Unpackaged Die and Wafer Storage

Proper storage conditions are necessary to prevent product contamination and/or degradation after shipment from National Semiconductor Corp. The following guidance is provided to insure the quality and reliability of our product after storage.

• Unsawn wafers and singulated die can be stored for up to 12 months in the original sealed packaging when maintained at room temperature with a controlled environment of 45% +/- 15% relative humidity (RH).
• Unsawn wafers and singulated die that have been opened can be stored for up to 30 days when returned to their containers and placed in a nitrogen (N) purged cabinet and maintained at room temperature with a controlled environment of 45% +/- 15% relative humidity (RH).
• To reduce the risk of contamination or degradation, it is recommended that product not being used in the assembly process be returned to their original containers and resealed with a vacuum seal process.
• Sawn wafers on a film frame are intended for immediate use and have a limited shelf life. This is primarily due to the nature of the adhesive tape used for mounting the product. This product can be stored for up to 6 months. This applies whether or not the material has remained in its original sealed container.
• Die in Surf Tape® type carrier tape are intended for immediate use and have a limited shelf life. This is primarily due to the nature of the adhesive tape used to hold the product in the carrier tape cavity. This product can be stored for up to 6 months. This applies whether or not the material has remained in its original sealed container.

Die Product packaging and the various shipping options utilized by National Semiconductor have been selected based on their ability to protect die and wafers during transit. In selecting these options we have considered the cost of use, level of automation, die orientation requirements, contamination potential, processing ease, multiple supplier commonality, equipment interface capability, inventory and storage control, resealibility and mechanical protection.

In all cases, the customer must determine the applicability of extended storage durations, the storage media and conditions with respect to their own assembly process and end product criteria.