What is moisture sensitive level (MSL) testing?
Packages are classified to a given moisture sensitivity level, which determines the proper packaging, storing, and soldering procedure for surface mount devices. Moisture sensitivity testing involves preconditioning test parts in a humidity chamber then subjecting them to solder reflow conditions. There are 8 JEDEC moisture sensitivity levels (level 1, 2, 2a, 3, 4, 5, 5a, and 6) with each MSL having different test conditions, such as temperature, humidity, and exposure time. Test conditions for level 1 are 85°C/85%RH/168 hours, and 85°C/60%RH/168 hours for level 2, for example. Conditioning is then followed by reflow soldering done at 220°C, 235°C, 240°C, 245°C, or 260°C depending on package thickness and solder type. Temperature ramp conditions are called out in the JEDEC specification as well as the number of reflow cycles (typically 3). If a device passes level 1 testing, it is classified as non-moisture sensitive and does not require dry packing. If a device fails level 1 but passe
