Integrated circuit device packages with buffering layer

A flip-chip packaged integrated circuit device, comprising:

• a package substrate having first pads on a first surface and second pads on a second surface, the first pads being electrically connected to the second pads by one or more wiring layers of the package substrate;
• a layer mounted on the package substrate and having third pads on a third surface facing the package substrate and fourth pads on a fourth surface facing away from the package substrate, a plurality of through-vias extending in the layer from the third surface to fourth surface to electrically connect the third pads to the fourth pads;
• an interposer mounted on the layer and having fifth pads on a fifth surface facing the layer and sixth pads on a sixth surface facing away from the layer, the interposer incorporating therein one or more wiring layers electrically connecting the fifth pads to the sixth pads;
• and
• a first die mounted on the interposer and having a seventh pad facing the interposer and electrically connected to at least one of the first pads of the package substrate via at least one the plurality of through-vias.

A method of manufacturing a packaged integrated circuit device, the method comprising:

• mounting a layer on a package substrate, the package substrate having first pads on a first surface and second pads on a second surface, the first pads being electrically connected to the second pads by one or more wiring layers of the package substrate, the layer having third pads on a third surface facing the package substrate and fourth pads on a fourth surface facing away from the package substrate, a plurality of through-vias extending in the layer from the third surface to fourth surface to electrically connect the third pads to the fourth pads;
• mounting an interposer on the layer, the interposer having fifth pads on a fifth surface facing the layer and sixth pads on a sixth surface facing away from the layer, the interposer incorporating therein one or more wiring layers electrically connecting the fifth pads to the sixth pads;
• and
• mounting a die on the interposer.