IEC 62435-7-2020 pdf free download – Electronic components – Long-term storage of electronic semiconductor devices – Part 7: Micro-electromechanical devices.
4storage considerations
4.1overview of MEMS applications
MEMS(Micro-electromechanical Systems) are miniaturized mechanical or electromechanicalelements that typically vary in size from 1 micron to 1 000 microns that are used to mechanically
measure or manipulate’matter，light or create electric signals from environmental inputs.Storage of MEMS devices should consider different sensitivities and risks compared to othersemiconductor devices due to the mechanical nature of the devices.MEMS may be subject to
additional mechanical related performance and failure mechanisms in addition traditionalsemiconductor performance mechanisms. The storage program should consider the end useand failure mechanisms related to the function of the MEMS device. Typical uses are listed for
initial consideration and risk assessment.
– Actuator mechanical movement related to electrostatics， thermal changes or piezoelectric effects.
Physical sensors related to acceleration, vibration, field/flux, force, magnetic field, electro-static, optical stimulus or radiation effects, pressure, temperature.
Chemisensors related to gas or liquid induced mechanical response changes (may alsohave requirements for moisture or solvent which also have shelf life).
Biosensors liquid，mechanical or fluidic induced mechanical response changes (may alsohave requirements for moisture or solvent which also have shelf life).
4.2Failure mechanisms
4.2.1 Occurrence of failure and driving force
Failures during long-term storage may be mitigated by control of the stimuli driving given failuremodes of interest as defined by risk assessment tools, for example, failure modes and effectsanalysis (FMEA).Storage related failures are often detected as modes of non-operation, visual
quality，reduced life time or other non-conformance. The modes of failure during storage aretypically related to a failure mechanism that is driven by a physical stimuli or condition.Example
failure stimuli are given in Table 1.Additional examples of deterioration mechanisms are found
in IEC 62435-2. Successful long-term storage is accomplished by mitigating failures throughcontrol of the stimuli or driving force.
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 limiting 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 could 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 reliability characterization evaluation and for estimation of reliability after storage, and added to the use reliability estimates.IEC 62435-7 pdf download.