Conductive material for connection parts which has excellent minute slide wear resistance

Abstract

A conductive material for connection parts includes a matrix, a Cu—Sn alloy covering layer having a Cu content of 20 to 70 at % and an average thickness of from 0.2 to 3.0 μm, and a Sn covering layer having an average thickness of from 0.05 to 5.0 μm. The matrix is a copper alloy strip containing specified amounts of Cr and Zr or specified amounts of Fe and P, or a Cu—Zn alloy strip containing a specified amount of Zn. The Cu—Sn alloy covering layer and the Sn covering layer are formed in this order on a surface of the matrix.

1 : A conductive material, comprising:
 (i) a copper alloy strip as a matrix, the copper alloy strip comprising:   Cu, and   at least one element selected from the group consisting of 0.15 to 0.70 mass % of Cr and 0.01 to 0.20 mass % of Zr,   (ii) a Cu—Sn alloy covering layer having a Cu content of 20 to 70 at %, and   (iii) a Sn covering layer, formed in this order on a surface of the matrix,   wherein:   a surface of the conductive material has been subjected to a reflow processing and has an arithmetic mean roughness Ra in at least one direction of 0.15 μm or more and an arithmetic mean roughness Ra in all directions of 3.0 μm or less,   the Sn covering layer has an average thickness of from 0.05 to 5.0 μm,   the Cu—Sn alloy covering layer has been formed to be partially exposed at a surface of the Sn covering layer,   the Cu—Sn alloy covering layer has an exposed area ratio of from 3 to 75% on the surface of the conductive material,   the Cu—Sn alloy covering layer has an average thickness of from 0.2 to 3.0 μm and an average grain size in a surface thereof of less than 2 μm, and   the copper alloy strip has an electrical conductivity of more than 50% IACS and a stress relaxation rate after holding at 200° C. for 1,000 hours of 25% or less.   
     
     
         2 : The conductive material according to  claim 1 , wherein the copper alloy strip further comprises at least one member selected from the group consisting of (A) and (B):
 (A) at least one member selected from the group consisting of 0.01 to 0.30 mass % of Ti and 0.01 to 0.20 mass % of Si; and   (B) 1.0 mass % or less in total of one or more members selected from the group consisting of 0.001 to 1.0 mass % of Zn, 0.001 to 0.5 mass % of Sn, 0.001 to 0.15 mass % of Mg, 0.005 to 0.50 mass % of Ag, 0.005 to 0.50 mass % of Fe, 0.005 to 0.50 mass % of Ni, 0.005 to 0.50 mass % of Co, 0.005 to 0.10 mass % of Al, and 0.005 to 0.10 mass % of Mn.   
     
     
         3 : A conductive material, comprising:
 (i) a copper alloy strip as a matrix, the copper alloy strip comprising:   Cu,   0.01 to 2.6 mass % of Fe, and   0.01 to 0.3 mass % of P,   (ii) a Cu—Sn alloy covering layer having a Cu content of 20 to 70 at %, and   (iii) a Sn covering layer, formed in this order on a surface of the matrix,   wherein:   a surface of the conductive material has been subjected to a reflow processing and has an arithmetic mean roughness Ra in at least one direction of 0.15 μm or more and an arithmetic mean roughness Ra in all directions of 3.0 μm or less,   the Sn covering layer has an average thickness of from 0.05 to 5.0 μm,   the Cu—Sn alloy covering layer has been formed to be partially exposed at a surface of the Sn covering layer,   the Cu—Sn alloy covering layer has an exposed area ratio of from 3 to 75% on the surface of the conductive material,   the Cu—Sn alloy covering layer has an average thickness of from 0.2 to 3.0 μm and an average grain size in a surface thereof of less than 2 μm, and   wherein the copper alloy strip has an electrical conductivity of more than 55% IACS and a stress relaxation rate after holding at 150° C. for 1,000 hours of 60% or less.   
     
     
         4 : The conductive material according to  claim 3 , wherein the copper alloy strip further comprises at least one member selected from the group consisting of (C) and (D):
 (C) at least one member selected from the group consisting of 0.001 to 0.5% of Sn and 0.005 to 3.0% of Zn; and   (D) from 0.001 to 0.5 mass % in total of one or more members selected from the group consisting of Mn, Mg, Ca, Zr, Ag, Cr, Cd, Be, Ti, Si, Co, Ni, Al, Au, and Pt.   
     
     
         5 : A conductive material, comprising:
 (i) a Cu—Zn alloy strip as a matrix, the Cu—Zn alloy strip comprising:   Cu, and   10 to 40 mass % of Zn,   (ii) a Cu—Sn alloy covering layer having a Cu content of 20 to 70 at %, and   (iii) a Sn covering layer, formed in this order on a surface of the matrix,   wherein:   a surface of the conductive material has been subjected to a reflow processing and has an arithmetic mean roughness Ra in at least one direction of 0.15 μm or more and an arithmetic mean roughness Ra in all directions of 3.0 μm or less,   the Sn covering layer has an average thickness of from 0.05 to 5.0 μm,   the Cu—Sn alloy covering layer has been formed to be partially exposed at a surface of the Sn covering layer,   the Cu—Sn alloy covering layer has an exposed area ratio of from 3 to 75% on the surface of the conductive material,   the Cu—Sn alloy covering layer has an average thickness of from 0.2 to 3.0 μm and an average grain size in a surface thereof of less than 2 μm, and   the Cu—Zn alloy strip has an electrical conductivity of 24% IACS or more and a stress relaxation rate after holding at 150° C. for 1,000 hours of 75% or less.   
     
     
         6 : The conductive material according to  claim 5 , wherein the Cu—Zn alloy strip further comprises from 0.005 to 1 mass % in total of one or more elements selected from the group consisting of Cr, Ti, Zr, Mg, Sn, Ni, Fe, Co, Mn, Al, and P. 
     
     
         7 : The conductive material according to  claim 1 , further comprising an undercoat layer comprising one layer or two layers selected from the group consisting of a Ni covering layer, a Co covering layer and a Fe covering layer, the undercoat layer having been formed between the surface of the matrix and the Cu—Sn alloy covering layer, wherein the undercoat layer has an average thickness, singularly in the case of one layer or in total of both layers in the case of two layers, of from 0.1 to 3.0 μm. 
     
     
         8 . (canceled) 
     
     
         9 : The conductive material according to  claim 1 , further comprising a Sn plating layer having an average thickness of 0.02 to 0.2 μm formed on the material surface which has been subjected to the reflow processing. 
     
     
         10 : The conductive material according to  claim 3 , further comprising an undercoat layer comprising one layer or two layers selected from the group consisting of a Ni covering layer, a Co covering layer and a Fe covering layer, the undercoat layer having been formed between the surface of the matrix and the Cu—Sn alloy covering layer, wherein the undercoat layer has an average thickness, singularly in the case of one layer or in total of both layers in the case of two layers, of from 0.1 to 3.0 μm. 
     
     
         11 : The conductive material according to  claim 5 , further comprising an undercoat layer comprising one layer or two layers selected from the group consisting of a Ni covering layer, a Co covering layer and a Fe covering layer, the undercoat layer having been formed between the surface of the matrix and the Cu—Sn alloy covering layer, wherein the undercoat layer has an average thickness, singularly in the case of one layer or in total of both layers in the case of two layers, of from 0.1 to 3.0 μm. 
     
     
         12 : The conductive material according to  claim 3 , further comprising a Sn plating layer having an average thickness of 0.02 to 0.2 μm formed on the material surface which has been subjected to the reflow processing. 
     
     
         13 : The conductive material according to  claim 5 , further comprising a Sn plating layer having an average thickness of 0.02 to 0.2 μm formed on the material surface which has been subjected to the reflow processing. 
     
     
         14 : The conductive material according to  claim 7 , further comprising a Sn plating layer having an average thickness of 0.02 to 0.2 μm formed on the material surface which has been subjected to the reflow processing. 
     
     
         15 : The conductive material according to  claim 2 , further comprising an undercoat layer comprising one layer or two layers selected from the group consisting of a Ni covering layer, a Co covering layer and a Fe covering layer, the undercoat layer having been formed between the surface of the matrix and the Cu—Sn alloy covering layer, wherein the undercoat layer has an average thickness, singularly in the case of one layer or in total of both layers in the case of two layers, of from 0.1 to 3.0 μm. 
     
     
         16 : The conductive material according to  claim 15 , further comprising a Sn plating layer having an average thickness of 0.02 to 0.2 μm formed on the material surface which has been subjected to the reflow processing. 
     
     
         17 : The conductive material according to  claim 10 , further comprising a Sn plating layer having an average thickness of 0.02 to 0.2 μm formed on the material surface which has been subjected to the reflow processing. 
     
     
         18 : The conductive material according to  claim 4 , further comprising an undercoat layer comprising one layer or two layers selected from the group consisting of a Ni covering layer, a Co covering layer and a Fe covering layer, the undercoat layer having been formed between the surface of the matrix and the Cu—Sn alloy covering layer, wherein the undercoat layer has an average thickness, singularly in the case of one layer or in total of both layers in the case of two layers, of from 0.1 to 3.0 μm. 
     
     
         19 : The conductive material according to  claim 18 , further comprising a Sn plating layer having an average thickness of 0.02 to 0.2 μm formed on the material surface which has been subjected to the reflow processing. 
     
     
         20 : The conductive material according to  claim 11 , further comprising a Sn plating layer having an average thickness of 0.02 to 0.2 μm formed on the material surface which has been subjected to the reflow processing. 
     
     
         21 : The conductive material according to  claim 6 , further comprising an undercoat layer comprising one layer or two layers selected from the group consisting of a Ni covering layer, a Co covering layer and a Fe covering layer, the undercoat layer having been formed between the surface of the matrix and the Cu—Sn alloy covering layer, wherein the undercoat layer has an average thickness, singularly in the case of one layer or in total of both layers in the case of two layers, of from 0.1 to 3.0 μm. 
     
     
         22 : The conductive material according to  claim 21 , further comprising a Sn plating layer having an average thickness of 0.02 to 0.2 μm formed on the material surface which has been subjected to the reflow processing.