The study of impacts on long-term storage reliability caused by IC packages and preventing measurements

Long term storage, usually in die/wafer, plastic or hermetic packages, has been proposed as one solution to the problem of component obsolescence. In this study, failure mechanisms of long-term stored ICs, including ESD, humidity, temperature, contamination and vibration, and vulnerabilities to each storage form are analyzed. Then general requirements on material and environment and special attention addressed to each form are detailed; and related standards from military and industry are summarized accordingly. Finally, the actual lifetime, merits and demerits of each storage form are compared. Because of performance, functionality and attractive cost benefit ratio derived from the latest generations of Commercial Off the Shelf (COTS), the military and high reliability markets rely heavily on COTS integrated circuits(IC). But the mismatch between rapid civilian technology obsolescence and typical 10-plus year military gears often forces semiconductor devices to be procured at Last Time Buy and stored for future use, providing no degradation of parts in decades storage[1]. Storage for such a long time is totally a tough task, but the policy and technology developments these days are making the situation even worse, such as Restriction on Hazardous Substances Directive (RoHS) token effect in 2006; decreased reliability caused by higher degree of IC integration, lower supply voltage, higher switching frequencies, smaller and thinner of packages[2]. In order to ensure adequate reliability is achieved, long-term storage requirements and measures should be studied thoroughly and continually.