An electrical connector assembly, for electrically interconnecting an IC package with a printed circuit board, includes a printed circuit board, an electrical connector mounted on the printed circuit board, an IC package mounted in the electrical connector, a heat sink seated on the electrical connector, a backboard located under the printed circuit board and a plurality of first and second elements. The electrical includes an insulative base and a load plate mounted on the insulative base, and the load plate defines a plurality of first holes. The heat sink defines a plurality of second holes, while the printed circuit board defines a plurality of third holes, and the backboard defines a plurality of fourth holes. The first elements are inserted through the first, the third and the fourth holes to fasten the IC package, the electrical connector, the printed circuit board and the backboard together. The second elements fasten the heat sink with the electrical together through the second holes by engaging with the first elements. Accordingly, a reason can be found out easily when the IC package can't work normally.