SMT007 Magazine

SMT-June2016

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8 SMT Magazine • June 2016 by Stephen Las Marias I-CONNECT007 Solder Paste Exploration The trend towards miniaturization and in- creasing complexity of board assemblies as more functionality is being packed in smaller and smaller electronics devices no doubt continues to be among the critical issues in the electron- ics assembly industry today. Not to mention the ever-shrinking component sizes that are further complicating the manufacturing challenges. To improve the electronics manufacturing process considering the challenges above, we have to drill down to the specific issues that have the greatest impact on the assembly line. And what better way to know these issues than to ask our readers? So for this month's issue of SMT Magazine, we did a survey to find out the biggest factors affecting the electronics assembly process as the industry moves to tighter and tighter tolerances (finer lines and spaces). In our survey, we found out that while the most common line and space widths range from 2 mils to 5 mils, some re- spondents said they are doing boards with line and space widths down to 1 mil. I remember when I was in the university, our electronics shop work included making basic and regulated power supplies, crude FM stereos, and digital clocks. Even then, our class was already having challenges in trying to fit the components in smaller boards to save on cost of copper clads (in case we confused our designs—wherein we used graphite transfer pa- pers—and etched the copper out already) and the overall packaging of the project; and all the while making sure that the circuit would work. I can still imagine the design I did for my digi- tal clock, and the meticulous way I laid out the lines for the circuit. We don't have computer programs to help us with those circuit designs then. But I digress. Back to our survey: Given such tighter toler- ances, respondents say PCBA testing and inspec- tion, and soldering—in particular, solder paste printing—are their greatest challenge when it comes to electronics assembly. This led me to what I would call my "sol- der paste printing exploration." From the manufacturers of solder pastes, to equipment makers, all the way to the solder paste inspec- tion guys—and most importantly the electron- ics assemblers themselves who are using these products—I talked to the "supply chain," so to speak, all the way from Shanghai (during the re- cent NEPCON China 2016 exhibition in April) to our science and technology parks here in the Philippines, to find out what's going on in the solder paste printing process, what factors impact the process, the challenges, and the best practices to consider to be able to address those challenges and improve efficiencies and yield in the SMT line. The users I talked to are Philippine-based EMS firms Integrated Micro-Electronics Inc. (IMI) and EMS Components Assembly Inc. (EM- SCAI). At IMI, I spoke with Joemar Apolinario, Aurelio Bantigue and Rodney Bebe to get their insights on the solder paste printing process given the tighter tolerances and finer pitches in line with the continuing miniaturization trend in the electronics manufacturing industry. We discussed the process challenges, the impact of solder pastes in the printing process, and the criteria for solder paste selection and qualifica- tion. We also talked about design and process strategies to get the best solder paste printing results. E DITOR'S NOTE

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