Microwave & RF PCBs: Manufacturing Prerequisites and Guidelines

Nov 19, 2020

Microwave & RF printed circuit boards are high on demand across the globe. These high frequency printed circuit boards (PCBs) are used for high-end industrial applications like networking and communications, military radar, cellular phone operation. Microwave & RF printed circuit boards are quite unlike the regular PCBs because they operate on radio frequency (RF). Certainly, the process of microwave & RF printed circuit boards design and manufacturing demands appropriate use of technology, precision, dedication from the designer and manufacturer. The design and manufacturing of these PCBs are not easy and they demand exceptional equipment, understanding of production constraints and guidelines, among others. How microwave and RF printed circuit boards manufacturing differs? This post discusses the prerequisites and guidelines of microwave and RF PCB manufacturing.

Prerequisites of Microwave & RF PCB Manufacturing

This section introduces you to various aspects of microwave and RF printed circuit boards manufacturing.

Materials: The use of the right material is an important requirement of microwave and RF PCB manufacturing. Since this type of PCBs is operated under high-frequency signals, most of the materials fail to sustain the radio frequency. Due to high-frequency radiations, heat generation is quite high in these PCBs, and also noise can disrupt the signal transmission. Therefore, the following properties are expected in materials used for microwave and RF PCBs.

High-temperature resistance/ low thermal conductivity
Effective thermal profile or the coefficient of thermal expansion (CoE) for better thermal distribution
Low dielectric constant
Low loss tangent
Higher impedance to sustain varying bend radius

Considering above mentioned properties, the following materials are found suitable for microwave & RF PCB manufacturing.

High-performance FR-4
Ceramic filled hydrocarbons
PTFE- Woven/micro glass fiber structure
Rogers RO laminates- 4003 and 4350 series
LCP
FEP

Special Purpose Processing Equipment: Although microwave & RF PCBs can be manufactured by using regular fabrication tools, to achieve precision, most industry experts would recommend using special-purpose processing equipment. This equipment help in ensuring the precision to design and dimensional accuracy along with fine manufacturing attributes. The following are some special purpose processing equipment used for microwave & RF PCB manufacturing.
Plasma Etching: This is a process used to clean drilled holes on the printed circuit board. Plasma etching is created using special plasma PCB etching machines. In these machines, plasma is produced under strict conditions and it is used to clean the material that is left in holes.
Laser Direct Imaging: Laser direct imaging (LDI) is the technology that can be used instead of conventional photo exposure tools. By using this technology, the manufacturing can be performed at extremely tight traces. It also helps in keeping track of front and back layout registration requirements.
Automated Optical Inspection Equipment: Automated optical inspection (AOI) is a technique that allows robotic optical/visual inspection of PCBs. The camera embedded in these systems helps scan microwave & RF PCBs to identify manufacturing defects, component dispositioning, and chances of catastrophic failure.

Microwave & RF Printed Circuit Board Manufacturing Guidelines

Following guidelines can help in efficient and error-free Microwave & RF printed circuit board manufacturing.

Utilize low impedance solid ground plane to avoid capacitance build-up at sensitive nodes
Design for zero cross-talk by distancing RF lines
Avoid the use of guard rings for system leakage reduction
Ensure that return current traces are not overlapping with RF or microwave signal blocks

From the discussion above, it is clear that microwave & RF printed circuit board manufacturing is a crucial procedure and demands specific resources. Therefore, it would be wise to get it done by experts. Accelerated Assemblies is a well-established PCB manufacturing company that offers a microwave and RF PCB manufacturing services assisted by the industry experts. The company has an extensive record of supplying quality microwave and RF PCBs to its clients from industries like data communication, military, aerospace, etc.