Electrical connection structure

An electrical connection structure comprising:

• a first metal member including copper or a copper alloy, a plated tin layer being formed on at least a portion of the first metal member;
• a second metal member that is electrically connected or connectable to the first metal member;
• and
• a surface treating layer formed on a surface of the first metal member,
• wherein the surface treating layer is formed by applying a surface treating agent containing base oil and a metal affinity compound having a lipophilic group and an affinity group that has an affinity for metal, and
• the metal affinity compound contains:
• an adduct (a) between an azole compound and an acidic alkyl phosphate ester including one or more of the compounds represented by General Formula (1):
• P(═O)(—OR1)(—OH)2 (1)
• and General Formula (2):
• P(═O)(—OR1)2(—OH) (2)
• where R1 represents an organic group having 4 or more carbon atoms;
• and
• an adduct (b) between a metal and/or an organic amine compound and an acidic alkyl phosphate ester including one or more of the compounds represented by General Formula (1) and General Formula (2).