Both RO4350B and RO4835 hydrocarbon ceramic materials belong to the RO4000® series, which is designed for commercial applications. The RO4000® series laminates are based on a hydrocarbon resin with ceramic filler. A key advantage of this series is their compatibility with FR-4 manufacturing processes, including the ability to be co-processed with FR-4 and compatibility with lead-free soldering. This allows PCB fabricators with standard capabilities to work with these high-performance materials, thereby reducing overall PCB fabrication costs.
These materials offer excellent electrical performance for 24 GHz radar front-ends and antennas, characterized by low loss (dissipation factor of 0.0037 @ 10 GHz) and a dielectric constant with superior temperature stability (50 ppm/°C from -50°C to +150°C). Compared to traditional PTFE materials, they offer better thermal management (thermal conductivity of 0.6 W/m/K) and a low Z-axis CTE (31 ppm/°C), which enhances plated through-hole reliability. Furthermore, they are rated UL 94V-0, contributing to the safety of the radar system.
The primary difference between the two materials is that RO4835 is formulated with an antioxidant, providing a 10x improvement in oxidation resistance compared to traditional thermoset materials. It also complies with IPC-4103 specifications for high-speed/high-frequency materials. While both offer excellent performance, products with glass reinforcement (common in these materials) can exhibit a slightly degraded Dk temperature stability, requiring tighter temperature control during operation. The Z-axis CTE is also higher than some non-reinforced materials, potentially limiting the maximum number of layers in a stack-up. Phase characteristics can be less stable at high frequencies, making them less ideal for phase-critical applications. The benefits of the reinforcement, however, include improved dimensional stability, rigidity, and lower moisture absorption.
24G security radar systems operate in the 24–24.25 GHz band with 250 MHz bandwidth, typically using FMCW waveforms. The high frequency and short wavelength necessitate the use of high-frequency microwave materials for the RF front-end and antenna. The competitive nature of the security industry demands that these materials not only offer high performance but also be cost-effective, providing an excellent value proposition.
Rogers Corporation, a leading manufacturer and developer of high-frequency circuit materials, addresses the 24G security radar market by offering both the RO4350B and RO4835 hydrocarbon ceramic laminates, catering to different application requirements and scenarios within this field.