SN 29500 is deficient (vs. IEC TR
62380) in accounting for failures that are due to silicon and package interactions.
Consequently, functional safety standards recommend that:
- Semiconductor component
manufacturers estimate failures caused by silicon interaction with package
materials and silicon-to-package connection points (pins)
- System integrators account for
failures attributable to the connection points between the semiconductor
component and the boards (solder joints). These failures are typically analyzed
at the element or system level.
- ISO 26262 defines:
- An element as a system,
components (hardware or software), hardware parts, or software units;
and
- A system as a set of components or subsystems that relates at least a
sensor, a controller and an actuator with one another.
IEC TR 62380 accounts for both the interaction between silicon die and the lead
frame/substrate and the connection between solder joints. In contrast, the package
failure rate in SN 29500 only considers die-to-package interactions, which leads to
inherent optimism in BFR estimations when using SN 29500.