Stripline Impedance Calculator

Provide values for three of the four parameters h, t, w, Z₀ 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/h <0.25; 1 < ε_r < 15 )

Select the units for all dimensions: mm mils

(Thickness):

mm mils

(Trace thickness):

mm mils

(Trace width):

mm mils

  (Relative permittivity)

(Characteristic impedance):

ohms

C₀   (Capacitance):

pF/cm pF/inch

T_pd  (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).
  
• Range of valid parameters specified in the Design Guide: w/(h-t) < 0.35; t/h <0.25; 1 < ε_r < 15
• Accuracy: For typical PCB parameters (ε_r = 4, h = 15 mil and t = 1.37 mil), the deviation of the calculated results from results obtained using a 2D numerical field solver, is listed below:

  Z₀

  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%

  C₀

  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%