Issue link: https://iconnect007.uberflip.com/i/1545206
34 SMT007 MAGAZINE I JUNE 2026 2. Dissolution: Once contact is made, the chemistry must effectively solubilize both polar and non-polar residue components. 3. Removal: The dissolved residue must then be transported out from under the compo- nent through spray impingement, immersion, or agitation. Failure at any stage compromises the entire cleaning process. Partial removal often results in residue redistribution instead of elimination, particu- larly in confined geometries. Ionic Residue Removal and Reliability While visible residues may raise cosmetic con- cerns, ionic contamination poses a far greater threat to long-term reliability. Ionic species can initiate cor- rosion, electrochemical migration (ECM), and degra- dation in surface insulation resistance (SIR). Flux, however, is not the sole source of ionic con- tamination. Additional contributors include: • Handling (e.g., salts and oils from skin contact) • Tooling materials such as tapes, gloves, and fixtures • Component-level contamination from prior manufacturing steps Modern analytical techniques, such as ion chromatography, frequently identify a range of ionic species present on production assemblies. Because ionic contaminants are inherently water- soluble, aqueous cleaning agents are particularly effective at removing them, provided that penetra- tion and rinsing are enough. Material Compatibility: Protecting the Assembly Cleaning performance must always be balanced against the risk of material damage. A clean- ing agent that removes residues effectively but degrades components, finishes, or equipment is not a viable solution. At the assembly level, potential risks include corrosion or etching of sensitive metallizations, degradation or removal of component markings, damage to improperly cured labels or coatings, and adverse effects on sensitive components or conformal coatings. At the equipment level, compatibility with seals, gaskets, and other elastomeric materials is equally important. Incompatible materials may swell, crack, or degrade over time, leading to equipment failure and contamination risks. Figure 1: Titration curves illustrating differences in buffering capacity between aqueous cleaning chemistries.