PCB Manufacturing

RF and Microwave

• What makes RF and microwave PCBs different from standard digital boards?

  RF and microwave PCBs are designed to operate at frequencies from ~100 MHz to 30 GHz (RF) and beyond 30 GHz (microwave), where signal loss, impedance stability, and dielectric performance are critical. They require specialized laminates such as Rogers, Taconic, Arlon, or PTFE composites with controlled dielectric constants (Dk) and low dissipation factors (Df). Fabrication must maintain precise impedance control per IPC-6018 to ensure minimal reflection and phase distortion.

• How do you control impedance in RF PCB manufacturing?


  Controlled impedance is achieved through tight control of trace width, dielectric thickness, copper plating, and laminate Dk. Summit uses advanced CAM modeling and in-process testing to hold tolerances within ±5% per IPC-6018 Class 2 or 3. Ground plane integrity, uniform copper distribution, and proper stack-up modeling are essential to maintaining impedance over temperature and frequency ranges.

• Which materials are best for high-frequency PCB designs?


  For frequencies above 1 GHz, low-loss materials such as Rogers RO4350B, RO3003, Taconic RF-35, and PTFE-based laminates are preferred. These materials provide stable Dk across a wide temperature range, low insertion loss, and minimal moisture absorption. IPC-4103 specifies base materials for high-speed/high-frequency PCBs, guiding dielectric and thermal performance requirements.

• What design features help minimize RF signal loss?


  Losses are minimized through smooth copper foils (low profile to reduce conductor loss), minimal via transitions, back-drilling of unused stubs, and optimized ground return paths. Plated through-holes and vias are modeled to avoid parasitic inductance, and transmission lines are routed with consistent geometry to meet IPC-2221/IPC-2222 design rules for high-frequency performance.

• How are RF/microwave PCBs tested for performance?


  Summit performs network analyzer measurements, time domain reflectometry (TDR), and S-parameter characterization to verify insertion loss, return loss, and impedance stability. Testing is done in accordance with IPC-TM-650 methods and IPC-6018 performance specifications, ensuring compliance for aerospace, defense, telecommunications, and high-reliability commercial applications.