US Patent 9502322 Molding compound supported RDL for IC package

One of the embodiments for a package substrate discloses a molding compound having plurality of metal pillar with middle portion embedded therein; a top end of the metal pillar protrudes above the molding compound; a bottom end of the metal pillar protrudes below the molding compound; a bottom RDL is configured on bottom of the molding compound; the RDL has a plurality of top metal pad and a plurality of bottom metal pad; a density of the plurality of bottom metal pad is higher than the density of the plurality of top metal pad; each metal pillar metal pad is electrically coupled to a corresponding first top metal pad.