The main factors that affect PCB impedance include:
- Line width: Changes in line width will directly affect the impedance value. Wider lines generally lead to lower impedance.
- Line spacing: The distance between adjacent conductors also has an impact on impedance.
- Copper foil thickness: Altering the copper foil thickness will cause changes in impedance.
- Dielectric constant: The dielectric constant of the PCB material is one of the key factors. Different materials have different dielectric constants, thus affecting impedance.
- Transmission line length: Changes in length may have a certain influence on impedance.
- Signal frequency: As the signal frequency increases, the impedance characteristics may also change.
- Reference plane: The integrity and continuity of the reference plane play an important role in impedance.
- Via: The presence of vias can change the local impedance to some extent.
- Etching process: The uniformity of etching will affect the actual line width and thus the impedance.
- Solder mask: Its thickness and dielectric constant may also have a slight impact on impedance.