PERIMETER MATRIX BALL GRID ARRAY CIRCUIT PACKAGE WITH A POPULATED CENTER

摘要

A BALL GRID ARRAY (BGA) INTEGRATED CIRCUIT PACKAGE (10) WHICH HAS AN OUTER TWO-DIMENSIONAL ARRAY OF SOLDER BALLS (34) AND A CENTER TWO-DIMENSIONAL ARRAY OF SOLDER BALLS LOCATED ON A BOTTOM SURFACE (16) OF A PACKAGE SUBSTRATE (12). THE SOLDER BALLS ARE TYPICALLY REFLOWED TO MOUNT THE PACKAGE TO A PRINTED CIRCUIT BOARD. MOUNTED TO AN OPPOSITE SURFACE OF THE SUBSTRATE IS AN INTEGRATED CIRCUIT (18) THAT IS ELECTRICALLY COUPLED TO THE SOLDER BALLS (34) BY INTERNAL ROUTING WITHIN THE PACKAGE (10). THE OUTER ARRAY OF SOLDER BALLS (34) ARE LOCATED THE DIMENSIONAL PROFILE OF THE INTEGRATED CIRCUIT (18) TO REDUCE SOLDER STRESSES INDUCED BY THE DIFFERENTIAL THERMAL EXPANSION BETWEEN THE INTEGRATED CIRCUIT (18) AND THE SUBSTRATE (12). THE CENTER SOLDER BALLS (34) ARE TYPICALLY ROUTED DIRECTLY TO GROUND AND POWER PADS OF THE PACKAGE TO PROVIDE A DIRECT THERMAL AND ELECTRICAL PATH FROM THE INTEGRATED CIRCUIT TO THE PRINTED CIRCUIT BOARD.