Copper alloy material for electric/electronic parts and method of producing the same

Abstract

A copper alloy material for an electric/electronic part, having a composition comprising Co 0.5 to 2.0 mass % and Si 0.1 to 0.5 mass %, with the balance of Cu and inevitable impurities, in which a copper alloy of a matrix has a grain size of 3 to 35 μm, a precipitate composed of Co and Si has a particle size of 5 to 50 nm, the precipitate has a density of 1×10 8 to 1×10 10 number/mm 2 , and the copper alloy material has a tensile strength of 550 MPa and an electrical conductivity of 50% IACS or more.

1 . A copper alloy material for an electric/electronic part, having a composition comprising Co (cobalt) 0.5 to 2.0 mass % and Si (silicon) 0.1 to 0.5 mass %, with the balance of Cu (copper) and inevitable impurities,
 wherein a copper alloy of a matrix has a grain size of 3 to 35 μm,   wherein a precipitate composed of Co and Si has a particle size of 5 to 50 nm, and the precipitate has a density of 1×10 8  to 1×10 10  number/mm 2 , and   wherein the copper alloy material has a tensile strength of 550 MPa and an electrical conductivity of 50% IACS or more.   
     
     
         2 . The copper alloy material for an electric/electronic part according to  claim 1 , comprising at least one of Sn (tin) and Mg (magnesium) 0.1 to 0.5 mass % in total. 
     
     
         3 . The copper alloy material for an electric/electronic part according to  claim 1 , comprising at least one of Zn (zinc) and Mn (manganese) 0.1 to 0.5 mass % in total. 
     
     
         4 . The copper alloy material for an electric/electronic part according to  claim 1 , comprising at least one selected from the group consisting of Fe (iron), Cr (chronium) and Ni (nickel) 0.1 to 1.0 mass % in total. 
     
     
         5 . The copper alloy material for an electric/electronic part according to  claim 1 , wherein a stress relaxation ratio after a lapse of 1,000 hours in an air atmosphere at a temperature of 150° C. is less than 40%. 
     
     
         6 . A method of producing a copper alloy material for an electric/electronic part, comprising the steps a and b of:
 step a: subjecting a copper alloy material having a composition comprising Co 0.5 to 2.0 mass % and S±0.1 to 0.5 mass %, with the balance of Cu and inevitable impurities, to an aging heat treatment at 500 to 600° C. for 1 to 4 hours; and   step b: after the step a, setting a cooling speed from the temperature at the time of the aging heat treatment to a temperature of the copper alloy material of 300° C. to be in a range of 20 to 100 K/hour (K representing the absolute temperature),   whereby a copper alloy material is obtained, in which a copper alloy of a matrix has a grain size of 3 to 35 μm, a precipitate containing Co and Si has a particle size of 5 to 50 nm, the precipitate has a density of 1×10 8  to 1×10 10  number/mm 2 , and the copper alloy material has a tensile strength of 550 MPa or more and an electrical conductivity of 50% IACS or more.   
     
     
         7 . The copper alloy material for an electric/electronic part according to  claim 1 , wherein the surface roughness as the copper alloy material is such that Ra is 0.2 μm or less and Rt is 2 μm or less. 
     
     
         8 . The copper alloy material for an electric/electronic part according to  claim 7 , comprising at least one selected from the group consisting of Zn, Sn and Mg 0.1 to 1.0 mass % in total. 
     
     
         9 . The copper alloy material for an electric/electronic part according to  claim 7 , comprising at least one selected from the group consisting of Fe, Cr and Ni 0.1 to 1.0 mass % in total. 
     
     
         10 . A method of producing a copper alloy material for an electric/electronic part, comprising the steps of:
 subjecting a copper alloy material having a composition comprising Co 0.5 to 2.0 mass % and Si 0.1 to 0.5 mass %, with the balance of Cu and inevitable impurities, to an aging heat treatment;   acid-dissolving the surface of the aged material; and   grinding the acid-dissolved surface,   whereby a copper alloy material is obtained, in which a copper alloy of a matrix has a grain size of 3 to 35 μm, a precipitate containing Co and Si has a particle size of 5 to 50 nm, the precipitate has a density of 1×10 8  to 1×10 10  number/mm 2 , and the copper alloy material has a surface roughness of 0.2 μm or less in Ra and 2 μm or less in Rt, and a tensile strength of 550 MPa or more, and an electrical conductivity of 50% IACS or more.   
     
     
         11 . The copper alloy material for an electric/electronic part according to  claim 1 , wherein the Co content is 0.7 to 2.0 mass %, the mass ratio of Co to Si (Co/Si) is from 3 to 5, the arithmetic mean of the grain size of the copper alloy of a matrix is 3 to 20 μm, the standard deviation is 8 μm or less, and the standard deviation is smaller than the arithmetic mean. 
     
     
         12 . The copper alloy material for an electric/electronic part according to  claim 11 , further comprising at least one selected from the group consisting of Cr, Ni and Fe 0.01 to 1.0 mass % in total, with the balance of Cu and inevitable impurities. 
     
     
         13 . The copper alloy material for an electric/electronic part according to  claim 11 , further comprising at least one selected from the group consisting of Sn, Mg, Zn and Mn 0.01 to 1.0 mass % in total, with the balance of Cu and inevitable impurities. 
     
     
         14 . The copper alloy material for an electric/electronic part according to  claim 11 , further comprising at least one selected from the group consisting of Zr (zirconium) and Ti (titanium) 0.01 to 1.0 mass % in total, with the balance of Cu and inevitable impurities.