Dissipation Factor (Df), also known as Loss Tangent (Tan δ). In printed circuit boards, Dissipation Factor is the measure of the power of signal loss due to the inherent dissipation of electromagnetic energy in the substrate. The lower a PCB material‘s loss tangent, the less power lost. The Tan δ of most PCB materials range from 0.02 for most commonly used materials to 0.001 for very low-loss high-end materials, like Rogers.
