PCB Materials
PTFE / Teflon PCB
Lowest-loss PCB substrate for millimeter-wave and ultra-low-loss applications.
PTFE (polytetrafluoroethylene) — commonly known by the DuPont trade name Teflon — is the lowest-loss dielectric material available for PCB substrates. With a dielectric constant of approximately 2.1 and a dissipation factor below 0.001 at 10 GHz, PTFE laminates enable microwave and millimeter-wave circuit boards that operate at frequencies where even Rogers hydrocarbon/ceramic laminates introduce unacceptable loss. AstroPCB manufactures PTFE PCBs on Rogers RT/duroid, Taconic and other PTFE-based laminate systems for radar, satellite, 5G mmWave, test equipment and defense applications.
When PTFE is necessary
PTFE PCB substrates are specified when the combination of operating frequency, trace length and loss budget cannot be met with lower-cost laminate alternatives. Below 5 GHz, Rogers 4350B (Dk 3.48, Df 0.0037) provides adequate performance for most applications at significantly lower cost and easier fabrication. Between 5 and 15 GHz, the choice between Rogers hydrocarbon and PTFE depends on the specific loss budget. Above 15 GHz and particularly at millimeter-wave frequencies (24 GHz automotive radar, 28/39 GHz 5G, 60 GHz V-band, 77 GHz automotive radar), PTFE is often the baseline requirement because the insertion loss per unit length on any other material exceeds the link budget allowance.
PTFE laminates are also specified for applications requiring extremely stable dielectric properties across temperature and humidity. The moisture absorption of PTFE is essentially zero, compared to 0.02-0.05% for Rogers hydrocarbon laminates and 0.1-0.3% for FR-4. In environments where boards are exposed to humidity cycling — outdoor base stations, marine electronics, automotive underhood — PTFE provides the most stable electrical performance.
Common PTFE laminate systems
Rogers RT/duroid 5880 (Dk 2.20, Df 0.0009) is the benchmark PTFE laminate for low-loss microwave circuits. It is a glass-fiber-reinforced PTFE suitable for microstrip and stripline designs from DC through 77 GHz. RT/duroid 6002 and 6010 offer higher Dk values (2.94 and 10.2 respectively) for applications requiring higher dielectric constant — such as miniaturized patch antennas or dielectric resonator filters.
Taconic RF-35 and TLY series provide alternative PTFE-based options with different glass reinforcement styles and Dk ranges. The choice between Rogers and Taconic often depends on regional availability, specific Dk/thickness combinations required, and cost.
Fabrication challenges
PTFE PCB fabrication requires specialized processing that differs from standard FR-4 in several important ways. PTFE is a soft, flexible material that does not hold its shape as rigidly as FR-4 during drilling and handling. Drill entry and exit conditions must be optimized to prevent delamination and smearing. Hole wall activation before plating requires sodium etch or plasma treatment because the PTFE surface does not naturally bond to electroless copper — unlike the glass-epoxy surface of FR-4 that provides mechanical adhesion.
Lamination of multilayer PTFE boards requires precise temperature and pressure control. PTFE-to-PTFE bonding uses fusion bonding or specialized bond plies (such as Rogers CuClad or Taconic FR-27). Hybrid stackups bonding PTFE layers to FR-4 layers use compatible prepreg systems that bridge the CTE and bonding chemistry differences between the two materials.
Hybrid PTFE/FR-4 stackups
Many practical RF designs combine PTFE layers for the RF signal path with FR-4 layers for digital control, power distribution and mechanical support. A typical hybrid might use a PTFE core for the top signal layer (antenna elements and RF front end) bonded to FR-4 cores for the remaining layers. This approach captures the RF performance of PTFE where it matters while keeping material cost manageable for the non-RF portions of the board.
AstroPCB manufactures hybrid PTFE/FR-4 stackups with controlled impedance across both material types. The engineering team manages the CTE matching, bonding process and impedance modeling across the material transition.
Request a PTFE PCB quote
Specify the PTFE laminate system (Rogers RT/duroid, Taconic or other), operating frequency range, impedance targets and whether a hybrid stackup is acceptable. Upload your design files and the engineering team will review for PTFE-specific manufacturability and return a quotation.