BS EN IEC 61249-2-54 Materials for printed boards and other interconnecting structures - Part 2-54. Reinforced base materials clad and unclad. Halogenated modified or unmodified resin system, woven E-glass laminate sheets of defined dissipation factor (less than 0,005 at 10 GHz) and flammability (vertical burning test), copper-clad for high speed applications