Abstract: A novel heat sink structure for being mounted to a module board to which semiconductor chips are attached and for dissipating or spreading heat generated from the semiconductor chips is disclosed. The heat sink comprises a heat sink base, and a coupling means for coupling the heat sink base to the module board. The coupling means passes through the heat sink base. The coupling means includes integrally formed upper and lower body portions, an orifice formed at least through the lower body portion, and a flanged base formed integral with the lower body portion. The flanged base fixes the coupling means to the heat sink base. The outer dimension of the upper body portion is smaller than the inner dimension of the lower body portion. As a result, many heat sinks can be stacked stably.

Abstract: A circuit board and a ball grid array (BGA) package having a solder joint with improved reliability are disclosed. The circuit board has a chip mounting surface in which wiring patterns are formed and a solder ball mounting surface in which a plurality of solder balls are mounted and electrically interconnected to the wiring patterns. The circuit board comprises a plurality of ball lands connected to the solder balls. The circuit board further includes solder ball opening area defined by a solder ball mask on the solder ball mounting surface and exposing the ball land from the solder ball mask, a plurality of pattern connecting portions each connected to corresponding one of the ball lands, and conductive wiring patterns linked together with the pattern connecting portions and electrically interconnected to the solder balls. The plurality of pattern connecting portions are aligned radially inwardly toward substantially a center point of the solder ball mounting surface.