What type of failure occurs with a damaged ESD if it passed a bench check but failed under stress?

The correct answer is latent failure. Latent failure refers to a situation where a component, such as an ESD (Electrostatic Discharge) protective device, initially appears to function properly during a bench check but subsequently exhibits failure under actual operating conditions or stress. This occurs because the damage may not be evident until the component is subjected to conditions that reveal its weaknesses or defects.

For example, during a bench check, the ESD may operate within specified parameters, but once it is exposed to the operational stresses like high voltage, temperature changes, or environmental factors, the hidden defects become apparent, leading to failure. This scenario illustrates the nature of latent failures, where the issue is not immediately detectable until the component is pushed beyond its safe operating limits.

Understanding that latent failures can often lead to unexpectedly poor performance is crucial in both troubleshooting and designing systems that require high reliability. The correct identification of latent failure helps engineers address potential risks associated with component performance over time.