High and low temperature and temperature cycling tests verify functional stability and structural reliability at temperature extremes. Temperature cycling exposes problems better than a constant temperature test, because materials fatigue as they are repeatedly heated and cooled — the most common failure mechanism in real vehicle use.
Test types
High and low temperature storage: the product is stored at extreme temperatures for an extended period, verifying tolerance in the non-operating state.
High and low temperature operation: the product is powered and operating at extreme temperatures, verifying that function remains normal.
Temperature cycling: the product is cycled repeatedly between the two temperature extremes at a set rate, reproducing a full day's cycle from solar soak to night-time condensation.
Rapid temperature change: reproduces the fast thermal shock of specific scenarios, such as moving into a cold environment after rain.
Choosing the severity
The upper and lower limits depend on the actual service environment and mounting location. A product on the dashboard face sees far higher solar soak temperatures than one on the door mirror.
The rate of temperature change matters a great deal. A real vehicle can move from solar soak to a cold environment at several degrees per minute, much faster than the standard default.
The number of cycles depends on the verification objective. Higher cycle counts are more informative for development-stage screening.
Dwell time at each temperature step determines how the thermal stress is distributed.
Common failure modes
SMT solder joint cracking: caused by mismatched thermal expansion coefficients, and worse when the PCB-to-enclosure fixing is poorly designed.
Rising connector contact resistance: metal expansion and contraction change contact pressure.
Seal failure: rubber seals shrink at low temperature and take a permanent set after high-temperature ageing.
Delamination: encapsulants and coatings crack under repeated temperature change.
Display colour shift or slow response: an inherent property of liquid crystal at temperature extremes; going outside the specification range is expected and has to be assessed.
Checks before and after the test
Visual inspection: look for cracks, deformation, seal failure and delamination.
Functional test: compare functional output and key parameters before and after.
X-ray inspection: check for morphological change in solder joints and internal connections.
Cross-sectioning: metallographic examination at the failure location to confirm where the fatigue crack started and how it propagated.
Frequently asked questions
Do temperature cycling and high/low temperature storage both need to be done?
They examine different failure mechanisms, so a combination is recommended. Storage testing looks at non-operating tolerance at extreme temperatures (material properties, package integrity), while cycling looks at fatigue under repeated thermal stress (SMT reliability, connector stability). The specific combination follows product risk and OEM requirements.
What does it mean if quality problems persist after temperature cycling?
It may mean the test conditions do not match the actual service environment. Check three things: whether the temperature limits cover the real extremes, whether the ramp rate is close to the real scenario, and whether the sample mounting matches the vehicle. Another common cause is insufficient design margin — for example, materials with very different thermal expansion coefficients rigidly fixed together.
Service notes
Our laboratory holds both CMA and CNAS accreditation, covers about 10,000 m2 and runs more than 500 sets of equipment. All testing is carried out in our own laboratories — nothing is subcontracted. Plant visits and on-site witnessed testing are welcome.
Scheduling follows the actual project pipeline. You can state your preferred lead time when you submit samples; we will confirm a feasible plan against current capacity and keep you updated at each milestone. Once the report is issued we send the electronic copy; corrective-action advice can be arranged separately.
