Jan 26, 2026 As electronics continue to evolve toward finer features and more advanced packaging, manufacturers face growing challenges in ensuring effective removal of flux residues. A newly released white paper, “Impact of Solder Powder Size on Cleaning Efficiency in Chip Resistor Assemblies for Future Advanced Packaging,” explores how solder powder size directly influences defluxing performance and long-term reliability.
Co-authored by Principal Engineer Ravi Parthasarathy in collaboration with Heraeus, the study investigates residue cleaning efficacy across advanced assemblies, including chip resistors, MLFs, and BGAs, and the impact of solder powder sizes and cleaning process conditions. The research was presented at both the IMAPS Symposium and the Electronics Packaging Technology Conference (EPTC).
Through a series of controlled experiments, the study evaluates aqueous-based defluxing processes under defined conditions, examining variables such as solder powder size, cleaning chemistry selection, conveyor speed, and process concentration. Solder powder sizes T5 (25–15 µm), T6 (15–5 µm), and T7 (11–2 µm) were systematically tested using assemblies containing MLF-68, BGA-208, and resistors of varying sizes.
The findings reveal that finer solder powders contain higher flux activator content, resulting in increased residue accumulation and significantly greater cleaning complexity, particularly under low-standoff components where access is restricted. Visual inspection following standardized defluxing processes confirmed that no single cleaning chemistry or process configuration is universally effective across all powder sizes.
The white paper concludes that one-size-fits-all cleaning approaches are insufficient for advanced semiconductor packaging. Instead, manufacturers must carefully align defluxing chemistry and process parameters with solder powder selection to achieve reliable residue removal and support long-term product performance.
The full white paper is now available for download at https://hubs.la/Q03_6LcR0.
ZESTRON is headquartered in Manassas, Virginia, and operates in over 35 countries. With eight technical centers worldwide and the industry’s most knowledgeable team of engineers focused on high-precision cleaning, ZESTRON’s commitment to ensuring that its customers surpass even the most stringent cleaning requirements is without equal.
For additional information or to tour one of our technical centers, please visit www.zestron.com.
