NXP Semiconductors AN10365, Примечание к применению

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AN10365_3 © NXP B.V. 2008. All rights reserved.
Application note Rev. 03 — 22 April 2008 11 of 24
NXP Semiconductors
AN10365
Surface mount reflow soldering description
An MSL corresponds to a certain out-of-bag time (or floor life). If IC packages are
removed from their sealed dry-bags and not soldered within their out-of-bag time, they
must be baked prior to reflow, in order to remove any moisture that might have soaked into
the package. MSLs and temperatures on the package bag labels are to be respected at all
times. Naturally, this also means that IC packages with a critical MSL may not remain on
the placement machine between assembly runs. Nor should partly-assembled boards,
between two reflow steps, be stored longer than indicated by the MSL level.
The IC package floor life, as a function of the MSL, can be found in Table 2 .
Fig 10. Example of MSL information on sticker; note the two MSLs, corresponding to the
two reflow processes
Table 2. Floor life as a function of MSL
MSL Floor life
Time Conditions
1 unlimited
≤
30
°
C/85 % RH
2 1 year
≤
30
°
C/60 % RH
2a 4 weeks
≤
30
°
C/60 % RH
3 168 hours
≤
30
°
C/60 % RH
4 72 hours
≤
30
°
C/60 % RH
5 48 hours
≤
30
°
C/60 % RH
5a 24 hours
≤
30
°
C/60 % RH
6 6 hours
≤
30
°
C/60 % RH
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