IEC 60749-31:2002

Overview

IEC 60749-31:2002 is an international standard published by the International Electrotechnical Commission (IEC) that specifies test methods for evaluating the flammability of plastic-encapsulated semiconductor devices caused by internal heating. This standard applies to both discrete semiconductor devices and integrated circuits. The primary objective is to determine whether these devices ignite as a result of excessive internal electrical overloads during operation.

The standard ensures safety and reliability in semiconductor device manufacturing by providing a rigorous test procedure to assess the risk of ignition due to internally induced heating. Compliance with IEC 60749-31 helps manufacturers verify that their plastic-encapsulated devices will not pose fire hazards under severe electrical stress conditions.

Key Topics

• Scope and Applicability
  IEC 60749-31 covers semiconductor devices including discrete components and integrated circuits encapsulated in plastic materials. It focuses on scenarios where overheating arises internally from electrical overloads.

• Test Objective
  The test identifies whether a device will ignite or smoulder when subjected to increasing internal power dissipation beyond its maximum rated limits.

• Test Procedure

  • The device is operated in free air without heat sinks.
  • Internal power dissipation is gradually increased from the device’s maximum rated power at 25 °C, up to five times that rating.
  • The power at five times the maximum rated level is maintained for at least one minute if reached without other failure modes.
  • Testing stops if:
    1. The device’s electrical resistance increases prohibitively, or it becomes open-circuited or short-circuited.
    2. The device ignites (smoulders or bursts into flame).

• Failure Criteria
  A device is considered defective only if it smoulders or ignites during the test.

• Standard Background and Maintenance
  The test method is aligned with IEC 60749 (1996) and updated with corrigenda from August 2003. The standard is managed by IEC Technical Committee 47 focused on semiconductor devices. The current version of the standard was set to remain unchanged until 2007, after which it could be reconfirmed, revised, replaced, or amended.

Applications

IEC 60749-31:2002 is essential in semiconductor quality assurance and reliability testing for:

• Semiconductor Device Manufacturers
  Ensuring the mechanical and climatic robustness of plastic-encapsulated semiconductors under extreme electrical overload conditions and preventing fire hazards during device failure.

• Electronics Industry Safety Compliance
  Supporting product safety certifications by demonstrating that devices can withstand overloads without ignition, conforming to international fire safety standards.

• Design and Development Testing
  Allowing engineers to validate the thermal resilience and material flammability characteristics of new semiconductor packaging designs.

• Risk Assessment
  Identifying potential fire risks in electronic components used in consumer electronics, automotive systems, industrial controls, and other critical applications.

Related Standards

• IEC 60749 Series
  A complete suite covering mechanical and climatic test methods for semiconductor devices, with separate parts addressing different test criteria such as electrical, mechanical, and environmental stresses.

• IEC 60034 Series
  Related IEC publications renumbered under the 60000 series for electrical device standards, illustrating IEC’s systematic approach to numbering and classification.

• ISO/IEC Directives, Part 3
  Applies to the drafting and maintenance of standards like IEC 60749-31, ensuring consistency and international acceptance.

• Other Flammability and Safety Standards
  While IEC 60749-31 focuses on semiconductor devices, related safety and flammability standards may cover broader electronic assemblies or fire prevention in electrical equipment.

Keywords: IEC 60749-31, semiconductor devices, plastic-encapsulated devices, flammability test, internal heating, electrical overload, semiconductor reliability, electronic component safety, fire hazard testing, mechanical and climatic test methods, IEC standards, integrated circuits, discrete devices.