Microwave and RF Printed Circuit Boards

Modern printed circuit boards (PCBs) implement several unique technologies to increase their performance and capabilities. One part of the PCB market that is rapidly developing is the use of radio frequency (RF) technology. With many well-known manufacturers scurrying to produce the best-in-class RF PCBs, their demand will likely continue to grow. In this blog, we will discuss what RF technology is and how it is being implemented on modern PCBs.

RF PCBs are specialty circuit boards that can communicate in the radio and microwave frequency range. In particular, radio frequency boards typically operate between 500 MHz to 2 GHz, while boards that are compatible with frequencies over 2 GHz are considered microwave. Compared to regular PCBs, RF and microwave boards have a particularly complex architecture and are thus more difficult to design. This is mostly due to the increased noise sensitivity and strict impedance tolerances that come with transmitting or receiving radio signals.

One of the most salient characteristics that determine the success or failure of an RF or Microwave PCB is the materials used in the manufacturing process. Choosing materials becomes a delicate interplay between intended application and budget since higher quality materials can be much more expensive than lesser quality ones. The quality of the selected material is determined by some unique properties:

• Dynamic Dielectric Constant: This value describes the material's capacity to store electrical energy. While useful to know, it can vary under RF conditions, making it less useful than other metrics in this context.
• Coefficient of Thermal Expansion: Since PCBs are frequently exposed to heat during their production and normal operation, it is important to know the coefficient of thermal expansion of the constituent materials. This number characterized the material's tendency to change in size when a temperature change occurs. As such, it is generally recommended to use materials with a lower coefficient to better handle a wide range of operating conditions.
• Spacing: As RF and microwave PCBs generally require tighter spacing between the small components, crosstalk is more likely to occur. However, the magnitude and frequency in which this phenomenon occurs can differ based on the components' material.
• Moisture Absorption: It is important to consider the operating environment to which the PCB will be exposed. In applications where the board will likely be exposed to humidity, such as the outdoors, it is crucial to choose a material that is more resistant to moisture.
• Cost: With all the previously mentioned factors considered, it is important to find an optimal balance between the target price and board performance.

RF boards are being implemented in a variety of communication applications, including smartphones, sensors, security, and more. In wireless technologies, such as remote controls, there are generally two paired PCBs that communicate in the RF range. Additionally, newer smartphones that are compatible with 5G technology are mostly dependent on RF PCBs to operate efficiently. Alternatively, microwave PCBs are typically reserved for high-fidelity communication systems such as those found in satellites and navigational systems. Regardless of the application, it is important to source your RF PCBs from a reputable distributor.

Aerospace Aces is a leading distributor of aviation, electronic, and IT components, and your number-one choice for high-quality PCBs. With an inventory of over 2 billion ready-to-purchase items and a team of industry experts, we can help you find any part you need for your operational requirements. Additionally, as an AS9120B, ISO 9001:2015, and FAA AC 00-56B accredited distributor with a NO CHINA Sourcing policy, you can purchase with the confidence that you are receiving the highest quality parts possible. Get started on the purchasing process with an RFQ form today and see why many customers choose Aerospace Aces as their strategic sourcing partner.

1. nick radcliff
2. Posted on February 7, 2022
electronics

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