To provide a method for mounting a circuit board for making it unnecessary to operate a strict bump shape control.
In this method for mounting a circuit board, a bump 3 is formed by plating treatment on either a terminal 2 face of a semiconductor element 1 or the electrode face of a substrate 4, and the semiconductor element is placed on the substrate so that the terminal is faced to the electrode 5, and the terminal and the electrode are electrically collectively connected with each other. In this case, the bump is formed so that a number of acicular protrusions are raised on the surface of the bump, and the terminal is connected with the electrode. The gold plating fluid consists of trivalent gold ion compound, chelate agent, conductive salt, buffer agent, and stabilizer, for forming the bump on which a number of acicular protrusions are raised, the gold plating fluid contains the trivalent gold ion of 0.005-0.12 mol/l, and either or both of ethylene diamine of 0.2-2.0 mol/l, or nitrilotriacetic acid of 0.05-0.5 mol/l as the chelate agent.