Driven by the desire for clear and quick root cause analyses of failures, failure signatures are often referred to as "fingerprints". However, the fundamental electrical failure mechanisms in electronic products depend on the time integral of the given voltage drop and/or current flow.
Therefore, failure signatures cannot by clearly attributed to waveforms of voltages and/or currents. In fact, many different waveforms of voltages and/or currents can result in the same failure signature. From the type and the extension of the failure signature only a few general characteristics of the causative electrical stress can be derived. Consequently, the metaphor of a "fingerprint" that is often used to describe failure signatures is misleading.