Combination of Spray and Soak Improves Cleaning under Bottom Terminations

摘要

The functional reliability of electronic circuits determines the overall reliability of the product in which the final products areused. Market forces including more functionality in smaller components, no-clean lead-free solder technologies, competitiveforces and automated assembly create process challenges. Cleanliness under the bottom terminations must be maintained inharsh environments. Residues under components can attract moisture and lead to leakage currents and the potential forelectrochemical migration.Removing flux residues from under bottom terminations is extremely challenging. As components decrease in size, the Zaxisgap height also reduces. When the Z-axis gap is less than 3 mils (75um), the capillary and wetting action of flux duringreflow underfills the bottom termination component with flux residue. To clean, the cleaning fluid and mechanical actionmust reach, wet and dissolve the soil in order to create a flow channel. Once a flow channel is created, the soils under theterminations are effectively cleaned.The purpose of this research study is to evaluate innovative spray and soak methods for removing low residue flux residuesand thoroughly rinsing under Bottom Termination and Leadless Components. Targeted spray nozzles deliver the cleaningagent to the soil. Following this interaction with an agitated soak allows the flux residues to dissolve. Targeted spray nozzlesrapidly move the dissolved residues and fully clean residues under terminations. This designed experiment will study processparameters in order to draw inferences from the data findings.