For reasonably using the space of a printed circuit board (PCB) an electrical connector assembly which is mounted on the PCB is provided and includes an upper an upper connector and a lower connector stacked together. The upper connector includes a plurality of first contacts each having a first horizontal soldering leg are soldered on a top surface of the PCB. The lower connector includes a plurality of second contacts each having a second vertical soldering leg soldered on a bottom surface of the PCB. The bottom surface of the PCB has a plurality of soldering holes which are not running through the top surface thereof for retaining said second vertical soldering legs therein so as to provide an available soldering area for said first horizontal soldering legs on the top surface thereof.