Safety App Warning: Understanding Potential Failures (Part 1) - Discussing Percentages of Malfunctions

Safety App Warning: Understanding Potential Failures (Part 1) - Discussing Percentages of Malfunctions

In the realm of system design, understanding the failure rates of electronic components is crucial to predicting overall system reliability. Several databases exist to provide these failure rates, including the IEC Technical Report 62380:2004, Siemens Standard SN 29500, the ADI component mean-time-to-fail (MTTF) data, field returns, and expert judgment.

The IEC Technical Report 62380 provides the failure rate of electronic components as the sum of the die failure rate, package failure rate, and overstress failure rates. The die failure rate for integrated circuits (ICs) is determined by factors such as the number of transistors, IC family, technology used, and mission profile data like temperature, working time, and influence factor of annual cycles. The overstress failure rate for ICs pertains to different external interfaces.

Analog Devices (ADI) provides reliability predictions for components in an IC's safety application note, which can be accessed when an IC is tagged as FS-enabled. IndustrialKnow offers a Safety Application Notes (Part 1): Failure Rates (Download) that provides details of reliability calculations, using the Arrhenius equation with an activation energy of 0.7 eV to translate data generated at the accelerated testing conditions of HTOL (1,000 hours at 125°C or equivalent) to lifetimes at the end-user operating conditions (10 years at 55°C).

Siemens Norm 29500 is a lookup-table-based standard used as the basis for reliability predictions in ISO 13849. The reference FIT values per device category determined from field returns of specific component classes. The LTC2933's safety application note, for example, shows the part's FIT values derived from HTOL, SN 29500, and IEC 62380 reliability prediction methods.

What is Siemens Norm 29500? The SN 29500 standard is a lookup-table-based standard that was initiated by Siemens and is widely used as the basis for the reliability predictions in ISO 13849. The reference FIT values per device category have basically been determined from field returns of the specific component class.

What is IEC Technical Report 62380: 2004? IEC 62380 is another commonly used standard for estimating the failure rate of an IC. It calculates the failure rate of an IC as a sum of the die, package, and EOS. The expression of FIT calculation according to IEC TR 62380 and ISO 26262-11:2018 is shown in Equation 3.

The package failure rate for ICs is influenced by thermal factors, thermal expansion, mission profile's temperature factor of cycle, and IC's packaging. Reliability prediction involves specifying the reliability model, the failure modes to be assumed, the diagnostic intervals, and the diagnostic coverage.

The Arrhenius HTOL method utilizes data from HTOL testing to provide the failure rate in FIT using the Arrhenius formula. Figure 1 shows the reliability bathtub curve model for failure of electronic components that can be divided into three sections: early life or infant mortality failures, useful life or constant (random) failures, and wear-out failures.

In essence, Arrhenius HTOL is a test-based, temperature-acceleration approach to predict IC reliability, Siemens Norm 29500 is a manufacturer/developer standard integrating multiple stresses with statistical and physics principles for IC failure rates, and IEC 62380:2004 is a comprehensive international guideline that models failure rates for electronics considering real-world environments, usage, and multiple stress factors.

Scientific data and technologies, such as the Arrhenius HTOL method and Siemens Norm 29500, are utilized for predicting failure rates in automotive electronics. The Arrhenius HTOL method employs data from HTOL testing to provide a failure rate in terms of FIT using the Arrhenius formula.

Siemens Norm 29500 is a manufacturer/developer standard that integrates multiple stresses with statistical and physics principles for IC failure rates, while IEC 62380:2004 is a comprehensive international guideline that models failure rates for electronics considering real-world environments, usage, and multiple stress factors.

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