High speed transmission and back-drilling technology.
Backplane PCBs are widely viewed as the system carrier onto which other cards (motherboards) are mounted. These will typically be large size, high layer count, thick PCBs, the thickness being required to give mechanical strength for the motherboards which are to be inserted to the backplane. They serve as a common connection point for the active motherboards.
Backplane design now makes use of other technologies and aside from HDI as previously discussed, backdrilling, RF/high speed materials and controlled impedance are common.
Typical applications include network communications and industrial computing.