Meaning
Standardized test methodologies define the procedures for biased life testing of semiconductor devices to ensure long term reliability. The document known as jesd22 a108 specifies the conditions for high temperature operating life tests to detect infant mortality or steady state failure rates. It requires the application of electrical bias at elevated temperatures to accelerate the physical aging process.
Stress Condition
Devices are subjected to a combination of maximum operating voltage and high ambient temperature to create a worst case environment. Under jesd22 a108, the goal is to trigger failure mechanisms like electromigration or dielectric breakdown in a controlled laboratory setting. The voltage is often boosted slightly above the nominal rating to increase the stress on the internal circuits.
Failure Criterion
Success is measured by the ability of the parts to remain within their electrical specifications after the test is complete. Any device that shows a parameter shift beyond the allowed limits of jesd22 a108 is considered a failure, even if it still functions. These strict rules ensure that the component will be stable throughout its entire service life in a customer system.
Test Duration
Typical qualification runs last for 1000 hours, which is intended to simulate many years of actual operation. The jesd22 a108 standard allows for shorter tests at higher temperatures if the acceleration factor is well understood and documented. This flexibility helps manufacturers bring new products to market faster without compromising on safety.
The data from these tests is often used to calculate the FIT rate and the MTBF of the component.
