The “Autoclave Test” (sometimes called “steam bomb test” or “pressure put test”) is performed to evaluate the moisture resistance of packaged solid state devices. It is a highly accelerated test using moisture-condensing or moisture-saturated environments. It utilizes conditions of pressure, temperature, and humidity to accelerate moisture penetration into the active circuits inside the package. This moisture generally penetrates in two areas:
1) directly through the encapsulant material or
2) at the sealing junction where the conductors pass into the device.
This test should be performed whenever a new package is being introduced OR whenever a package has undergone a redesign that has required material changes, such as a change in molding compound, die attach adhesive, or perhaps die passivation. It should also be done when there have been mechanical changes such as a change in die size or a change in leadframe dimensions. Autoclave testing is not to be regarded as being the same as “HAST” (highly accelerated stress test).