BS EN IEC 62435‑8:2020 pdf download – Electronic components — Long-term storage of electronic semiconductor devices Part 8: Passive electronic devices.
Long-term storage assumes that the device is going to be placed in uninterrupted storage for a number of years. It is essential that it is useable after storage. Particular attention should be paid to storage media surrounding the devices together with the local environment. These guidelines do not imply any warranty of product or guarantee of operation beyond the storage time given by the manufacturer. The IEC 62435 series is intended to ensure that adequate reliability is achieved for devices in user applications after long-term storage. Users are encouraged to request data from suppli- ers to applicable specifications to demonstrate a successful storage life as requested by the user. These standards are not intended to address built-in failure mechanisms that would take place regardless of storage conditions. These standards are intended to give practical guide to methods of long-duration storage of electronic components where this is intentional or planned storage of product for a number of years. Storage regimes for work-in-progress production are managed according to company internal process requirements and are not detailed in this series of standards. The overall standard is split into a number of parts. Parts 1 to 4 apply to any long-term stor- age and contain general requirements and guidance, whereas Parts 5 to 9 are specific to the type of product being stored. It is intended that the product specific part should be read alongside the general requirements of Parts 1 to 4. Electronic components requiring different storage conditions are planned to be covered sepa- rately starting with Part 5.
4 Storage considerations 4.1 Overview of passive components Passive components are not able to control current where the instantaneous power cannot be negative therefore there is no power gain before the application of electric energy. Common examples of passives are resistors, capacitors, inductors, transformers and diodes of all types. Often electromechanical relays, quartz crystals and fuses are also to be considered passive components for the purpose of long-term storage requirements. Passive components are made using a wide range of technologies, materials and manufacturing processes. Passive components are surface mounted to electronic packages, modules and boards as ei- ther discrete components or packaged components that vary in size, typically larger than 1 mm in the smallest dimension. Passive miniaturization has led to packaged passives. Pas- sives are also integrated or embedded into other packaged components, modules and boards. Passive components can experience many of the same failure modes as other components and the storage program should consider the end use and failure mechanisms related to the function of the component. An example list below may be used as a basis for consideration in storage related risk assessments. 4.2 Failure mechanisms 4.2.1 Occurrence of failure and driving force Failures during long-term storage should be mitigated by control of the stimuli driving given failure modes of interest as defined by a failure modes and effects analysis (FMEA). Storage related failures are often detected as modes of non-operation, visual quality or other non- conformance.
4.2.2 Storage environment and mitigation for stimuli to prevent failure Mitigation of failures during and after long-term storage occurs by directly controlling or limit- ing the stimulus for failure by a number of means. Common requirements for sustained long- term storage are given in Table 2. Knowledge and control of the storage environment is of primary importance to identify the risk of failure occurrence and to control or eliminate failure stimuli during storage. Examples of the storage environment are contained in IEC 62435-4. Other storage environment parameters related to long-term storage that may be important for products or devices with certain sensitivities are presented in Annex A. It is the responsibility of the end customer to maintain the storage environment as well as to ensure that terms and conditions are in place successful long-term storage at the time of product purchase. The full component thermal and environmental chain should be considered in planning relia- bility characterization evaluation and for estimation of reliability after storage and added to the use reliability estimates.