Reasons for Impedance of PCBA Circuit Board

2019-08-09 12:34:29

Reasons for Impedance of PCBA Circuit Board

PCB circuit board impedance refers to the parameters of resistance and reactance, which hinders AC power supply. Impedance processing is indispensable in PCB production. Why should PCBA factories make impedance for PCB?

PCB circuit boards need to be plugged in and installed with electronic components. After plugging in, the electrical conductivity and signal transmission performance should be planned. Therefore, the lower the impedance, the better. Resistivity per square centimeter should be less than 0.000001. In the production process of PCB circuit boards, there are copper deposition, tin plating, soldering and other processes. The materials used in these processes should ensure low resistivity, so that the overall impedance of PCB can meet the quality requirements of products. Tin plating is the most common problem in PCB fabrication process, which has a great impact on impedance. The electroless tin plating layer has a big defect, such as easy oxidation or deliquescence, poor solderability, which will make PCB board difficult to weld, high impedance and lead to poor conductivity and instability of board performance.

There will be various kinds of signal transmission in the conductor of PCB circuit board. When the transmission rate is increased, the frequency of PCB circuit board must be increased. If the circuit itself is different due to etching, stack thickness, wire width and other factors, the impedance will be changed, the signal will be distorted, and the performance of PCB will be degraded. Therefore, resistance control is needed. The resistance value is within a certain range.