IEC 60749-2:2002

Overview

IEC 60749-2:2002 is an international standard published by the International Electrotechnical Commission (IEC) that defines the mechanical and climatic test methods focused on low air pressure effects on semiconductor devices. Specifically designed for military and space-related applications, this standard establishes a test procedure to evaluate semiconductor components operating above 1000 V, housed in cavity-type packages, against performance degradation caused by reduced atmospheric pressure.

Low air pressure testing simulates the harsh environments encountered in high-altitude aircraft and space vehicles where the dielectric strength of air and insulating materials drops, increasing the risk of voltage breakdown and corona discharge effects. The standard helps ensure the electrical and mechanical reliability of high-voltage semiconductor components under these conditions.

Key Topics

• Scope and Applicability

  • Tests are applicable exclusively to semiconductor devices with operating voltages exceeding 1000 V.
  • Only relevant for devices in cavity-type packages used in military and aerospace environments.

• Test Conditions

  • Testing simulates atmospheric pressures from sea level down to high altitudes (up to 45,000 meters).
  • Pressure conditions correlate to altitudes from 4,500 m to 45,000 m, with specific pressure levels defined in Pa.
  • Ambient testing temperature is maintained at 25°C ± 10°C for at least 20 minutes before and during the test.

• Test Apparatus

  • A vacuum pump coupled with a sealed test chamber capable of maintaining reduced pressures.
  • Equipment to allow visual observation of specimens.
  • Pressure indicator for precise altitude simulation.
  • Microammeter or oscilloscope to monitor electrical currents including corona discharge from DC to 30 MHz.

• Test Procedure

  • Specimens are subjected to voltage and monitored for current anomalies during pressure reduction and restoration.
  • Observations focus on any corona effects, ionization, or voltage breakdown failures.
  • Measurements ensure the specimens maintain electrical integrity under varied pressure conditions.

• Technical Rationale

  • Low air pressure leads to reduced dielectric strength of air, increasing corona discharge risks.
  • Changes in insulating material properties and heat dissipation under thin air conditions may impact device performance.

Applications

IEC 60749-2:2002 is essential for organizations and engineers involved in:

• Military avionics and aerospace systems design, where semiconductors experience extreme altitudes and reduced atmospheric pressure.
• Spacecraft and satellite electronics manufacturing, ensuring devices tolerate vacuum and near-vacuum environments.
• Qualification and reliability testing of high-voltage semiconductor devices in critical safety applications.
• Development of semiconductor products requiring certification for high-altitude or space environments, contributing to improved mission reliability.

By implementing this standard, manufacturers can avoid costly failures linked to corona discharge and voltage breakdown during high-altitude operation, delivering safer and more robust semiconductor components.

Related Standards

• IEC 60068-2-13: Environmental testing - Part 2: Tests - Test M: Low air pressure, general environmental test procedures for low air pressure which IEC 60749-2 references and extends for semiconductors.
• IEC 60749 series: Other parts of the standard address mechanical and climatic testing of semiconductor devices under varied environmental stresses.
• ISO/IEC Directives, Part 3: The drafting guidelines followed for the preparation and publication of IEC standards including IEC 60749-2.

By adhering to IEC 60749-2, engineers and manufacturers ensure semiconductor devices meet rigorous performance requirements for low air pressure environments, offering peace of mind for critical high-altitude and space applications. This standard supports the advancement of reliable electronic technology resilient to the unique challenges of military and aerospace fields.