6.2.1 Terminology in electronics failure analysis

The terminology used in the failure analysis of electronic devices and materials is somewhat different from that used in other kinds of failure analyses. In this context, failure mode refers to the nature of malfunction of the device, which results in the observed failure characteristic (e.g., open circuit, short circuit, leakage). The nature of the actual fault that causes the device to malfunction is called the failure defect (e.g., microcracks and growths). Phenomena such as electromigration and corrosion that produce failure defects are called the failure mechanisms. The nature of the actions (e.g., high current density, stress concentrations) that cause failure mechanisms to occur are referred to as failure causes. When a device operates but not to the desired specification (e.g., a timing problem), it is referred to as a specification failure, while a device in which certain or all functions are inoperative is referred to as a hard failure. Using this terminology, Table 6.1 shows examples of the correlation between modes, defects, and mechanisms for some typical failures. The table is by no means exhaustive. Table 6.2 shows the distribution of failure mechanisms within integrated-circuit (IC) packages.