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Understanding Highly Accelerated Stress Test (HAST) in IC Qualification

April 15, 2018, anysilicon

The highly accelerated stress test (HAST) involves the effects of humidity and temperature on an IC or ASIC. The HAST is designed to test the package of the ASIC under extreme humidity and temperature conditions. Devices that pass such tests will be able to withstand the normal rigors of temperature and humidity in most environments.

 

The HAST is sometimes called the pressure-cooker test because it simulates the conditions found inside a typical household pressure cooker. By increasing the amount of water vapor pressure inside a test chamber while also increasing the temperature, this provides an excellent test of the inherent strength, design, and protection of the electronic components inside. The testing involves increasing the pressure which helps to force water vapor inside the device.

 

Effects of HAST

 

Compared to the former standard of high-temperature/high-humidity, the HAST will cause more damage to the components due to how the moisture helps accelerate the corrosive effects of the water vapor. There will also be more damage to the insulation as well, causing fast deterioration, especially in devices that are not up to the HAST standards.

 

This type of test is mostly done on components that are plastic-sealed, followed by an evaluation of the results. For the most part, the temperatures that are used reach at least 212 degrees F or that of boiling water. This provides for a full state of water vapor to be present in the air and pressurized for maximum effect.

 

HAST test is performed based on JEDEC standard JESD22-A110 (Biased HAST) and JESDA118 (Unbiased HAST). With conditions: 130°C/85%RH/33.3 psia and 110°C/85%RH.17.7 psia. Test duration is 96 or 264 hours.