What is “Popcorning” During SMT Reflow?
Plastic encapsulated microcircuits absorb atmospheric moisture over time. When passed through a 260°C lead-free reflow oven, trapped moisture rapidly vaporizes into high-pressure steam, cracking the silicon package or delaminating bond wires.
MSL Ratings Breakdown (JEDEC J-STD-020):
- MSL 1: Unlimited floor life at ≤30°C/85% RH (e.g., standard ceramic packages, many passives).
- MSL 2: 1 year floor life at ≤30°C/60% RH.
- MSL 3: 168 hours (7 days) floor life. (Most fine-pitch QFP and BGA packages).
- MSL 4: 72 hours floor life.
- MSL 5 / 5a: 48 hours / 24 hours floor life.
- MSL 6: Mandatory bake before use.
Every reel dispatched from By Technology is shipped in vacuum-sealed moisture-barrier bags with fresh silica desiccant and humidity indicator cards.