NXP Semiconductors
IMXRT500HDG
i.MX RT500 Hardware Design Guide
Layer type
Thickness
Material
Layer
Layers stackup
Routing
1 Oz
Copper
Top
2.7 MIL
TU-768
Prepreg
Plane
1 Oz
Copper
L2 Inner
4 MIL
TU-768
Prepreg
Routing
1 Oz
Copper
L3 Inner
40 MIL
TU-768
Prepreg
Plane
1 Oz
Copper
L4 Inner
4 MIL
TU-768
Prepreg
Plane
1 Oz
Copper
L5 Inner
2.7 MIL
TU-768
Prepreg
Top
Prepreg
L2 GND_1
Prepreg
L3 INT_1
Prepreg
L4 PWR_1
Prepreg
L5 GND_2
Prepreg
Routing
1 Oz
Copper
L6 Inner
Bottom
Figure 18. Dimensions of microvias
7.9 HDI escape routing
HDI trace spacing is reduced to allow the escape routing of interior signals through the
narrow pin (ball) pitches. Since all balls are routed on three layers (top, L2, and L3), only
the top layer and L3 require smaller trace and space dimensions under the package. The
outside ring of balls is routed on the top layer. These signals may later connect to other
layers, but the escape route is the top layer.
The inside ring of balls is routed on L3 to take advantage of the L2 ground plane. The L1
to L3 transitions use via-in-pad microvias.
"Outside ring" signals from MCU begin
routing on top layer.
"Inside ring" signals from MCU begin routing
on L3 from via-in-pad microvias on L 1.
Figure 19. HDI escape routing
7.10 HDI recommendations, layers 1 - layers 3
In general, 2 common power balls on the package are routed to one microvia on the top
layer as shown at the bottom of the left figure. Some microvias connect to 3 or 4 common
power balls. These are on supplies that have multiple capacitors, like the
VDD1V8
,
VDDCORE
,
VDDIO_0
, and
VDDIO_1
supplies.
IMXRT500HDG
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User guide
Rev. 0 — 15 November 2022
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