Which stress is applied in HTOL but not in a high-temperature storage test?

Answer: C. Electrical bias such as supply voltage

The high-temperature storage test (HTS) holds products at high temperature, for example around 150 °C, for a long time without applying voltage and compares their electrical characteristics before and after. HTOL operates products at high temperature under supply voltage, so it also accelerates degradation driven by electric field or current, such as TDDB and electromigration, whereas the high-temperature storage test isolates degradation driven by temperature alone. Typical targets are intermetallic growth and voiding at wire-bond joints, which raise resistance or cause the bond to lift, data retention in nonvolatile memory, and degradation of materials such as mold compound. The test that applies humidity and voltage together is the temperature-humidity-bias test (THB).

• A. High temperature is applied in both tests; the high-temperature storage test applies temperature only.
• B. Neither test applies humidity. Humidity and voltage are applied in the temperature-humidity-bias test.
• C. Correct. The high-temperature storage test applies no voltage and accelerates degradation with temperature alone.