Microstrip Trace Width Calculator

W     Trace width

I_max   Maximum current carrying capacity of microstrip

T      Trace Thickness

ΔT    Temperature Rise

According to IPC-2221A Par. 6.2 (“Conductive Material Requirements”), their values for inner layers are

k        0.48

b        0.44

c        0.725

Microstrip:    Microstrip is a PCB trace over a ground plane with dielectric material above it.  Models have been created to approximate the characteristics of the microstrip transmission line. A good approximation is provided by the formulas contained in the document IPC-2141A. Microstrip is the conducting medium used to transmit the electric signals at microwave frequency and fabricated using PCB - printed circuit board. Usually, Microstrip separated from the ground by using a dielectric substrate to avoid unnecessary interferences. Microstrips are very light and low power consuming components used in microwave technology such as antennas, couplers, etc. 

Microwave antennas and couplers as well as some filters can be created using the microstrip. However, microstrips cannot handle power levels as high as waveguides can. Microstrips also have issues in power loss, cross-talk, and unintentional radiation because they are not enclosed like the waveguide. Embedded microstrips also find themselves in high-speed digital PCB designs where entail signal travel with minimal distortion and no cross-talk and/or radiation is required.

Microstrips are also subject to maximum ratings. Microstrips are similarly used as capacitors and inductors as well as tuned circuits, filters, phase shifters. The maximum current that a microstrip can handle is a function of its width. This is the reason why engineers specify the trace width in their designs.