TI Confidential – NDA Restrictions
2 Hardware Component FMEDA (Failure Modes Effects and Diagnostics Analysis)
This section describes the device FMEDA, the assumptions made within, the options for tailoring, and provides
an example calculation of device functional safety metrics.
2.1 Random Fault Estimation
In order to conduct quantitative failure analysis, estimates of the random failure rates for the components that will
be considered in the analysis must be generated. There are many different models and techniques that can be
used for failure rate estimation. Neither IEC 61508 nor ISO 26262 mandate the use of a particular failure
estimation methodology. Estimation methods commonly used include:
• IEC/TR 62380:2004, "Reliability Data Handbook - Universal Model for Reliability Prediction of Electronics,
PCBs, and Equipment"
• Siemens Norm SN29500:2010, "Failure Rates of Components"
• IEC 61709:2017, "Electric components - Reliability - Reference conditions for failure rates and stress models
for conversion"
• Supplier reliability data from similar products already in production and deployed under similar operating
conditions
• Targeted studies and experiments that seek to induce failures on silicon under conditions that simulate
accelerate lifespan (such as temperature, voltage, frequency, vibration, humidity, or radiation exposure).
Estimations of failure rate are often defined in terms of Failures In Time (FIT). TI's data respects FIT in terms of
failures per 10^9 hours of operation, as is consistent with most handbooks. However, certain handbooks, such
as those for military applications, may refer to FIT based on failures per 10^6 hours of operation. Take care when
using such data to respect a common definition of FIT in all calculations.
In TI's experience, all of the models generate estimations of failure rate that are not consistent with failure rates
which are observed and reported in the field or predicted based on data generated from targeted experiments.
The models consistently predict higher failure rates than those observed in the field or predicted via targeted
experiments. One possible reason for this discrepancy is that these standards consider reliability data that does
not make a distinction between random and systematic failure. In both IEC 61508 and ISO 26262, the focus for
quantitative analysis is on random failure rate. TI's data indicates that the vast majority of field failure issues
seen in semiconductors are due to systematic failures, whether traced to semiconductor supplier, system
integrator, or end user. TI has quality and reliability programs in place that constantly improve our products and
processes to reduce these systematic failures.
The failure rates derived from SN29500 tend to be conservative as compared to TI product field failure rate data
or TI accelerated lifetime testing. TI considers the IEC 61709 to be similar to the SN29500 and we refer to this
model as the IEC 61709/SM 29500 model in the FMEDA. The IEC/TR 62380, while still conservative, provides
the closest match available to TI product data. Although this standard has been formally withdrawn, the
equations have been incorporated inside ISO 26262-10:2018. As such, TI has used IEC/TR 62380 as the basis
for our random failure rate estimation, augmented with data from targeted studies for failure modes not
considered in the base model.
When considering failure rates for semiconductors, TI applies the following partition and methodology:
Table 2-1. Summary of TI Random Failure Rate Estimation
Design Element Failure Mode Estimation Method
Device Packaging Permanent faults IEC/TR 62380
Die (silicon) Permanent faults IEC/TR 62380
Die (silicon) Transient faults (soft error) Targeted radiation exposure
2.1.1 Fault Rate Estimation Theory for Packaging
TI uses the IEC/TR 62380 model to estimate package FIT rate for the BGA package used for this device. The
IEC/TR 62380 package model is primarily concerned with wear-out due to thermal expansion between the
package and the PCB. The model includes several variables that have been replaced with device-specific data
when available, such as power consumption and package thermal characteristics. It is highly recommended that
the user applies their own application mission profile in the 'Mission Profile Tailoring' tab as this has a large
TI Confidential - NDA Restrictions
www.ti.com Hardware Component FMEDA (Failure Modes Effects and Diagnostics Analysis)
SPRACQ8 – DECEMBER 2020
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