Moisture Sensitivity Levels on PCB – is a guideline needed?

What is the MSL level for a PCB – Jan Pedersen shares his thoughts!

At Elmatica we get from time to time requests from customers to give the MSL level for a list of articles. And, since they come to us, all of them are PCBs. But, basically no one have defined the MSL level for a PCB. There are no standards for it. So what do we do? Just reply there is no such standard? Yes, and No.

Elmatica MSL guide

To meet customers needs and question of how long a PCB can stay in the production environment before a baking, or re-baking, is required, Elmatica we have developed a simple guide that describes the most used PCB technologies and materials. We categorize PCB technologies related to how much the PCB will absorb water over time. Basically the different levels relate to the base material moisture absorption. As shown in the table below we have given each group MSL levels as defined in IPC/JEDEC J-STD-020.

* Baking before thermal processing is required for MSL 5 and 6.** Floor life Conditions for all All MSL levels maximums are 300C at 60%RH. *** Recommended Floor life until baking is required for MSL 6 is important materials with higher moisture absorption such as flexible Polyimide material will need baking after 3 hours, while such rigid materials should be baked after 6 hours.

Shall we create an official document?

Now, where is IPC in the discussion? I have given this suggestion to IPC, but is seems not recognized to be of general interest. Based on larger EMS customers requesting MSL levels from Elmatica I am sure there is a need out there. From my point of view IPC is the correct organisation, but it does not need to be a standard. We could at least start up as a guideline.

So, engineers, production managers of EMS companies: If MSL level of the PCB is interesting and important, we should bring this forward and develop an official guideline. I can lead a group within IPC (or not) But to do that I need support from larger EMS and OEM companies. So, if you read this and want to support it, please give a comment – it is enough to reply “I support this initiative”.