FR-2

{{Short description|Designation for synthetic resin bonded paper}}

{{About|the PCB material||FR2 (disambiguation){{!}}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

class="wikitable"
Property ! Value
Dielectric constant, or relative permittivity \| 4.5 @{{nbsp}}1{{nbsp}}MHz
Dissipation factor \| 0.024–0.26 @{{nbsp}}1{{nbsp}}MHz
Dielectric strength \| 29{{nbsp}}kV/mm (740{{nbsp}}V/thou)

class="wikitable"

Property

! Value

Dielectric constant, or relative permittivity

| 4.5 @{{nbsp}}1{{nbsp}}MHz

Dissipation factor

| 0.024–0.26 @{{nbsp}}1{{nbsp}}MHz

Dielectric strength

| 29{{nbsp}}kV/mm (740{{nbsp}}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
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

References

{{Reflist|refs=

{{cite web |url=http://www.lamitec.de/ |title=lamitec.de |access-date=2006-08-05 |archive-url=https://web.archive.org/web/20060804083728/http://lamitec.de/ |archive-date=2006-08-04 |url-status=dead}}

{{cite book |title=Kunstharzpreßstoffe und andere Kunststoffe - Eigenschaften, Verarbeitung, Anwendungen |language=de |author-first=Walter |author-last=Mehdorn |edition=3 |date=1949 |page=240 |doi=10.1007/978-3-662-12205-1 |isbn=978-3-662-12206-8 |url=https://www.nonstopsystems.com/radio/pdf-hell/article-Mehdorn-400.pdf |access-date=2021-03-20 |url-status=live |archive-url=https://web.archive.org/web/20210320125527/https://www.nonstopsystems.com/radio/pdf-hell/article-Mehdorn-400.pdf |archive-date=2021-03-20}} (viii+355 pages)

{{cite web |title=Pertinax – ein traditionsreiches Material mit neuer Zukunft |language=de |publisher=Müller Ahlhorn |date=2014-01-06 |url=https://www.mueller-ahlhorn.com/de/pertinax-ein-traditionsreiches-material-mit-neuer-zukunft/ |access-date=2021-03-20 |url-status=live |archive-url=https://web.archive.org/web/20201203192341/https://www.mueller-ahlhorn.com/de/pertinax-ein-traditionsreiches-material-mit-neuer-zukunft/ |archive-date=2020-12-03}}

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