Moisture Sensitivity Level

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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 (approximately 30°C/60%RH).

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.

The expansion of trapped moisture can result in internal separation (delamination) of the plastic from the die or lead-frame, wire bond damage, die damage, and internal cracks. Most of this damage is not visible on the component surface. In extreme cases, cracks will extend to the component surface. In the most severe cases, the component will bulge and pop. This is known as the "popcorn" effect.

The IPC — Association Connecting Electronic Industries created and released IPC-M-109, Moisture-sensitive Component Standards and Guideline Manual.

Moisture sensitive devices are packaged in an ESD bag with a desiccant and a moisture indicator card which is vacuum sealed.

There are eight levels of moisture sensitivity. Components must be mounted and reflowed within the allowable period of time (floor life out of the bag).

  • MSL 6 - TOL (Time on label)
  • 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
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