FR-2

FR-2 (Flame Resistant 2) is a NEMA designation for synthetic resin bonded paper, a composite material made of paper impregnated with a plasticized phenol formaldehyde resin, used in the manufacture of printed circuit boards. Its main properties are similar to NEMA grade XXXP (MIL-P-3115) material, and can be substituted for the latter in many applications.

Applications FR-2 sheet with copper foil lamination on one or both sides is widely used to build low-end consumer electronics equipment. While its electrical and mechanical properties are inferior to those of epoxy-bonded fiberglass, FR-4, it is significantly cheaper. It is not suitable for devices installed in vehicles, as continuous vibration can make cracks propagate, causing hairline fractures in copper circuit traces. Without copper foil lamination, FR-2 is sometimes used for simple structural shapes and electrical insulation.

Properties Property Value Dielectric constant, or relative permittivity 4.5 @1MHz Dissipation factor 0.024–0.26 @1MHz Dielectric strength 29kV/mm (740V/thou)

Fabrication FR-2 can be machined by drilling, sawing, milling and hot punching. Cold punching and shearing are not recommended, as they leave a ragged edge and tend to cause cracking. Tools made of high-speed steel can be used, although tungsten carbide tooling is preferred for high volume production.

Adequate ventilation or respiration protection are mandatory during high-speed machining, as it gives off toxic vapors.

Trade names and synonyms Carta Haefelyt Lamitex Paxolin, Paxoline Pertinax, taken over by Lamitec and Dr. Dietrich Müller GmbH in 2014 Getinax (in the Ex-USSR) Phenolic paper Preßzell Repelit Synthetic resin bonded paper (SRBP) Turbonit Veroboard Wahnerit

Bron en licentie