4层板：L1-L2=6.7mil, L2-L3=40mil

6层板：L1-L2=4mil, L2-L3=8mil, L3-L4=45mil

50Ω微带：1oz铜, FR-4, H=3.5mil → W≈6mil

50Ω带状线：1oz铜, FR-4, B=10mil → W≈4mil

100Ω差分：微带, W=4mil, S=6mil, H=3.5mil

90Ω差分(USB)：微带, W=5mil, S=5mil, H=3.5mil