SMT Moisture Sensitivity Level Classifications and Floor Life Limits
Component floor life compliance requires strict tracking, verified moisture barrier packaging, and controlled bake protocols before surface reflow.
Surface Mount Component Storage
Moisture Protection
An environmental control practice ensures that electronic parts remain in a solderable and functional state while awaiting assembly. Effective surface mount component storage involves maintaining specific humidity and temperature levels to prevent the absorption of water into plastic packages. This discipline is necessary for avoiding the damage that occurs when trapped moisture expands during the heat of reflow.
Oxidation Prevention
Cabinets equipped with desiccant units or nitrogen purge systems create a dry atmosphere that stays well below five percent relative humidity. Maintaining surface mount component storage in this manner halts the moisture absorption clock for sensitive devices. Without these controls, the floor life of a component might expire in as little as 24 hours.
The use of moisture indicator cards inside the storage area provides a visual check of the current conditions. Dry air preserves parts.
Inventory Duration
Protection of lead finishes from corrosion is a secondary benefit of a dry environment. In addition to moisture control, surface mount component storage reduces the rate of intermetallic growth and oxidation on the solderable surfaces. This preservation ensures that the parts achieve high quality wetting when they eventually reach the soldering station.
Proper rotation of stock ensures that the oldest parts are used first to minimize the risks associated with long term storage.