Description
Overview: This check determines if the traces in a single-ended impedance net are within a provided tolerance of the desired width provided by the board stackup
Passing Criteria: This check passes if the length of trace segments that are outside the width tolerance falls below an acceptable percentage
Reporting Units: Length Percentage
Examples
Passing Message:
Trace length outside width tolerance of 3.7% within acceptable range (0% to 10%)
Failing Message:
Trace length outside width tolerance of 26.1% outside acceptable range (0% to 10%)
Physics Justification
Controlled Impedance:
The trace width, combined with the dielectric material and distance to the reference plane, determines the impedance. Incorrect width can cause reflections, signal distortion, and degraded signal integrity.
Current Carrying Capacity:
Trace width affects how much current the trace can safely carry without excessive heating. Too narrow a trace can lead to overheating and potential damage.
Electromagnetic Interference (EMI):
Proper trace width minimizes EMI by maintaining consistent transmission line behavior, reducing noise and radiation.
Design Consistency:
The layer stack defines the PCB's physical and electrical properties, so deviating from specified widths can misalign with the expected performance.
Helpful Definitions
Electromagnetic Interference (EMI)
Unwanted electromagnetic radiation or coupling that disrupts the operation of nearby electronic devices or circuits.