Detailed analysis of high frequency PCB parameters
Detailed analysis of high frequency PCB parameters
High-frequency electronic equipment is the
trend of development, especially in the wireless network, satellite
communications. Information products moving toward high speed and high
frequency, Therefore, the development of a new generation of products need
high-frequency PCB, satellite systems, mobile phone base stations and other
communications products must be used high frequency circuit board, is bound to
develop rapidly in the next few years, high-frequency PCB would have a large
number of demands.
1）The thermal expansion coefficient of the base material and copper
foil of high frequency PCB must be consistent, otherwise it will cause
copper foil separation.
2）The water absorption of high frequency PCB’s base material must be
low. High water absorption will cause the dielectric constant and dielectric
loss when damp.
3）High frequency circuit board substrate dielectric constant (Dk) must
be small and stable. In general, the smaller the better, the transmission rate
of the signal is inversely proportional to the square root of the material
dielectric constant, high dielectric constant causes delay in signal
transmission.
4）High frequency circuit board substrate material dielectric loss (DF)
must be small, which mainly affect the quality of the signal transmission, the
smaller the dielectric loss, the smaller the signal loss.
5）The other heat resistance, chemical resistance, impact strength,
peel strength, etc of high frequency circuit board materials must also be good.
In general, high-frequency can be defined as the frequency of more than 1GHz.
At present, the high frequency circuit board base material is fluorine series dielectric substrate, such as PTFE, usually known as Teflon, commonly used in more than 5GHz. Also use FR-4 or PPO material, can be used for the PCB between 1ghz~10ghz.When the product application frequency is higher than 10GHz, only fluorine resin printed circuit board can be applied. It is obvious that the performance of fluorine resin high frequency material is much higher than that of other materials, but its deficiency is rigidity difference and large coefficient of thermal expansion besides high cost. The whole fluorine system high frequency board's development, needs the raw material supplier, the research unit, the equipment supplier, the PCB manufacturer and the communication product manufacturer‘s various cooperation, in order to keep up with the high frequency PCB rapid development needs.
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