Electronic component reliability tests determine how long a particular component can perform under different stress conditions. The High Temperature Operating Life test (HTOL) is a critical reliability test. In the HTOL reliability test, the component is operated at a high temperature, accelerating aging and revealing latent failures early. Therefore, for the long-term perseverance for any element, HTOL is a worthwhile and highly executed reliability test.
What is HTOL?
High Temperature Operating Life test (HTOL) subjects a component to a high-temperature environment and electrical stress, commonly at full working voltage or more. HTOL imitates and accelerates the component’s aging process over the years into a few hundred to a few thousand hours. It can disclose failures that normally may occur after years of regular use within weeks or months.
In particular, HTOL quantifies the component’s activation energy (Ea) and failure rate in Failure In Time (FIT) or Mean Time To Failure (MTTF). Long-term reliability and durability in grueling conditions depend on the outcomes.
Importance of HTOL
HTOL estimates the long-term reliability of a semiconductor component, for example, MTTF, under accelerated stress conditions that compress the time to simulate the component’s lifespan while heating it (junction temperature of 125°C or above) and maintaining its operational voltages (or higher). It helps detect electromigration, time-dependent dielectric breakdown, or hot carrier injection issues, if any.
Early identification of potential failure modes, including assembly packaging concerns, promotes design ruggedness and motivates process control to lower expensive field failures and recalls. HTOL data could also enhance parametric drift models for predictive maintenance schedules and warranty estimates. This cuts lifecycle costs and boosts the confidence of consumers.
HTOL and The Bathtub Curve
The Operating Life Test (OLT) of an Integrated Circuit (IC) simulates the long operational environment with accelerated temperature and voltage alterations at a shorter duration. The bathtub Curve is divided into Infant Mortality, Useful Life and Wearout.
- Infant Mortality: The failure rate decreases quickly from high to low, as most failures are caused by design or process flaws. The HTOL assesses such early failures to improve Early Life Failure Rates (ELFR) through methodologies like Burn-in (BI). For that reason, the rate is indicated by Parts Per Million (PPM).
- Useful Life: The failure rate remains low and steady, with random causes (e.g., EOS failure). At this time, HTOL testing helps ensure stability during this phase.
- Wearout: The failure rate rises sharply due to product aging. In that case, using HTOL to predict failure rates is important for lifecycle planning.
Industry Applications of HTOL Reliability Test
In semiconductor manufacturing, HTOL testing is key to improving IC reliability under prolonged thermal and electrical stress. For example, microprocessors may undergo thousands of hours of HTOL reliability tests at 135°C with gate biases up to 1.43V.
Simulating real-world situations finds possible failure mechanisms. Similarly, HTOL guarantees the endurance of safety-critical electronic control units and sensors in hostile automotive environments. In the aircraft sector, HTOL tests power transistors, which must resist high temperatures while remaining functional.
Examples of tests for other Solid State Devices
Similar to HTOL, High-Temperature Gate Bias (HTGB) and High-Temperature Reverse Bias (HTRB) are critical for discrete semiconductors (e.g. transistors, diodes, etc.). For example, automotive powertrain MOSFETs are subjected to HTGB tests under elevated gate voltage and temperature, allowing for the identification of gate oxide weaknesses and providing insights into the device’s long-term reliability. On the other hand, the HTRB test may expose diodes and transistors to reverse bias conditions at around 150°C to discover early failures.
Impact on Failure Rates, FIT, and MTTF Calculations
Failure rates, FIT, and MTTF are calculated from HTOL testing. By increasing stress, HTOL helps manufacturers forecast the frequency of component failure under typical operating circumstances. For example, after 1,000 hours of HTOL at 150°C and extreme bias, the outcome may show a failure rate of 10 FIT (1 failure per billion hours).
It is essential for MTTF calculation and design considerations. as Design Engineers may need to change material or manufacturing procedures if HTOL shows a lower MTTF.
Henceforth, the HTOL reliability test helps improve product designs to fulfill industry-wide reliability standards and needs.
The Superiority of iST
- Comprehensive series of Burn-in systems to meet varieties of power consumptions, pin counts, and temperature control.
- Extensive series of general and customized Burn-in Board (BIB)
- Abilities in external circuit design, PCB layout, PCB assembly and customized burn-in socket.
Reference Specification
- JESD 47
- JESD 74
- JESD22-A108
- Products for automotive/business/industry/ consumer
Contact Window
| Mr. Diaw Tseng | Tel:886-3-5799909 Ext.6417 | Email:[email protected]
| Mr. Haoyu Lin | Tel:886-3-5799909 Ext.6690 | Email:[email protected]