IEC 60749-39:2021

Overview

IEC 60749-39:2021 - "Semiconductor devices - Mechanical and climatic test methods - Part 39" defines standardized laboratory procedures for measuring moisture diffusivity and water solubility in organic materials used for semiconductor packaging. These material properties are critical for predicting the reliability of plastic‑encapsulated semiconductors after moisture exposure and high‑temperature solder reflow. The 2021 edition includes a significant technical update to the dry weight determination procedure.

Key topics and technical requirements

• Scope and purpose: Procedures to quantify moisture uptake behavior (diffusivity and solubility) in mould compounds and other organics used in semiconductor packages.
• Sample geometry and preparation:
  • Samples shall be flat, parallel‑sided discs or coupons with accurately measured dimensions (±0.02 mm).
  • To approximate 1‑D diffusion, thickness h must satisfy h < 0.05·r for discs (or equivalent relation for coupons). Recommended thickness range: 0.3 mm to 1.0 mm.
  • Samples should be inspected for voids (e.g., acoustic microscopy, x‑ray).
• Apparatus specifications:
  • Analytical balance with resolution of 0.00001 g or 0.001% of sample mass.
  • Temperature/humidity chambers covering 30 °C–85 °C and 60%–85% RH with ±2 °C and ±3% RH tolerances.
  • High‑temperature oven for 100 °C–250 °C (±2 °C).
• Procedures:
  • Dry weight determination: bake at 125 °C for 24 h and continue with 12 h intervals until mass loss is <0.002% between consecutive measurements (updated method, references IEC 60749‑20).
  • Absorption below 100 °C: controlled exposures in humidity chambers, periodic mass measurements, and data collection designed to capture early and late diffusion behavior.
  • Desorption above 100 °C and post‑processing: measurements to assess reversible and irreversible moisture behavior.
• Calculations and outputs:
  • Determination of moisture diffusivity, solubility functions, activation energy for diffusion, and functional fits for solubility based on measured data.

Practical applications and users

IEC 60749‑39:2021 is intended for:

• Reliability and packaging engineers assessing moisture sensitivity and solder‑reflow robustness.
• Materials scientists and resin suppliers supplying moisture absorption parameters.
• Qualification and test laboratories performing standardized moisture/diffusivity testing for device qualification.
• Failure analysis teams investigating moisture‑related popcorning, delamination, or HAST/IR‑reflow failures.

Benefits include consistent, reproducible material property data to support material selection, package qualification, and predictive reliability models for moisture‑induced failures.

Related standards

• IEC 60749‑20 - Resistance of plastic encapsulated SMDs to combined moisture and soldering heat (referenced for dry weight procedure)
• JEDEC JESD22‑A120B - Source document used for this edition

Keywords: IEC 60749-39:2021, moisture diffusivity, water solubility, semiconductor packaging, plastic encapsulation, moisture absorption, solder reflow, test methods, reliability testing.