Abstract: A method includes forming a composite package substrate. The formation of the composite package substrate includes encapsulating an interconnect die in an encapsulant, with the interconnect die including a plurality of through-vias therein, and forming a first plurality of redistribution lines (RDLs) and a second plurality of RDLs on opposite sides of the interconnect die. The method further includes bonding an organic package substrate to the composite package substrate, and bonding a first package component and a second package component to the first plurality of RDLs. The first package component and the second package component are electrically interconnected through the interconnect die and the first plurality of RDLs.

Abstract: An in-process structure including an interposer is provided. The interposer includes first interposer bonding pads. An array of copper pillar structures is bonded to the first interposer bonding pads using interposer-side solder material portions. A packaging substrate is attached to the array of copper pillar structures by bonding the array of copper pillar structures to substrate bonding pads located on the packaging substrate using substrate-side solder material portions.