RF stands for “radio frequency.” It makes the PCBs a part of operating at a much higher frequency than standard PCBs, starting from 100 megahertz (MHz).
It is a significant difference between RF PCBs and standard PCBs. The issues that surround RF PCB design will come back to this, as micromanaging high frequencies are integral to designing an RF PCB.
Basic Design Concepts of RF PCBs
The higher frequency of RF PCBs makes it more complicated in their creation and design. There are four factors to consider before developing a blueprint for designing an RF PCB.
The first difference between RF and non-RF PCBs are the constants. Dielectric constants, for example, can be treated as a single value in non-RF applications. But because the frequency of an RF board is much higher, they should be treated as multiple values.
Due to the higher frequency used in RF PCB, temperatures within the board can fluctuate. If the materials used to create the board are not appropriately placed, these fluctuations can get out of hand.
The most optimized RF PCBs contain four layers. Constructing a four-layer PCB means that individual components will need to be spaced together in a way where everything can work together correctly.
It is creating a four-layer PCB that has consistent temperatures demands that you choose materials that will allow the least margin for error. Read ahead to discover exactly what these materials are and how to use them.
Material Selection for RF PCBs
Choosing the right materials is the most crucial aspect when it comes to RF PCB design. Whether you want to use two layers or four layers, materials will make or break an RF PCB.
There are three things to consider when choosing RF PCB materials.
The coefficient of thermal expansion
This coefficient pertains to an object’s size about temperature changes. Because RF PCBs deal with temperatures that are not only high but variable, this coefficient requires continuous use as a method of micromanaging temperature levels.
Moisture must also be taken into account as water affects temperatures since moisture does affect temperatures. Moisture is directly related to the environment that the device utilizing the RF PCB operates in.
Cost vs. Performance
If this debate wasn’t relevant enough when selecting non-RF PCBs, it is even more relevant when selecting materials for RF PCBs. The best thing to do is to know what your budget is to the penny, then aim to choose a cost-balanced material, electrical performance, and thermal robustness.
Optional Materials for RF PCBs
There are many ways to design an RF PCB. While there are required materials, there are many variations of these materials. It is where the options come in..
Polytetrafluoroethylene (aka PTFE), ceramics, hydrocarbon, and various types of glass are necessary, but many combinations are possible.
The following materials are added to these combinations.
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