Key takeaways
Automotive displays need three classes of test: mechanical and climatic environment, display optical performance, and EMC. The three look at completely different things — environment asks whether it survives, optics ask whether you can see it clearly, EMC asks whether it interferes with anything else. The class most often overlooked on real projects is optical performance: it is not traditional reliability work, yet it is frequently the OEM acceptance focus.
An automotive display is a textbook composite part: cover glass, display module, touch layer, backlight, control board and FPC connections. That form factor means a generic reliability plan has to be reworked from scratch.
1. Common failure modes
- Cover glass fracture: thermal shock after a high-temperature solar soak, or stone impact where the requester calls for it
- Display abnormality: abnormal LCD response at temperature extremes, colour shift or image retention in heat
- Touch failure: false touches and drift with wet hands or oily contamination
- Backlight degradation: luminance decay and colour shift after temperature cycling
- FPC connection failure: connector back-out or poor contact after vibration and thermal cycling
- EMC exceedance: radiated emission from the backlight driver and touch IC over the limit
2. Three classes of test item
Mechanical and climatic
- High and low temperature storage and operation
- Temperature cycling
- Constant and cyclic damp heat
- Random vibration and mechanical shock
- Ingress protection (IP)
- Solar radiation and UV ageing
- Salt spray (for specific applications)
Display optical performance
This class is often left out of traditional reliability plans, yet it is frequently the OEM acceptance focus:
- Luminance and uniformity
- Colour and chromaticity coordinates
- Contrast ratio
- Response time and dynamic contrast
- Viewing angle and colour shift
- All-black and all-white display states
- Dead and bright pixel inspection
- Light leakage and Mura inspection
Optical items should be measured once before and once after the environmental tests, so that the degradation the tests cause can be quantified.
EMC
- Radiated and conducted emission
- Radiated and conducted immunity
- Electrostatic discharge
- Transient pulses (simulating vehicle conditions)
3. Sequencing the tests
The sequence affects the conclusion. The usual approach:
- EMC exploratory round first — surface interference problems as early as possible in development
- Then high and low temperature and temperature cycling — covers temperature-related failure
- Then vibration and mechanical shock — covers mechanically driven failure
- Then damp heat and ingress protection — covers environmental attack
- Optical performance as the final inspection — evaluates overall performance after every test
The logic behind the order: easy before hard, baseline before accumulation, final inspection last. Testing is scheduled according to the project, and the feasible combination should be agreed with the laboratory.
4. Preparing the samples
For display testing, the sample state should be as close as possible to the installed state:
- Assembled as in the vehicle (backlight, touch, cover glass included)
- Supply and communication interfaces provided as the unit requires
- Driving system supplied, or the signal requirements stated
- The functions to be monitored and the acceptance criteria defined
An unclear sample definition makes it impossible to attribute a failure after the test.
