high-Dk
Materials with dielectric constant significantly above FR-4, used for size reduction or embedded capacitance.
Definition
High-Dk (high dielectric constant) materials have Dk values significantly above standard FR-4's 4.2-4.5. Applications: embedded capacitance (Dk 10-35 for FaradFlex, Interra), antenna miniaturization (higher Dk shrinks antenna dimensions), and filter design. Trade-offs: higher Dk usually means higher loss (Df), and signal propagation slows (velocity ≈ c/√Dk). Cost increases substantially with Dk. Materials include ceramic-filled PTFE, barium titanate composites, and specialty laminates. Use high-Dk strategically for specific layers or applications, not throughout the stackup.