McDry Ultra-Low Humidity Storage Cabinets: IC Package Storage Specified by IPC/JEDEC
Recommendations for IC Package Storage after Opening Moisture-Barrier Bags
As specified by IPC/JEDEC Standard 033D
Storage Method
Workability and Cost
Result
1
Use before floor life ends
The floor life differs according to each IC package. Once an MBB has been opened, it is difficult to use leftover components for the next mounting process before the floor life ends.
Insufficient
2
Storage in dry box
When IC packages are stored in a dry box at 5%RH or lower, the floor life is indefinite permitting storage and use of a quantity of components as needed. Just-in-time mounting is possible.
Unlike repacking and baking, management of man-hours is unnecessary and substantial reduction in costs is possible.
The floor life can be reset in a dry box(10%RH or under). (MS Level 2-3: Resetting possible when the exposure time is within 12 hours.)
The floor life can be reset in a dry box(5%RH or under). (MS Level 4-5,5a: Resetting possible when the exposure time is within 8 hours.)
It is possible to store tape reels that are vulnerable to heat and cannot be baked.
IC packages can be placed in a dry box temporarily when trouble occurs during mounting operation.
Optimal storage and easy operation
3
Repacking
There is a time limit to repacking. For example, NEC Electronics has set 168 hours as the allowable time after repacking for storage of MSDs.
It takes time to check moisture-barrier bags for damage and holes as well as to replace desiccants with fresh ones.
Only 60 minutes are available to reseal after moisture-barrier bags are opened so quick operation is necessary.
Resealing performance may not be completely reliable.
Time consuming
4
Baking
IC packages that have exceeded their floor life must be baked in time for mounting which is a troublesome process.
Baking oxidizes pins deteriorating wettability of solder.
It is a requirement to put baked IC packages on a heat-resistant tray and displacement or pin bending may result.
Tape reels cannot be baked.
Process heavy
Level and Floor Life of IC packages
IPC/JEDEC J-STD-033D (Joint Electron Device Engineering Council)
The floor life of IC packages after removal from moisture-barrier bags is classified into the levels shown below.
Level
Floor life (Moisture absorption life when IC packages are left in factory conditions at < 30℃ and < 60%RH after removal from moisture-barrier bags)
1
No specific floor life in factory conditions < 30℃ and < 85%RH
2
1 year
2a
4 weeks
3
168 hours
4
72 hours
5
48 hours
5a
24 hours
6
Baking is required.
Label on Moisture-Barrier Bags
It is compulsory to indicate the level, floor life and storage temperature after unpacking on the moisture-barrier bags.
