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Handling and Storage within McDry

IC Package Storage Standard
New IPC/JEDEC J-STD-033C (Joint Electron Devices Engineering Council)

5% or 10% RH storage using low-humidity cabinets

The new IPC/JEDEC J-STD-033C standard stipulates that once the moisture barrier bag for an IC package has been opened, the package is to be stored in a low-humidity cabinet at no more than 5% or 10% RH to prevent the absorption of ambient moisture.
However, at sites where IC packages are surface mounted, the cabinet doors are opened frequently to put in and take out devices, allowing ambient humidity into the cabinet and raising its internal humidity. To prevent this and maintain a humidity level of 5% or 10% RH in the cabinet at all times, the cabinet must have an even lower level of humidity.

For this reason, the McDry cabinets are classified into different grades depending on the frequency with which the cabinet is opened at the work site.
IC packages are also classified by JEDEC into 7 levels according to how readily they absorb moisture, namely 5a, 5, 4, 3, 2a, 2 and 1. It is recommended that G1 or G2 cabinet be used for level 5a, 5, 4, and 3 packages, since they most readily absorb moisture.


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