A cavity semiconductor package has a pre-molded leadframe construction. The leadframe is formed by molding around a die pad, and plural terminal lands. The leadframe has a hole for an acoustic port, such that the package can be soldered on a back side of a printed circuit board and have air access to a sensor die in the package from a front side of the printed circuit board via the acoustic port. The leadframe may also have a hollow or concave recess that defines an acoustic cavity in conjunction with the sensor die or printed circuit board.