Chemistry: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 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
| 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
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 (in de) Kunstharzpreßstoffe und andere Kunststoffe - Eigenschaften, Verarbeitung, Anwendungen (3 ed.). 1949. p. 240. doi:10.1007/978-3-662-12205-1. ISBN 978-3-662-12206-8. https://www.nonstopsystems.com/radio/pdf-hell/article-Mehdorn-400.pdf. Retrieved 2021-03-20. (viii+355 pages)
- ↑ "lamitec.de". http://www.lamitec.de/.
- ↑ "Pertinax – ein traditionsreiches Material mit neuer Zukunft" (in de). Müller Ahlhorn. 2014-01-06. https://www.mueller-ahlhorn.com/de/pertinax-ein-traditionsreiches-material-mit-neuer-zukunft/.
Further reading
- Industrial Laminated Thermosetting Products. National Electrical Manufacturers Association (NEMA). 2012-02-01. NEMA LI 1-1998 (R2011). http://www.nema.org/Standards/Pages/Industrial-Laminated-Thermosetting-Products.aspx.
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