AVR-Chat

On Fri, Mar 15, 2013 at 12:01 PM, Steven Hodge <steve@terrafirma.us> wrote:
>
>
>
> I realize this is off-AVR topic, but why the sudden(?) proliferation of
> putting parts in moisture-sealed packaging (e.g., by Digi-Key and Mouser),
> when they were previously not so packaged? Must the accompanying Threat of
> Dire Doom be taken seriously if limits are exceeded? Why does it seem
> limited to just SMT devices and not DIP?

Don't know why things have change, other than perhaps a better
awareness of the issue.

What you want to find is the MSL rating in the datasheet for your
respective part.

http://en.wikipedia.org/wiki/Moisture_Sensitivity_Level

MSL 6 - Mandatory Bake before use
MSL 5A - 24 hours
MSL 5 - 48 hours
MSL 4 - 72 hours
MSL 3 - 168 hours
MSL 2A - 4 weeks
MSL 2 - 1 year
MSL 1 - Unlimited

In some cases the MSL is not in the datasheet but in some secondary
file related to packages and/or quality reports.
Some manufacturer report it as the empty package so they don't put it
in a part datasheet, and you have to dig for it.


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