Alloy solder and alloy solder manufacturing method

Abstract

The present invention solves the problem of the bonding strength of a Pb-free alloy solder being inferior to that of the conventional Pb-containing alloy solder and provides a Pb-free alloy solder satisfactory in bonding reliability. An alloy solder is manufactured by adding a predetermined amount of carbon to a Pb-free solder in a high-temperature atmosphere of a temperature in the range of 800° C. to 1200° C. An alloy solder manufacturing method includes a melting process for melting a Pb-free solder by heating the Pb-free solder in a high-temperature atmosphere of a temperature in the range of 800° C. to 1200° C., a carburizing process for carburizing the molten Pb-free solder held in the high-temperature atmosphere by adding a predetermined amount of carbon to the molten Pb-free solder, a stirring process for stirring a mixture of the molten Pb-free solder and carbon, and a cooling process for cooling the mixture of the Pb-free solder and carbon stirred by the stirring process and poured into a mold to solidify the mixture.

1 - 18 . (canceled) 
     
     
         19 . An alloy solder manufactured by adding carbon to a Pb-free solder in a predetermined carbon content in a range of 0.01 to 0.7 wt %, the carbon being graphite of a hexagonal system. 
     
     
         20 . The alloy solder according to  claim 19 , wherein the carbon is added in a high-temperature atmosphere in a range of 800° C. to 1200° C. 
     
     
         21 . The alloy solder according to  claim 19 , wherein the Pb-free solder contains 96.5 wt % Sn, 3 wt % Ag and 0.5 wt % Cu. 
     
     
         22 . The alloy solder according to  claim 19 , wherein the Pb-free solder contains 99.3 Wt % Sn and 0.7 wt % Cu. 
     
     
         23 . The alloy solder according to  claim 19 , wherein the Pb-free solder contains 99.0 wt % Sn, 0.7 wt % Cu and 0.3 wt % Ag. 
     
     
         24 . An alloy solder manufacturing method comprising:
 a melting process for melting a Pb-free solder by heating a high-temperature metal melting system containing the Pb-free solder at a temperature for a high-temperature atmosphere in a range of 800° C. to 1200° C.;   a carburizing process for carburizing the molten Pb-free solder held in the high-temperature atmosphere by adding carbon as a recarburizer to the molten Pb-free solder such that the Pb-free solder has a predetermined carbon content in a range of 0.01 to 0.7 wt %;   a stirring process for stirring a mixture of the molten Pb-free solder and carbon; and   a cooling process for cooling the mixture of the Pb-free solder and carbon stirred by the stirring process for stirring the mixture of the Pb-free solder and carbon and poured into a mold to solidify the mixture.   
     
     
         25 . The alloy solder manufacturing method according to  claim 24 , wherein the high-temperature metal melting system includes a melting furnace to be charged with the Pb-free solder and the recarburizer, a sealed heating space forming part for forming a sealed heating space over the melting furnace, a heating unit for supplying a heating fuel into the sealed heating space to heat the sealed heating space and the furnace, and an exhaust pipe connected to the heating space forming part. 
     
     
         26 . The alloy solder manufacturing method according to  claim 25 , wherein the supply of the heating fuel is regulated such that a gas exhausted through the exhaust pipe during the melting process contains no oxygen. 
     
     
         27 . The alloy solder manufacturing method according to  claim 24  further comprising:
 a carbon content adjusting process for adjusting the carbon content of the mixture to a desired carbon content by charging a low-temperature melting system with the mixture solidified by the cooling process, melting the mixture in a low-temperature atmosphere and charging a predetermined additional amount of the Pb-free solder into the low-temperature melting system such that the mixture has a desired carbon content; and   a recooling process for cooling and solidifying the mixture having the desired carbon content adjusted by the carbon content adjusting process by pouring the molten mixture into a mold.   
     
     
         28 . The alloy solder manufacturing method according to  claim 27  further comprising an analyzing process for determining the carbon content of the mixture solidified by the cooling process to be executed before the carbon content adjusting process;
 wherein the carbon content adjusting process determines the predetermined additional amount on the basis of the result of the analysis made by the analyzing process.   
     
     
         29 . The alloy solder manufacturing method according to  claim 27 , wherein the mixture solidified by the cooling process has a higher one of carbon contents in the range of 0.01 to 0.7 wt %, and the desired carbon content is a lower one of the carbon contents in the range of 0.01 to 0.7 wt %. 
     
     
         30 . The alloy solder manufacturing method according to  claim 27 , wherein the temperature of the low-temperature atmosphere is in the range of 250° C. to 400° C. 
     
     
         31 . The alloy solder manufacturing method according to  claim 24 , wherein the carbon is graphite of a hexagonal system. 
     
     
         32 . An alloy solder manufactured by the alloy solder manufacturing method according to  claim 24 . 
     
     
         33 . An alloy solder manufactured by the alloy solder manufacturing method according to  claim 25 . 
     
     
         34 . An alloy solder manufactured by the alloy solder manufacturing method according to  claim 26 . 
     
     
         35 . An alloy solder manufactured by the alloy solder manufacturing method according to  claim 27 . 
     
     
         36 . An alloy solder manufactured by the alloy solder manufacturing method according to  claim 28 . 
     
     
         37 . An alloy solder manufactured by the alloy solder manufacturing method according to  claim 29 . 
     
     
         38 . An alloy solder manufactured by the alloy solder manufacturing method according to  claim 30 . 
     
     
         39 . An alloy solder manufactured by the alloy solder manufacturing method according to  claim 31 .