A reliability test that operates products at high temperature under voltage for a long time to accelerate and evaluate chip lifetime and failure rate. A typical condition is 1000 hours at around 125 °C.
Japanese name: HTOL(高温動作寿命試験)
HTOL (high-temperature operating life test) appears in 4 practice questions across 1 topic, including Reliability.
Field: Reliability
HTOL stands for high temperature operating life. Products are held at high temperature and operated for a long time with supply voltage and input signals applied, to see whether failures occur. Temperature and voltage accelerate degradation, so stress equivalent to years of field use is applied in a short time. The targets are degradation of the chip itself and latent defects, such as time-dependent dielectric breakdown (TDDB) of gate oxides, threshold voltage shifts from BTI and electromigration in interconnects. Electrical characteristics are measured during and after the test to check for parametric or functional failures.
Typical conditions are a junction temperature of around 125 °C, a supply voltage at or somewhat above the maximum operating voltage, and a duration of 1000 hours. Conditions like these are typical in JEDEC standards (the JESD22 series), and the automotive AEC-Q100 requires, for example, zero failures when 77 units from each of 3 lots are tested for 1000 hours, with higher temperatures for some temperature grades. High-power products can self-heat to excessive junction temperatures, so the oven temperature is lowered or devices are temperature-controlled individually to hit the target. Parts are pulled and measured at intermediate points such as 168 and 500 hours to track how degradation progresses.
Burn-in is a screen that applies short high-temperature, high-voltage stress to all or many shipped units to remove those prone to early failure. HTOL is a qualification test that applies long stress to a sample to confirm that the design and manufacturing process meet the target lifetime and failure rate; the units tested are not shipped. HAST adds humidity and pressure to evaluate the package's moisture resistance and targets different failures from HTOL, which operates parts at dry high temperature. Early-life failure rate is evaluated separately, for example with ELFR tests that run more units for a shorter time than HTOL.
HTOL results are converted to time under use conditions by estimating a temperature acceleration factor with the Arrhenius model and a voltage acceleration factor with a voltage model. For example, assuming an activation energy of 0.7 eV, one hour at 125 °C corresponds to roughly 80 hours at 55 °C. From a zero-failure result, the chi-square distribution gives an upper bound on the failure rate in FIT at a chosen confidence level. Activation energy differs by failure mechanism, however, and the assumed value changes the result greatly, so the figures are treated as estimates.
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).
High temperature operating life. Parts are operated continuously at high temperature under voltage to accelerate and evaluate chip lifetime and failure rate.
Burn-in is a screen that removes early-failure units from products to be shipped, applied for a short time to many units. HTOL is a qualification test that confirms long-term lifetime on a sample, and the tested units are not shipped.
1000 hours is a common benchmark, with measurements at intermediate points such as 168 and 500 hours. Temperature, voltage and duration depend on the applicable standard, the product's temperature grade and agreements with the customer.
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.
Which stress is applied in HTOL but not in a high-temperatu…HTOL (high temperature operating life) testing runs products at around 125 °C at or slightly above their maximum operating voltage for long periods to observe failures.
Which typical reliability test evaluates lifetime and failu…HTOL tests chip lifetime and IDDQ tests for manufacturing defects.
For mobile devices such as smartphones, which test is espec…TDDB and NBTI are wear-out mechanisms, and HTOL and HAST are accelerated life tests.
Among ESD (electrostatic discharge) test models, which pair…As an Amazon Associate I earn from qualifying purchases.
TDDB (time-dependent dielectric breakdown) Temperature cycling High-temperature storage test (HTS) Electromigration Nonvolatile memory THB (temperature-humidity-bias test) AEC-Q100 BGA Underfill ESD (electrostatic discharge)