Copper alloy with excellent stress relaxation resistance property and production method therefor

Abstract

The present invention provides a copper alloy, that includes an Sn content of 3 wt % to less than 4 wt %; a Ni content of 0.5 wt % to less than or equal to 1.0 wt %; a Zn content of 0.05 wt % to less than or equal to 5.0 wt %; and Cu and unavoidable impurities combined as the balance; wherein a total content of insolubles is less than or equal to 0.02 wt %. The present invention also relates to a method for producing the above-described copper alloy, which includes holding a copper alloy at a temperature ranging from 550 to 700° C. for a time period ranging from 5 sec to less than or equal to 5 min in the course of cold working; subsequently heat treating the copper alloy to cool the copper alloy to room temperature at a cooling speed of 5° C./sec or higher; subsequently cold working the copper alloy to a target dimension; and stabilizing annealing the copper alloy at a temperature ranging from 325 to 450° C. and a time period ranging from 5 sec to less than or equal to 180 min. By the present invention, a copper alloy is obtained that has excellent stress relaxation resistance, particularly at temperatures in excess of 140° C. The present invention is as good or better than phosphor bronze, and is excellent in the balance between a tensile strength and elongation, separation of the Sn plating layer, whisker generation from the Sn plating layer, ingot metal cost and stress corrosion cracking sensitivity.

What is claimed is:  
     
         1 . A copper alloy, comprising: 
 an Sn content of 3 wt % to less than 4 wt %;    a Ni content of 0.5 wt % to less than or equal to 1.0 wt %;    a Zn content of 0.05 wt % to less than or equal to 5.0 wt %; and    Cu and unavoidable impurities combined as the balance; wherein 
 a total content of insolubles is less than or equal to 0.02 wt %.  
   
     
     
         2 . The copper alloy according to  claim 1 , further comprising: 
 a P content of 0.001 wt % to less than 0.03 wt %;    a B content of 0.0001 wt % to less than or equal to 0.02 wt %;    an Mg content of 0.0001 wt % to less than or equal to 0.05 wt %; and    a Ca content of 0.0001 wt % to less than or equal to 0.01 wt %; wherein 
 a total content of one or more elements selected from the group consisting of P, B, Mg, Ca, and mixtures thereof is in the range of 0.0001 wt % to less than or equal to 0.1 wt %.  
   
     
     
         3 . The copper alloy according to  claim 1 , wherein a total content of one or more elements selected from the group consisting of P, B, Mg, Ca, and mixtures thereof is in the range of 0.0001 wt % to less than or equal to 0.1 wt %.  
     
     
         4 . The copper alloy according to  claim 1 , further comprising a P content of 0.001 wt % to less than 0.03 wt %.  
     
     
         5 . The copper alloy according to  claim 1 , further comprising a B content of 0.0001 wt % to less than or equal to 0.02 wt %.  
     
     
         6 . The copper alloy according to  claim 1 , further comprising an Mg content of 0.0001 wt % to less than or equal to 0.05 wt/o.  
     
     
         7 . The copper alloy according to  claim 1 , further comprising a Ca content of 0.0001 wt % to less than or equal to 0.01 wt %.  
     
     
         8 . The copper alloy according to  claim 1 , further comprising: 
 an Ag content of less than or equal to 0.1 wt %;    a Pb content of less than or equal to 0.01 wt/o;    an Fe content of less than or equal to 0.05 wt %;    an Si content of less than or equal to 0.05 wt %;    an Mn content of less than or equal to 0.1 wt %; wherein 
 a total content of one or more elements selected from the group consisting of Ag, Pb, Fe, Si, Mn and mixtures thereof is less than or equal to 0.3 wt %.  
   
     
     
         9 . The copper alloy according to  claim 1 , wherein a total content of one or more elements selected from the group consisting of Ag, Pb, Fe, Si, Mn and mixtures thereof is less than or equal to 0.3 wt %.  
     
     
         10 . The copper alloy according to  claim 1 , further comprising an Ag content of less than or equal to 0.1 wt %.  
     
     
         11 . The copper alloy according to  claim 1 , further comprising a Pb content of less than or equal to 0.01 wt %.  
     
     
         12 . The copper alloy according to  claim 1 , further comprising an Fe content of less than or equal to 0.05 wt %.  
     
     
         13 . The copper alloy according to  claim 1 , further comprising an Si content of less than or equal to 0.05 wt %.  
     
     
         14 . The copper alloy according to  claim 1 , further comprising an Mn content of less than or equal to 0.1 wt %.  
     
     
         15 . The copper alloy according to  claim 1 , further comprising: 
 an S content of less than or equal to 20 ppm;    an O content of less than or equal to 30 ppm; and    an H content of less than or equal to 2 ppm.    
     
     
         16 . The copper alloy according to  claim 1 , further comprising one or more elements selected from the group consisting of Be, Al, Ti, Cr, Co, Zr, Sb, In and mixtures thereof in total content of less than or equal to 0.1 wt %.  
     
     
         17 . The copper alloy according to  claim 1 , comprising an average grain size in a range of 1 to 15 μm.  
     
     
         18 . The copper alloy according to  claim 1 , comprising a stress relaxation coefficient of 30% or less after the copper alloy is held at 150° C. for 1000 hr under a load of a bending stress corresponding to 80% of a 0.2% yield strength at room temperature.  
     
     
         19 . An article, comprising the copper alloy as claimed in  claim 1 .  
     
     
         20 . A method for producing the copper alloy according to  claim 1 , comprising: 
 holding a copper alloy at a temperature ranging from 550 to 700° C. for a time period ranging from 5 sec to less than or equal to 5 min in the course of cold working;    subsequently heat treating the copper alloy to cool the copper alloy to room temperature at a cooling speed of 5° C./sec or higher;    subsequently cold working the copper alloy to a target dimension; and    stabilizing annealing the copper alloy at a temperature ranging from 325 to 450° C. and a time period ranging from 5 sec to less than or equal to 180 min.