Fuzzy clearance in printed circuit board designs

Presents a concept of clearance using fuzzy sets theory in printed circuit board (PCB) designs. In PCB designs, a clearance that means the allowable minimum spacing between conductors is defined. Existing routing systems deal with clearances by simple numeric values, which specify the boundaries of an area to keep out other conductors. Routing of automated routers based on numeric clearances induces the placing of traces along boundaries of a clearance and makes routing subsequent nets virtually unfeasible. We have proposed a method of clearance defined by fuzzy sets and applied fuzzy clearance to maze routing. In this method, the final completion rate of routing is dependent upon how a routing system varies the vagueness of clearances according to the routing condition. We report on the way of assigning membership of fuzzy clearance based on the completion rate