A memory module assembly (1) includes a printed circuit board (10) having an electronic heat-generating electronic component (40) thereon, a heat sink (20) and a clip (30) for securing the heat sink onto the heat-generating electronic component. The clip includes a pressing portion (32) and a pair of latching portions (33) respectively extending from two ends of the pressing portion. Each latching portion includes a latching leg (332) and a retaining hook section (334) formed at a bottom end of the latching leg. The retaining hook sections tightly engage a bottom face of the printed circuit board and the pressing portion presses the base toward the heat-generating electronic component. The latching legs extend through an opening and a through hole in the printed circuit board. The through hole has a L-shaped configuration and does not communicate with a periphery side of the printed circuit board.