FR-2
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- For the Fostex Field Memory Recorder, see Fostex.
FR-2 is an abbreviation for Flame Resistant 2. It is a NEMA designation for a composite material made of paper impregnated with a plasticized phenol formaldehyde resin, used in the manufacture of printed circuit boards. Its properties are similar to NEMA grade XXXP (MIL-P-3115) material, and can be substituted for the latter in many applications.
[edit] 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.
[edit] Properties
| Property | Value |
| Dielectric Constant (Permittivity) | 4.5 @1 MHz |
| Dissipation Factor | 0.024-0.26 @1 MHz |
| Dielectric Strength | 740 V/mil |
[edit] 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.
[edit] Trade names and synonyms
- Bakelite
- Lamitex - Franklin Fibre brand
- Paxoline
- Pertinax - Dielektra brand (now defunct and taken over by Lamitec)
- Synthetic Resin Bonded Paper (SRBP)
[edit] See also
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