Solder alloy, solder paste, and electronic circuit board

A solder alloy consisting essentially of:

• tin, silver, copper, bismuth, antimony, indium, nickel, and cobalt, wherein
• 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 0.7 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;
• 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.