Reliability Engineering

15Product Screening and Burn-In Strategies

Burn-in is a screen performed to precipitate defects by exposing the parts to accelerated stress levels. The goal is to prevent failures from occurring in the field (Pecht et al. 1995).

Burn-in as a requirement was instituted during the time of the Minuteman Missile Program where it was shown to be effective in uncovering defects in low-volume immature parts. By 1968, burn-in was incorporated in a military standard, MIL-STD-883 (1968).

Burn-in processes commonly consist of placing parts in a thermal chamber for a specific amount of time under an electrical bias. During and/or after thermal environmental exposure, functional tests are conducted. Parts that fail to meet the device manufacturer's specifications are discarded; parts that pass are used.

The temperature applied during burn-in is higher than the temperature the part will encounter in the field, as a perceived means of reducing the time to precipitate defects. Other accelerated conditions (stresses), which may be part of the burn-in process, include voltage, humidity, electric field, and current density (Lycoudes et al. 1990). To determine which stress condition and stress magnitudes precipitates defect-related failures, the failure modes and mechanisms must be known. The interested reader can find more information on these methods in the book Quality Conformance and Qualification of Microelectronic Packages and Interconnects (Pecht et al. 1994).

Over the last decade, there has been ...