Automated printed circuit routing with a stepping aperture

A computer program for routing interconnections on a two-sided printed circuit board with a regular pattern of lines, pins (terminals), and vias (feed-through holes) is described. In this program, each interconnection is given a planned routing—typically, down from the upper pin, through a via, and horizontally to the lower pin. From the top, a virtual aperture (i.e. a long horizontal slit) is stepped down the board. The planned routing is the basis for rerouting interconnections within the aperture to resolve conflicts for lines and vias below the aperture and to maximize the effective line usage. If a conflict has not been resolved before the aperture arrives at the lower pin, interconnections are deleted to resolve the conflict. Extensions of this technique to the control of crosstalk between routed interconnections and to the problem of obtaining 100 percent interconnect are also discussed.

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