FR4 is a multipurpose glass epoxy laminate that features flame-retardant properties, as indicated by the letters “FR” in its name. It is often the substrate material of choice for electrical insulation, recognizable by its signature green color. The material’s low coefficient of thermal expansion allows it to resist contraction and expansion under exposure to fluctuating operating temperatures, making it ideal for high-temperature applications. FR4’s exceptional dielectric properties also contribute to its capability as an insulator.

FR4 has no moisture absorbing properties, so it will not expand or contract when humidity changes and is not affected by direct exposure to water, making it excellent for marine components.

Properties of FR4

Flame Retardant 4 is a glass epoxy laminate and a defined standard by National Electrical Manufacturers Association (NEMA). It complies with UL94V-0 standards for flame-retardant plastic material. Insulators and structural components made from FR4 with the UL standard marking are guaranteed to prevent fire propagation and extinguish the fire quickly.

The glass transition (Tg) for Flame Retardant 4 lies between 115°C and 200°C, depending on the manufacturing method and resin material. The material gains its fire-resistant properties from the presence of the halogen chemical element bromine. FR4 also features a high strength-to-weight ratio and high hardness, ensuring the material will not break easily under load or during machining.

Common Applications for FR4

While Flame Retardant 4 is well-known for fabricating PCBs, it also provides an ideal material for:

  • Industrial Wear Applications
  • Electrical Insulation
  • Screw Terminal Strips
  • Transformers
  • Arc Shields
  • Washers
  • Busbars
  • Standoffs
  • Switches
  • Relays

WS Hampshire: Your Custom Fabricator/Supplier for FR4 & Nonmetallic Materials

FR4 is a flame-retardant material used for various components in electronics and industrial or marine applications. Flame Retardant 4 is known for its good dielectric properties and acts as a good insulator for electronics. It withstands high temperatures, temperature fluctuations, and humidity and moisture exposure without expanding or contracting. Flame Retardant 4 can also be machined, making it ideal for use in mass production.

At WS Hampshire, we fabricate and supply FR4 for use in electronics, marine applications, and more. Our CNC machines provide high-precision components with fast turnarounds in any production volume. We can custom-fabricate a range of nonmetallic materials and provide wear solutions, bearings, bushings, plastic forming, and paper and film fabrication. 

Contact us today to learn more about our FR4 fabrication capabilities.

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