Grounding SMT Setup Delays and Attrition Limits in Assembly Agreements
Assembly agreements define line setup boundaries and package specific attrition limits to prevent unexpected downtime surcharges and inventory deficits.
Moisture Sensitive Component Scrap
Exposure Loss
Quality assurance standards classify discarded surface mount devices that exceed permitted ambient atmospheric exposure times without undergoing mandatory baking procedures. Accumulating moisture sensitive component scrap occurs when moisture-sensitive devices absorb ambient humidity beyond specified floor life limits before reflow soldering. Absorbed internal moisture expands rapidly during thermal soldering profiles, causing internal delamination and micro-cracking failures in plastic integrated circuit packages.
Standardized classifications from IPC and JEDEC assign floor life hours based on ambient humidity and temperature ratings.
Environmental Degradation
Surface mount assemblies utilizing humidity-sensitive packages require strict tracking of floor exposure counters from the moment dry bags open. High ambient humidity accelerates internal moisture absorption, reducing available floor life before soldering. When floor life limits expire, components must undergo multi-hour baking cycles in specialized environmental ovens to remove trapped moisture safely.
Devices subjected to repeated baking cycles suffer pin oxidation and carrier tape degradation, rendering them unusable on automated placement lines. Scrap classification occurs when baking limits are exceeded or component pins oxidize beyond solderability standards.
Responsibility Boundary
Scrap classifications apply exclusively to raw, unmounted components affected by ambient atmospheric exposure before entering the reflow oven. Defect tracking shifts to thermal stress failure metrics once populated boards exit the soldering process.