Centered Stripline Impedance Calculator

ross-sectional diagram of a stripline structure with dimensions labeled: width (W), height (H), conductor thickness (T), and substrate permittivity (Er)

Provide values for three of the four parameters H, T, W, Zo and the relative permittivity of the dielectric. Click the button corresponding to the unknown parameter to calculate its value. ( W/(H-T) < 0.35; T/Hr < 15 )

Select the units for all dimensions: mm mils
H (Thickness):   mm mils
T (Trace thickness):   mm mils
W (Trace width):   mm mils
εr (Relative permittivity):  
(Characteristic impedance):   ohms
C0   (Capacitance):   pF/cm pF/inch
Tpd  (Propagation delay time):   psec/cm psec/inch

 

Notes:

  • The formulas used here are taken from the Design Guide for Electronic Packaging Utilizing High-Speed Techniques (4th Working Draft, IPC-2251, February 2001).
Stripline Formula
  • Range of valid parameters specified in the Design Guide: W/(H-T) < 0.35; T/H r < 15;
  • Accuracy: For typical PCB parameters (εr = 4, H = 15 mil and T = 1.37 mil), the deviation of the calculated results from results obtained using XFX, a 2D numerical field solver from Innoveda, is listed below:

 

Zo:  
W/(H-T) < 0.05 more than 30%
0.05 < W/(H-T) < 0.08 within 2%
0.08 < W/H < 0.32 within 1%
0.32 < W/(H-T) < 0.35 within 2%
Co:  
W/(H-T) < 0.05 more than 100%
0.05 < W/(H-T) < 0.08 within 2%
0.08 < W/H < 0.32 within 1%
0.32 < W/(H-T) < 0.35 within 2%