How to Select PCB Substrates for Automotive Radar? Analyzing the Performance Advantages of Hydrocarbon Resins

As Advanced Driver Assistance Systems (ADAS) evolve toward Full Self-Driving (FSD), automobiles have become intelligent terminals integrating numerous precision sensors. Among these, millimeter-wave radars operating in the 24GHz and 77GHz bands have emerged as core technologies for achieving precise environmental perception, thanks to their all-weather, all-time operational capabilities. Radar performance—particularly detection range, resolution, and angular accuracy—largely depends on antenna and RF front-end circuit design. The foundation for all this rests on the seemingly unassuming automotive radar PCB substrate.

Signals in the millimeter-wave band possess extremely short wavelengths, making them exceptionally sensitive to the properties of the transmission medium. Any minute material defect or performance fluctuation is dramatically amplified at the millimeter-wave scale, leading to a precipitous decline in radar performance. Traditional PCB substrate materials face two core challenges at this frequency: First, excessively high dielectric loss severely attenuates signal energy, directly reducing the radar's effective detection range; Second, unstable dielectric constants, particularly drift under varying temperatures and humidity, cause phase misalignment in antenna arrays. This compromises beamforming precision and leads to inaccurate target angle calculations.

Against this backdrop, high-performance hydrocarbon resins developed specifically for high-frequency applications emerge as the ideal choice for automotive radar PCB substrates. The core advantage of this material lies in its exceptional performance tailored for millimeter-wave signals. First, its exceptionally pure non-polar molecular structure delivers industry-leading low dielectric loss factor (Df). This minimizes energy attenuation (insertion loss) during millimeter-wave signal transmission within the substrate. For radar systems, lower loss directly translates to higher signal-to-noise ratio, enabling detection of farther, fainter targets with clearer target contours.

Second, the high-frequency, high-speed hydrocarbon resin exhibits outstanding dielectric constant (Dk) stability. Whether in the high-temperature environment adjacent to the engine compartment or in humid conditions during rain or snow, its extremely low moisture absorption rate (<0.05%) and high glass transition temperature (>180°C) ensure Dk values remain highly consistent. This stability is critical for phased array radar, guaranteeing precise control over the signal phase of each antenna array element. This enables accurate beam scanning and target localization, providing reliable data inputs for vehicle safety decision-making.

Furthermore, automotive applications demand exceptionally stringent reliability. Through specialized interface treatment technology, hydrocarbon resin substrates achieve robust adhesion to copper foil (peel strength >8 lb/in), effortlessly withstanding prolonged vibration on rough roads and repeated thermal cycling impacts. This effectively eliminates radar failures caused by delamination or circuit breakage.
Therefore, selecting automotive radar PCB substrates centered on high-performance hydrocarbon resins is not merely a cost consideration but a fundamental safeguard for the “safety first” principle in autonomous driving. By providing the radar's “keen eyes” with an ultra-low-loss, ultra-stable operating platform, it directly enhances the vehicle's environmental perception capabilities, serving as a key material technology driving the intelligent and safe development of automobiles.