Covers the requirements for high speed / high frequency laminate or bonding layers to be used primarily for the fabrication of rigid or multilayer printed boards for high speed / high frequency electrical and electronic circuits. Some of the improvements over the IPC-L-125A specification include updated bonding layer testing parameters, inspection lot requirements, revised visual acceptance criteria, and new specification sheets for hydrocarbon and polyester resin systems. Supersedes IPC-L-125A.