Issue link: https://iconnect007.uberflip.com/i/1489269
64 SMT007 MAGAZINE I JANUARY 2023 work with José to identify four people who, with the proper training, had the potential to become fully-fledged process engineers. Andy would oversee developing and executing that training. Eventually, these engineers would have the capability to set up lines for new jobs and, essentially, run the factory if José was not there. Sue decided that she would help Carlos develop a plan to address the defects identified in the Pareto chart the two of them had made together (Figure 1). Once everyone was clear on their tasks, Sue met with Carlos. "Carlos, we've identified graping as the most common defect," Sue said. "Who would be the best person to discuss this with?" Carlos answered that she should meet with Miguel San- tos, so together they found Miguel at his desk. "How can I help?" Miguel asked, once every- one had introduced themselves. Sue explained that she and Carlos had iden- tified graping as the company's biggest quality issue, and she wanted to discuss how to mini- mize it (Figure 2). "Sue, can you explain how graping happens?" Miguel asked. "Sure," she said. "Graping occurs when the oxygen barrier in the solder paste is exhausted. is situation can occur for a few different reasons. e major reason for graping is that the printed solder paste deposit is too small. Because the deposit is so small, it has too much surface area-to-volume ratio, which exhausts the oxygen barrier materials in the flux— meaning they can no longer protect the sol- der particles from oxidation. Once solder par- ticles oxidize, graping can occur. Graping usu- ally occurs on solder joints that were printed Figure 1: A Pareto Chart of the defects at Castellanos Electronics. Figure 2: An artist's conception of graping.