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What is the MSL of a PCB

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#73329

What is the MSL of a PCB | 13 January, 2015

Hi All,

I have been trying to find what the MSL level is for a populated and unpopulated PCB.

I realise there will be a difference in moisture sensitivity of the PCB depending on the PCB material.

I am interested in High Tg FR4(Tg>170 degrees Celsius) and regular FR4 materials.

I am trying to see if we can use table 5 on page 14, "Recommended Equivalent Total Floor Life (Days)" to find out how long (at specific humidity and temperature) our populated and unpopulated PCB's can be stored in the open (in PCB cassettes).

There is a committeee looking in to the PCB moisture sensitivity side but no real standards that have come out under IPC 1601 "Board handling and storage".

Thanks!

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#73332

What is the MSL of a PCB | 14 January, 2015

MSL is used for components (and possibly bare pcbs) that are going to go through a reflow oven process in the future. In most cases, populated pcb assemblies will not be going through the reflow oven process again. Therefore, it is not necessary to track MSL for populated pcb assemblies. They can be stored in the open indefinitely.

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