Since modern MCM (Multi Chip Module) is required to provide higher performance, MCM's density and power consumption has been increased very rapidly. Increase of chip density and power consumption lead to hot spots which accelerate the device's life time and result in device failure in the long run. In this paper, a new placement method is presented to improve the MCM's reliability using a TPSA (Two-Phase Simulated Annealing) algorithm. The TPSA searches the lowest failure rate placement of MCM perturbing higher failure rate phase and lower failure rate phase at the same time to generate a new movement. The proposed algorithm is applied to the IBM (International Business Machines) MCM device for searching an optimal solution and for comparing optimized results with other optimization results. The result shows improvement in reliability and temperature distribution satisfying constraints.