An electric appliance has a first terminal and a second terminal electrically connected to the first terminal. The first terminal has a soldering portion for soldering the second terminal thereon. The soldering portion has a smooth face and a rough face disposed on one imaginary plane. The rough face has a flat portion and a plurality of concavities disposed on the flat portion at intervals. Further, the soldering portion may have a through hole adjacent to the rough face to insert the second terminal. The first terminal is embedded in an insulator. The insulator has an opening exposing the soldering portion therein. The insulator includes a frame forming a housing of an electric appliance. A seal seals a connection gap at a margin of the frame in the housing. A partition wall may be disposed between the soldering portion and the seal.