The creation of printed circuit boards relies on circuit diagrams to fulfill the needs stipulated by circuit designers.
What is Printed Circuit Board design?
PCB is the abbreviation of printed circuit board. Its design mainly refers to layout design. Its layout needs to consider various factors.
For instance, when designing a product, it is important to consider external connections. It is also crucial to arrange internal electronic components efficiently. Additionally, optimizing metal connections and through holes is necessary.
Adding electromagnetic protection is another important step. Lastly, we should also consider improving heat dissipation.
Simple layout design can be achieved manually. Complex layout design requires the help of computer-aided design.

Design Introduction
Firstly, we need to comprehend what a transmission line is: it is made up of two conductors of a specific length. (send signal & receive signal)
In a multi-layered board, every line serves as a part of the transmission line. The neighboring reference plane can serve as an alternate line or loop. To make a transmission line perform well, it's important to maintain a consistent characteristic impedance along the entire line.
To make a circuit board a "controlled impedance board," all lines must have the same specified characteristic impedance value. This specified value is usually between 25 ohms and 70 ohms.
In a multilayer circuit board, it is important to maintain a consistent characteristic impedance for optimal transmission line performance.
The simplest method to comprehend characteristic impedance is to observe what the signal comes across during transmission.
As it travels along a transmission line of consistent cross-section. Think of it as adding a small amount of electricity to a wire. This is similar to connecting a small battery to one end.
Once linked, the voltage wave signal propagates down the line at light speed. The speed of light is typically around 6 inches per nanosecond.
This signal represents the voltage disparity between the transmission line and the loop. You can measure it from any point on the transmission line and the nearby point on the loop.
The above is the introduction to what PCB is.