Disclosed are chip module structures, each having a robust in-package interconnect for reliable performance. Some of the chip module structures achieve interconnect robustness through the use of vias in a spiral step pattern within the interconnect itself. Some chip module structures achieve interconnect robustness through the use of an interconnect stabilizer (referred to herein as a stabilization structure, fence or cage)), which includes vias in a repeating step pattern encircling the in-package interconnect, which is electrically isolated from back side solder balls, front side collapse chip connections (referred to herein as C4 connections), and the interconnect itself, and which is optionally connected to ground. Some chip module structures achieve interconnect robustness through the use of a combination of both vias in a spiral step pattern within the interconnect itself and an interconnect stabilizer.