Another Component of FR - 4 Substrate: Resin!

Reinforcement materials refer to the materials that serve as the framework inside the substrate and usually include:

· Cellulose Paper

· Glass Felt

· Woven Glass Fabric

· Non - Woven Fiber

The most widely - used one is the electronic - grade glass fabric (E - Glass), such as the substrate usually known as FR - 4.

Thermount  E210             Glass  Style  1080             Glass  Style  7628

Thermount: Chopped Polyamide Mat, which is a trade name for a kind of fiber developed by DuPont.

The fiber paper substrate and glass felt substrate are mainly used in low-end printed circuit boards and some special circuit boards. While the non-woven fiber substrate has been increasingly applied to HDI (High Density Interconnect) circuit board manufacturing due to its advantages such as good laser processability, low dielectric constant and light weight.

Advantages of Glass Fibers:

1. High Strength: It has extremely high strength compared with other types of fibers.

2. Heat Resistance/Fireproof: Glass is an inorganic substance and will not burn.

3. Chemical Resistance: Glass can resist most chemicals and will not be attacked by bacteria or insects.

4. Moisture Resistance: Glass does not absorb water and still maintains its mechanical strength under high humidity conditions.

5. Thermal Stability: Glass has a very high melting point, a very low coefficient of expansion and a high heat transfer coefficient.

6. Electrical Properties: It has excellent insulation performance.