PCB + ASSEMBLY Void percent area as a function of solder pastes. Note the significant difference between pastes, some giving as low as 5 % voids and others 45 %. Source: Indium Corporation 4.5, and Type 5). The results were encouraging. Profile #2 (termed the ‘Void reducing optimized profile’) significantly reduced voiding from 22 % to 8 %, as compared to Profile #1. In addition, the standard deviation of the data was much “tighter” for Profile #2. The 125 μm stencil reduced voiding about 4.5 % as compared to a 100 μm stencil. The difference likely being that the 125 μm stencil provided a slightly better standoff to vent the vapors. Regarding solder paste particle size, the company found that only Type 3 solder powder produced statistically significantly different results as compared to Types 4, 4.5, and 5. The Type 3 solder paste produced about 15 % more voiding. A final experiment was performed in which the effect of different solder paste flux vehicles on voiding was evaluated. Three PCBs, with 12 QFNs each, were used for each solder paste, for a total of 36 QFNs per paste. The results were striking. Some pastes produced only about 5 % voids, while others produced as much as 45 %. These results were not only surprising, but also very encouraging. solder pastes have now been developed that essentially eliminate voiding. productronica, Booth A4.214 www.indium.com This was created in a collaboration, with: Chris Nash, Product Manager PCB Assembly Materials, Indium Corporation Ron Lasky, PhD, PE, Senior Technologist, Professor of Engineering/Director of the Cook Engineering Design Center, Dartmouth College, and Andreas Karch, Regional Technical Manager – Germany, Austria and Switzerland, Indium Corporation Zusammenfassung Der Artikel zeigt neue Verfahren bei Low-Standoff-Bauteile während dem Reflowlöten zur Reduzierung von Voiding auf. Dazu wurden Untersuchungen zur Bestimmung der kritischen Variablen für die Minimierung von Voids durchgeführt. Die Ergebnisse waren nicht nur verblüffend sondern auch anspornend. Denn nun sind Lotpasten verfügbar, die Voiding deutlich minimieren. Résumé L’article présente de nouvelles procédures pour les éléments de bas niveau lors du soudage par refusion pour réduire des soufflures. À cette fin, des recherches ont été menées pour déterminer les variables critiques pour la minimisation de soufflures. Les résultats n’étaient pas seulement surprenants mais aussi inspirants. Pour le moment, les pâtes à souder aident à réduire considérablement des formations de soufflures. Резюме В статье рассматриваются новые методы, применяемые при пайке оплавлением компонентов с малым зазором между корпусом микросхемы и печатной платой (stand-off) с целью уменьшения образования пустот. Для этого были проведены исследования, целью которых было определение критических переменных процесса минимизации пустот. Результаты превзошли все ожидания и подстегнули интерес к дальнейшим исследованиям. Теперь доступны паяльные пасты, значительно снижающие образование пустот. 56 EPP EUROPE November 2017
PCB + ASSEMBLY PRODUCT UPDATES Board handling and material management Seho North America, Inc. has recently focused on the Select- Line-C selective soldering system in an automated production line together with different modules from the company’s streamline product line. The company believes that their customers profit from complete solutions. With the aim of making production processes more efficient, the company completely automates production lines for board handling and material management, particularly in through-hole processes. Workplaces for assembly of electronic components, buffer and paternoster stations, turn stations, automatic lifts, and, of course, The company assists customers with creative ideas during planning and construction, and also manufactures, assembles and installs the production line. This not only improves the overall workflow but also reduces manufacturing costs. The streamline product line includes a batch loader system and a lift station, that are both linked with the lines’ soldering system. The line also features a modular design, which allows for the integration of additional processes, such as selective brushing or automated optical inspection. Particular highlights for the soldering area are the Synchro software feature that can double the The SelectLine-C includes a batch loader system and a lift station. Source: Seho North America CONTACT TECHNOLOGIES AT THE HIGHEST LEVEL the completely automated conveyor units in between are only a few examples. Moreover, the company implements manual, semi-automatic, and automatic workplaces for the final assembly of products and subsequent testing procedures, either in individual production islands, or in interconnection with the entire production process. production volume without major investments, and the automatic ultrasonic cleaning of solder nozzles, that guarantees maximum machine availability and a nozzle service life up to several months. productronica, Booth A4.578 www.seho.de PRODUCTRONICA MUNICH 14. - 17. November 2017 Hall A1 | Booth 181 Singapore Downtown, Viprobe® Card and Coaxial Probes. Best Contacts Worldwide. EPP EUROPE November 2017 57
