IEC 61249-4-15:2009

Overview

IEC 61249-4-15:2009 is an international sectional specification for unclad prepreg materials used as bonding sheets in the manufacture of multilayer printed boards. The standard covers a multifunctional epoxide woven E‑glass prepreg with a defined flammability rating (vertical burning test) and is specifically intended for lead‑free assembly processes. The flammability performance is achieved by brominated fire retardants chemically bound into the polymer. After cure, the prepreg’s glass transition temperature (Tg) is defined at 150 °C or 200 °C per manufacturer instructions.

Key topics and technical requirements

• Material construction
  • Reinforcement: woven E‑glass fabric
  • Resin system: majority di‑functional and modified epoxide; curing agent ≠ dicyandiamide
  • Optional inorganic fillers and contrast agents for AOI
• Flammability
  • Defined vertical burning test rating; flame retardance provided by brominated polymer chemistry
• B‑stage (partially cured) prepreg properties
  • Resin content, treated weight
  • Rheology/reactivity: resin flow, scaled flow thickness, melt viscosity
  • Optional: volatile content, gel time
• Post‑cure properties
  • Electrical strength, relative permittivity, dissipation factor
  • Cured thickness, glass transition temperature (Tg) of 150 °C or 200 °C
  • Decomposition temperature, thermal resistance, Z‑axis expansion
• Appearance and quality
  • Limits for dewetted areas (fish eyes), broken filaments, distortion, creases, edge finish
  • Requirements for delivery form (rolls, sheets, cut panels), packaging, shelf life
• Quality assurance
  • Supplier qualification, conformance inspection, certificate of conformance, and safety data sheet requirements

Applications

• Designed primarily as bonding prepreg for multilayer printed circuit boards (PCBs) manufactured to IEC 62326‑4.
• Suitable for lead‑free assembly and high‑reliability electronics where defined flammability performance is required.
• Can be used to bond other laminate types where the specified Tg and flammability characteristics are needed.
• Typical end sectors: telecommunications, automotive electronics, industrial controls, and consumer electronics that require compliant multilayer PCB construction.

Who should use this standard

• PCB material manufacturers and prepreg suppliers
• PCB designers and process engineers specifying bonding materials for multilayer boards
• Electronic manufacturing services (EMS) providers and quality engineers validating materials for lead‑free assembly
• Procurement teams requiring documented material specifications and compliance evidence

Related standards

• IEC 61249‑2‑35 (reinforced base materials for lead‑free assembly)
• IEC 62326‑4 (rigid multilayer printed boards – sectional specification)
• IEC 61189‑2 (test methods for materials)
• ISO 11014‑1 (safety data sheets)

Keywords: IEC 61249-4-15, prepreg, epoxide E-glass, lead-free assembly, Tg 150°C, flammability, vertical burning test, PCB materials, multilayer boards.