The thing that needs to be noticed in the ball grid array is there is no direct lead that connects the ball grid with the circuit. Instead of leads, the ball grid uses solder balls to make a connection with the circuit and to pass the electric current. There is a physical connection made between the substrate and these balls during the smt assembly process. The physical structure is connected to the substrate by a wire which is responsible for the flow of the current. The conductive traces present in the trace are responsible for sending electric signals. This flow happens between the bonds and the substrate and the base of the balls.