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Q&A(FAQ) What is MSL(Moisture Sensitivity Level)?

1. MSL(Moisture Sensitivity Level)

Semiconductor components with resin-sealed packages may be damaged during reflow soldering if moisture trapped inside the package expands.
MSL is an electronic standard established by JEDEC that defines the period during which a moisture-sensitive device can be exposed to ambient room conditions.
According to this standard, there are eight levels of moisture sensitivity.
Components must also be packed with a desiccant and may require baking.
Floor life is defined as the allowable storage time at less than 30°C and 60% RH.

Table.1 The definition of MSL
# MSL Floor Life
1 1 Unlimited (30°C less than 85%RH)
2 2 1 year
3 2a 4 weeks
4 3 168 hours (7 days)
5 4 72 hours (3 days)
6 5 48 hours (2 days)
7 5a 24 hours (1 day)
8 6 Mandatory Bake before use

2. MSL of COSEL product

Power supplies are not semiconductor devices and are therefore generally not subject to MSL classification.

However, some COSEL products—specifically certain PCB-mount models designed for surface-mount applications—are classified as MSL 2.
For further details, please refer to the instruction manual.