A card edge connector includes an insulative elongated housing, two rows of contacts disposed in the housing. The housing includes a pair of side walls extending along the longitudinal direction with a receiving slot therebetween in a transverse direction perpendicular to the longitudinal direction. The receiving slot is configured to receive a card type memory module. Each contact is equipped with the solder ball for surface mounting upon the printed circuit board. The contact includes a retaining section secured to the housing, a deflectable contacting section extending upwardly from the retaining section, and a tail section extending downwardly from the retaining section and including a connecting section and a solder pad. The solder pads of the contacts in a same row along the longitudinal direction are alternately arranged in opposite directions in the transverse direction perpendicular to the longitudinal direction.