A PCB is called a high-frequency PCB if it is made from a material with a dielectric constant of less than 3. They are created using techniques that employ high-frequency processes. These techniques are used to prevent the PCB from being damaged by high heat, humidity, or chemicals. HFPCB is a top-quality, high-performance PCB. It has many benefits over other PCBs.
High-frequency PCBs find their requirement in radio frequency, microwave, mobile, and satellite applications. With the increasing complexity of electronic circuits and fast data transmission rates, high-frequency PCBs are the preferred choice for developing products.
Features of High-Frequency PCB
Dielectric Constant
While working in the high-frequency range, selecting a material having a low dielectric constant is a must. Because it leads to less signal delay.
Dissipation Factor
The dissipation factor of the dielectric material should be less to avoid any signal loss.
Thermal Expansion
The thermal expansion of the dielectric must be the same as the conductive copper layer. Otherwise, due to the difference in the temperature between the layers, they break apart. This problem eliminates by selecting a proper dielectric material.
Others
The dielectric must have less water absorption capacity. Otherwise, high water absorption increases the dissipation factor and dielectric constant of the material.
Other specific features like heat resistant property, impact endurance, peel-off resistance, chemical resistant are also important while designing a perfect PCB board.
Materials used in a High-Frequency PCB
Different substrate materials are preferred depending upon the user requirement, frequency of operation, and material properties. The popular choices include FR4, PPO, and PTFE (Teflon).
Standard FR4 substrate is used up to a frequency of 1GHz. It is cost-effective among the three and has less thermal resistance. PPO-based PCB boards work best in the frequency range of 1-10GHz.
For frequencies greater than 10GHz, Teflon is the preferred choice for the substrate in PCB boards. The material is best among the others to operate in the high-frequency range. Despite such a good performance, the material has a high thermal resistance and is costly.
Problems faced with Teflon and their rectification
Silicon dioxide or fiberglass is added as a filling material to reduce the thermal resistance and improve Teflon stiffness.
Due to the molecular inertia of Teflon, it becomes difficult to combine it with the copper layer. So, it becomes necessary to increase the surface roughness. For this, one way is to treat the combining surface with certain materials. The treatment includes chemical or plasma etching. Another way to eliminate molecular inertia is to insert an adhesive layer between Teflon and copper foil.
Applications of High Frequency PCB
1. Advanced communication systems in industrial, medical, and defense applications requires high-frequency PCB.
2. High-frequency PCBs are a perfect choice for satellites, airborne, and ground-based radar systems.
3. Cell phones, GPS receivers, and RF remote control use high-frequency PCBs for better signal transmission.
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