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 for electrical/electronic equipments, and to an electrical/electronic part.
• Parts of electrical/electronic equipments for example, spring contact materials of connectors, are required to have properties, for example, mechanical strength, stress relaxation resistance, electrical conductivity, bending property, heat resistance, plating adhesiveness, and migration property.
• properties for example, mechanical strength, stress relaxation resistance, electrical conductivity, bending property, heat resistance, plating adhesiveness, and migration property.
• phosphor bronze has been used in many cases, but phosphor bronze is not completely satisfactory in the properties described above.
• beryllium copper which is higher in mechanical strength and excellent in stress relaxation resistance, has become used widely.
• beryllium copper is very expensive, and metal beryllium is regarded as a substance of concern (SoC).
• Corson alloy Cu-Ni-Si-based alloy
• nickel (Ni) and silicon (Si) are added to copper
• Corson alloy is a precipitation-hardening-type alloy, which is strengthened by dispersing and precipitating fine particles of Ni 2 Si intermetallic compounds in Cu, and there have been reports on the attempts to enhance mechanical strength and electrical conductivity by defining the amounts of addition of Ni and Si or the ratio of Ni/Si (see Patent Literatures 1, 2, and 3).
• the ratio of the contents of Ni and Si in terms of percentage by mass is preferably within the range around 4.2, which is a stoichiometric ratio of the Ni 2 Si compound that mainly contributes to strengthening.
• the Ni/Si is within the range of Ni/Si of 3 to 7 in Patent Literature 1, within the range of Ni/Si of 3.5 to 5.5 in Patent Literature 2, and within the range of Ni/Si of 4 to 5 in Patent Literature 3.
• Patent Literature 2 also describes that the Ni/Si is preferably close to 4.2, which is the stoichiometric ratio of Ni 2 Si, with concerns about a possible lowering of the electrical conductivity due to an increase in the amounts of solid solutions of Ni and Si when the value of Ni/Si is away from 4.2.
• the Ni/Si in the conventional alloys has been such that, while the stoichiometric ratio of Ni 2 Si, or a value corresponding to an excess amount of Ni compared to the stoichiometric ratio of Ni 2 Si, is considered preferable, the definition of the range of the ratio is broad and ambiguous. Further, investigations have been extensively made to maintain the balance between mechanical strength and electrical conductivity, but sufficient investigations have not been made on the conditions of obtaining high mechanical strength and favorable bending property. Thus, the present invention is contemplated for providing a copper alloy material for electrical/electronic equipments, having a remarkably high mechanical strength and a favorable bending property, and an electrical/electronic part utilizing the same.
• the inventors of the present invention have found a region to make grains finer and to enhance aging strength, at a side of Si in excess of the stoichiometric ratio of Ni 2 Si even in the conventional Ni/Si range; and we have found that, although such a copper alloy slightly sacrifices the electrical conductivity as compared with conventional Corson alloys, the copper alloy has an electrical conductivity that is higher than 12 %IACS of phosphor bronze C5210 for springs and is equal to or higher than 25 %IACS of high-strength beryllium copper C17200, can retain sufficient electrical conductivity for the use in connectors, and can retain high strength and favorable bending property.
• the present invention has attained based on these findings above. According to the present invention, there is provided the following means:
• the copper alloy material for electrical/electronic equipments of the present invention has an electrical conductivity that is higher than 12 %IACS of conventional phosphor bronze C5210 for springs and equal to or higher than 25 %IACS of conventional high-strength beryllium copper C17200, thus has a sufficient electrical conductivity for the use in connectors, and has a remarkably high mechanical strength and a favorable bending property. Further, since the electrical/electronic part of the present invention is obtained by working the copper alloy material for electrical/electronic equipments, the part has a remarkably high mechanical strength and also has a favorable bending property required for parts of the connector use. Other and further features and advantages of the invention will appear more fully from the following description.
• the resultant copper alloy material can have a favorable bending property and a remarkably high mechanical strength.
• the content of Ni exceeds the upper limit value, a coarse compound having no effects on mechanical strength is crystallized or precipitated, upon casting and hot-working, so that a mechanical strength appropriate for the content is not obtained, and the hot-workability and bending property are deteriorated.
• the content of Ni is less than the lower limit value, the electrical conductivity is enhanced, but the mechanical strength tends to be deteriorated.
• the Ni/Si mass ratio of the contents
• the ratio is defined to be within the range of 2.8 to 3.8.
• the ratio is less than the lower limit value, the required effect of enhancing the strength upon the aging cannot be obtained, and the electrical conductivity is lowered by the amount of solid solution of Si is more noticeable than the effect of controlling the grain size, which exerts an adverse influence.
• a more preferable range of the Ni/Si is around 3.3, which is 3.0 to 3.5. When the ratio is in this range, a material can be obtained which is favorable in the balanced of the tensile strength, the electrical conductivity, and the bending property.
• Mg improves the stress relaxation resistance, but its content is defined to 0.01 to 0.2 mass%, since when the content is less than 0.01 mass%, an improvement in the stress relaxation resistance cannot be seen, and when the content is greater than 0.2 mass%, Mg in such a too high content gives adverse affects on the bending property.
• the content of Mg is preferably 0.05 to 0.15 mass%.
• Sn is interrelated with Mg, thereby to improve the stress relaxation resistance further.
• the content of Sn is defined to 0.05 to 1.5 mass%, because when the content is less than 0.05 mass%, the effects are not sufficiently obtained, and when the content is greater than 1.5 mass%, the electrical conductivity is lowered.
• the content of Sn is preferably 0.1 to 0.7 mass%.
• Zn slightly improves the bending property.
• the amount of Zn is defined to 0.2 to 1.5 mass%, the bending property can be obtained at a level that is free of problem for practical use even if Mg is added in an amount up to 0.2 mass% at the maximum.
• Zn improves the adhesiveness of Sn plating or solder plating, or the migration property.
• the content of Zn is more preferably 0.3 to 1.0 mass%.
• the copper alloy material of the present invention may also contain one or two or more of Ag, Co, and Cr in 0.005 to 2.0 mass% in a total of those, in addition to the elements described above.
• Ag improves the heat resistance and enhances the strength, and also inhibits coarsening of the grains, thereby to improve the bending property.
• the amount of Ag is less than 0.005 mass%, the effects are not sufficiently obtained, and even if Ag is added in an amount greater than 0.3 mass%, the production cost increases without any adverse affects on the properties. From those points of view, the content of Ag is defined to 0.005 to 0.3 mass%.
• Co forms a compound with Si, to enhance the strength.
• the content of Co is less than 0.05 mass%, the effects are not sufficiently obtained, and when the content is greater than 2.0 mass%, crystallization and precipitation products which do not contribute to the strength are present even after the solution treatment, so that the bending property is deteriorated.
• Cr precipitates as a second phase with Ni and/or Si, and is effective in the control of the grain size.
• the content is less than 0.05 mass%, the effects are not sufficiently obtained, and when the content is greater than 1.0 mass%, the bending property is deteriorated.
• the contents are determined within the range of 0.005 to 2.0 mass%, according to the required properties.
• the copper alloy material for electrical/electronic equipments of the present invention is preferably produced by the steps of: casting, hot rolling, dough rolling, and solution treatment, followed by intermediate rolling, aging, finish rolling, and low-temperature annealing.
• the shape of the copper alloy material for electrical/electronic equipments of the present invention is not particularly limited, and examples include sheet (plate), strip, wire, rod, and foil.
• a preferred method of producing the copper alloy material of the present invention is explained in detail below.
• a method of producing a copper alloy sheet or a copper alloy strip is described in detail as a representative example.
• the casting is conducted by a usual DC (direct chill casting) method, or the like. It is preferable that, immediately after conducting a homogenization treatment of the resultant ingot at a temperature of 850°C to 1,000°C for 0.5 to 12 hours, the hot rolling is conducted at a temperature of 700°C to 950°C, followed by water cooling to prevent precipitation in the cooling. After the hot rolling, an oxide layer is face-milled, followed by the cold rolling.
• this cold rolling is referred to as dough rolling.
• the dough rolling is conducted to a sheet thickness, to give a given working ratio in the intermediate rolling and the finish rolling, respectively.
• the solution treatment is conducted at a material's substantial temperature of 800°C and 950°C, followed by maintaining for approximately 3 to 6 seconds, and cooling with a cooling speed of 15°C/sec or more (more preferably 30°C/sec or more) to prevent precipitation.
• the solution treatment temperature is lower than 800°C, such problems occur that it is not possible to obtain a sound recrystallized structure, to affect as negatively to the bending property, and that the amounts of the solid solution of Ni and Si become insufficient, to result in an insufficient precipitated amount of the Ni-Si-based precipitation upon the aging, thereby to fail to obtain a sufficient proof stress.
• the solution treatment temperature is higher than 950°C, coarsening of the recrystallized grains occur, to cause lowering of the strength, exhibition of an anisotropy, and deterioration of the bending property.
• the intermediate rolling As the intermediate rolling, a cold-rolling is conducted, to enhance the tensile strength and the proof stress upon the aging.
• Dislocations are introduced into the matrix of the copper alloy upon the intermediate rolling, but a part of the dislocations function as the heterogeneous nucleation sites of the Ni-Si-based compound in the subsequent aging step, aiding the formation of the compound at a high density with a fine size, and enhancing further the effect of increasing the precipitation density owing to the controlling of the Ni/Si.
• the aging makes it possible to precipitate and disperse the Ni 2 Si and Ni 3 Si 2 compounds uniformly into the copper matrix, to enhance the strength and improve the electrical conductivity. It is preferable to conduct the aging with a batch-type furnace, to maintain at a material's substantial temperature of 400°C to 600°C for 0.5 to 12 hours. When the substantial temperature is lower than 400°C, a quite longer period of time is necessary to obtain a sufficient precipitation amount of the Ni-Si-based compound, or the proof stress and the electrical conductivity result in insufficient. When the substantial temperature is higher than 600°C, the Ni-Si-based compound becomes coarsened, to fail to obtain the proof stress sufficiently.
• the aging is carried out in two stages of: aging at a substantial temperature of the material of 300 to 400°C for 0.5 to 8 hours, and then aging at a substantial temperature of 425 to 600°C for 0.5 to 12 hours, it is possible to increase the precipitation density of the Ni-Si-based compound and to further enhance the strength and improve the bending property.
• the intermediate rolling may not be carried out; but by conducting the intermediate rolling, the strength can be further enhanced.
• the finish rolling As the finish rolling, a cold-rolling is conducted to enhance the proof stress. When the proof stress after the aging is sufficient, it may be possible to omit the finish rolling and the subsequent low-temperature annealing. When the rolling ratio in the finish rolling is too high, the bending property is deteriorated and the stress relaxation resistance is deteriorated. Thus, the finish rolling is preferably conducted with a rolling ratio of 30% or less.
• the low-temperature annealing is conducted to recover an elongation, the bending property, and a spring limit value, while maintaining the strength in a certain degree.
• the substantial temperature at the low-temperature annealing is too high, recrystallization occurs, to cause lowering of the proof stress.
• the substantial temperature is lower than 300°C, the recovery of the elongation, the bending property, and the spring limit value becomes insufficient.
• the substantial temperature is higher than 600°C, it results in lowering of the strength.
• the electrical/electronic part of the present invention can be obtained by appropriately working the copper alloy material for electrical/electronic equipments.
• This working method is not particularly limited, and the part may be fabricated into a desired part shape in a usual manner, for example, by plastic working, such as press working.
• Copper alloys having compositions shown in Table 1 were melt, followed by casting into ingots with thickness 30 mm, width 100 mm, and length 150 mm, by the DC method, respectively. Then, the ingots were heated to 900°C, to maintain at this temperature for 1 hour, followed by hot rolling to thickness 12 mm, and cooling immediately thereafter. Then, the oxide film layer was removed by face-milling the respective face in 1.5 mm for each, followed by dough rolling to thickness 0.25 to 0.50 mm. Then, the resultant sheets were subjected to a solution treatment under any of conditions at 800°C and 950°C, followed, immediately thereafter, by cooling with a cooling speed of 15°C/sec or more.
• the resultant sheets were subjected to intermediate rolling with rolling ratio 5 to 50%. Then, the resultant sheets were subjected to aging at 450 to 550°C for 2 hours in an inert gas atmosphere, followed by finish rolling with rolling ratio 30% or less, to adjust the final sheet thickness to 0.20 mm. After the finish rolling, the sheets were subjected to a low-temperature annealing at 500°C for 30 seconds, and the thus-obtained materials were utilized to conduct the following various property evaluations.
• the unit for elements of the copper alloy (Ni, Si, and the like) indicated in the respective table is all percentage by mass (mass%), except for the value of Ni/Si (no unit) which is in terms of mass ratio.
• Examples 1 to 10 according to the present invention exhibited excellent characteristics in both of a remarkably high tensile strength and a favorable bending property.
• Examples 1 to 10 according to the present invention each had an electrical conductivity of 28 %IACS or higher, a tensile strength of 850 MPa or higher, and the bending property with the value of R/t of 0.5.
• Reference examples 11 and 12 had the Ni/Si within the defined range, but since the amount of Ni was less than the lower limit value, they failed to exhibit such a remarkably high strength as in the examples according to the present invention.
• Example 4-2 according to the present invention, and Comparative examples 15-2 and 22-2 were produced, in the same production process as described in the above Example 1, except for changing the aging to a two-stage aging treatment to conduct aging at 350°C for 2 hours and then aging at 500°C for 2 hours.
• Example 4-3 according to the present invention, and Comparative examples 15-3 and 22-3 were produced, in the same production process as described in the above Example 1, except for not conducting the intermediate rolling immediately before the aging treatment, and changing the aging to a two-stage aging treatment to conduct aging at 350°C for 2 hours and then aging at 500°C for 2 hours.
• Reference example 4-4 was a test example in which the same production process as described in the above Example 1 was carried out, except for not conducting the intermediate rolling immediately before the aging treatment, and changing the aging to a single stage aging treatment at 500°C for 2 hours, which is a comparative example with respect to the invention according to the item (3) above.
• the investigation on the properties was carried out, with respect to the copper alloy sheets, in the same manner as in the above Example 1, on (1) grain size, (2) tensile strength, (3) electrical conductivity, and (4) bending property. The results are shown in Table 2.
• Examples 4-2 and 4-3 according to the present invention each had achieved a further higher mechanical strength than Example No. 4 according to the present invention of the above Example 1, and a favorable bending property.
• Comparative examples 15-2 and 15-3 which had the Ni/Si larger than the upper limit value, were lower in the mechanical strength with no effects of modifying the process, as compared to Examples 4-2 and 4-3 according to the present invention; and since they were larger in the grain size, they were poor in the bending property.
• Comparative examples 22-2 and 22-3 which had the Ni/Si less than the lower limit value, were low in the electrical conductivity, and low in the mechanical strength, as compared to Examples 4-2 and 4-3 according to the present invention with no effects of modifying the process.
• Reference example 4-4 which was a test example in which the finish rolling ratio was increased so as to try to enhance the mechanical strength, but the resultant strength was rather lowered, and the bending property was poor.
• the copper alloy material for electrical/electronic equipments of the present invention has a remarkable high mechanical strength and a favorable bending property, and thus can be favorably used in parts for electrical/electronic equipments, particularly in spring contacts of connectors, and the like. Furthermore, since the electrical/electronic part of the present invention is one obtained by working the copper alloy material for electrical/electronic equipments, the part is favorable as a part for the use in connectors, where a favorable bending property is required, despite of having a remarkably high mechanical strength.

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• 2009
  • 2009-03-30 CN CN2009801117819A patent/CN101981213B/zh not_active Expired - Fee Related
  • 2009-03-30 JP JP2009536501A patent/JP4653240B2/ja not_active Expired - Fee Related
  • 2009-03-30 KR KR1020107023904A patent/KR101114116B1/ko not_active IP Right Cessation
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• 2010
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