Automatic multilayer routing for surface mounted technology

The authors present an automatic routing procedure for multilayer technology, especially surface-mounted devices. The problem is to perform a wiring in a minimum number of routing layers. The pads to be connected are rectangular regions on the top layer. A channel model has been developed in which routing layers are arbitrarily divided into horizontal and vertical (HV) channels containing pads within the channel area. They may also contain areas blocked with wiring. The method is composed of global and final routing, performing a modified HV routing, allowing jogs within every layer. Global routing is based on a graph-theoretical model. Final routing then becomes an assignment problem and is solved by a cut-strategy.<>