Final Test and Binning

Once the die has received its finished package through assembly and encapsulation, it undergoes one last, comprehensive functional test – the final test. Unlike the wafer test, which typically offers only limited test coverage due to a restricted number of needles and contact quality, the finished, packaged chip can be tested far more comprehensively and under more realistic electrical conditions through its regular pins.

Tests performed include:

• Complete functional verification of all logic and analog circuit blocks
• Electrical parameters such as operating voltage, current consumption and signal timing
• Behavior under varying temperature and voltage conditions
• For memory devices: a complete cell test across the entire address range

Only after passing the final test is a chip considered ready for sale. Defective components are sorted out and typically scrapped, since repair at this stage of production is no longer economically viable.

For applications with particularly strict reliability requirements (such as automotive or aerospace electronics), a so-called burn-in process is often performed before the final test itself. During burn-in, chips are stressed for a defined period – ranging from a few hours to several days – under elevated temperature and, in some cases, elevated operating voltage.

The rationale lies in the so-called bathtub curve of electronic component failure rates: an unusually high proportion of early failures typically occurs within the first operating hours of a component, most often caused by hidden manufacturing defects such as material flaws or contamination that the final test alone would not catch. After this early-failure phase, the failure rate drops to a low, stable level before rising again toward the end of the component lifetime due to wear-related effects.

The burn-in process anticipates these early failures: components with hidden defects fail during burn-in itself and are sorted out before ever reaching a customer. The surviving portion of chips consequently exhibits significantly higher reliability during subsequent field use.