Environmental Stress
A reliability evaluation technique subjects electronic components to high temperature and high humidity under increased atmospheric pressure to accelerate moisture penetration. The highly accelerated stress test is performed to evaluate the corrosion resistance and packaging integrity of non-hermetically sealed semiconductor devices. By operating beyond the boiling point of water, this method compresses testing cycles from weeks to hours.
Humidity Acceleration
Saturated or unsaturated steam environments are created inside a sealed pressure vessel at temperatures typically ranging from one hundred and ten to one hundred and thirty degrees Celsius. The elevated chamber pressure drives water vapor through the polymer packaging materials of the device far more rapidly than standard non-condensing humidity tests. This rapid migration exposes internal metallization paths and bonding pads to potential corrosive agents.
The combination of thermal and moisture stresses reveals hidden flaws in the passivation layer.
Electrical Monitoring
Electrical bias is applied to the devices under test to simulate active operation and stimulate electrochemical corrosion processes. Leakage currents are tracked continuously during the test to detect insulating material breakdown or dendritic metal growth. After the test completes, full parametric testing is conducted to identify any permanent damage or parameter drift.
These electrical checks ensure the device can survive harsh field conditions.
Packaging Integrity
The test is restricted to non-hermetic packages as hermetically sealed ceramic or metal packages are impervious to moisture penetration. Testing hermetic devices under these conditions only evaluates external surface corrosion rather than internal package reliability.
