Millimeter wave radar sensors are transitioning layer by layer from 24GHz to 77GHz, and more forward facing and angle radars are considering it appropriate to use the 77GHz scheme. For circuit engineers, selecting the appropriate PCB material is crucial for preset millimeter wave radar. In general, when selecting, it is necessary to consider the selection of thinner PCB circuit board materials, better dielectric constant uniformity, and smaller media damage; At the same time, it is also important to consider the reliable electrical performance and mechanical properties of materials that have reliable external office backgrounds such as time, temperature, and humidity.

　　8-layer second-order HDI mobile phone board

　　In the preset array receiving antenna of millimeter wave radar, the circuit structure dimensions of different types of channel transmission lines, the phase difference or delay of different channel transmission lines, and the successful implementation of spacing control between receiving antennas of each unit are all confirmed by the dielectric constant of the material. The variation of dielectric constant within the same board can cause a certain phase difference between the transmission and reception of traffic radar, especially millimeter wave traffic radar, which affects the precision of vehicle or speed inspection and measurement, leading to deviation in its positioning.

　　At the same time, changes in the dielectric constant of different batches of materials can cause differences in different millimeter wave radar systems, affecting the complete consistency of the system. Because the exact consistency of the dielectric constant of the PCB circuit board material used is crucial for its stability.