Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
  • H01B1/02—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of metals or alloys
  • H01B1/026—Alloys based on copper
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C9/00—Alloys based on copper
  • C22C9/06—Alloys based on copper with nickel or cobalt as the next major constituent
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/08—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of copper or alloys based thereon

Definitions

• the present invention relates to a copper alloy material applied to electric/electronic parts.
• the CXXXXX denotes types of copper alloys specified in JIS, and “% IACS” is an abbreviation of “International Annealed Copper Standard” and is a unit which indicates an electrical conductivity of a material.
• electrical conductivity and mechanical strength are incompatible properties.
• a method for enhancing the strength include solid-solution strengthening, working strengthening, precipitation strengthening, and the like.
• the precipitation strengthening is a promise as a method for enhancing the strength of the copper alloy without deteriorating the electrical conductivity.
• an alloy, to which an element(s) which precipitates is added is heat-treated at a high temperature, so as to cause solid solution of the element(s) in a copper matrix, and then, the resultant alloy is heat-treated at a temperature lower than said high temperature, thereby to precipitate the element(s) of the solid solution.
• this strengthening method is adopted for beryllium copper, the Corson alloy, and the like.
• JP-A means unexamined published Japanese patent application
• the present invention is contemplated for providing a copper alloy material for electric/electronic parts, which can be favorably used in products subjected to severe bending, such as connectors or the like, and which is excellent in mechanical strength, electrical conductivity, and bending property.
• a copper alloy material for an electric/electronic part comprising Co 0.5 to 2.5 mass % and Si 0.1 to 1.0 mass %, at a ratio of Co/Si of 3 to 5 (mass ratio), with the balance of Cu and inevitable impurities, which is obtained by subjecting to a solution treatment at a temperature Ts (° C.) from 800° C. to 960° C. and lower than ⁇ 122.77X 2 +409.99X+615.74, in which X represents the content (mass %) of Co;
• a copper alloy material for an electric/electronic part comprising Co 0.5 to 2.5 mass % and Si 0.1 to 1.0 mass %, at a ratio of Co/Si of 3 to 5 (mass ratio), and comprising 0.01 to 1.0 mass % of one or two or more selected from the group consisting of Cr, Mg, Mn, Sn, V, Al, Fe, Ni, Ti and Zr, with the balance of Cu and inevitable impurities, which is obtained by subjecting to a solution treatment at a temperature Ts (° C.) from 800° C. to 960° C. and lower than ⁇ 94.643X 2 +329.99X+677.09, in which X represents the content (mass %) of Co;
• the value (R/t) representing a bending property means a value R/t obtained as follows: cutting out samples with a respective sheet thickness and with a sheet width w of 10 (mm) from a test specimen; rubbing lightly the surface of the sample with metal polishing powders, to remove an oxide layer; subjecting the resultant sample to W-bending, such that the inner angle of bending would be 90°, with respect to two kinds of: [1] bending (GW) of the sample parallel to the rolling direction, and [2] bending (BW) of the sample perpendicular to the rolling direction; and dividing the smallest bending radius R (mm) at which no micro-cracks occur, by a sample's sheet thickness t (mm).
• the bending property is evaluated with this value R/t.
• the copper alloy material of the present invention for electric/electronic parts is excellent in all of the mechanical strength, the electrical conductivity, and the bending property.
• the copper alloy material of the present invention for electric/electronic parts can be favorably used even in the products subjected to severe bending, such as connectors or the like.
• the copper alloy material of the present invention is a copper alloy material having a specific shape, such as a sheet material, a strip material, a wire material, a rod material, a foil, and the like, and the copper alloy material can be used for any electric/electronic parts.
• the electric/electronic parts are not specifically limited.
• the copper alloy material is favorably used, for example, for connectors, terminal materials, and the like; particularly, high-frequency relays and switches, which are desired to be high in electrical conductivity, or connectors, terminal materials, lead frames, and the like, which are mounted in vehicles or the like.
• Co and Si are essential elements.
• Co and Si in the copper alloy mainly form a precipitate of a Co 2 Si intermetallic compound, thereby to enhance the strength and the electrical conductivity.
• the content of Co is 0.2 to 2.5 mass %, preferably 0.3 to 2.0 mass %, more preferably 0.5 to 1.6 mass %.
• the content of Si is 0.1 to 1.0 mass %, preferably 0.1 to 0.7 mass %, more preferably 0.1 to 0.5 mass %.
• these mainly form the precipitate of the intermetallic compound of Co 2 Si, to contribute to the precipitation strengthening. If the content of Co is less than 0.5 mass %, the precipitation strengthening degree is small, and if the content of Co is more than 2.5 mass %, the effect due to Co is saturated.
• the optimum addition ratio of the compound is Co/Si nearly equals to 4.2, and the addition amount of Si is determined to be in this range. It is preferable to control the Co/Si to be within a range of 3.0 to 5.0, more preferably within a range of 3.2 to 4.5, with the above-mentioned value to be the central value.
• Si and Co may be referred to as “elements I to be added”.
• the temperature Ts (° C.) for conducting the solution treatment is from 800° C. to 960° C., and lower than ⁇ 122.77X 2 +409.99X+615.74 (° C.), in which the Co content (mass %) is represented by X.
• the copper alloy of the present invention it is preferable to add one or two or more kinds of any of Cr, Mg, Mn, Sn, V, Al, Fe, Ni, Ti, and Zr, and the addition amount thereof is 0.01 to 1.0 mass %.
• these Cr, Mg, Mn, Sn, V, Al, Fe, Ni, Ti, and Zr may be referred to as “element(s) II to be added”.
• Mg, Mn, and Sn have an action of making a solid solution in the copper matrix, to strengthen the copper alloy. Mg and Mn also exhibit an effect for improving a hot workability.
• V, Al, Ni, Ti, and Zr have an action of forming a compound together with Co and Si, to strengthen and suppress coarsening of the grains.
• a preferable method of producing the copper alloy material according to the present invention includes the following steps. That is, such steps are: melt-casting ⁇ re-heat-treatment ⁇ hot rolling ⁇ cold rolling ⁇ solution treatment ⁇ aging heat-treatment ⁇ final cold-rolling ⁇ stress-relief annealing. The order of the aging heat-treatment and the final cold-rolling may be reversed. The stress-relief (low-temperature) annealing to be finally conducted may be omitted.
• the solution treatment before subjecting to the final rolling is conducted at a temperature from 800° C. to 960° C.
• the solution treatment temperature Ts (° C.) is set to a temperature (° C.) lower than ⁇ 122.77X 2 +409.99X+615.74, in which the Co content (mass %) is represented by X.
• the solution treatment temperature Ts (° C.) is set to a temperature (° C.) lower than ⁇ 94.643X 2 +329.99X+677.09, in which the Co content (mass %) is represented by X.
• the heat treatment at this temperature determines the grain size in the copper alloy material.
• a rapid cooling at a cooling speed of 50° C./sec or more, from this solution heat-treatment temperature Ts. If the cooling speed in the quenching is too low, the elements made to be a solid solution at the aforementioned high temperature, may precipitate.
• Particles (compounds), precipitated upon cooling at such a too low cooling speed (for example, at a cooling speed lower than 50° C./sec), are non-coherent precipitates that do not contribute to the strength. Further, this non-coherent precipitate may contribute as a nucleation site when a coherent precipitate is formed in the subsequent aging heat-treatment step, and may accelerate the precipitation of a part in which the coherent precipitate formed, and resultantly may affect as negatively to the properties.
• the cooling speed is preferably 50° C./sec or more, more preferably 80° C./sec or more, and even more preferably 100° C./sec or more. Unless the cooling speed is not over a practical upper limit, it is preferably as fast as possible.
• This cooling speed means an average cooling speed from the high temperature of the solution heat-treatment temperature to 300° C. Since the structure is not varied largely at a temperature less than 300° C., it is enough to control appropriately the cooling speed to this temperature.
• the solution treatment temperature is defined.
• the grain size is preferably 20 ⁇ m or less, and more preferably 10 ⁇ m or less.
• the reason as assumed is because, if the grain size is more than 20 ⁇ m, due to the coarse grain size, a grain boundary density is low and a bending stress cannot be sufficiently absorbed, to deteriorate the workability.
• the lower limit of the grain size is not particularly limited, but is generally 3 ⁇ m or more.
• the “grain size” means a value measured according to JIS-H0501 (cutting method) described below.
• the “size of a precipitate” is an average size of the precipitate, as determined by a method described below.
• the copper alloy material of the present invention has properties of: a yield stress of not less than 500 MPa but less than 650 MPa; an electrical conductivity of 60% IACS or more; and a bending property (R/t) of less than 0.5.
• the “bending property (R/t) of less than 0.5” means that, at least, a R/t value, in the bending of the sample parallel to a rolling direction, is less than 0.5; and it is preferably that R/t values are less than 0.5, in both of the bending of the sample parallel to the rolling direction and the bending of the sample perpendicular to the rolling direction.
• the copper alloy material of the present invention has properties of: a yield stress of 650 MPa or more; an electrical conductivity of 50% IACS or more; and a bending property (R/t) of less than 1.5.
• the “bending property (R/t) of less than 1.5” means that, at least, a R/t value, in the bending of the sample parallel to the rolling direction, is less than 1.5; and it is preferably that R/t values are less than 1.5, in both of the bending of the sample parallel to the rolling direction and the bending of the sample perpendicular to the rolling direction.
• the copper alloy material of the present invention has properties of: a yield stress of not less than 500 MPa but less than 650 MPa; an electrical conductivity of 60% IACS or more; and the value (R/t) representing the bending property of 1.2 or less (more preferably 1.0 or less, and even more preferably 0.6 or less), in both of the bending of the sample parallel to the rolling direction and the bending of the sample perpendicular to the rolling direction.
• the copper alloy material of the present invention for electric/electronic parts, has properties of: a yield stress of 650 MPa or more; an electrical conductivity of 50% IACS or more; and the value (R/t) representing the bending property of 1.5 or less (more preferably 1.2 or less), in both of the bending of the sample parallel to the rolling direction and the bending of the sample perpendicular to the rolling direction.
• the copper alloy material of the present invention high in the electrical conductivity and mechanical strength, and excellent in the bending property, can be favorably used in electric/electronic parts, such as connectors, subjected to severe bending.
• Alloys (Nos. 1 to 9) composed of elements as shown in Table 1, with the balance of Cu and inevitable impurities, were melted with a high-frequency melting furnace, followed by casting at a cooling speed of 10 to 30° C./sec, to obtain ingots with length 180 mm, width 30 mm, and height 110 mm, respectively.
• the thus-obtained ingots were maintained at 1,000° C. for 30 minutes, followed by working to thickness 12 mm by hot rolling. After the hot rolling, the thus-hot-rolled alloys were immediately quenched by water cooling, followed by face-milling to thickness about 10 mm to remove an oxide layer on the surface of the alloy, and then working by cold rolling. Then, for the purposes of conducting solution-treatment and recrystallization, the resultant alloys were heat-treated by maintaining at 950° C. for 30 seconds, followed immediately by quenching by water cooling.
• the temperature raising speed to reach the highest temperature from the room temperature was within the range of 10 to 50° C./sec, and the cooling speed was within the range of 30 to 200° C./sec.
• the surface oxide layer was removed, and the alloys were subjected to cold rolling, according to necessity.
• This cold-rolling also functioned to work hardening, and acceleration of precipitation hardening in heat treatment of the subsequent step.
• the alloys were subjected to a heat treatment at 525° C. for 120 minutes.
• the temperature raising speed to reach the highest temperature from the room temperature was within the range of 3 to 25° C./min, and in the temperature lowering, the cooling was conducted at a speed within the range of 1° C./min to 2° C./min in the furnace, to 300° C. which was a temperature sufficiently lower than the temperature range presumed to affect the precipitation.
• test materials were produced with sheet thickness 0.10 mm, 0.15 mm, 0.20 mm, and 0.25 mm, respectively.
• the resultant materials were subjected to a heat treatment at 350° C. for 30 minutes.
• the temperature raising speed to reach the highest temperature from the room temperature was within the range of 3 to 25° C./min, and in the temperature lowering, the cooling was conducted at a speed within the range of 1° C./min to 2° C./min in the furnace, to 300° C. which was a temperature sufficiently lower than the temperature range presumed to affect the precipitation.
• ⁇ represents a proof stress (N/mm 2 ) calculated by the offset method
• F represents a force, which was determined, by obtaining a relationship curve diagram between a force and a ratio of elongation using an elongation meter, drawing a line parallel to the straight line part of the early stage of the test, from the point on the axis of elongation corresponding to the predetermined permanent elongation ( ⁇ %), and determining the force shown at the point at which the parallel line intersects the curve diagram.
• the electrical conductivity (% IACS) was calculated, by measuring a specific resistance of the material through a four terminal method in a thermostatic bath maintained at 20° C. ( ⁇ 0.5° C.). The distance between the terminals was set to 100 mm.
• alloy materials were obtained, which were excellent in both of the strength and the electrical conductivity with a favorable balance.
• the resultant alloy materials contained more of solid-solution elements of Co and Si which did not precipitate, to cause a conspicuous deterioration in the electrical conductivity.
• Alloy materials of Examples 1 to 3 and 10 to 16 according to the present invention and Comparative examples 1 to 3 and 18 to 22 were obtained in the same manner as in Reference example 1, except that alloys, composed of the components shown in Table 4 with the balance of Cu and inevitable impurities, were used, and that the temperature for the solution treatment was changed to temperatures of Processes A to H shown in Table 2, respectively.
• Alloys Nos. 1 to 3 shown in Table 4 had the same compositions as those of Alloys Nos. 1 to 3 shown in Table 1, respectively.
• Alloys Nos. 10 to 12 of Examples shown in Table 4 were those prepared by adding Cr to Alloys Nos. 1 to 3 shown in Table 1 and Table 4, respectively, in the amounts within the defined ranges; and Alloys Nos.
• the yield stress (YS), the tensile strength (TS), and the electrical conductivity (EC) were measured in the same manner as in Reference example 1. Further, a grain size (GS) and a bending property (R/t) were measured, according to the methods described below. The results are shown in Table 5.
• the solution treatment temperature Ts (° C.) was set at a temperature (° C.) of 800° C. to 960° C. and lower than ⁇ 122.77X 2 +409.99X+615.74, in which the Co content (mass %) was represented by X.
• the grain size was able to be maintained at less than 20 ⁇ m, and it was possible to obtain the copper alloy materials, which were excellent in the balance of the mechanical strength, the electrical conductivity, and the bending property.
• the yield stress was not less than 500 MPa but less than 650 MPa
• the electrical conductivity was 60% IACS or more
• the values (R/t) representing the bending property were 1.0 or less in both of GW and BW.
• some of the Examples according to the present invention had the values (R/t) representing the bending property of 0.6 or less, or even less than 0.5, in both of GW and BW.
• Example 10 to 16 according to the present invention in Table 5 one or more of Cr, Mg, Mn, Sn, V, Zn, Al, Fe, Nb, Ni, Ti, and Zr was added (that is, the element(s) II to be added was added in the total amount of 0.01 to 1 mass %), and the solution treatment temperature Ts (° C.) was set at a temperature (° C.) of 800° C. to 960° C. and lower than ⁇ 94.643X 2 +329.99X+677.09, in which the Co content (mass %) was represented by X.
• the grain size was set at a temperature as high as that in Reference example 1, and the copper alloy materials had the same level of mechanical strength as that in Reference example 1 and were excellent in the bending property.
• the values (R/t) representing the bending property were 1.2 or less in both of GW and BW.
• Some of Examples had the values (R/t) representing the bending property of 1.0 or less, even 0.6 or less, or further even less than 0.5, in both of GW and BW.
• the values (R/t) representing the bending property were 1.5 or less, or 1.2 or less, in both of GW and BW.
• Comparative examples 18 to 22 in which the addition amount of the element II to be added exceeded 1% due to the formation of oxides upon the casting and excessive precipitation in the high-temperature heat-treatment, the productivity was conspicuously deteriorated to make it difficult to obtain products.
• Comparative example 21 in which the addition amount of the element II to be added exceeded 1% the electrical conductivity was conspicuously lowered when the solid-solution-type elements were added, the yield stress was less than 650 MPa, but the value of R/t exceeded 1.2 in BW, which means that the bending property was poor. Further the value (R/t) representing the bending property showed a tendency to be poor in BW, as compared to that in GW.
• the copper alloy material for electric/electronic parts of the present invention can be favorably used in electric/electronic parts, such as connectors, terminal materials, and the like, for electric/electronic equipments, and particularly in high-frequency relays or switches that are required to have a high electrical conductivity, or connectors, terminal materials, and lead frames, to be mounted on vehicles or the like.

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• 2009
  • 2009-03-19 JP JP2010503942A patent/JP5065478B2/ja not_active Expired - Fee Related
  • 2009-03-19 EP EP09722228A patent/EP2267172A1/en not_active Withdrawn
  • 2009-03-19 CN CN200980110059.3A patent/CN101978081B/zh not_active Expired - Fee Related
  • 2009-03-19 WO PCT/JP2009/055531 patent/WO2009116649A1/ja active Application Filing
• 2010
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