Change of Temperature — IEC 60068-2-14

The temperature change test examines the product by repeatedly transferring it between two different temperatures. IEC 60068-2-14 defines two basic methods: Na (thermal shock), in which the transition is abrupt, and Nb, in which the transition is applied at a defined rate.

The purpose is to reveal the stresses that temperature transitions create in structures where materials with different thermal expansion coefficients coexist. Solder cracking, coating delamination, loss of sealing and micro-cracks most often become apparent in this test.

• Electronic boards and modules
• Automotive electronics and sensors
• LED lighting fixtures
• Fasteners and connectors
• Coated and bonded components

• IEC 60068-2-14temperature change test test

Method

Na (abrupt transition) or Nb (gradual transition at a defined rate) — from the product standard

Lower and upper temperature

From the product's declared operating/storage temperature limits

Dwell time

The time needed for the specimen to reach the temperature; depends on its mass

Number of cycles

From the product standard or the specification

• Two-chamber thermal shock cabinet (for Na)
• Programmable climatic chamber (for Nb)
• Specimen temperature measurement thermocouples
• Functional check rig

• The specimen must be in its ready-for-sale configuration
• The declared operating and storage temperature range must be stated
• If it will be operated during the test, a supply and monitoring interface must be provided
• The test may be destructive; keeping a spare specimen is recommended

Duration is directly proportional to the number of cycles and the dwell times. A low-cycle Na test can finish in a day, while a programme with hundreds of cycles can extend to weeks.

1. 1The specimen is examined in its initial condition and its function is checked.
2. 2The specimen is held at the lower temperature for the defined duration.
3. 3It is transitioned to the upper temperature according to the method defined in the standard.
4. 4It is held at the upper temperature for the defined duration.
5. 5This cycle is repeated the specified number of times.
6. 6At the end of the test the specimen is conditioned and a final inspection is performed.
7. 7Functional checks are repeated.

The method standard defines how the experiment will be performed, not at what level it will be performed. The severity level comes from the product standard, customer specification, or the use environment class of the product.

The result is evaluated on whether the product retains its declared function at the end of the test and whether visual inspection finds no damage of the type defined in the standard. The damage acceptance criterion comes from the product standard.

• Sample description, serial number and configuration
• Applied standard and year of printing
• Selected intensity level and basis for the level
• Experimental setup and measurement points
• Functional checks performed during the experiment
• Observations, measurement results and photographs
• A statement that the result applies only to the specimen submitted for testing

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

• Product standards under EU 2014/35/EU LVD
• ISO 16750 series (automotive electrical/electronic equipment)

The section below describes the field that the Change of Temperature test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

• UV Ageing
• IP Water Ingress
• IP Dust Ingress
• IP69K
• Free Fall
• Automotive Vibration
• Battery Vibration
• Aerospace Vibration
• UNECE R10 EMC
• Vehicle Emission
• Component Emission
• RF Immunity