PCB Classification “Pattern and Drill Specification” are used shorthandly to measure the manufacturability of the PCB: this generate a classification which is related to the PCBoard’s Services. Any way these classes generally permit to control the price of the PCB on demand service.
Parameter of these specification are: - the minimum width for copper tracks (conductors) and gap (isolation) between them both for Outer and Inner layers; - the minimum gap (distance) between cu-plated trough hole and lay out copper both for Outer and Inner layers; - the minimum copper rings (difference between copper pad and hole sizes) both on outer and inner layers; - the holes characteristic (minimum size and related production process); - the required or needed hole accuracy (location and align registration); - the solder mask characteristic (size of clearance related to copper lay out, minimum line size, devolpment in holes) - mechanical requirements
Small or large values of these characteristics determine the class of PCB technology, production, or its complexity. For details on said class values, reference is made to the relevant tables.