Figure 19-1. Via Placement For Good Power Distribution; Figure 19-2. Good Current Flow Resulting From Correct Via Placement; Figure 19-3. Poor Current Flow Resulting From Incorrect Via Placement - Nvidia Jetson AGX Xavier Series Design Manual

Figure 19-1. Via Placement for Good Power Distribution
Care should also be taken to avoid use of "thermal spokes" (also referred to as "thermal
relief") on power and ground vias. Thermal spokes are not necessary for surface-mount
components, and the narrow spoke widths contribute to increased inductance. The metal on
the inner layers between vias may not be flooded with copper if enough spacing is not
provided. The diminished spacing creates a blockage and forces the current to find another
path due to lack of copper, as shown in Figure 19-2 and Figure 19-3. This leads to power
delivery issues and impedance discontinuities when traces are routed over these plane voids.
Figure 19-2. Good Current Flow Resulting from Correct Via Placement
With sufficient via spacing
Correct via implementation
Figure 19-3. Poor Current Flow Resulting from Incorrect Via Placement
With insufficient via spacing
Incorrect via implementation
In general, a dense via population should be avoided and good PCB design principles and
analysis should be applied.
Jetson AGX Xavier Series Product
General Layout Guidelines
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