IEC 60068 2 38 Test Z/AD: Composite temperature/humidity cyclic test – Ensuring Component Performance in high temperature/humidity and cold conditions

Standard: IEC 60068‑2‑38: Environmental Testing – Part 2‑38: Tests – Test Z/AD: Composite temperature/humidity cyclic test

Scope: IEC 60068-2-38: Test Z/AD outlines a composite test method that combines temperature and humidity cycling to simulate environmental conditions that may cause corrosion, insulation failure, or material degradation. It is particularly useful for identifying latent defects in products exposed to fluctuating climates, especially during storage, transport, or operation in humid environments.

Applicable Products: This standard applies to a range of products, including:

Electronic control units (ECUs)
Sensors and actuators
Battery systems
Lighting and Infotainment systems
Mechanical assemblies and enclosures

Test Procedure: In our specialized lab, we conduct IEC 60068‑2‑38 Test Z/AD: Composite temperature/humidity cyclic test using state‑of‑the‑art equipment to ensure accurate and reliable results. Like IEC 6006-2-30, this testing includes temperature and humidity cycling, but IEC 60068-2-38 is often seen as more severe due to more frequent changes in conditions and the cold sub cycle down to -10°C.

Preconditioning: The unpackaged, unpowered samples are exposed to a drying phase of 24 hours at +55°C with less than 20% relative humidity. The samples are then allowed to reach thermal stability at standard atmospheric conditions for testing prior to the initial measurements.
Temperature/Humidity Sub cycle: This subcycle begins each of the ten 24-hour cycles and consists of two sequential ramps from +25°C and high humidity to +65°C and high humidity, dwell, and ramp back to +25°C and high humidity. For cycles that do not include the Cold Subcycle, the rest of the 24-hour cycle is maintained at +25°C and high humidity.
Cold Subcycle: Five of the first nine cycles require a dwell at -10°C by means of lowering the temperature of the chamber or transferring to a second chamber.
Intermediate Measurements: If operation of the samples does not interfere with the severity of the climatic stress, then functional checks should be carried out while the samples dwell at the high temperature and high humidity setpoints.

End Result: Successful completion of IEC 60068‑2‑38 Test Z/AD: Composite temperature/humidity cyclic test confirms that components can withstand and function effectively in conditions of high humidity – combined with cyclic temperature changes.

Test Lab Locations: Detroit (Plymouth), MI; Grand Rapids (Kentwood), MI