Automotive Radar PCB
Millimeter wave automotive radars are becoming increasingly popular to boost driver safety. In fact, many ADAS systems depend on radar’s sensing capabilities.
To ensure your 77 GHz radar sensor performs at its best, choose the right PCB material. The ideal PCB materials must possess a number of unique properties, including stable electrical and mechanical performance over time and in varying working conditions.
While radar may have been seen as a bit experimental a few years ago, today it has established itself as an essential component of new-vehicle safety systems. By bouncing short-wavelength signals at 77 GHz off potential “targets” front and rear, radar sensors detect objects and their velocity to warn drivers of nearby obstructions. In order to perform this critical function reliably, a radar sensor PCB must provide high stability and low loss.
Stability is the ability of a circuit board to remain stable over time and in different operating conditions. This is particularly important in high-volume RF/microwave applications, as small changes in the thickness of the circuit material can lead to significant variations in transmission-line impedance. In addition, the surface roughness of copper foil can also influence circuit performance.
To achieve high stability, an automotive radar PCB should use a layered construction and ultra-low loss RF laminate materials. These materials are typically ceramic-filled PTFE or polyimide and offer a wide range of electrical properties that are ideal for radars. Using these materials in a multilayer structure allows for greater flexibility and can reduce the overall size of the radar module. The resulting high-performance PCB can also handle higher antenna counts as autonomous driving technology requires more and more radar sensors to be integrated into vehicle design. This trend is set to accelerate in the coming years as automakers continue to update their vehicles with ADAS capabilities.
A Radar PCB gathers environmental data inside and outside your vehicle. This information can help identify static and dynamic objects, like a potential road hazard or pedestrian. This can be done through the use of sensors that detect light, heat, and pressure. Once the sensor collects this information, it passes it to a technical processing circuit that identifies these hazards.
The key is that the sensors and the circuit board need to have low loss. This allows for better performance, especially in the high frequency range of a Radar PCB, which is typically 77GHz. To reduce this loss, a hybrid PCB is often used. This type of PCB combines low-cost flame retardant FR-4 with a layer of circuit material that’s well-suited to high frequencies. This lowers cost and maintains reliability while supporting a range of frequency bands through 77GHz.
This combination of materials also helps reduce the overall size of the radar module. This can be done by using ultra-low loss materials in multiple layers, which increases flexibility and reduces the footprint of the modules. The PCBs can then be plated with ED copper, which has a lower thermal expansion coefficient than standard bare copper. This helps the Heavy copper power PCB PCB maintain its integrity in high-humidity environments. A specialized test called solderability examination is another important testing procedure for a Radar PCB. This test assesses the strength and quality of the wetting of solder by simulating the contact between the component and the circuit boards.
Many radar PCBs use multiple antennas, and these antennas have to be designed with low loss. This is because high insertion loss causes the transmission and reception of signals to lose quality. In order to prevent this, the copper traces that carry the signals must be etched with a very low insertion loss. This will also ensure that the reflected signals are detected and evaluated correctly.
Using multiple antennas is necessary because of the way that Heavy Copper Power PCB Supplier radar sensors work. They are capable of measuring the speed, direction, and distance of objects with a high degree of accuracy. This is not possible with a single camera because the range, heading, and speed of each object must be tracked independently.
The antennas are typically etched into the surface of the circuit board. They are often slotted waveguides, which help reduce the loss of RF signals by utilizing an air-filled waveguide with slots that have been etched into the conductive material. This allows the RF signals to pass through without interference, even at higher frequencies.
During the manufacturing and assembly process, it is important to make sure that the Radar PCB has a low insertion loss and a high-performance frequency band. It is essential to consider the design of the antennas and their layout, as well as the etching and copper layer thickness. Choosing the right assembly process is also vital, as this will determine how efficient and reliable the Radar PCB will be. Surface mount technology is a popular choice for applications that require reliability and dependability, as it allows you to connect components on all sides of the PCB, saving time and effort.
Henkel’s High-Performance Connecting Materials
A quality Automotive Radar PCB requires high reliability and stability over time and in varying working environments. To ensure these requirements are met, it’s important that the circuit board has excellent solderability, and this can be achieved by using Henkel’s portfolio of high-performance connecting materials.
The choice of materials for hybrid multilayer PCBs used in millimeter-wave applications like automotive radar sensors is a key factor in meeting cost and performance goals. Often, these applications call for a combination of low-cost flame-retardant FR-4 material with a high glass transition temperature (Tg) and one layer of more advanced circuit material that’s suitable for use at higher frequencies.
For best results, it’s preferable for the Tg of a circuit material to be closely matched to the CTE of copper. This ensures that the plated-through hole (PTH) diameter stays consistent across temperature ranges and allows for dependable interconnections between layers on the PCB. Rogers’ RO3003 thermoset laminate, for example, has a Tg of 17 ppm/degC that’s well-matched to the CTE of copper and is ideal for 77-GHz automotive radar sensor applications.
Its excellent moisture absorption also means minimal changes in dielectric constant (DCDk) over temperature, allowing for stable electrical performance. This is especially important for millimeter-wave applications at temperatures close to the operating temperature of 77-GHz automotive radar sensors.