Renesas R-IN32M3 Series User Manual page 71

R-IN32M3 Series: Board design edition
(3) Increase the Number of Board Layers, and Bring the GND Pattern out to the Surface Layer
Increasing the number of Cu wiring layers in the printed circuit board expands the area for hear release. Where possible,
place areas of the GND pattern on the surface layer and connect them to the main GND pattern via thermal vias. This
further improves heat dissipation. The board should have at least four layers, and we recommend six.
L1
L2 (GND)
L3
L4
(4) Consider Other Factors of Placement that will Affect Heat Flows and Take the Appropriate
Action
Placing heat-generating components close to this device affects its heat efficiency, so do not place heat-generating
components in its vicinity.
Caution. For example, placing a regulator with high power consumption in the vicinity of this device has
the effect of significantly reducing its heat dissipation.
(5) Residual Copper Ratio of Cu Layers
Increasing the residual copper ratio in all layers of the board layers increases the breadth of the paths for heat transfer.
(6) Cu Thickness
Designing all Cu layers of the board to be thick increases the volume of paths for heat dissipation. Since thinner Cu
layers reduce the effectiveness of heat dissipation, care is required on this point. We recommend that the power supply
and GND layers be at least 35-um thick.
R18UZ0021EJ0400
Dec. 28, 2018
L1
L2 (GND)
L3
L4
L5
L6
The heat of the GND layer diffuses through L1 to L6.
25. Thermal Design <R>
Thermal vias
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