FR-2 (Flame Resistant 2) is a
NEMA
The National Electrical Manufacturers Association (NEMA) is the largest trade association of electrical equipment manufacturers in the United States. Founded in 1926, it advocates for the industry, and publishes standards for electrical product ...
designation for synthetic resin bonded paper, a
composite material
A composite material (also called a composition material or shortened to composite, which is the common name) is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or ...
made of
paper
Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distrib ...
impregnated with a plasticized
phenol formaldehyde resin
Phenol formaldehyde resins (PF) or phenolic resins (also infrequently called phenoplasts) are synthetic polymers obtained by the reaction of phenol or substituted phenol with formaldehyde. Used as the basis for Bakelite, PFs were the first commerc ...
, 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 electronic 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
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
Tungsten carbide (chemical formula: WC) is a chemical compound (specifically, a carbide) containing equal parts of tungsten and carbon atoms. In its most basic form, tungsten carbide is a fine gray powder, but it can be pressed and formed into ...
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
Phenolic paper is a material often used to make printed circuit board substrates (the flat board to which the components and traces are attached). It is a very tough board made of wood fibre and phenolic polymers. It is most commonly brown in c ...
* Preßzell
* Repelit
* Synthetic resin bonded paper (SRBP)
* Turbonit
*
Veroboard
* Wahnerit
See also
*
Formica (plastic)
Formica Laminate is a laminated composite material invented at the Westinghouse Electric Corporation in the United States in 1912. Originally used to replace mica in electrical applications, it has since been manufactured for multiple applicat ...
*
Micarta
Micarta is a brand name for composites of linen, canvas, paper, fiberglass, carbon fiber, or other fabric in a thermosetting plastic. It was originally used in electrical and decorative applications. Micarta was developed by George Westinghouse ...
References
Further reading
*
Composite materials
Printed circuit board manufacturing
Synthetic paper
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