Due to rapid changes in packaging design and material, many companies find themselves forced to purchase additional quantities of components in order to guard against the impact of component obsolescence on their final product designs. This in turn creates an issue of long term inventory storage.
Product lifecycles continue to shorten, with new models being released sooner than ever before. Many manufacturers, such as automobile suppliers, must guarantee the availability of replacement parts including PCBs for up to ten years. This situation also necessitates the advance purchase and extended storage of components and materials. Further complicating the problem is that most components cannot be stored for more one year without very special handling procedures. (ref IPC/JEDEC-Std-033C)
In addition to the dangers of moisture diffusion into the materials and oxidation and contact corrosion, long term storage introduces the additional concern of inter-metallic growth. Three years of testing in cooperation with several European automotive electronics manufacturers has culminated in the release of the Super Dry XSDC series of low humidity long term storage cabinets. In addition to providing 1% RH and closed loop desiccant regeneration, the XSDC can reduce and control temperature to below ambient, which has proven to significantly reduce the inter-metallic growth that is characteristic of long term storage. The insulated enclosure maintains set point temperature to with 2 degrees C, and studies have shown 17-19C as optimal at minimizing IMC growth without inducing tin whiskers.