What Are the High-Frequency PCB Products? PCB MASTER COMPANY Leads You into the World of High-Frequency PCBs

High-frequency PCB is a special kind of circuit board designed specifically for high-frequency circuits.  Generally speaking, when the frequency reaches or exceeds 1 GHz, it can be called a high-frequency PCB. High-frequency PCB products mainly include Rogers PCB, microwave circuit boards, radar circuit boards, radio frequency circuit boards, microstrip circuit boards, antenna PCBs, heat dissipation PCBs, arlon PCBs, hybrid laminated printed circuit boards, F4B printed circuit boards, ceramic PCBs and inductive PCBs, etc.  They are applicable to slot antennas, radio frequency antennas, broadband antennas, swept-frequency antennas, microstrip antennas, ceramic antenna power dividers, couplers, combiners, power amplifiers, dry amplifiers, base stations and so on.  Now, let PCB MASTER company introduce the relevant knowledge of high-frequency PCBs for you.

I. What is a High-Frequency Circuit?

High-frequency PCB design engineers believe that a high-frequency circuit refers to a circuit with a frequency greater than 1 GHz.  High-frequency circuits are basically composed of passive components, active devices and passive networks.  Passive components or passive networks mainly include high-frequency oscillation circuits, high-frequency transformers, resonators and filters, etc., aiming to fulfill the functions of signal transmission, frequency selection and impedance transformation.

With the rapid development of science and technology, more and more devices are designed for applications in the microwave frequency band (> 1 GHz) or even the millimeter-wave frequency band (above 30 GHz).  This also means that the frequencies are getting higher and higher, and the requirements for high-frequency PCB substrates are becoming more and more stringent.  For example, substrate materials need to have excellent electrical performance and good chemical stability. With the emergence of 5G signals, the importance of high-frequency PCBs has become increasingly prominent.

II. What Are the Characteristics of High-Frequency PCBs? 

1. The DK (Dielectric Constant) and DF (Dissipation Factor) of high-frequency PCBs should be small and stable enough. Generally speaking, the smaller, the better. A high DK may lead to signal transmission delay, and a smaller DF can correspondingly reduce signal loss.

2. The coefficient of thermal expansion of high-frequency PCBs should be as close as possible to that of copper foil; otherwise, it will cause the copper foil to separate when undergoing temperature changes.

3. In a humid environment, the water absorption rate of high-frequency PCBs must be low; otherwise, it will affect the DK and DF of the PCBs.

4. High-frequency PCBs must have good heat resistance, chemical resistance, impact resistance and peel resistance.

III. What Are the Precautions in High-Frequency PCB Manufacturing?

1. Currently, the most commonly used high-frequency dielectric is the fluorine dielectric substrate, such as polytetrafluoroethylene PCB.

2. Usually, the through holes and surfaces need to be roughened with the help of plasma treatment equipment to increase the adhesion between the PTH (Plated Through Hole) hole copper and the solder mask ink.

3. High-frequency PCBs cannot be grounded before resistance welding; otherwise, the adhesion will be very poor, and only micro-etching solution can be used for roughening.

4. Most of the high-frequency PCB materials are polytetrafluoroethylene PCB materials. Using ordinary milling cutters for shaping will result in a lot of burrs, so special milling cutters are required.

5. High-frequency PCBs have high requirements for physical properties, precision and technical parameters and are widely used in fields such as automotive anti-collision systems, satellite systems and radio systems.

6. High-frequency PCBs have strict requirements for PCB impedance control. Compared with line width control, the general tolerance is about 2%.

IV. How to Layout High-Frequency PCBs?

1. High-frequency circuits often have high integration and high layout density. The use of multilayer high-frequency PCBs is not only a necessary condition for layout design but also an effective means to reduce interference.

2. The smaller the lead bending between the pins of high-speed circuit devices, the better. The leads of high-frequency PCB speakers are preferably a straight line. If a turn is needed, it can be achieved through a 45° broken line or arc rotation. Meeting this requirement can reduce the external transmission and mutual coupling of high-frequency signals.

3. The shorter the leads between the pins of high-frequency circuit devices, the better.

4. The fewer the lead layer alternations between the pins of high-frequency circuit devices, the better. Measurement results show that one through hole can generate 0.5 pf of distributed capacitance. Reducing the number of through holes can significantly improve the speed.

5. In the layout of high-frequency circuits, attention should be paid to the "crosstalk" introduced by the close parallel wiring of signal lines. If parallel distribution cannot be avoided, a large area of "ground" can be arranged on the back of the parallel signal lines to greatly reduce the interference.

6. For particularly important signal lines or local units, ground enclosure measurement should be carried out, that is, draw the outer contour of the selected object. Of course, applying this function to the ground packaging treatment of local clocks and other units is very beneficial to high-speed systems.

7. The various signal wirings in high-frequency circuit boards should not form loops, and the ground lines should not form current loops.

8. A high-frequency decoupling capacitor should be set near each integrated circuit block.

9. When connecting the analog ground and digital ground to the common ground, a high-frequency choke should be used. In actual assembly of high-frequency chokes, high-frequency ferrite beads are usually used, with the wire passing through the center hole, which is usually not shown in the circuit schematic diagram of high-frequency PCBs.

10. Analog circuits and digital circuits should be arranged separately. After independent arrangement, the power supply and ground should be connected at one point to avoid mutual interference.

11. Before connecting DSP, off-chip program memory and data memory to the power supply, filtering capacitors should be added and placed as close as possible to the power pins of the chips to filter out power supply noise.

12. Off-chip program memory and data memory should be placed as close as possible to the DSP chip, and at the same time, be reasonably arranged so that the lengths of data lines and address lines are basically the same.

13. After mastering the use of high-frequency PCB layout tools and manual layout, in order to improve the reliability and producibility of high-frequency circuit boards, it is usually necessary to use advanced PCB simulation software for simulation.

V. About PCB MASTER Company

The high-frequency PCBs in stock at PCB MASTER Company include Rogers, Arlon, Taconic, Isola, Panasonic, TUC, ITEQ, Shengyi, Wangling, Nelco, Doosan,Nanya, Wentai, EMC, Hitachi.

PCB MASTER Company has professional high-frequency PCB manufacturing experience and can provide customers with the overall solution of the whole value chain from design to test and delivery.  The company's products are widely used in various fields such as communications, industrial control, computer applications, aerospace, military industry, medical treatment and testing instruments.  

It is hoped that this article can help everyone better understand the relevant knowledge of high-frequency PCBs and the information about high-frequency PCBs provided by PCB MASTER Company.  If you have any questions, please feel free to consult us.  We will serve you wholeheartedly!

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