High frequency circuit board is a special circuit board with high electromagnetic frequency, in general, high-frequency can be defined as frequency above 1GHz. Its physical properties, precision, technical parameters require very high, often used in automotive anti-collision systems, satellite systems, radio systems and other fields. It is also useful for FR-4 or PPO substrates, which can be used in the products between 1ghz~10ghz, the three kinds of high-frequency substrate physical property is as follows.
At present, the epoxy resin, PPO resin and fluorine resin are used in the three main types of high-frequency substrate materials, the cost of epoxy resin is the cheapest, while fluorine resin is the most expensive, and the dielectric constant, dielectric loss, water absorption rate and frequency characteristics of the best fluorine resin, poor epoxy resins. When the product application frequency is higher than 10GHz, only fluorocarbon resin printed board can be applied. It is obvious that the high frequency substrate performance of fluoro-resin is much higher than other substrates, but its disadvantage is that the rigidity is poor and the coefficient of thermal expansion is larger than the high cost. For Polytetrafluoroethylene (PTFE), a large amount of inorganic material (such as silica SiO2) or glass cloth is used to improve the properties of the substrate to improve the rigidity of the base material and reduce its thermal expansion. In addition, due to the molecular inertia of PTFE resin itself, it is not easy to bind with copper foil, so it is more necessary to combine with the special surface treatment of copper foil. The treatment method has the PTFE surface to carry on the chemical etching or the plasma etching, increases the surface roughness or between the copper foil and the PTFE resin to increase the bonding film layer to enhance the adhesion, but may affect the media performance, the entire fluorine series high frequency electric Subgrade board development, needs to have the raw material supplier, the research unit, the equipment supplier, the PCB manufacturer and the communication product manufacturer and so on various cooperation, in order to keep up with the high frequency circuit board this field rapid development need.