Moisture sensitivity level
Moisture sensitivity level relates to the packaging and handling precautions for some semiconductors. The MSL is an electronic standard for the time period in which a moisture sensitive device can be exposed to ambient room conditions (30 °C/85%RH at Level 1; 30 °C/60%RH at all other levels).
Increasingly, semiconductors have been manufactured in smaller sizes. Components such as thin fine-pitch devices and ball grid arrays could be damaged during SMT reflow when moisture trapped inside the component expands.
- MSL 5A – 24 hours
- MSL 5 – 48 hours
- MSL 4 – 72 hours
- MSL 3 – 168 hours
- MSL 2A – 4 weeks
- MSL 2 – 1 year
- MSL 1 – Unlimited
Practical
MSL-specified parts must be baked before assembly if their exposure has exceeded the rating. Once assembled, MSL is generally no longer a factor.
References
IPC/JEDEC J-STD-020E, Moisture/Reflow Sensitivity Classification for Nonhermetic Surface Mount Devices, December 2014.