A fuzzy expert system for hierarchical placement of parts on printed circuit board

For computer aided design (CAD)/design automation (DA) for printed circuit board (PCB), automatic placement of parts has been a difficult problem. For realizing good placement, not only the structures but also the functions of the circuit should be grasped and some hierarchical methods for the placement should be done. This paper presents a new hierarchical method of placement of parts on the PCB with fuzzification of parts connections. The devices in a circuit are divided into several blocks based on the flows of main signals of the circuit. However it is difficult to judge which device belongs to which block based on only the information included in the CAD data. We propose a method to fuzzify the degrees of belonging of the devices to the blocks. The boundaries of the areas for the blocks are also fuzzified. Each device is placed based on fuzzy areas of blocks, The feasibility of the method is verified using an actual PCB.