Moisture Control Storage for Wafer & Die
Semiconductor wafers and die are not inherently moisture sensitive. However, wire bond pads are quite sensitive and any presences of moisture may accelerate failure, such as bonding issues and delamination, which may only be discovered during product packaging. KGD (known good die) parts are typically shipped in tape and reels packaging which cannot be baked to remove moisture.
The best preventive measure is to maintain optimal controlled storage environments to prevent any failures. When in storage, die and wafers, should be stored die banks with temperature between 18°C and 24°C and relative humidity of less than 30%.
- Vacuum sealed packaging are not recommended for the long term and should be considered temporary transport packing to avoid moisture absorption and other contamination.
- Storing wafers and dies below <10%RH can result in build-up of electrostatic fields, storing over <40%RH will result in condensation and moisture ingress.
- Typically, storage in nitrogen cabinets are recommended, however, the long term cost with N2 storage is quite high.
- Desiccants could cause mechanical abrasion of particulates and the effectiveness may become harmful in the long term if excessive moisture is present.
Eureka Dry Tech’s Fast Super Dryer offers the same moisture & humidity controlled storage options with fast recovery times without using costly nitrogen (N2) purging. However, if customer has specific requirements N2 purging is available as an option.
IC Devices, Packages and Components
All semiconductor devices are susceptible to damage or degradation during storage and handling. Non-hermetic, plastic-encapsulated surface-mount devices are particularly sensitive to moisture-induced stress during printed wiring board assembly.
IPC/JEDEC J-STD-033 provides guidelines for various moistures sensitivity levels (MSL) and allowable exposure time to specific ambient temperature and moisture levels before baking is required.
- When opened packages or lots are used, the remaining devices should be resealed or placed in a dry box at no more than 10% RH within one hour of bag opening.
- If the exposure to ambient environment exceeds the allowable time, the devices must be baked before mounting. However, baking will cause oxidation and intermetallic growth causing solderability issues.
Eureka's dry cabinet utilizes powerful multi-porous molecular sieve desiccants which will provide alternative drying methods to baking oven and reduce oxidation problems caused by heating cycles.
Eureka recommends our series for storage of wafers and die banks to maximize shelf life. today for further information about our Fast Super Dryer or inquire about how to become an agent, distributor or dealer.