The Effect Of The Impedance Of The Pcb Board And The Cause Of The High Impedance Of The Pcb Board
Impact of pcb board impedance
PCB board impedance refers to the resistance and reactance parameters of the PCB board, which mainly hinders the AC current. Impedance processing is essential in the production of PCB boards, so why does reactance impede currents and Reactance?
1. During the production process, the PCB board should pass through process steps such as sinking copper, electroplating tin, soldering of connectors, etc. The materials used in these links must ensure low resistivity to ensure that the overall impedance of the PCB board is low and does not match. Product quality requirements. It can run normally.
2. tin plating of pcb board is the most problematic in the production of the whole pcb board, is the key link affecting the impedance. The biggest disadvantage of the electroless tin plating layer is that it is easy to change color (easy to oxidize or deliquesce), and the brazing property is poor, which may cause the PCB board to be difficult to solder and the impedance is also high, resulting in poor conductivity or unstable performance of the whole board.
3. There are various signal transmissions in the PCB board conductor. When the transmission frequency increases, the frequency must be increased. If the pcb itself is different due to etching, laminate thickness, line width, etc., the impedance value will change. Signal distortion causes the performance of the PCB to degrade, so the impedance value must be controlled within a certain range.
4. In the production process of pcb board, must consider the mounting components behind the plug, should consider the electrical performance and signal transmission problems, so the lower the impedance, the better.
The reason why the impedance of the PCB is too high
There are more reasons for the PCB board impedance process. If the impedance is too high, it should be divided into the inner layer is too high, or the outer layer is too high. Under normal circumstances, the reason why the impedance of the pcb board is too high is mainly the following cases. .
1. The line of the pcb board is relatively thin, resulting in a higher impedance of the PCB board.
2. The copper thickness of the PCB board is relatively thin, resulting in a higher impedance of the PCB board.
3. The line spacing of the printed circuit board, the thickness of the dielectric layer is thick, and the thickness of the outer layer of ink is thick, resulting in a high impedance of the circuit board.
The above is the reason for the high impedance of the pcb board