IEC 60749-24:2025

Overview

IEC 60749-24:2025 - "Semiconductor devices - Mechanical and climatic test methods - Part 24: Accelerated moisture resistance - Unbiased HAST" specifies an unbiased Highly Accelerated Stress Test (HAST) for evaluating the moisture sensitivity and reliability of non‑hermetically packaged semiconductor devices in humid, non‑condensing environments. This destructive, highly accelerated moisture resistance method uses elevated temperature and humidity (without electrical bias) to accelerate moisture penetration through encapsulants or along interfaces and to reveal failure mechanisms (for example, galvanic corrosion) that may be masked when bias is applied.

This second edition (2025) updates the 2004 edition, including clause reorganization and additions to post‑test electrical procedures.

Key topics and requirements

• Test purpose: Accelerated moisture resistance evaluation of solid‑state devices in humid, non‑condensing conditions.
• Unbiased HAST specifics: No electrical bias applied - used to uncover failure modes potentially obscured by bias.
• Test conditions (examples from the standard):
  • Condition A: 130 ± 2 °C, 85 ± 5 % RH (typical duration ~96 h)
  • Condition B: 110 ± 2 °C, 85 ± 5 % RH (typical duration ~264 h)
  • Non‑condensing environment and controlled vapor pressure; 85 °C/85 % RH cited as a less accelerated reference.
• Apparatus and records: Chamber capable of holding temperature, RH and pressure; permanent temperature profile records and calibration to avoid condensation.
• Device placement and mounting: DUTs positioned to minimize temperature gradients, ≥30 mm from chamber surfaces, avoid direct radiant heaters; boards oriented to avoid vapor circulation blockage.
• Materials control: Use distilled/deionized water (≥1 MΩ·cm resistivity) and minimize ionic contamination to avoid spurious corrosion.
• Safety and cautions: Moisture lowers polymer glass transition temperature (Tg); stress above effective Tg can create non‑representative failures - exercise caution when selecting temperatures.
• Destructive test: Intended to reveal internal package failure mechanisms; post‑test electrical procedures included.

Applications and users

• Reliability and qualification testing for semiconductor manufacturers, component suppliers, and independent test laboratories.
• Used by reliability engineers, qualification teams, and OEMs designing components for electronics in humid or demanding environments (consumer, industrial, automotive, aerospace), where moisture ingress and internal corrosion are concerns.
• Employed as an alternative or complement to unbiased autoclave testing to accelerate moisture‑related failures.

Related standards

• IEC 60749-5 (steady‑state temperature humidity bias life test)
• IEC 60749-33 (Accelerated moisture resistance - Unbiased autoclave)
• JEDEC JESD22‑A118B.01 (basis for this IEC edition)

Keywords: IEC 60749-24:2025, Unbiased HAST, accelerated moisture resistance, semiconductor humidity testing, non-hermetic packages, reliability testing.