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What are High Frequency (HF) Printed Circuit Boards (PCB)?

High Frequency Printed Circuit Boards (HF PCBs) are fabricated with special materials that can transmit high frequency signals above 500MHz with minimal losses. They are used in variety of applications including telecommunications, RF microwave, military and aerospace. When designing a high frequency PCB, a designer must and take into considerations a number of parameters to meet the signal requirements of the particular high frequency application. These parameters include dielectric constant (Dk), dissipation factor (Df), coefficient of thermal expansion (CTE), temperature coefficient of dielectric constant (TCDk) and thermal conductivity.

Properties of High Frequency PCBs

  • Low Dielectric Constant (Dk) – reduces signal delay and improves frequency transmission
  • Low Dissipation Factor (Df) – minimizes signal loss and enhances signal transmission
  • Low Dimensional Stability – size and shape of PCBs do not change with temperature variations
  • Low Moisture Absorption - PCBs can withstand a humid environment
  • Chemical Resistance – PCB are less likely to corrode

Materials used for Fabricating High frequency PCBs

FR4 material at high frequencies has a relatively high dielectric constant however, it can be used to fabricate HR PCBs when it is combined with other high frequency laminates. Other materials used for high frequencies boards are:

  • Rogers RO4350B
  • Rogers RO3001
  • Rogers RO3003
  • ISOLA IS620 E-fibre glass
  • Taconic RF-35 Ceramic
  • Taconic TLX
  • ARLON 85N

High Frequency PCB Design Tips

Select a material with a dielectric constant and a dissipation factor that meet your application requirements.
Use low profile copper foil to prevent signal loss.
Implement impedance matching.
Keep trace lengths as short as possible to reduce coupling.
Avoid trace bending to reduce impedance variations.
Increase spacing between adjacent traces to minimize crosstalk.
Use the 3W rule whenever possible to reduce crosstalk.
Group signal and component types whenever possible

High Frequency PCB Applications

High frequency PCBs are used in projects with complex electronic circuits where rapid data transfer rates are needed. Below are some examples where they are used:

  1. Medical electronics, including monitoring and diagnostic equipment
  2. Cell phones, GPS devices and RF remote controls
  3. Communication systems including receivers, filters, amplifiers, couplers, radars, antennas
  4. Automotive
  5. RF microwave
  6. Military and aerospace

PCB Unlimited is truly the best source for printed circuit boards including high frequency PCBs. We offer domestic and offshore PCBs. We have an extensive network of PCB manufacturing partner in Taiwan and China. Each partner has a unique set of manufacturing capabilities. We can make your prototypes or mass produce the boards you need. You will find our pricing highly competitive and our customer service excellent. For a custom quote please email your Gerber files to or contact us to discuss your requirements at (800) 348-9250.