Moisture Sensitive Devices - Absorption Labels

I've heard of a series of labels that absorb moisture at different rates and/or change appearance when a specific saturation level is reached. If such labels exist and if they could be correlated to the exposure limits of specific moisture sensitivity levels (based on assembly-specific ambient), these labels could be instrumental in the control of moisture sensitive devices (MSDs) in the assembly/reflow process. Currently, we manually log cumulative exposure times, and it's quite tedious. The labels would likely be very similar to those already used by component vendors to indicate moisture barrier bag leaks. I've heard of a company that has used these labels (not for MSD control though), but they are based in Scotland, and my contacts have not been able to provide me with a supplier for the labels. Has anyone heard of such labels; if so, do you know of any sources? Yves Trudell Quality System Engineering Nortel, Wireless Networks Calgary

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