Delamination Defect
Rapid vaporization of trapped moisture within plastic-encapsulated components during solder reflow can cause severe physical damage to the package. This destructive mechanism, known as SMT reflow popcorning, occurs when internal moisture turns to steam and generates pressure that exceeds the strength of the plastic molding compound. High internal pressure results in cracking or delamination of the component body.
Cracking Mechanism
The defect originates when moisture from the ambient air is absorbed by the porous packaging material of the integrated circuits during storage. During the reflow oven’s heating phase, the temperature rises quickly to melt the solder alloy, causing the absorbed moisture to expand rapidly into steam. This localized pressure builds up at the interface between the silicon die and the plastic encapsulant, forcing them apart.
If the pressure exceeds the structural limits of the package, the encapsulant cracks with an audible sound, creating paths for moisture and contaminants to enter the component during subsequent operation.
Quality Impact
Undetected packaging cracks allow moisture to reach the silicon die over time, leading to corrosion and latent field failures. Preventing SMT reflow popcorning requires strict adherence to dry storage protocols and the monitoring of component floor life before assembly. This protocol maintains the physical integrity of sensitive surface-mount components.
