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66 SMT Magazine • December 2017 window covered conveyors, and strategically lo- cating ionized air blowers along the path from bare panel to reflow. Method Printing parameters such as pressure, speed, separation, etc., are programmable and stan- dard recipes are called up and loaded at job set- up. Ensure tight management of parameters and recipes, so they remain constant from batch to batch, and are not left to random trials in reac- tion to process outputs. Yet, many job set-up elements rely on man- ual interventions: mounting stencil, squeegee, and board support, dispensing paste (unless au- to-dispense is used), cleaning stencils, squee- gee, process carriers, and equipment, etc. Thor- oughly document procedures for each step and only allow formally trained people to operate the process. Perhaps the most important, yet most com- plex "manual" operation is the response to SPI alarms: are calls allowed to be interpreted as "false" and overrun? Are there different catego- ries of "true" calls and different panel disposi- tion for each? What are the criteria to stop and fix (call technical support)? Manpower Sound methods, procedures, and training re- main theory, subject to mishaps in each execu- tion. Minimize deviation by error-proofing the methods: visual indicators, templates, sensors, alarms, etc. Schedule short and frequent audits by peers and management. Include serialization and traceable records so causes of deviations can be investigated. Communicate methodical- ly with your operators, providing feedback on problems, their cause, their fix, and means of prevention, so lessons learned are shared and engage your entire organization in a constant learning process. Conclusion Narrowing the distribution of solder paste volume benefits product quality, reliability, and cost. Several process inputs impact the dis- tribution and are reviewed following the 6M classification. Process, equipment, and human factors are included, with guidelines for best practices. SMT Alain Breton is the director of operations at C-MAC Microcrocircuits ULC. Marco Lajoie is a business development manager at C-MAC Microcrocircuits ULC. SOLDER PRINTING PROCESS INPUTS IMPACTING DISTRIBUTION OF PASTE VOLUME Jerry Sidone, product manager for the en- gineered materials at Alpha Assembly So- lutions, speaks with I-Connect007 Manag- ing Editor Patty Goldman about the voiding challenge, especially with bottom terminat- ed components, and how solder technolo- gies from Alpha are helping PCB assemblers address this issue. Read the full interview here. Solder Preforms 101: Ask the Expert

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