Generally speaking, high frequency can be defined as the pre-rate above 1GHz. The most commonly used high-frequency circuit board substrates are fluorine-based dielectric substrates. For example, polytetrafluoroethylene (PTFE) is usually called Teflon, which is usually used above 5GHz. , In addition, FR-4 or PPO substrate is also used, which can be used for products between 1GHz-10GHz. The physical properties of these three high-frequency substrates are compared as follows.

The three types of high-frequency substrate materials currently used: epoxy resin, PPO resin and fluorine-based resin, epoxy resin is the cheapest, and fluorine-based resin is the most expensive; Considering the frequency characteristics, fluorine-based resins are the best, and epoxy resins are poor. When the frequency of product application is higher than 10CGHz, only fluorine resin printed board can be applied. Obviously, the performance of fluorine-based resin high-frequency substrates is much higher than other substrates, but its disadvantages are poor rigidity and high thermal expansion coefficient in addition to high cost. For polytetrafluoroethylene (PTFE), in order to improve the performance, a large amount of inorganic substances (such as dihydride SiO2) or glass cloth are used as reinforcing filler materials to improve the rigidity of the substrate and reduce its thermal expansion. In addition, due to the molecular inertness of the PTFE resin itself, it is not easy to bond with the copper foil, so special surface treatment of the bonding surface with the copper foil is required. The treatment method includes chemical etching or plasma etching on the surface of polytetrafluoroethylene to increase the surface roughness or add an adhesive film layer between the copper foil and the polytetrafluoroethylene resin to improve the bonding force, but it may affect the performance of the medium. influential.

The development of the entire fluorine-based high-frequency circuit board requires the cooperation of raw material suppliers, research units, equipment suppliers, PCB manufacturers and communication product manufacturers to keep up with the rapid development of high-frequency circuit boards.

PTFE Radar Board is a very good PCB dielectric. Advantages:

Low loss, low dielectric constant, good consistency, stable chemical properties, and almost no moisture absorption. Often used in demanding RF and microwave circuits.

In the 5G era, PTFE will replace FR-4 as the best substrate for PCB boards. The reason for this is that phenolic resins and epoxy resins are mostly used for low-frequency printed circuit board (PCB) substrates. The most widely used product is glass fiber epoxy resin FR-4. In high frequency circuits, these traditional PCB substrates can "distort" the signal. At present, CCL manufacturers modify the substrate through resin modification, glass fiber modification, and adjusting the PCB dielectric layer, so that it can meet the needs of high-frequency circuits. Currently commercialized organic high-frequency substrates mainly include: polytetrafluoroethylene (PTFE)/ceramic filler substrates, hydrocarbon thermosetting materials/ceramic material substrates, thermal engineering plastics/ceramic filler substrates, LCP substrates, etc. The copper clad laminate is in the upstream position in the 5G industry chain, providing the substrate material for the PCB to construct the 56 base station. The cost of polytetrafluoroethylene resin in high-frequency copper clad laminates accounts for 40%, and its dielectric loss can meet the requirements of 5G base stations under high-frequency and high-speed working conditions, with huge commercial potential.