Chamber Standardization
Standardized profiles for environmental stress testing are verified using high precision sensors to ensure that the actual board temperatures match the programmed test limits. In these setups, thermal cycling calibration establishes the correlation between the control sensor of the test chamber and the actual temperature of the test vehicle. This procedure is necessary to guarantee repeatable test conditions across different machines.
The process aligns the heating and cooling ramp rates with national or international testing standards.
Temperature Mapping
Execution of the calibration routine utilizes multi-channel data loggers connected to thermocouples attached to the surface of a dummy printed circuit board. During this thermal cycling calibration, the chamber is run through several cycles while temperature profiles are recorded at various points across the board. The recorded data shows the spatial temperature uniformity and the rate of temperature change at the components.
Discrepancies between the chamber’s air temperature and the board surface temperature are corrected by adjusting the controller parameters. This profiling prevents both under-stressing and over-stressing of the electronic components during reliability trials.
Error Prevention
Instrument drift and degradation of heating elements can cause the chamber to deviate from its calibrated state over time. This variation can invalidate the reliability data gathered during long-term life testing. Regular recalibration intervals are required to maintain the traceability of the test data.
Keeping the chamber calibrated prevents costly re-testing and ensures compliance with aerospace or automotive testing specifications.
