M9 copper clad laminate is the lowest-loss copper clad laminate in volume production today. Dielectric loss runs 0.0005 to 0.0009 at 10 GHz. Four material families carry that number: a hydrocarbon-dominant resin, quartz fiber cloth instead of glass cloth, HVLP4 or HVLP5 ultra-low profile copper foil, and low-alpha spherical silica filler. Swap any one of them and the stack drops back toward M8. Why M9 exists at all: the loss problem at 224 Gbps Every serial link loses amplitude as it travels. Higher frequency means faster loss, and a shorter distance before the receiver cannot tell a one from a zero. Equalization buys margin back. It also costs power and…