This publication examines the LTS requirements of wafers, dice, and packaged solid-state devices. (Note: Packaging may include encapsulation, under-fill, over-mold, or other techniques to attach a die to the next level of assembly.) The user should evaluate and choose the best practices to ensure their product will maintain as-received device integrity and minimize age- and storage-related degradation effects. Major degradation concerns can be driven by moisture-induced corrosion, contamination, electrostatic fields, temperature effects, and outgassing. Please refer to J-STD-033 for non-LTS criteria as well as requirements for moisture sensitivity levels, environmental conditions, dry bag requirements, handling, shipping, and desiccant calculations.

Wafers and dice that are in process or finished may require LTS depending upon program needs. Environmental factors should be evaluated to avoid electrostatic discharge (ESD) damage and to protect the wafer and die bond pads and the device terminal leads against corrosion and damage until any die is packaged or otherwise attached in its next level of assembly. Specific ESD requirements and procedures can be found in ANSI/ESD S20.20, EOS/ESD S8.1, and JESD625 as applicable.

Solid-state devices may be constructed from either organic or ceramic materials. Many organic packaged solid-state devices are designed to attach the semiconductor die to copper die bond pads or heat spreaders or stiffeners. These packages utilize organic resins and other carbon-based materials which can absorb and retain moisture, leading to failure mechanisms such as delamination, corrosion, and warpage. Ceramic solid-state devices are constructed from inorganic materials such as alumina or glass frit. Ceramic devices can develop corrosion from moisture exposure. Ceramic devices can be damaged from handling.

Effective use of this publication is intended to prevent environmental damage to and maintain reliability of wafers, dice and unassembled solid-state devices during LTS. Product destined for LTS should be free from any initial storage concerns, including contamination from process chemicals, fluxes, handling damage, etc. LTS product should be inspected prior to use to ensure no detrimental effects. Metallic whiskers (such as tin, silver, copper) could develop depending upon moisture and temperature environmental conditions. This document does not relieve the supplier of the responsibility to meet internal or customer specified requirements or qualification programs.