What is the definition of high-speed PCB?
In many articles, we often see expressions like high speed/high-fre quency PCBs, high-speed PCB manufacturer, high-frequency PCB design, and so on. But we rarely see an article to distinguish between high-speed PCBs and high-frequency PCBs. Are high-speed PCBs and high-frequency PCBs the same? In this article, we will illustrate everything clearly.
Part 1. What is High-Speed PCB
There is a point about the definition of high-speed PCBs: a high-speed PCB is a circuit board having the digital circuit speed at or above 45 to 50MHZ, and digital circuit signals account for more than one-third of the entire system’s. But is this definition of high-speed PCBs correct? If you take it for granted, and when you are doing a PCB project whose maximum signal speed reaches 49.9MHz, you feel relieved because this is not a high-speed PCB and keep moving on. Finally, the PCB fails, the delivery has to delay, and you miss the expected bonus.
In fact, high-speed PCBs do not have an authoritative definition. Back in the 1960s, when digital electronics began developing, the signal speed was low, and PCB design could be done without much effort. Later, the digital circuit signal speed elevates, and engineers find that traditional PCB designing doesn’t work for these high-speed circuits, so they optimize the circuit design and use specific PCB base materials. The PCBs developed for these high-speed circuits are called high-speed PCBs. But no specific signal speed value is defined for speed-speed values, and no necessity to do it. How to define high-speed PCBs depends on practices: whether the signal speed is high enough to affect the circuit impedance or other circuits/components, whether there appears signal radiation in the circuit board, whether there appears the skin effect or ionization loss, etc.