NORTHBROOK, IL -- Underwriter's Labs has modified its testing requirements for the two "new" categories of FR-4, a move that should facilitate new material certification, an industry trade group says.

The move obviates the need for users to subject new FR-4 laminate and prepreg materials to complete testing for certification by UL.

Last year, a UL technical panel decided that per the UL 746E Polymeric Materials Safety Standard, any laminate classified as "non-traditional" must be subject to full testing in order to gain UL certification. The certification body said that traditional and non-traditional FR-4 materials have different behavior characteristics in terms of thermal stability and flammability, for example.

Now, however, full testing is not mandated for what is effectively traditional FR-4 material.

The newly defined categories include FR-4.0, which covers continuous filament woven glass fabric reinforcement material with brominated epoxy resin (flame retardant). UL also created FR-4.1, which covers FR-4 formulations with non-halogenated epoxy resins. Regardless of which category the material belongs to, provided the material contains at least 50% epoxy and no more than 45% inorganic filler in the resin portion of the laminate, it can be certified using metal-clad industrial laminate abbreviated test procedures.

IPC, which pushed for the changes, said it is pleased about UL's decision.

“IPC was proud to support this modification to UL 746E. This redefinition of FR-4 and splitting this material category into the two categories of FR-4.0 and FR-4.1 will definitely help the global printed board industry as it removes a tremendous amount of uncertainty. It makes the new material certification process defined within the UL 746E much simpler, quicker and more cost-effective,” said Tom Newton, IPC’s director of PCB programs, standards and technology.