Mitigation of Thermo-cycling effects in Flip-chip FPGA-based Space-borne Systems by Cyclic On-chip Task Relocation.

Thermal cycling is one of the major factors that influences aging, failure and thus, the reliability of FPGA-based systems deployed on spacecrafts performing orbital missions. Circular motion of the spacecrafts around the Earth or other planets causes significant variations of temperature in their electronic systems, resulting in thermo-cycling. For FPGA-based systems, thermal cycling depends on: off-board temperature variations, power dissipation of on-board components and on-chip temperature variations. The on-chip level of the system utilizing flip-chip FPGAs is the most sensitive to thermo-cycling. This paper presents a method for mitigating the thermo-cycling effects on flip-chip FPGAs. It is based on cyclically relocating tasks with high power dissipation to regions where tasks with low power emission are allocated and vice-versa. The cycle period depends on the difference between clock frequencies associated with the tasks and area occupied by the task circuits. The proposed approach utilizes the experimental results gained on the Xilinx 7000 series FPGA, Zynq-7020. It was determined that control of relocation cycle can keep the dynamics of temperature variations on the board and chip level coherent and thus can minimize the thermo-cycling effect on FPGA-based space-borne computing platforms.