NXP Semiconductors
IMXRT500HDG
i.MX RT500 Hardware Design Guide
Dielectric
constant
Layer type
Thickness
The total thickness: 1.6 mm +/- 10 %
Material
Layer
Layers stackup
Loss
tangent
Routing
1 Oz
Copper
Top
4
2.7 MIL
TU-768
Prepreg
0.02
Plane
1 Oz
Copper
L2 Inner
4.2
4 MIL
TU-768
Prepreg
0.02
Routing
1 Oz
Copper
L3 Inner
4.5
40 MIL
TU-768
Prepreg
0.02
Plane
1 Oz
Copper
L4 Inner
4.2
4 MIL
TU-768
Prepreg
0.02
Plane
1 Oz
Copper
L5 Inner
4
2.7 MIL
TU-768
Prepreg
Top
Prepreg
L2 GND_1
Prepreg
L3 INT_1
Prepreg
L4 PWR_1
Prepreg
L5 GND_2
Prepreg
0.02
Routing
1 Oz
Copper
L6 Inner
Bottom
Thin dielectric
Thin dielectric
Thin dielectric
Thick dielectric
Thin dielectric
Figure 14. Layers stack-up
First, notice the dielectric thicknesses between the successive layers. L1 is tightly
coupled to L2 with a 2.7 mil dielectric. L3 is tightly coupled to L2 with a 4 mil dielectric.
•
L3 is isolated from L4 with a thick 40 mil dielectric.
•
L4 is tightly coupled to L5 with a 4 mil dielectric.
•
L6 is tightly coupled to L5 with a 2.7 mil dielectric.
The tight coupling of signals to planes with thin dielectrics is the basis of impedance
control. The trace widths and spaces on the signal layers determine the desired signal
impedance.
The recommended stack-up for each package is six or more layers. The MIXMRT595-
EVK uses six layers for the 7 mm x 7 mm FOWLP package.
•
L1 - Signals and components
•
L2 - Ground plane
•
L3 - Signals, power, and ground
Thick core:
•
L4 - Power and ground
•
L5 - Ground plane
•
L6 - Signals, power, ground, and components
L2 and L5 are solid ground planes that provide the reference planes:
•
L1 and L3 are tightly coupled to L2 as the reference plane
•
L4 and L6 are tightly coupled to L5 as the reference plane
7.3 EVK Stack-up comments, top 3 Layers
demonstrates the coupling of the top 3 PCB layers.
Layers 1 and 3 are tightly coupled to the ground plane on layer 2.
IMXRT500HDG
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User guide
Rev. 0 — 15 November 2022
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