Solder alloy, solder paste, and electronic circuit board

Abstract

In a solder alloy consisting essentially of tin, silver, copper, bismuth, antimony, indium, nickel and an additional element, the content ratios of the silver, the copper, the bismuth, the antimony, the indium, the nickel and the additional element, which is at least one of germanium, gallium, iron or phosphorus, are defined, the content ratio of the tin is the remaining ratio, and the mass ratio (Bi/Ni) of the bismuth content with respect to the nickel content is 35 or more and 1500 or less. In a further embodiment, the solder alloy additionally contains a defined amount of cobalt.

1 . A solder alloy consisting essentially of:
 tin, silver, copper, bismuth, antimony, indium, nickel, and an additional element, wherein the additional element is at least one element selected from the group consisting of germanium, gallium, iron, and phosphorus,   with respect to the total amount of the solder alloy, the content ratio of the silver is 0.05 mass % or more and below 0.2 mass %;   the content ratio of the copper is 0.1 mass % or more and 1 mass % or less;   the content ratio of the bismuth is above 4.0 mass % and 10 mass % or less;   the content ratio of the antimony is 0.005 mass % or more and 8 mass % or less;   the content ratio of the indium is 0.005 mass % or more and 2 mass % or less;   the content ratio of the nickel is 0.003 mass % or more and 0.4 mass % or less;   the content ratio of the additional element is above 0 mass % and 1 mass % or less; and   the content ratio of the tin is the remaining ratio, and   the mass ratio (Bi/Ni) of the bismuth content with respect to the nickel content is 35 or more and 1500 or less.   
     
     
         2 . A solder paste comprising:
 a solder powder made from the solder alloy described in  claim 1  and flux.   
     
     
         3 . An electronic circuit board comprising:
 a soldering portion soldered by the solder paste described in  claim 2 .   
     
     
         4 . A solder alloy consisting essentially of:
 tin, silver, copper, bismuth, antimony, indium, nickel, cobalt, and an additional element, wherein the additional element is at least one element selected from the group consisting of germanium, gallium, iron, and phosphorus,   with respect to the total amount of the solder alloy,   the content ratio of the silver is 0.05 mass % or more and below 0.2 mass %;   the content ratio of the copper is 0.1 mass % or more and 1 mass % or less;   the content ratio of the bismuth is above 4.0 mass % and 10 mass % or less;   the content ratio of the antimony is 0.005 mass % or more and 8 mass % or less;   the content ratio of the indium is 0.005 mass % or more and 2 mass % or less;   the content ratio of the nickel is 0.003 mass % or more and 0.4 mass % or less;   the content ratio of the cobalt is 0.001 mass % or more and 0.1 mass % or less;   the content ratio of the additional element is above 0 mass % and 1 mass % or less; and   the content ratio of the tin is the remaining ratio, and   the mass ratio (Bi/Ni) of the bismuth content with respect to the nickel content is 35 or more and 1500 or less.   
     
     
         5 . A solder paste comprising:
 a solder powder made from the solder alloy described in  claim 4  and flux.   
     
     
         6 . An electronic circuit board comprising:
 a soldering portion soldered by the solder paste described in  claim 5 .