An apparatus relates generally to a microelectronic assembly. In such an apparatus, a contact arrangements are disposed on a first surface of a first substrate, including first contacts disposed as a first ring array; second contacts disposed interior to the first contacts as a second ring array; third contacts disposed interior to the second contacts as a third ring array; and fourth contacts disposed interior to the third contacts on the first surface as an innermost array. The first ring array, the second ring array, and the third ring array are concentric rings with the innermost array in a central region of the concentric rings. The first contacts and the fourth contacts are for interconnection with first microelectronic dies. The second contacts and the third contacts are for interconnection with second microelectronic dies.