The selection of appropriate PCB materials is the first step towards the development of a successful circuit design. In the past, this selection was based primarily on mechanical and thermal considerations because there were no significant problems encountered from the electrical routing of the signal and power paths at relatively low data rates. As data rates have increased to reach transfer levels in the range of gigabits per second, accounting for fundamental transmission line concepts in circuit design has become mandatory. In this regard, the corresponding delay and losses introduced by the non-ideal properties of the media where the signals propagate affect the integrity of the digital information sent from one point to other within a circuit. Thus, it is important for the circuit designer to minimize these effects by selecting appropriate materials for implementing interconnect channels operating at a given bandwidth.