Radiation Hardened Application Specific Integrated Circuits (ASICs) provide for the highest performance, lowest power and size for Space Missions. In order to dramatically reduce the development cycle and reduce the cost to tapeout Rad Hard ASICs, we propose a Structured ASIC approach. In this approach we fix an array of complex logic cells and provide a fixed Area Array for I/O pads supporting in excess of 400 CMOS GPIO pins. In addition, we fix the power grid and the pins associated with power (core and I/O) and ground. Thus, we require only routing in a subset of the metal layers in order to configure the Structured ASIC to a specific design. This leads to substantial reduction in design and verification time to tapeout, and results in reduced cost by requiring a subset of Mask changes per design. In this work, we will build on existing 90nm Silicon proven Radiation Hardened Structured ASIC platform and develop a Structured ASIC platform at the 45nm SOI technology node with the objective to increase the clock speeds to hundreds of MHz with SEU mitigation in sequential logic. We will also use High Density Interconnect (HDI) for packaging the Die in BGA and LGA packages. The HDI design does not change for each configuration of the Structured ASIC so that the same benefits of Structured ASIC are extended to packaging the part with high pinout and high speed I/O requirements eliminating layout design costs.