Paul Austen, ECD, explains why information gathering and reflow profile characterization can be wasted practices without the verification step to maintain proper oven operation. Reflow oven profiles can be out of spec due to flux residue build up, belt speed changes, and other small changes that deliver significant alterations to the assembly being processed.
S. Manian Ramkumar, Ph.D., Center for Electronics Manufacturing and Assembly, Rochester Institute of Technology (RIT), discusses recent industry-university collaborative research on PoP, QFN, and mixed lead-free alloy SMT processing.
With many electronics manufacturers still running leaded and lead-free assembly jobs, reflow ovens are tasked to run both solder-type profiles. Hans Bell, Ph.D., of Rehm Thermal Systems, shows how implementing both processes simultaneously with a single reflow soldering system can be approached with leaded and lead-free reflow profiles set up next to each other within a thermal system with two conveyor lanes.
Kevin Gaugler, solder group research and development manager, EFD Inc., a Nordson Company, discusses how component miniaturization, the emergence of complex assembly methods, finer-pitch connections, changes in plating methods, nanometer-scale materials, and the requirements of new electrical generation and distribution technologies, along with environmental directives, have shaped solders and flux formulations. Slight changes to alloy compositions can tailor a soldering process to specific needs.
Greg Goodell, process development technician, A.C.E. Production Technologies, recounts tests done in the company's Selective Soldering Applications Lab. A component had oxidized leads. During process development, the operator found that no matter which flux was selected, or which profile was used, the solder would not wet to the part. Process development for the application was stalled by the solder dewetting. Solderability tests were performed to analyze the wetting curve and determine the cause of wetting failure.