FR-4
FR-4 or FR4 refers to a class of flame-retardant and flame-retardant composite materials consisting of epoxy resin and glass fiber fabric . The abbreviation FR stands for English flame retardant (dt. Flame retardant) and corresponds to the requirements of UL94V-0 . FR-4 is available on the market in different versions. In order to improve the flame retardancy, chemical substances such as polybrominated diphenyl ethers based on bromine are added to the composite material ; this additive is omitted in the halogen-free variant. The properties of the FR-4 composite material, along with other composite materials, were specified in the NEMA LI1 specification by the National Electrical Manufacturers Association (NEMA) in 1968 .
FR-4 is used, among other things, as an electrically non-conductive carrier material for electrical circuit boards . FR-4 is one of the most widely used materials in this area of application because, in contrast to similar composite materials such as FR-2, so-called hard paper , it has better tracking resistance and less water absorption. Another advantage of FR-4 is the good adhesion, which ensures the permanent attachment of conductor track structures made of copper to the carrier material. Further applications are in the field of electromechanics as spacer or support elements of various shapes.
FR-4 has a maximum operating temperature of 115 to 140 ° C, the dielectric strength is 20 kV / mm. The especially in the area of high-frequency applications and fast digital circuits significant dielectric constant is in the range of 3.8 ... 4.5.
literature
- Karl Sauter: PCB Laminates . Ed .: Jasbir Bath. Springer, 2007, ISBN 978-0-387-32466-1 .
Individual evidence
- ↑ NEMA Standards Publication No. LI 1-1998: Industrial Laminating Thermosetting Products . National Electrical Manufacturers Association (NEMA), accessed May 28, 2014 .
- ↑ PCB Dielectric Material Selection and Fiber Weave Effect on High-Speed Channel Routing AN-528-1.1. Altera, 2011, accessed May 28, 2014 .