Routing USB 3.1 traces app note from ON Semiconductor. Link here (PDF)
The introduction of USB Type−C has provided a significant launch opportunity for USB3.1 data rates across an array of platforms from portable to desktop and beyond. This proliferation of Type−C will certainly create challenges due to the high speed nature of the interface. High Speed USB2.0 presented enough of a system design challenge for tiny mobile device OEM’s trying to pass USB eye compliance. A 10X or even 20X increase in data rates will propagate that challenge far beyond the issues that were raised with HS. PCB traces in these systems must be treated as sensitive transmission lines where low-loss impedance control is king. Every effort must be made to make these paths as ideal as possible to prevent signal loss and unwanted emissions that could infect other systems in the device.