Description
High-frequency PCBs are used to transmit GHz frequency electromagnetic waves with minimum loss. All high-frequency PCBs operating above 100 MHz are called RF PCBs, while microwave RF PCBs operate above 2 GHz. Special consideration needs to be given to signal loss tolerance, heat dissipation, production possibilities, and cost when designing High-frequency PCBs.
(1) High-frequency circuits tend to have high integration and high-density wiring. The use of multilayer boards is both necessary for wiring and an effective means of reducing interference.
(2) The less lead bending between the pins of a high-speed circuit device, the better. Leads for high-frequency circuit wiring are preferably solid, need to be wound, and can be folded in 45° folded lines or arcs. External transmission and mutual coupling of high-frequency signals can be minimized to meet this requirement.
(3) The alternation between wiring layers between pins of the high-frequency circuit device is minimized. By “minimizing layer crossings,” it is meant that the fewer the number of via holes (Via) used in the connection of the components, one of which is estimated to result in a distribution capacitance of about 0.5 pF, the better. It has been estimated that a single via can result in a distributed capacitance of about 0.5 pF. The speed can be greatly improved.
(4) High-frequency circuit wiring should pay attention to the parallel lines of the signal line introduced by the “cross-talk”. If you can not avoid parallel distribution, you can arrange a large area of parallel signal lines on the back of the “ground” to greatly reduce interference. Parallel alignments in the same layer are almost unavoidable, but in two adjacent layers, the alignments must be oriented perpendicular to each other.
(5) Signal alignments of all types must not form loops, and grounding wires must not form current loops.
(6) High-frequency turbulence links shall be used when connecting analog and digital ground wires to a common ground.
(7) Analog and digital circuits shall be laid out separately. When wired independently, power and ground shall be connected at a single point to avoid mutual interference.
1. High-frequency PCB materials
For the above reasons, special care is needed when selecting materials. The following materials are commonly used:
(1) Rogers – RO4350B, RO4835, RO3003, RT6035
(2) Taconic – RF-35, TLX
(3) ISOLA – IS620, 370HR
2. High-Frequency PCB Advantages
(1) Complex circuit layout can be realized;
(2) Circuit crossings reduce board size;
(3) Suitable for complex circuit layouts.
3. High-frequency PCB disadvantages
(1) Copper sinking: the hole wall is not easy to copper plate;
(2) Control image conversion, etching, line width, line gap, and sand holes;
(3) Green oil process: control of green oil adhesion and blistering;
(4) Strictly control the surface scratches and other defects in each process.
4. High-frequency PCB processing difficulties
(1) Higher manufacturing costs;
(2) The manufacturing process is more complex than single-layer PCB;
(3) Not applicable to ultra-large circuit layout.
(2) The manufacturing process is more complex than single-layer PCBs;
(3) Not applicable to ultra-large circuit layout.
5. Applications
(1) Automotive radar systems
(2) Global positioning satellite antennas
(3) Cellular telecommunication systems – power amplifiers and antennas
(4) Direct Broadcast Satellite
(5) E-band point-to-point microwave links
(6) Radio Frequency Identification (RFID) tags
(7) Airborne and Ground-based Radar Systems
(8) Millimeter Wave Applications
(9) Missile Guidance Systems
(10) Space Satellite Transceivers
OPCBA.COM often produces High-frequency PCBs for customers, with rich production experience, and always have high frequency materials RO5880, RO4350B, etc. If you need any assistance, please contact us without any hesitation.
