WHAT IS THE EFFECT OF 90° TRACE CORNER IN PCB DESIGN ?

In this tutorial we are going to learn about WHAT IS THE EFFECT OF 90° TRACE CORNER IN PCB DESIGN ?

Arguments against 90° corners fall into two categories:

Impedance mismatch: A 90° corner is, necessarily, wider than the rest of the trace. This results in a decrease in Impedance , the intrinsic impedance of the trace, & therefore causes an impedance mismatch at the corner. This, in turn, causes reflections, signal distortions, & noise along the trace. Impedance of the trace varies with trace width, but is approximately a 15 – 20% decrease in Impedance at that point. The distance over which the effect is felt is equal to the trace width, W. Thus, the impedance goes from nominal to about 20% below nominal in a distance of W/2 & then returns back to nominal in another W/2. For most traces, this is VERY quick.

EMI: The main problem  against 90° corners trace  that electronic fields become concentrated at the sharp corners, causing destructive EMI radiation from that point that manifests itself as EMI.

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