Reliability Standard
Semiconductor evaluation procedures use steady-state temperature and humidity bias testing to determine the long-term reliability of non-hermetic packaged microcircuits. The standard jesd22-a101 establishes a uniform test method to evaluate the moisture resistance of electronic components. This document provides a baseline for comparing different package materials and passivation designs.
Stress Conditions
Environmental chambers maintain a constant temperature of eighty-five degrees Celsius and a relative humidity of eighty-five percent for an extended duration. During this exposure, which typically runs for one thousand hours, test boards inside the chamber are connected to an electrical bias source. This bias voltage is applied to the devices to create galvanic corrosion conditions and to stimulate ion migration across insulating surfaces.
The combination of high humidity and electrical bias accelerates the entry of moisture through the plastic packaging.
Degradation Acceleration
The primary degradation mechanisms stimulated by this test are electrolytic corrosion of the aluminum metallization on the chip and dendritic growth between adjacent circuit traces. By applying a constant electrical bias under the jesd22-a101 standard, researchers can force mobile ions to migrate toward electrode areas, leading to early dielectric breakdown. This test is a critical milestone for qualifying new sensor interface integrated circuits before they are released to high-volume manufacturing.
If a design exhibits early failure during this test, the manufacturer must revise the plastic mold compound or the passivation layer to improve moisture resistance.
Method Boundary
Extreme conditions can sometimes trigger failure mechanisms that are not representative of real-world application environments. High-temperature and high-humidity environments can cause physical changes in the plastic encapsulant that would not occur during normal operation, leading to over-stress failures. For this reason, results must be correlated with field data to avoid rejecting packages that are perfectly suited for typical industrial environments.
