Fuzzy thermal placement for multichip module applications

This paper presents an algorithm based on the fuzzy logic approach for the placement of the power dissipating chips on the multichip module substrate. In the conventional force-directed placement method. the forces are relate d to the number of connection among the modules. However, unlike the conven tional force-directed placement method, the fuzzy approach is used to model the force interaction among the chips in our placement method. The force i nteraction and the distance between two chips are chosen as linguistic vari ables. The fuzzy placement analysis uses the Z and S membership functions t o describe the repulsive and attractive forces among the modules. The propo sed thermal force-directed placement method is then to relate the force equ ations to the power dissipation values of the individual bare chip. Details of implementation of our placement algorithm are provided. To verify the t hermal placement prediction, the finite element analysis is carried out to map the thermal distribution of all the chips in the multichip module. Our fuzzy logic-based thermal placement method is applied to a multichip module for a case study. The finite element simulation results show our approach can obtain better thermal distribution than other traditional placement met hods. (C) 2001 Elsevier Science B.V. All rights reserved.