Whether a signal arrives at the receiving end the right shape. Matters at high speeds.
How it looks
Real geometry: CORE3588 copper, drawn from our board file (2D plan view)
Where signal integrity shapes CORE3588: three camera pairs (amber) in a 15 x 15 mm patch. Every visible choice here (constant spacing, bumps, few vias) is there so the signal arrives the right shape.
1Length-matching bumps, so both wires of each pair arrive together.
2Pairs routed in parallel at a fixed width and gap, over an unbroken ground plane.
How it works
Where it fits
Signal integrity is why high-speed pairs get their own net class, why their impedance is controlled by the stackup, and why they keep an unbroken ground plane underneath.
Its twin concern is EMI: the same mistakes that ruin a signal also make it radiate.