NEWS & EVENTS

Composition Differences Between G10 and FR4

Explore the key differences in composition between G10 and FR4 materials, including their properties, applications, and why these distinctions matter in various industries.

When it comes to glass fiber reinforced epoxy laminates, G10 vs FR4 is a frequent topic in electronics, aerospace, and industrial manufacturing. Although both materials share similar ingredients, their specific formulations create unique performance profiles. This guide explains the differences in resin systems, fiberglass structures, and additives—and how these affect physical and electrical properties.

Resin System Differences

FR4 Resin System

  • Flame Retardants:
    Contains brominated flame retardants (e.g., TBBPA) to meet UL94 V-0 standards, ensuring superior fire safety.
  • Modified Resins:
    Uses multifunctional epoxy resins (such as dicy-cured systems) to enhance thermal resistance and raise the glass transition temperature (Tg).

G10 Resin System

  • No Brominated Additives:
    Utilizes standard bisphenol-A epoxy resins without brominated compounds, resulting in limited flame resistance (not V-0 compliant).
  • Cost Efficiency:
    Employs simpler curing systems with high fiberglass content (>60%), emphasizing mechanical strength and lower cost.

Fiberglass Structure

FR4 Fiberglass Structure

  • Weave Type:
    Uses finer woven glass cloth (e.g., 1080 or 2116 styles) for uniform lamination ideal for printed circuit boards (PCBs).
  • Fiber Content:
    Contains 40–60% fiberglass balanced with resin to maintain stable dielectric properties.

G10 Fiberglass Structure

  • Coarse Weave:
    Utilizes thicker glass cloth (e.g., 7628 style) with higher fiber content (>60%) for enhanced rigidity.
  • Layup Orientation:
    Often employs unidirectional lamination, resulting in pronounced anisotropy, which benefits structural applications.

Additives

  • FR4:
    May include silica or ceramic fillers to improve thermal conductivity and control the coefficient of thermal expansion (CTE).
  • G10:
    Typically lacks specialized additives, focusing on cost efficiency and high mechanical strength.

Physical Performance Comparison

PropertyFR4G10
Flexural StrengthLower (~400 MPa)Higher (~500 MPa)
HardnessLower (Rockwell M100–M110)Higher (Rockwell M110–M120)
Impact ResistanceBrittle, prone to delaminationTougher, better delamination resistance
CTE (Z-axis)Higher (50–70 ppm/°C)Lower (30–50 ppm/°C)
Thermal ResistanceTg 130–180°C (grade-dependent)Tg typically <130°C (unmodified)

Key Impacts:

  • Mechanical Strength:
    G10’s high fiber content makes it ideal for structural parts (e.g., insulators, gears), whereas FR4’s uniformity is crucial for PCB lamination.
  • Thermal Stability:
    FR4’s high-Tg resins are suited for lead-free soldering (up to 260°C), while G10 softens at high temperatures.
  • Machinability:
    FR4’s fine weave eases drilling but may emit fumes, whereas G10’s increased hardness can accelerate tool wear.

Electrical Performance Comparison

Electrical PropertyFR4G10
Dielectric Constant (Dk)4.3–4.7 (1 GHz)4.7–5.2 (1 GHz)
Dissipation Factor (Df)0.015–0.025 (1 GHz)0.025–0.035 (1 GHz)
Insulation Strength20–40 kV/mm15–30 kV/mm

Key Impacts:

  • High-Frequency Use:
    FR4’s lower Dk and Df are preferred for high-speed circuits (up to 10 GHz), whereas G10’s higher losses limit its use to low-frequency applications.
  • Insulation Performance:
    FR4’s flame retardants may slightly affect insulation, but resin optimization compensates for it. In contrast, G10’s higher moisture absorption can degrade insulation in humid environments.

Design Trade-offs

Functional Priorities

  • FR4:
    Optimized for flame retardancy, consistent lamination, and high-frequency circuit compatibility.
  • G10:
    Prioritizes mechanical strength and cost efficiency, with a trade-off in electrical performance.

Regulations & Cost

  • FR4:
    Brominated additives face ROHS restrictions, encouraging the development of halogen-free alternatives.
  • G10:
    Costs 10–30% less due to its simpler formulation and lower additive content.

Industry Standards

  • FR4:
    Adheres to IPC-4101 for controlled dielectric properties.
  • G10:
    Follows mechanical standards such as MIL-I-24768.

Typical Applications

  • FR4 Applications:
    Ideal for PCBs, RF modules, and automotive control units that require flame-retardant materials and high-frequency performance.
  • G10 Applications:
    Suited for transformer insulation, robotic structural parts, and marine equipment where high mechanical stress is prevalent and high-frequency performance is not critical.

Conclusion

The compositional differences between G10 and FR4 highlight a cost-performance trade-off:

  • FR4 balances superior electrical performance and flame retardancy via specialized additives, making it essential for electronics and high-temperature applications.
  • G10 maximizes mechanical strength and cost efficiency through a higher fiber content and simpler resin system, ideal for structural and industrial applications.

Future Trends:
Emerging modified variants—such as high-frequency FR4 and ceramic-filled G10—are blurring traditional boundaries and driving the development of multifunctional composite laminates.

Related Topics

Explore these topics to learn more about advanced materials and their applications in modern industries!

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