A Detailed Explanation! High Frequency And High Speed PCB Material
When selecting a substrate for high-frequency circuit PCBs, the variation characteristics of the material DK at different frequencies should be specially studied. For requirements that focus on high-speed signal transmission or characteristic impedance control, focus on DF and its performance under frequency, temperature and humidity conditions. Today, Taike Electronics brings you a little knowledge of high-frequency and high-speed PCB board materials!
High frequency and high speed PCB board
In the case of frequency changes, the DK and DF values of general substrate materials vary greatly. Especially in the frequency range of 1MHz to 1 GHz, their DK and DF values change more obviously. For example, the DK value of ordinary epoxy glass fiber cloth base material (ordinary FR-4) is 4.7 at lmhz frequency, and the DK value becomes 4.19 at lghz frequency. Above lghz, the change trend of DK value is gentle. The trend of its change is to decrease with the increase of frequency (but the magnitude of change is small). For example, at l0ghz, the DK value of FR-4 is usually 4.15. For substrate materials with high-speed and high-frequency characteristics, the DK value changes little with frequency. Under the change frequency from lmhz to lghz, DK remains in the range of 0.02. At different frequencies from low to high, the DK value tends to decrease slightly.
Under the influence of frequency changes (especially in the high frequency range), the dielectric loss factor (DF) of the general substrate material changes more than DK. The law of change tends to increase. Therefore, when evaluating the high-frequency characteristics of substrate materials, the focus of research is the change in its DF value. For substrate materials with high-speed and high-frequency characteristics, in terms of high-frequency change characteristics, there are two distinct types of general substrate materials: one is that its (DF) value changes very little with frequency. Another reason is that although the variation range is similar to that of general substrate materials, its (DF) value is lower.
The above is the little knowledge about high-frequency and high-speed PCB board materials! Hope it can help you!
