Process Control Plan to Monitor Acceptable Levels of Flux and Other Residues

In today’s dense electronic assemblies, flux entrapment under bottom terminated components creates serious risks of electrochemical failures, leakage currents, and dendritic growth. Traditional bulk cleanliness tests like ROSE often miss these site-specific risks, leaving manufacturers exposed to reliability issues. This paper presents a process control methodology built on Surface Insulation Resistance (SIR) testing under temperature-humidity-bias conditions to monitor residues at high-risk component sites. By defining upper and lower control limits with representative test vehicles (QFN-88, QFN-124), manufacturers can establish a “golden process image” that identifies deviations early, ensures processes remain in control, and improves product reliability for IPC Class 3 high-performance electronics. The result: a clear framework for electronics manufacturers to manage contamination risks, validate cleaning processes, and maintain long-term reliability in mission-critical assemblies.