Cu-ni-si system alloy

Abstract

The present invention provides Cu—Ni—Si system alloys for electronic material that with the addition of other alloy elements minimized, simultaneously exhibits enhanced electric conductivity, strength, bendability and stress relaxation performance. There are provided Cu—Ni—Si system alloys comprising 1.2 to 3.5 mass % Ni, Si in a concentration (mass %) of ⅙ to ¼ of Ni concentration (mass %) and the balance Cu and impurities whose total amount is 0.05 mass % or less, the Cu—Ni—Si system alloys having its configuration of crystal grains and width of a precipitate-free zone regulated so as to fall within appropriate ranges by controlling solution treatment conditions, aging treatment conditions and degree of a reduction ratio. Thus, there can be provided copper alloys strip of 55 to 62% IACS electric conductivity and 550 to 700 MPa tensile strength, being free from cracking at 180° bending test of 0 radius and exhibiting a stress relaxation ratio, as measured on heating at 150° C. for 1000 hr, of 30% or less.

1 . A Cu—Ni—Si system alloy comprising 1.2 to 3.5 mass % Ni, Si in a concentration (mass %) of ⅙ to ¼ of the Ni concentration (mass %), the balance being Cu and impurities whose total amount is 0.05 mass % or less, the alloy having the following characteristics:
 (A) electric conductivity of 55 to 62% IACS;   (B) tensile strength of 550 to 700 MPa;   (C) bendability determined as freedom from cracking at 180° in a bending test of 0 radius; and   (D) stress relaxation performance 30% or less as measured on heating at 150° C. for 1000 hour.   
     
     
         2 . Cu—Ni—Si system alloy comprising 1.2 to 3.5 mass % Ni, Si in a concentration (mass %) of ⅙ to ¼ of the Ni concentration (mass %), 0.5 mass % or less of Zn, and the balance being Cu and impurities whose total amount is 0.05 mass % or less, said alloy having the following characteristics:
 (A) electric conductivity of 55 to 62% IACS;   (B) tensile strength of 550 to 700 MPa;   (C) bendability determined as freedom from cracking at 180° in a bending test of 0 radius;   (D) stress relaxation performance of 30% or less as measured on heating at 150° C. for 1000 hr; and   (E) thermal peel resistance of plating determined as the absence of visible peeling of an Sn plating after a thermal peel resistance test of said Sn plating.   
     
     
         3 . A Cu—Ni—Si system alloy comprising 1.2 to 3.5 mass % Ni, Si in a concentration (mass %) of ⅙ to ¼ of the Ni concentration (mass %), 0.5 mass % or less of Zn as an optional ingredient, the balance being Cu and impurities whose total amount is 0.05 mass % or less, wherein when an average grain size transverse to a rolling way is set to “a” and an average grain size parallel to the rolling way is set to “b” in a metal structure of the alloy whose cross-section is parallel to a rolling direction, “a” is 1 to 15 μm, and “b/a” is 1.05 to 1.67, and
 an average range of a precipitate-free zone in the metal structure is 10 to 100 nm.   
     
     
         4 . A wrought copper product comprising the Cu—Ni—Si system alloy of any one of  claims 1  to  3 . 
     
     
         5 . An electronic component comprising the Cu—Ni—Si system alloy of any one of  claims 1  to  3 . 
     
     
         6 . A method for manufacturing Cu—Ni—Si system alloys of any one of  claims 1  to  3  comprising steps of a solution treatment, a cold rolling, an age hardening and a cold rolling in series, wherein each step is conducted under the following conditions:
 for said solution treatment, an average grain size is adjusted within 1 to 15 μm upon solution treatment   for said age hardening, a maximum temperature of materials during a heat treating is 550° C. or less, the temperature of materials is maintained within 450 to 550° C. for 5 to 15 hours, and an average rate of the temperature increase of materials is 50° C./hour or less in each temperature province of 200 to 250° C., 250 to 300° C. and 300 to 350° C. during a temperature increase process; and   for cold rolling, sum of a rolling reduction ratio at the cold rolling before the age hardening and a reduction ratio at the cold rolling after the age hardening is 5 to 40%.