What is a high-frequency PCB? What is a high-speed PCB? And what is the difference between the two?

PCB circuit boards are an important part of electronic products, and the PCB circuit boards used in different application scenarios also have different characteristics. High-frequency boards and high-speed boards are two special boards that are more important in the field of printed circuit board (PCB) manufacturing. They have different characteristics and application scenarios compared with ordinary PCB circuit boards. Below, we compare and analyze the high-frequency board and the high-speed board.

I. The definition and characteristics of high frequency board and high speed board

High-frequency PCB materials and high-speed PCB materials are used in the electronics industry to process high-speed and high-frequency signals and have different characteristics and application scenarios. Here are their definitions and characteristics:

High-frequency PCB

• Definition: used to make high-frequency analog circuit boards, usually used in data transmission, microwave, RF and millimeter wave bands.
• Features:

1. Low dielectric constant, small loss tangent, and low dielectric loss coefficient.
2. Low moisture absorption, good radiation tolerance and stability.
3. Suitable for circuit applications that require high reliability and precision.

High-speed PCB

• definition: Designed for high-speed circuits and high-throughput applications, usually used for high-speed digital and low-frequency analog circuit boards.
• Features:

1. Low dielectric constant, small signal transmission delay, and small signal distortion.
2. Small thermal expansion coefficient, good overall stability, and can provide high-frequency noise removal.
3. Achieve larger bandwidth and reduce crosstalk and reflections.

II. The difference between high-frequency boards and high-speed boards

Although both high-frequency boards and high-speed boards are circuit boards used to transmit signals, there are several differences between the two in practical applications.

1. Different frequency ranges. High-frequency boards are used in frequency bands exceeding 500MHz, while high-speed boards are mainly used to transmit digital signals, with modulation and demodulation frequencies ranging from tens of MHz to GHz.

2. Different line widths and board thicknesses. Because high-frequency boards require fine lines, their line widths and line spacings are finer than those of high-speed boards, and the board thickness is relatively thin. The line isometry of high-speed boards is better, so the line width and line spacing can be appropriately increased, and the board thickness can also be slightly thickened.

3. Different materials. The dielectric constant of materials commonly used in high-frequency boards is smaller than that of high-speed boards to reduce signal transmission losses. The main material of high-frequency boards is PTFE (polytetrafluoroethylene), which is a low dielectric constant and low loss material; while the materials commonly used in high-speed boards are usually better than general PCB circuit boards, such as FR4 high TG material, FR-4 (glass fiber copper), which is a material between ceramics and plastics, and is usually used in ordinary PCBs. This material requires good dielectric properties, high anti-interference ability and low signal propagation delay to accurately transmit data to the target device.

4. Different manufacturing processes The manufacturing process requirements for high-frequency boards are very high. The outer layer of the high-frequency board should be flat enough to accommodate fine-tuning conductive materials. The inner layer copperization process of the high-frequency board is very special, requiring the copper layer to be very thin, usually only a few microns thick. In the PCB production process, special processes and procedures are required to ensure the manufacturing accuracy and quality of high-frequency circuit boards. Compared with high-frequency boards, the process of manufacturing high-speed boards is relatively simple. High-speed boards can be produced by using basic equipment such as drill bits of different sizes and cutting machines. On the final form of the board, the outer metal can be cut off with a rotary engraving tool to change the shape and size of the board and remove unnecessary parts. These cuts must be precise and ensure that they will not cause damage to the circuit or signal interference and other adverse effects.

5. Different design requirements In terms of PCB design, high-frequency boards and high-speed boards have different design requirements. For high-frequency boards, important design parameters are the structure and physical properties of the board, such as impedance, smoothness, adhesion and conductivity. The design of high-speed boards focuses on the transmission speed of signals, which requires accurate measurement of parameters such as delay time (TDR) and peak-to-peak value of differential signals. In actual material selection and application, it is necessary to select the appropriate PCB type based on specific needs and scenarios to ensure stable product performance and accurate signal transmission.

III. Application scenarios of high-frequency boards and high-speed boards

High-frequency boards are widely used in wireless communications (such as mobile phones, satellite communications), radar systems, and antennas. Its main function is to help the transmission and transmission accuracy of high-frequency signals. Due to the use of fine lines, it can reduce signal attenuation and crosstalk, enhance the output power of circuit signals, improve transmission rate and receiving sensitivity, and have good transmission and reception characteristics. High-speed boards are used in data transmission, such as networks, computer motherboards, industrial computers, measurement and control instruments, and high-speed memory.

Focusing on data transmission, its main requirement is to maintain signal integrity, stability, and high accuracy. High-speed boards are generally used in high-speed differential signals, coaxial cables, and serial communications. Because of the good equilength of its lines, it can ensure better signal integrity and anti-interference capabilities when transmitting high-speed digital signals.