Why Impedance Design is Necessary in Rigid-flex PCB?

Analysis of the purpose of the rigid-flex board with controlled impedance

1. The rigid-flex PCBs are often assembled with electronic components. After plugging, the conductivity and signal transmission performance should be considered. Therefore, the lower the impedance, the better, and the resistivity should be less than 1/cm².&TImes:10-6 the following.

2. The rigid-flex pcb board has to go through technological process, and process required low resistivity to ensure that the overall impedance of the rigid-flex board meets the product quality requirements.

3. There will be various signal transmissions in the conductors in the rigid-flex board. When the frequency must be increased in order to increase its transmission rate, if the line itself is different due to factors such as etching, laminate thickness, wire width, etc., the impedance will be worth The change causes the signal to be distorted, and the performance of the PCB is reduced, so it is necessary to control the impedance value within a certain range.

The pads used for soldering external assembly components are not allowed to be used as inspection points, and special test pads must be preset to ensure that solder joint inspection and production debugging can be carried out. The pads used for testing should be arranged on the unified side of the rigid-flex board as much as possible. Even for testing, it helps to reduce the cost of testing.