Meaning
Environmental stress tests evaluate the ability of a component to withstand prolonged exposure to heat without electrical bias. The high temperature storage life test is used to identify weaknesses in the materials and the assembly of the package. It focuses on failure modes like intermetallic growth, outgassing, and the degradation of adhesives.
Thermal Aging
Sustained heat accelerates the chemical reactions that cause electronic components to fail over time. During the high temperature storage life test, parts are placed in an oven at 125 or 150 degrees Celsius for 1000 hours or more. This treatment simulates years of shelf life or non operational time in a harsh environment.
Qualification Standard
Industry bodies like JEDEC define the specific durations and temperatures required for this reliability screen. A successful high temperature storage life qualification means the part can be stored or shipped without losing its electrical characteristics or physical integrity. Engineers compare the pre test and post test measurements to ensure that parameters like leakage current and resistance remain within the datasheet limits.
Package Integrity
Structural issues like delamination or lead oxidation often appear during these long periods of thermal stress. The high temperature storage life test reveals if the moisture in the package will cause internal cracking when the part is eventually soldered to a board. Manufacturers use these results to refine the materials used in the molding compound and the lead frame plating.
This ensures that the component remains reliable throughout its entire life from the factory to the end user.
