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JUNE 2026 I SMT007 MAGAZINE 37 istries through benchtop exposure and is useful for initial evaluation. Meanwhile, dynamic testing, conducted in actual cleaning equipment, accounts for real-world variables such as pressure, flow, temperature, and exposure time. Dynamic testing offers a more accurate representation of produc- tion performance. Both are essential components of a comprehensive qualification strategy. Reliability Testing and Standards Ultimately, cleaning effectiveness must be validated through reliability testing. Standards such as IPC-J-STD-001 emphasize the need for objective evidence demonstrating that clean- ing processes support long-term performance. Common validation methods include SIR test- ing, electrical performance testing, and histori- cal process data analysis. Supporting standards such as IPC-J-STD-004, IPC-5704, and IPC-CH-65 provide additional guidance on flux classification and cleanliness requirements. Design for Cleaning: Enabling Success Even the most advanced cleaning chemistry cannot compensate for poor design. As assembly geom- etries become more constrained, design decisions increasingly influence cleanability. Challenges are not limited to bottom-terminated components; features such as thick solder masks, poorly placed silkscreen, and continuous copper pours can restrict cleaning access and trap residues. Good practices in designing for cleanability include introducing copper relief beneath com- ponents, optimizing solder mask geometry, and controlling silkscreen placement. Viewing these features in 3D during the design phase is essential to ensuring effective cleaning. Conclusion Selecting an aqueous cleaning agent for highly dense assemblies is a system-level optimization problem. Chemistry, design, process conditions, equipment, and regulatory requirements must all be considered together. When approached holis- tically, cleaning agent selection can significantly improve not only cleanliness but also process stability, product reliability, and long-term manufac- turing success. The choice of cleaning chemistry plays a cen- tral role in mitigating contamination risks. It is not merely a process variable; it is a strategic decision that directly impacts product performance. SMT007 Adam Klett, Ph.D. is director of science at KYZEN Corporation. Figure 3: Example of poor rinsing beneath a low-standoff component.