Since the emergence of 5G applications, mmWave has seen rapid growth in various commercial markets such as automotive radar, autonomous vehicles, body scanners, satellite communication, and more. However, designing mmWave circuits poses more significant challenges compared to other RF circuits. To ensure the success of these applications, careful consideration of circuit materials is essential when designing PCB for mmWave frequencies.
mmWave refers to millimeter wave, which is a high-frequency electromagnetic wave that operates within the frequency range of 30 GHz to 300 GHz. Due to its high-frequency characteristics, mmWave has shorter wavelengths and is suitable for high-capacity wireless communication and data transmission, particularly excelling in 5G mobile communications.
However, it’s essential to note that while the mmWave frequency band offers larger bandwidth for supporting high-speed data transmission, signals in this frequency range are susceptible to atmospheric absorption and obstruction by buildings, leading to signal integrity issues. To achieve seamless communication, it’s necessary to deploy more small-scale base stations and antennas to ensure signal coverage and stability.
When designing PCB for handling millimeter waves, often referred to as mmWave PCB, it involves a high level of technical expertise. Designers need richer experience in circuit design, the use of higher-grade substrate materials, and manufacturers with precision manufacturing capabilities.
mmWave PCB is often designed as multilayer structure to achieve denser circuit layouts. Additionally, addressing signal interference and electromagnetic compatibility issues is a focal point. These challenges and requirements necessitate designers to shorten transmission paths for optimal transmission efficiency, employ rational signal, ground, and power layer distribution to address signal issues like crosstalk, and arrange antenna positions and signal guide structures to meet radiation and reception requirements.
The behavior and transmission of electrical signals at mmWave frequencies significantly differ from lower-frequency circuits. Challenges include resistance due to reflection, refraction, scattering during transmission, higher losses due to the shorter wavelength, and increased sensitivity to electromagnetic interference. A key solution is the adoption of advanced substrate materials such as PTFE, RO4350Bそして PTFE ceramic composite substrates, which possess lower dielectric constants and loss factors to meet signal requirements.
Aside from signal challenges, temperature is a critical factor. This encompasses the heat generated by high currents and external environmental temperatures. These factors can lead to catastrophic consequences for mmWave PCB, such as increased resistance, changes in thermal expansion coefficients, dielectric constants, etc., affecting circuit performance. To counteract the threat of high temperatures, Metal core PCB is a more common choice, including aluminum-based and copper-based substrates. However, these may struggle to meet signal requirements.
When selecting materials for mmWave PCB, designers must consider a multitude of characteristics to achieve optimal performance and effectiveness.
The high precision circuit layout of mmWave PCB demands manufacturers with advanced facilities and technology for fabrication. To accommodate more circuits on smaller boards, multilayer structures and smaller line spacings are required, necessitating manufacturers with precise process control techniques and nanometer-level manufacturing capabilities. Additionally, advanced boards may involve more advanced holes, such as blind vias and buried vias. To ensure the quality and performance of PCB, manufacturers need to employ advanced metrology methods to monitor and test various aspects of the PCB. This includes using high-precision testing equipment and instruments to measure signal transmission losses, phase stability, and other critical performance parameters.
mmWave PCB’s contribution to 5G
High Speed Transmission
mmWave PCB is considered a vital component of 5G systems, and its operation is governed by the millimeter-wave frequency band. As mentioned earlier, the millimeter-wave frequency range typically falls between 30-300GHz, with a potential bandwidth of up to 273.5GHz. Even in scenarios affected by atmospheric conditions, the total bandwidth for four specific frequency bands can still reach 135GHz. In the field of wireless signal transmission, two approaches can be used to enhance transmission speed: increasing spectral efficiency and expanding spectral bandwidth. The method employed by 5G millimeter-wave technology is to expand the spectral bandwidth, thereby achieving higher transmission speeds.
Millimeter-wave frequencies offer a broader bandwidth, further enhancing data transfer rates. You can liken data transmission to the transportation of goods between two points, where goods represent data, and the distance between the two points corresponds to the propagation distance of electromagnetic waves. To transport more data, it’s akin to needing more lanes to transport more goods. The increase in bandwidth allows for the transfer of more data between devices, enabling high-speed data transmission.
In the early stages of 5G technology, signal transmission often suffered from significant resource wastage due to signals spreading indiscriminately, lacking precision. Later, the introduction of millimeter-wave and Massive MIMO technology addressed this issue. Millimeter-wave technology features narrow beam characteristics, enabling it to more accurately identify dense targets and achieve precise signal transmission. The application of 5G PCB has significantly improved the accuracy of signal transmission.
5G signals are susceptible to the influence of the natural environment during air transmission, where even trace elements such as oxygen, water vapor, and suspended particles can affect signal quality. Therefore, the introduction of millimeter-wave technology in 5G applications plays a crucial role in reducing signal interference between different terminals. However, there is a limitation to millimeter-wave PCB used in 5G, as they can only cover either an indoor or outdoor area at a time. This means that if we install antennas outdoors, indoor areas may not receive 5G signals.
The integration of millimeter-wave PCB lies at the core of 5G systems, enhancing the compatibility of 5G technology. The combination of millimeter-wave technology with 5G facilitates large-scale data transmission and meets the high bandwidth requirements of connected devices in the fifth-generation technology. These functionalities are also applied in various projects, including educational systems, traffic signal control, and various vehicle operations.
5G represents a significant technological advancement in cellular communication systems. With the integration of mmWave technology, 5G can offer more cost-effective unlimited bandwidth data plans. Through the mmWave technology of 5G, a variety of different types of services can be provided, making it the ideal choice for mobile operators. Utilizing 5G not only enables the delivery of outstanding services to users but also generates substantial profits for service providers, driving continuous business growth. These advantages contribute to creating new business opportunities for operators. Millimeter-wave technology has become an integral part of fifth-generation mobile communication, enhancing network efficiency and meeting users’ demands for high-quality communication experiences.
Applications of 5G mmWave PCB
高周波基板 is considered the optimal choice for creating high-level projects. These boards are used for advanced mobile broadband, meeting the demands of high data-capacity devices.
Common applications include security scanners, telecommunications systems, and more. The high bandwidth of 5G millimeter-wave PCB makes it an ideal choice for wireless communication. Additionally, these boards are used in medical instruments, industrial equipment, electronic devices, and various engineering projects.
Here are some common application areas for these boards:
- Mobile phones and laptops
- Wireless communication
- Military equipment
Despite some integration challenges with 5G, the combination with millimeter-wave PCB enhances its short-range transmission and high-bandwidth capabilities, making it suitable for various application areas.