The Moisture Sensitivity Level (MSL) is a factor that refers to the humidity and the time period to which semiconductor components or chips
may be exposed during storage, transport and assembly. The MSL value is a type of classification used to make a statement about the moisture exposure of electronic components and encapsulated integrated circuits
.MSL, for example MSL-2. There are six numerical MSL values which indicate the exposure duration, the room temperature and the room humidity to which the electronic assemblies may be exposed.