Circuit panels are provided with resistors in vias extending between the top and bottom surfaces of the panels. The resistors may be formed by depositing a composite in each via, as by depositing a dispersion of a conductive material and a dielectric or by depositing one or more thin layers of a conductor....http://www.google.es/patents/US7049929?utm_source=gb-gplus-sharePatente US7049929 - Resistor process
