Optimality Criteria for Topological Design of Boards

The goal of topological design is the development of printed patterns on the board of minimum dimensions that ensure the placement of a REF with a given electrical circuit diagram, a set of IET and auxiliary structural elements with limitations caused by the following main factors: operating conditions, requirements of standardization and unification, electromagnetic compatibility and thermal modes, ensuring high reliability and manufacturability, acceptable costs for development and manufacture.

The topological design of boards is usually divided into two stages: the placement of IET and the routing of connecting lines, with the separation of a single task undertaken to simplify its solution.

The following criteria are used as the optimal placement criteria: minimum total length of all printed conductors; minimum maximum length of signal conductors; the closest spatial arrangement of the modules with the largest number of mutual relationships. All criteria are aimed at achieving a dense placement, but most often they use minimization of the total length.

Some criteria for optimal traceability match the placement criteria, but their semantic content is different. These are criteria aimed at reducing time delays: the minimum length of parallel sections of adjacent conductors; minimum length of conductors (total, signal, longest); uniform distribution of conductors on conductive layers. The criteria of the other group is based on ensuring the reliability of the EFR and the manufacturability of the conductive pattern, for example, the minimum number of conductive layers and transitions between them.