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SEPTEMBER 2025 I SMT007 MAGAZINE 61 ing optimisation necessitates the selection of which application method suits the product best (ultrasonic spray or the more precise drop-jet precision drop- let dispenser), pathing of the fluxer for speed of application, and the selection of flux itself. Flux selection involves balancing activity, solids content, and pres- ence of halides, dependent upon product requirements. Post-pro- cess cleaning and the risks of electrochemical migration must be considered to extend the life- time of the product. When considering preheating, the copper content of the PCB and the thermal capacities of the components and their temper- ature limits must be balanced. The board and its components should reach the target temper- ature (to achieve flux activation and ensure proper solder wet- ting) within the required cycle time without damage. Using closed-loop control with a pyro- meter allows for monitoring the surface temperatures of sensi- tive components. Soldering itself involves pro- gramming bath positions and vectoring to quickly join compo- nents without damaging them. The choice of solder is another point for optimisation; the liquid and solid properties must be explored for proper control during deposition, wetting to the component, and final joint strength. The performance of low-temperature solders is advancing quickly, but their operating environment must be considered, and we must ask whether they meet the thermal and mechanical requirements. Lower-cost manufacturing does not justify failures in the field due to poorly chosen materials. Conclusion Sustainability presents rich oppor- tunities for the electronics industry. As adaption drivers increase, there will undoubtedly be challenges, but industry collaboration will increase our toolset for adapting to changes. Manufacturing processes such as selective soldering are tunable to allow for more sustainable joining of components to PCBs. SMT007 Dr. Samuel J. McMaster is currently working as a Research and Development Specialist at Pillarhouse International and as a Visiting Academic at Coventry University. He recently developed a patented longer life selective soldering nozzle.