An integrated circuit, IC, package assembly , comprising: - a die , - a first package substrate , and - a second package substrate , - the first package substrate configured to route input/output (I/O) signals and ground between the die and the second package substrate , - the first package substrate having a - first side configured to receive the die and - a second side opposite the first side, - the first package substrate including: - a plurality of contacts disposed on the second side of the first package substrate; and - at least two ground vias (242, 244, 246; 252, 254, 256) of a same layer of vias, and - signal vias of the same layer of vias , wherein an individual contact of the plurality of contacts is configured to form an individual solder joint with the second package substrate, wherein - the at least two ground vias form a cluster of ground vias (242, 244, 246; 252, 254, 256) electrically coupled with the individual contact, - the cluster of ground vias is surrounded by the signal vias of the same layer of vias, - the signal vias route input/output (I/O) signals through the first package substrate, and - the cluster of ground vias routes ground through the first package substrate, characterized in that the signal vias are configured in a hexagonal arrangement around the cluster of ground vias. - a die , - a first package substrate , and - a second package substrate , - the first package substrate configured to route input/output (I/O) signals and ground between the die and the second package substrate , - the first package substrate having a - first side configured to receive the die and - a second side opposite the first side, - first side configured to receive the die and - a second side opposite the first side, - the first package substrate including: - a plurality of contacts disposed on the second side of the first package substrate; and - at least two ground vias (242, 244, 246; 252, 254, 256) of a same layer of vias, and - signal vias of the same layer of vias , wherein an individual contact of the plurality of contacts is configured to form an individual solder joint with the second package substrate, wherein - the at least two ground vias form a cluster of ground vias (242, 244, 246; 252, 254, 256) electrically coupled with the individual contact, - the cluster of ground vias is surrounded by the signal vias of the same layer of vias, - the signal vias route input/output (I/O) signals through the first package substrate, and - the cluster of ground vias routes ground through the first package substrate, characterized in that the signal vias are configured in a hexagonal arrangement around the cluster of ground vias. - a plurality of contacts disposed on the second side of the first package substrate; and - at least two ground vias (242, 244, 246; 252, 254, 256) of a same layer of vias, and - signal vias of the same layer of vias , wherein an individual contact of the plurality of contacts is configured to form an individual solder joint with the second package substrate, wherein - the at least two ground vias form a cluster of ground vias (242, 244, 246; 252, 254, 256) electrically coupled with the individual contact, - the cluster of ground vias is surrounded by the signal vias of the same layer of vias, - the signal vias route input/output (I/O) signals through the first package substrate, and - the cluster of ground vias routes ground through the first package substrate, characterized in that the signal vias are configured in a hexagonal arrangement around the cluster of ground vias. <EOS>