Copper alloy having high strength and high softening resistance

Abstract

Disclosed is a Cu—Fe—P alloy capable of enabling high strength, high electrical conductivity, and excellent softening resistance to coexist. The Cu—Fe—P alloy is suitable for use as a constituent material of a lead frame for a semiconductor device. With the Cu—Fe—P alloy with strength rendered higher by micronizing Fe-containing compounds, when enhancing softening resistance by increasing Sn content so as to exceed 0.5 mass %, at least one element selected from the group consisting of Ni, Mg, Ca, Al, Si, and Cr, in trace amounts, are caused to be additionally contained to thereby check cracking likely to occur at the time of forging and hot rolling in a process of producing the copper alloy, as a result of an increase in the Sn content.

1 : A copper alloy having a high strength, and high softening resistance comprising Fe in a range of 0.01 to 4.0 mass %, P in a range of 0.01 to 0.15 mass %, Sn in excess of 0.5 mass %, not higher than 5.0 mass %, and at least one element selected from the group consisting of Ni, Mg, Ca, Al, Si, and Cr, in a range of 0.001 to 0.02 mass %, in total, the remainder being Cu and unavoidable impurities, wherein a ratio of an amount of Fe in extracted residue that is extracted and separated over a filter 0.1 μm in opening size by an extracted residue method to an amount or Fe contained in the copper alloy is not more than 80%,
 said extracted residue method comprising the steps of:   immersing 10 g of the copper alloy in 300 ml of methanol solution containing 10 mass % concentration of ammonium acetate, and using the copper alloy as an anode;   applying a galvanostatic electrolytic method using platinum as a cathode at a current density of 10 mA/cm 2 , thereby dissolving the copper alloy into the methanol solution;   subjecting the methanol solution with the copper alloy dissolved therein to filtration under reduced pressure by use of a polycarbonate membrane filter with an opening size of 0.1 μm; and   separating and extracting undissolved residue on the filter,   the amount of Fe in the extracted residue being found by dissolving the undissolved residue on the filter into a solution prepared by mixing aqua regia with water at a ratio of 1 to 1 to be subsequently analyzed by the ICP emission spectroscopy.   
   
   
       2 : The copper alloy according to  claim 1 , wherein Fe content is a range of 0.01 to 0.5 mass %. 
   
   
       3 : The copper alloy according to  claim 1 , further comprising Zn in a range of 0.005 to 3.0 mass %. 
   
   
       4 : The copper alloy according to  claim 2 , further comprising Zn in a range of 0.005 to 3.0 mass %. 
   
   
       5 : The copper alloy according to  claim 1 , wherein the copper alloy is in the form of a copper alloy sheet for use as an IC lead frame. 
   
   
       6 : The copper alloy according to  claim 2 , wherein the copper alloy is in the form of a copper alloy sheet for use as an IC lead frame. 
   
   
       7 : The copper alloy according to  claim 3 , wherein the copper alloy is in the form of a copper alloy sheet for use as an IC lead frame. 
   
   
       8 : The copper alloy according to  claim 4 , wherein the copper alloy is in the form of a copper alloy sheet for use as an IC lead frame.