IPC-HDBK-001 discusses this beginning on page 97 and ending with a table
on page 98. The digest version is:
80C 18-48 hours
100C 8-16 hours
120C 3.5-7 hours
Maximum storage time after bake out
30%RH 20 days
40%RH 11 days
50%RH 7 days

> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Macko, Joe @ IEC
> Sent: Friday, January 10, 2003 2:20 PM
> To: [log in to unmask]
> Subject: [TN] board bakeout recommendations
>
>
> Fellow Techheads,
>
> I am continually being challenged about the amount of time &
> temperature required to safely remove moisture from
> multilayered FR4 bare boards so they can be safely populated
> and reflowed.  And, the time/temperature required to remove
> moisture from a populated board when a BGA needs to be
> replaced using a hot air rework station such as an AIR-VAC
> DRS24.  I realize that baking out boards at an elevated
> temperature will degrade solderability with time as well as
> age components so ideally boards should not be baked out any
> longer than necessary.
>
> Everyone seems to have a slightly different idea of the time
> vs. temperature required which generally ranges from 4 to 24
> hours at temperatures as low as
> 85 to 125 C.    85C definitely seems to low to me.  IPC/JDEC
> J-STD-033A list
> bakeout times for components depending on thickness which
> seems excessive
> for a circuit board.   I have not found any IPC guidelines for circuit
> boards.
>
> Anyone like to comment on what has worked for them?   Is
> there an industry
> standard out there?   thanks in advanced for the feedback.
>
> joe
>
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