scope:

This classification procedure applies to all non-hermetic SMDs, which, because of absorbed moisture, could be sensitive to damage during solder reflow. The term SMD as used in this document means plastic encapsulated devices and other devices made with moisture-permeable materials designed for surface mount assemblies. The MSL classification levels are intended to be used by SMD producers to inform users (board assembly operations) of the level of moisture sensitivity of their SMDs, and by board assembly operations to ensure that proper handling precautions are applied to moisture/reflow sensitive devices. If no major changes have been made to a previously qualified SMD, this method may be used for reclassification according to 4.3.

This standard cannot address all possible device, board assembly and product design combinations. However, the standard does provide a test method and criteria for commonly used technologies. Where uncommon or specialized devices or technologies are necessary, the development of the MSL rating should include customer and device supplier involvement and the criteria should include an agreed definition of product acceptance.

SMDs classified to a given moisture sensitivity level by using procedures or criteria defined within any previous version of J-STD-020 do not need to be reclassified to the current revision unless a change in classification level or a higher peak classification temperature is desired.

If the procedures in this document are used on packaged devices that are not included in this specification's scope, the failure criteria for such packages must be agreed upon by the device supplier and their end user.

Past evaluations have shown that SMDs that have been classified to a MSL for SnPb eutectic temperatures per this document may be attached using the same MSL for a Vapor Phase reflow process for SnPb eutectic temperatures only. Currently there is no intent to perform similar evaluations for Pb-free temperatures.