A method of soldering an electrical connection is described. A plurality of terminals is formed on an insulating casing, a plurality of slots being formed on a bottom of the insulating casing to communicate respectively with the terminals. A solder material is applied over electrical contacts of a circuit board for bonding the electrical connection to the circuit board, wherein the slots in the bottom of the insulating casing correspond to the solder material. The solder material is melted by heating, and the height of the solder material increases due to a cohesion effect so as to extend into the slots and bond to the terminals. The terminals need not contact the solder material before being soldered. Therefore, soldering quality is improved, while problems of short circuits and soldering failure due to deformation of the terminals are eliminated.