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.
Floor Life Pause
Exposure Suspension
Procedural handling controls permit stopping the active floor life timer of exposed moisture-sensitive components by transferring them to low-humidity storage. This temporary halt in cumulative atmospheric exposure time is known as a floor life pause. Placing partially used component reels inside a dry cabinet maintained below ten percent relative humidity prevents further water vapor ingress.
The protocol preserves remaining allowable exposure time without requiring high-temperature thermal baking.
Preservation Mechanics
Moisture diffusion into plastic packaging halts when ambient relative humidity drops below critical equilibrium thresholds. During a floor life pause, the moisture vapor pressure inside the dry storage enclosure matches or falls below the internal moisture pressure of the molding compound. For exposure times under twelve hours, storing components in sub-ten percent relative humidity immediately stops the countdown timer, retaining the remaining allowance.
When exposure exceeds twelve hours, components must remain in dry storage for a duration equivalent to the previous exposure time before the timer resumes. Intelligent material control software records these storage transitions automatically through barcode scanning, ensuring accurate calculation of remaining floor life across multiple production runs.
Re-entry Protocol
Returning components to active feeder lines resumes the accumulated exposure countdown from the exact point of interruption. Executing a valid floor life pause extends total production utility without exceeding safe moisture saturation limits prior to reflow.