In the transmission signal line of electronic devices, the resistance encountered in the transmission of high-frequency signals or electromagnetic wave propagation is called impedance. Why does PCB board must have impedance during the manufacturing process? Let's analyze the following four reasons:

?? 1. PCB circuit boards need to consider the installation of electronic components through plug connections, and later SMT patch connections also need to consider issues such as conductivity and signal transmission performance, so the lower the impedance, the better.

?? 2. During the production process of PCB circuit boards, they undergo processes such as copper deposition, electroplating tin (or chemical plating, hot spraying tin), and connector soldering. The materials used must have a low resistivity to ensure that the overall impedance value of the circuit board meets the product quality requirements and can operate normally.

?? 3. The tin plating of PCB circuit boards is the most common problem in the entire circuit board production process, and it is a key link that affects impedance; Its biggest defects are easy oxidation or deliquescence, poor solderability, making it difficult to solder the circuit board, high impedance, and resulting in poor conductivity or unstable overall board performance.

?? 4. The conductors in a PCB circuit board can transmit various signals. Due to factors such as etching, stack thickness, and wire width, the impedance value of the circuit itself can change, leading to signal distortion and a decrease in the performance of the circuit board. Therefore, it is necessary to control the impedance value within a certain range.