| 词条 | FR-2 | ||||||||
| 释义 |
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. ApplicationsFR-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
FabricationFR-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
See also
References1. ^{{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 |dead-url=yes |df= }} {{material-stub}}{{electronics-stub}} 3 : Composite materials|Printed circuit board manufacturing|Synthetic paper |
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