Electrical circuitry 32 is comprised of a plurality of layers 30, 100, each layer 30, 100 including one or more electrical pathways 36, 38, each layer 30, 100 also including insulation 34 for insulating at least part of one layer 30 from another layer 100. The pathways 36, 38 comprise repeating patterns...http://www.google.es/patents/US4700214?utm_source=gb-gplus-sharePatente US4700214 - Electrical circuitry
