FR-2

This article is about the PCB material. For other uses, see FR2.

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 @ 1 MHz
Dissipation factor	0.024–0.26 @ 1 MHz
Dielectric strength	29 kV/mm (740 V/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^[1]
• Haefelyt
• Lamitex
• Paxolin, Paxoline
• Pertinax,^[1] taken over by Lamitec^[2] and Dr. Dietrich Müller GmbH in 2014^[3]
• Getinax (in the Ex-USSR)
• Phenolic paper
• Preßzell^[1]
• Repelit^[1]
• Synthetic resin bonded paper (SRBP)
• Turbonit^[1]
• Veroboard
• Wahnerit^[1]

See also

• Formica (plastic)
• Micarta^[1]