IEC 61249-2-36:2008

Overview

IEC 61249-2-36:2008 is an international standard published by the International Electrotechnical Commission (IEC) that specifies the requirements for reinforced base materials used in printed boards and other interconnecting structures. This part of the IEC 61249 series focuses on epoxide woven E-glass laminate sheets that are copper-clad and designed for lead-free assembly processes. The standard covers laminates with thicknesses from 0.05 mm up to 3.2 mm, emphasizing materials with defined flammability characteristics, as assessed by a vertical burning test. Importantly, these materials possess a minimum glass transition temperature (Tg) of 120 °C, ensuring thermal stability for electronic applications.

Key Topics

• Material Composition
  The standard specifies the use of di-functional brominated epoxide resin systems reinforced with woven E-glass fabric. The copper cladding is applied to meet stringent electrical and mechanical requirements suitable for manufacturing lead-free electronic assemblies.

• Flammability Requirements
  IEC 61249-2-36 includes detailed testing for flame resistance using the vertical burning test method. Laminates must meet defined levels of flammability to ensure safety and reliability in electronic devices.

• Physical Properties
  The standard covers non-electrical properties such as:

  • Surface appearance and quality (e.g., pits, dents, wrinkles, and surface waviness)
  • Dimensional stability including thickness tolerance, bow, and twist parameters
  • Mechanical performance like flexural strength and punchability
  • Thermal properties including glass transition temperature, decomposition temperature, and thermal resistance
  • Moisture absorption and resistance to measling (blistering or honeycombing)

• Electrical Performance
  Requirements for electrical characteristics critical to printed circuit board (PCB) performance are specified, ensuring low dielectric losses and stability under operating conditions.

• Quality Assurance & Testing
  The document mandates procedures for qualification inspection, quality conformance inspections, and certificates of conformance. Detailed guidance ensures consistent manufacturing quality and traceability.

• Packaging and Ordering
  Recommendations on packaging, marking, and ordering information help maintain material integrity throughout shipment and storage.

Applications

IEC 61249-2-36:2008 laminate sheets are primarily intended for:

• Printed Circuit Boards (PCBs) used in consumer electronics, telecommunications, automotive, and industrial equipment
• Lead-Free Assembly Processes, accommodating higher soldering temperatures associated with RoHS compliance
• High-Reliability Electronics requiring materials with controlled flammability and thermal stability
• Multilayer Interconnects where reinforced glass laminates ensure mechanical strength and electrical insulation

By adhering to the standard, manufacturers and designers ensure the use of materials that deliver predictable performance, safety, and compliance with environmental directives.

Related Standards

• IEC 61249 Series
  This part fits within the broader IEC 61249 family addressing various materials for printed boards and interconnecting structures, including different resin systems and reinforcements.

• IEC 61089 / IPC-2221
  Standards on design and performance of copper-clad laminates and interconnections provide complementary guidelines on PCB fabrication.

• UL94
  Flammability testing standards that may be referenced alongside vertical burning tests for material safety certifications.

• RoHS Directive
  European Union regulations for restricting hazardous substances, relevant for lead-free assembly requirements.

Summary

IEC 61249-2-36:2008 delivers a comprehensive specification for epoxide woven E-glass copper-clad laminates with defined flammability characteristics tailored for lead-free electronic assemblies. It ensures that materials used in printed boards meet stringent mechanical, thermal, electrical, and safety criteria. Compliance with this standard supports manufacturers in producing reliable, high-quality PCBs suitable for modern electronic applications, enhancing product safety and environmental compatibility.