What are Xilinx's guarantees on long-term storage of devices in plastic packages?
Xilinx cannot give any guarantees on long-term storage of plastic packages as this is more the customer's responsibility. Here are some motivating reasons justifying Xilinx's position:
1. Long-term storage means storing devices for 5 years and longer.
2. Possibilities for needing long-term storage include:
-- Having established products which require components that are no longer manufactured by Xilinx.
-- Manufacturers (OEMs) offering extended warranties to end customers. Some are legally bound to make available replacement parts for up to 10 years after end of life of the original product (e.g., automotive industry).
3. Using MBBs guarantees safe solderability for up to only 1 year. Although MBBs are sealed, they will still absorb moisture from the environment at a slow, but measurable, rate. This is as indicated by the HIC in the MBB.
4. For storage over 1 year, it is recommended that the customer:
-- Inspect MBBs for signs of damage before storing.
-- Store in low humidity area (i.e., dry nitrogen environment).
-- Inspect humidity indicator controls periodically and refresh desiccant in all bags and re-seal them when required.
5. So, the long-term storage strategy Xilinx suggests is:
-- Pre-bake ALL devices to remove moisture before soldering.
-- Maintain relatively low humidity to protect against corrosion.