What Is Temperature Cycling?
The temperature cycling test is one in which the sample is cycled a defined number of times between high and low temperature at a controlled transition rate. It is defined as method Nb in IEC 60068-2-14 and involves a slower transition than thermal shock.
Purpose of Temperature Cycling
The purpose is to reveal fatigue caused by repeated temperature change in joints combining materials with different expansion coefficients.
Which Products Is Temperature Cycling Applied To?
- Electronic boards and solder joints
- Automotive control units
- Battery modules
- LED lighting
- Connector and cable connections
In Which Sectors Is Temperature Cycling Used?
Standards Related to Temperature Cycling
- IEC 60068-2-14temperature change test test
- ISO 16750-4Environmental conditions in vehicle electrical/electronic equipment test
- MIL-STD-810 Method 503
- JEDEC JESD22-A104
Temperature Cycling Conditions
- Temperature range
- Upper and lower temperature defined in the specification
- Transition speed
- Controlled at IEC 60068-2-14 Nb, typically 1–5 °C/min
- Holding time
- Time to allow the sample to equilibrate at each extreme temperature
- Number of cycles
- Defined in the specification (e.g. 100, 500, 1000 cycles)
Equipment for Temperature Cycling
- Programmable temperature chamber
- Multi-channel temperature recording
- Function or resistance monitoring setup
- Data logging system
Sample Requirements for Temperature Cycling
- The sample must be placed with free air circulation in the chamber
- Continuous resistance monitoring is recommended for solder joints
- Function must be checked before the test
- Thermocouples must be connected at critical points
Duration of Temperature Cycling
Depends on the number of cycles. A 500-cycle programme can take several weeks depending on cycle duration.
Temperature Cycling Procedure
- 1The sample is placed in the chamber and monitoring is set up.
- 2The cycle profile (temperatures, transition rate, dwell) is loaded.
- 3The defined number of cycles is run.
- 4An interim function check is performed at defined intervals.
- 5A final function check and visual inspection are performed at the end of the programme.
Temperature Cycling Acceptance Criteria
The acceptance criterion is defined in the specification: continuity of function, no increase in solder or connection resistance beyond the defined limit, and no cracking.
Evaluation of Results
If continuous resistance monitoring is used, open-circuit events are recorded along with the cycle count. A cross-section is taken to examine solder cracks if required.
Temperature Cycling Report
- Standard and method applied
- Temperature range, transition rate and dwell time
- Number of cycles
- Function/resistance monitoring results
- Visual and, if required, metallographic examination
Accreditation
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.
Scope and authorisationsRelated Regulations
- Automotive and electronic component specifications
Environmental and Climatic Testing — What Does This Testing Field Cover?
The section below describes the field that the Temperature Cycling 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.
Environmental testing shows whether a product withstands ambient factors such as temperature, humidity, pressure, solar radiation, dust, water and corrosive atmospheres. The aim is not to break the product but to bring forward, in ACCELERATED form, the conditions it will meet over its life.
Test profiles are derived from the product's real exposure, and that derivation is the actual engineering work of the field. A device operating in an enclosed office and one mounted on a pole are not tested with the same profile. The IEC 60068 series defines general methods, MIL-STD-810 military profiles, RTCA DO-160 aviation profiles and the ISO 16750 series location-based automotive profiles. A test applied without a profile selection produces both unnecessary cost and false confidence.
Temperature tests simulate three separate phenomena and all three produce different failure modes. Steady high/low temperature tests whether the material can operate at that temperature. Temperature CYCLING creates fatigue at joints between materials with different expansion coefficients — solder cracks appear here. Thermal SHOCK intensifies this effect through an abrupt transition.
There is a distinction in humidity testing too. Steady damp heat shows the diffusion of moisture into the material and its effect on insulation properties. Cyclic damp heat creates condensation: water droplets form on the cooling surface, and this is far more aggressive than dry humidity. Water ingress into enclosures, increased leakage current and corrosion usually appear in the cyclic test.
Dust and water protection is a separate body of work and is expressed by the IP code. The point to note here is that an IP test is not a DURABILITY test: it shows that protection is provided under defined and short-duration conditions, not resistance to long-term immersion or pressure washing.
The most common mistake in this family is translating a test result directly into a LIFE PREDICTION. Accelerated tests are designed for comparison and design verification; a reliable conversion between hours in a chamber and years in the field can only be established with a material-specific acceleration model calibrated against field data.
Functional monitoring determines the value of the test. Keeping a product in a temperature chamber and then switching it on does not show what happened DURING the test. In critical applications the product is operated throughout the test and its parameters are monitored; intermittent faults that appear and disappear can only be caught this way.
Method groups in this field
Temperature
Dry heat, cold, change of temperature and thermal shock; steady and cyclic profiles.
Humidity
Steady damp heat and cyclic damp heat; cycles with condensation are more aggressive.
Water and dust
IP protection tests: dripping, spraying, jets, immersion and dust tightness.
Radiation and ageing
Accelerated ageing by xenon arc and fluorescent UV, solar radiation simulation.
Pressure and altitude
Low pressure (altitude) and rapid pressure change tests.
Corrosive atmosphere
Salt spray, mixed flowing gas corrosion (simulating industrial atmospheres), mould and fungus tests.
Commonly confused in this field
- Test duration cannot be converted into field life; a conversion made without an acceleration model is misleading.
- Temperature cycling and steady temperature produce different failure modes; neither replaces the other.
- If the product is not operated during the test, intermittent faults remain invisible; functional monitoring determines the value of the test.
- IP protection is not evidence of durability; it shows protection under defined and short-duration conditions.
- A test applied without profile selection both increases cost and gives false confidence.
- The mounting and orientation arrangement affects the result; the report must document it.
Which decisions these results support
- Design verification and qualification
- Declaration of the protection class and operating temperature range
- Reproducing field failures in the laboratory and root cause analysis
- Supplier component approval
- Decisions on warranty period and storage conditions
Related Tests
Frequently Asked Questions About Temperature Cycling
What is the difference between temperature cycling and thermal shock?
In temperature cycling, the transition is controlled and slow (IEC 60068-2-14 Nb). In thermal shock, the sample is transferred between two chambers in a very short time (method Na) and the stresses are more severe.