A coupling assembly includes a first board and a second board. The first board includes a plurality of first conductive pieces located at an end surface thereof and spaced from one another in a predetermined interval. The second board includes a plurality of second conductive pieces spaced from one another in a predetermined interval and located at at least one end surface thereof close to a lateral edge thereof. The second board includes a plurality of recessed portions recessed inward from the lateral edge thereof and located among the second conductive pieces. The first and second boards are perpendicular to each other. The conductive pieces of at least one of the two boards are provided with soldering. The soldering of each of the conductive pieces is heated to liquate out and then contact the perpendicular corresponding conductive pieces to couple the corresponding first and second conductive pieces with each other.