FR-4 (Glass Epoxy Laminate)
Flame retardant woven fiberglass cloth with epoxy resin binder — the worldwide standard substrate material for printed circuit boards (PCBs). Designated NEMA grade FR-4 and IPC-4101. Good mechanical strength, dimensional stability and electrical insulation up to 130°C (Tg). Dielectric constant 4.2–4.7 at 1 MHz. Self-extinguishing (UL94 V-0). Used for single/multilayer PCBs, electrical insulation boards, structural composites in electronics, test fixtures and jigs. Available in thicknesses 0.1–50 mm.
Chemical composition comparison (wt%)
Side-by-side: FR-4 (Glass Epoxy Laminate) (COMPOSITION) (IPC-4101) vs ASTM
| Element | FR-4 (Glass Epoxy Laminate) (COMPOSITION) | ASTM | Overlap |
|---|---|---|---|
| Epoxy Resin Matrix | 35–45% | — | — |
| Glass Fiber (E-Glass) Cloth | 55–65% | — | — |
Mechanical properties
General
| Property | Value | Unit |
|---|---|---|
| Flexural Strength | 380–480 | MPa |
| Tensile Strength | 280–340 | MPa |
| Compressive Strength | 350–420 | MPa |
| Density | 1.8–1.9 | g/cm³ |
| Glass Transition Temp (Tg) | 130–140 | °C |
| Dielectric Constant (1MHz) | 4.2–4.7 | - |
| Dielectric Strength | 40–50 | kV/mm |
| UL94 Flammability | 0 | V-0 |
| Water Absorption (24h) | 0.1–0.2 | % |
Related materials
EPDM (Ethylene Propylene Diene Rubber)
Ethylene propylene diene monomer rubber — THE outdoor/weather elastomer. Saturated backbone gives outstanding ozone, UV, and weathering resistance. Excellent resistance to steam, hot water, and polar solvents. NOT resistant to oils/fuels (opposite of NBR). Good electrical insulation. ρ 0.85-1.3 (lightest common rubber). Used for automotive door/window seals, roofing membranes, radiator hoses, HVAC gaskets, and pond liners.
Epoxy/Carbon Fiber (CFRP)
Carbon fiber reinforced epoxy — the benchmark structural composite material. Unidirectional ply: tensile strength 1500–2000 MPa, modulus 120–150 GPa at density 1.55 g/cm³ (5x stronger than steel at 1/5 the weight). Quasi-isotropic layup: UTS ~600 MPa, E ~50 GPa. Autoclave-cured prepreg (aerospace) or infusion/RTM (industrial). Used in aerospace primary structures (fuselage, wings), Formula 1 chassis, bicycle frames, wind turbine blades, pressure vessels (Type IV) and high-end sporting goods. Fiber types: T300, T700, T800, M40J, M55J.
FKM (Fluoroelastomer / Viton)
Fluoroelastomer — THE high-temperature and chemical-resistant rubber. Outstanding resistance to oils, fuels, acids, and solvents at temperatures up to 200°C (short-term 230°C). Fluorine content (64-70%) determines chemical resistance. Trade names: Viton (Chemours), Tecnoflon (Solvay), Dai-El (Daikin). 5-10x more expensive than NBR. Used for aerospace fuel seals, chemical process seals, automotive fuel injector O-rings, semiconductor processing, and any seal exposed to aggressive chemicals at high temperature.
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