Komisyon Konsèy PCB impedance refers to the parameters of resistance and reactance, which hinder alternating current. In the production of PCB circuit boards, impedance processing is essential. Why do PCB circuit boards need impedance?

1. The PCB circuit (bottom of the board) should consider plugging and installing electronic components, and the conductivity and signal transmission performance should also be considered after the later SMT patch is plugged. Therefore, the lower the impedance, the better, especially the microwave signal. For equipment, the requirement for resistivity is: less than 1&TImes;10-6 per square centimeter.

2. In the production process of pcb circuit boards, they have to go through processes such as copper immersion, tin plating (or chemical plating, or thermal spray tin), connector soldering, etc., and the materials used in these links must ensure that the resistivity is low, in order to ensure The overall impedance of the circuit board is low to meet the product quality requirements and can operate normally.

Third, the tin plating of pcb circuit boards is the most prone to problems in the production of the whole circuit board, and it is a key link that affects the impedance. The biggest defect of the electroless tin coating is easy discoloration (easy to be oxidized or deliquescent) and poor solderability, which will lead to difficult soldering of the circuit board, high impedance, poor electrical conductivity, or instability of the overall board performance.

4. There are various signal transmissions in the conductors of the pcb circuit board. When the frequency must be increased in order to increase its transmission rate, if the circuit itself is different due to factors such as etching, stack thickness, wire width, etc., the impedance value will change. , So that its signal is distorted and the performance of the circuit board is degraded, so it is necessary to control the impedance value within a certain range.