A ball grid array socket connector (1) includes an insulative base (10), a number of conductive contacts (18) fixed to the base, a number of solder balls (30) attached to tail portions (32) of corresponding contacts and a cover (20) movably attached to the base. The base has a top surface (14), a bottom surface (16) and defines a number of cavities (12) through the top surface and the bottom surface. The cavities are arranged in a matrix. The contacts are received in corresponding cavities of the base. The base provides a number of stand-offs (28) which downwardly protrude from the bottom surface of the base and terminate at a plane (D) generally parallel with the bottom surface of the base. The solder balls each have a bottom tip (31) that downwardly extends beyond the plane D. The base defines a number of notches (26) in the bottom surface thereof. The notches are located at outer sides of the matrix of cavities.