Halogen-free flame-retardant epoxy board

Base Composition and Production Process of Epoxy Laminate Sheets

Epoxy laminate sheets are mainly composed of electronic-grade fiberglass cloth and epoxy resin. The fiberglass cloth is woven from alkali-free glass fibers, available in various weave densities. Different fabric densities affect the sheet’s mechanical strength and insulation performance. The epoxy resin is typically a bisphenol-A or phenolic type, offering good wet-out and adhesion to the fibers.

During production, the fiberglass cloth is first impregnated with epoxy resin and pre-cured at controlled temperatures to reach a semi-cured state. Multiple layers are then stacked according to the desired thickness and hot-pressed under specific temperature and pressure conditions to fully cure the resin and form a uniform laminate. This process ensures consistent sheet thickness and good flatness.

Key Physical and Mechanical Properties

Epoxy sheets are relatively lightweight compared to metal materials, making them suitable for applications where weight reduction is important. They exhibit high hardness and are resistant to surface scratching. Their tensile and flexural strengths are excellent, offering good resistance to deformation and mechanical failure under load. Epoxy sheets also have better impact resistance than phenolic laminates and are less likely to crack upon impact.

Electrical Insulation Properties

As an insulating material, epoxy laminate excels in electrical performance. It features high volume and surface resistivity, maintaining reliable insulation even under high voltage. The dielectric constant and dissipation factor are suitable for use in high-frequency circuit environments. The breakdown strength meets high insulation standards and can reach UL94 V-0 flame-retardant rating.

Environmental Resistance

Epoxy laminates perform well under thermal stress, maintaining stability across a broad temperature range and resisting deformation under short-term high heat. They are also resistant to moisture: after prolonged exposure to humid environments, their water absorption remains low, and insulation performance is not significantly affected. These sheets exhibit good resistance to organic solvents such as alcohol and acetone and are not easily corroded by acids or alkalis, maintaining mechanical strength under harsh conditions.

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Differences Among Epoxy Sheet Types

FR-4 Epoxy Sheet: Contains brominated flame retardants; achieves UL94 V-0 rating. Cost-effective and widely used for general electrical insulation.

Halogen-Free Epoxy Sheet: Uses phosphorus- or nitrogen-based flame retardants with extremely low halogen content. Meets environmental protection standards and emits much less smoke than FR-4 when burned.

Halogen-Free Epoxy Sheet (also known as G10)

This type is a laminate made from electronic-grade fiberglass cloth impregnated with halogen-free epoxy resin and heat-pressed. It is also referred to as G10 epoxy sheet, halogen-free fiberglass board, or insulating board.

Key Characteristics

Superior Environmental Performance:

• Free from halogens (e.g., fluorine, chlorine, bromine, iodine, arsenic), it does not emit harmful halogen compounds during production or use, nor does it release toxic gases when burned. It complies with EU halogen-free standards and green manufacturing requirements, minimizing environmental impact and health risks.

Excellent Flame Retardancy:

• Incorporates inorganic flame retardants such as aluminum hydroxide (Al(OH)₃), magnesium hydroxide (Mg(OH)₂), expandable graphite, and ammonium polyphosphate, as well as organic types like organophosphorus and phosphoric ester or nitrogen-based retardants. Achieves UL94 V-0 rating, effectively suppressing flame spread and enhancing safety.

Outstanding Mechanical Properties:

• High Strength: Offers excellent hardness and load-bearing capability without deforming or breaking, suitable for structural applications.
• Good Toughness: Resistant to cracking under impact, increasing reliability and service life.
• Superior Insulation Performance:
• With a dielectric breakdown voltage of up to 40kV, it provides excellent insulation, preventing leakage or short-circuit failures and ensuring the safe operation of electrical systems.
• Good Heat Resistance:
• Can withstand continuous temperatures up to 150 °C, and short-term exposure up to 288 °C, maintaining mechanical and electrical performance without softening or warping.
• Excellent Machinability:
• Can be processed by cutting, drilling, stamping, and milling into components of various shapes and sizes. Processing does not easily cause cracking or delamination.
• High Chemical Stability:
• Strong resistance to acids and alkalis; not easily corroded in chemical environments, preserving its performance over time.

Applications

Electronics and Electrical Engineering:

• Used in printed circuit boards (PCBs), IC packaging, insulation barriers, and brackets in electronic devices. Ensures safe and stable operation, preventing short circuits and leakage.

Mechanical Manufacturing:

• Ideal for structural parts, molds, and fixtures requiring high strength and precise processing.

Aerospace Industry:

• Due to its lightweight, strength, flame resistance, and insulation, it’s suitable for structural and insulating components in aircraft and satellites.

Automotive Industry:

• Applied in electronic control systems, engine compartments, and structural parts, improving safety and reliability.

Medical Equipment:

• Used for insulating components and housings in medical devices, meeting safety, performance, and environmental standards.

Packaging Industry:

• Serves as protective and insulating packaging for high-end electronics and precision instruments.