R / t), TS is 550 MPa or more and less than 650 MPa. /T≦0.5, R / t ≦ 1 when TS is 650 MPa or more and less than 700 MPa, and R / t ≦ 2 when TS is 700 MPa or more and less than 800 MPa. . On the other hand, in the comparative example shown in Table 2, at least one of strength, conductivity, and bending workability is not practical. Among these, sample No. Nos. 101, 107 to 112, and 125 to 126 had a tensile strength of less than 500 MPa and were less than the practical level.

While this invention has been described in conjunction with its embodiments, we do not intend to limit our invention in any detail of the description unless otherwise specified and are contrary to the spirit and scope of the invention as set forth in the appended claims. I think it should be interpreted widely.
This application claims priority based on Japanese Patent Application No. 2008-202467 filed in Japan on August 5, 2008, which is hereby incorporated herein by reference. Capture as part.

Claims

A copper alloy material for electrical and electronic parts containing Co and Si as additive elements,
Compound A having an average particle diameter of 5 nm or more and less than 50 nm, made of Co and Si, is dispersed.
Further, Compound B having an average particle diameter of 50 nm to 500 nm and not containing one or both of Co and Si; and Compound C having an average particle diameter of 50 nm to 500 nm containing both Co and Si and other elements; , At least one compound selected from the group consisting of Compound D having a mean particle diameter of 50 nm to 500 nm composed of Co and Si is dispersed,
A copper alloy material for electrical and electronic parts, characterized in that the crystal grain size of the base copper alloy is 3 to 35 μm and the electrical conductivity is 50% IACS or more.
A copper alloy material for electrical and electronic parts containing Co and Si as additive elements,
Compound A composed of Co and Si having an average particle diameter of 5 nm or more and less than 50 nm, Compound B having an average particle diameter of 50 nm or more and 500 nm or less that does not contain one or both of Co and Si, both Co and Si, and other Compound C having an average particle size of 50 nm or more and 500 nm or less containing compound and Compound D having an average particle size of 50 nm to 500 nm composed of Co and Si are dispersed,
The ratio of the dispersion densities of the compounds A to D is 0.0001 ≦ {(dispersion density of compound B + dispersion density of compound C + dispersion density of compound D) / dispersion density of compound A} ≦ 0.1,
A copper alloy material for electrical and electronic parts, characterized in that the crystal grain size of the base copper alloy is 3 to 35 μm and the electrical conductivity is 50% IACS or more.
Further, at least one selected from Al, Ag, Sn, Zn, Mg, Mn, and In is contained in a total of 0.05 to 1.0 mass%, and the balance is made of Cu and inevitable impurities. Item 3. A copper alloy material for electrical and electronic parts according to Item 2.
4. The composition according to claim 1, further comprising at least one selected from Fe, Cr, Ni, Zr, and Ti in a total amount of 0.05 to 1.0 mass%, with the balance being Cu and inevitable impurities. The copper alloy material for electrical and electronic parts according to claim 1.
The copper alloy material for electrical and electronic parts according to claim 1 or 2, comprising Co and Si as additive elements, the balance being made of Cu and inevitable impurities.
The copper for electric and electronic parts according to any one of claims 1 to 5, wherein the Co content is 0.4 to 2.0 mass% and the Si content is 0.1 to 0.5 mass%. Alloy material.
The copper for electric and electronic parts according to any one of claims 1 to 6, wherein an average cooling rate from a solid phase temperature to 500 ° C during ingot production is 5 to 100 ° C / sec. Alloy material.