# Summarize the impedance calculation model encountered in PCB design

Summarize the impedance calculation model encountered in PCB design

1. The calculation model of outer single-ended impedance

H1: Dielectric thickness Er1: Dielectric constant W1: Bottom width of impedance line W2: Width at the top of impedance line T1: Finished copper thickness C1: Solder mask thickness of substrate C2: Solder mask thickness on copper or traces CEr: Solder mask Dielectric constant

This impedance calculation model is suitable for: single-ended impedance calculation after the outer circuit is printed and soldered.

Second, the outer layer differential impedance calculation model

H1: dielectric thickness Er1: dielectric constant W1: bottom width of impedance line W2: top width of impedance line S1: impedance line spacing T1: finished copper thickness C1: solder mask thickness of substrate C2: solder mask on copper skin or trace Thickness C3: the thickness of the solder mask on the base material CEr: the dielectric constant of the solder mask

This impedance calculation model is suitable for: the differential impedance calculation after the outer circuit is printed and soldered.

3. Coplanar calculation model of outer single-ended impedance

H1: dielectric thickness Er1: dielectric constant W1: width of the bottom of the impedance line W2: width of the top of the impedance line D1: distance from the impedance line to the surrounding copper skin T1: finished copper thickness C1: green oil thickness of the substrate C2: copper skin or go Green oil thickness on the line CEr: the dielectric constant of the green oil

This impedance calculation model is suitable for: the single-ended coplanar impedance calculation after the external circuit is printed and soldered.

Fourth, the outer layer differential impedance coplanar calculation model

H1: dielectric thickness Er1: dielectric constant W1: width of the bottom of the impedance line W2: width of the top of the impedance line D1: distance from the impedance line to the copper skin on both sides T1: finished copper thickness C1: green oil thickness of the substrate C2: copper skin or go Green oil thickness on the line C3: Green oil thickness on the substrate CEr: Dielectric constant of the green oil

This impedance calculation model is suitable for the calculation of the differential coplanar impedance after the outer circuit is printed and soldered.

5. Calculation model of inner single-ended impedance

H1: dielectric thickness Er1: dielectric constant H2: dielectric thickness Er2: dielectric constant W1: bottom width of impedance line W2: width of impedance line top T1: finished copper thickness

This impedance calculation model is suitable for: single-ended impedance calculation of inner line.

Six, the inner layer differential impedance calculation model

H1: dielectric thickness Er1: dielectric constant H2: dielectric thickness Er2: dielectric constant W1: bottom width of impedance line W2: top width of impedance line S1: impedance line spacing T1: finished copper thickness

This impedance calculation model is suitable for the calculation of the differential impedance of the inner line.

Seven, the inner single-ended impedance coplanar calculation model

H1: Dielectric thickness Er1: H1 Corresponding dielectric constant of the dielectric layer H2: Medium thickness Er2: H2 Corresponding dielectric constant of the dielectric layer W1: Width of the bottom of the impedance line W2: Width of the top of the impedance line D1: Distance between the impedance line and the surrounding copper skin T1: Line copper thickness

This impedance calculation model is suitable for: inner single-ended coplanar impedance calculation.

8. Coplanar calculation model of inner layer differential impedance

H1: dielectric thickness H2: dielectric thickness W1: bottom width of impedance line W2: top width of impedance line S1: impedance line spacing D1: distance between impedance line and surrounding copper skin T1: line copper thickness Er1: H1 corresponding to dielectric constant Er2 of the dielectric layer ：H2 corresponds to the dielectric constant of the dielectric layer

This impedance calculation model is suitable for: inner differential coplanar impedance calculation.