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The high frequency of electronic equipment is the development trend, especially with the increasing development of wireless networks and satellite communications, information products are moving towards high speed and high frequency, and communication products are moving towards the standardization of voice, video and data for wireless transmission with large capacity and speed.
Therefore, the development of a new generation of products requires high-frequency substrates. Communication products such as satellite systems and mobile phone receiving base stations must use high-frequency circuit boards. In the next few years, they will inevitably develop rapidly, and high-frequency substrates will be in large demand. The details are as follows Talk about the characteristics and parameters of high-frequency boards and high-frequency circuit boards.
High frequency circuit board introduction
Special circuit boards with higher electromagnetic frequency. Generally speaking, high frequency can be defined as the frequency above 1GHz. Its various physical properties, accuracy, and technical parameters require very high requirements, and are often used in automotive anti-collision systems, satellite systems, radio systems and other fields.
High frequency board circuit board characteristics
1. The impedance control requirements are relatively strict, and the relative line width control is very strict, with a general tolerance of about 2%.
2. Due to the special plate material, the adhesion of PTH during copper sinking is not high. It is usually necessary to roughen the vias and the surface with the help of plasma processing equipment to increase the adhesion of PTH hole copper and solder mask ink.
3. Do not grind the board before doing solder mask, otherwise the adhesion will be poor, and only use micro-etching potion to roughen it.
4. Most of the plates are polytetrafluoroethylene materials, and there will be a lot of burrs when molding with ordinary milling cutters, and special milling cutters are required.
5. High-frequency circuit boards are special circuit boards with higher electromagnetic frequencies. Generally speaking, high-frequency can be defined as frequencies above 1GHz.
Its various physical properties, accuracy, and technical parameters require very high requirements, and are often used in automobile anti-collision systems, satellite systems, radio systems and other fields.
Parameters of high frequency board
1. The thermal expansion coefficient of the high-frequency circuit board base material and copper foil must be the same. If they are inconsistent, it will cause the copper foil to separate during the process of cold and heat changes.
2. The high-frequency circuit board substrate should have low water absorption, and high water absorption will cause dielectric constant and dielectric loss when exposed to moisture.
3. The dielectric constant (Dk) of the high-frequency circuit board substrate must be small and stable. Generally speaking, the smaller the better. The signal transmission rate is inversely proportional to the square root of the material's dielectric constant. High dielectric constant is likely to cause signals. Transmission delays.
4. The dielectric loss (Df) of the high-frequency circuit board substrate material must be small, which mainly affects the quality of signal transmission. The smaller the dielectric loss, the smaller the signal loss.
5. Other heat resistance, chemical resistance, impact strength, peel strength, etc. of high-frequency circuit board substrate materials must also be good. Generally speaking, high frequency can be defined as the frequency above 1GHz. At present, the most commonly used high-frequency circuit board substrate is a fluorine-based dielectric substrate, such as polytetrafluoroethylene (PTFE), which is usually called Teflon, and is usually used above 5 GHz. In addition, FR-4 or PPO substrates are also used, which can be used for products between 1GHz and 10GHz.
