» PCB & ASSEMBLY 3.
» PCB & ASSEMBLY 3. With solder paste at 91% fan power and 180° C Component blow-off was observed at 180° C with 91% fan power. As shown in the graph on page 41, the yield point of the solder paste decreases as a function of temperature. In zone 2, in which the knocked over components were discovered, the PCB had a temperature of 67° C. No results for the yield point of the solder paste are available for this temperature. For this reason, the yield point for solder paste 3 is extrapolated from the graph based on the assumption of a linear characteristic curve. The yield point is 162 N/m² and the resulting yield force is 43.74 µN. This is smaller than the simulated force of 65 µN, and the component is blown off. Considerable deviation of these forces can be attributed to the lack of yield point data at higher temperatures. Zusammenfassung Der erste Teil des Whitepapers zeigte auf, wie die Untersuchung zur Bestimmung des Einflusses der Vorlauftemperatur auf wegfliegende SOD323-Bauteile durchgeführt wurde. In diesem zweiten Teil werden die Testergebnisse untersucht und die besten Methoden aufgezeigt, um eine zuverlässige Verarbeitung dieser Bauteile zu gewährleisten. Résumé La première partie du livre blanc détaille le protocole des recherches autour de la détermination de l’influence de la température du flux sur les pièces SOD323 projetées. Cette seconde partie expose les résultats des tests et les meilleures méthodes pour garantir une préparation fiable de ce composant. Резюме В первой части технического описания было показано, как проводилось исследование для определения влияния температуры подаваемого теплоносителя на отлетающие в сторону компоненты SOD323. В этой второй части рассматриваются результаты испытаний и показаны наилучшие методы, гарантирующие надежную обработку этих компонентов. Schematic representation of shear stress on the solder paste due to wind force Summary The investigation results presented here show that the SOD323 can be reliably processed by selecting appropriate solder and using the right oven settings. The default setting, i.e. 73% fan power, provides a sufficient safety margin relative to determined limit loads at 91% fan power. For some PCBs, for example with very large coils or pin-in-paste technology, frequencies and thus fan power as well must be increased in order to intensify heat transfer into the PCB. It’s advisable to check these PCBs for the presence of flow-sensitive SOD323s and, if necessary, to run a test with an assembled PCB if the frequencies need to be increased. If fluctuations occur for other parameters like connection surface tolerances or solder paste properties, different relationships must be reckoned with. For example, the tolerance-related reduction of the connection surface area to 0.25 x 0.3 mm, instead of the typical 0.3 x 0.45 mm, causes a yield force reduction to 40.9 µN. As a result, the component can no longer withstand the ascertained blowing force of 71.3 µN. Productronica, Booth A4.335 www.rehm-group.com Check out part one The first part of this white paper was published in our April 2023 issue, and described how the investigation on the influence of flow temperature on SOD323s being blown away was set up and conducted. Source: Rehm Thermal Systems 42 EPP Europe » 11 | 2023
Product Updates « PCB & ASSEMBLY On show at Productronica 2023 Sustainable replacements for discontinued cleaning fluids MicroCare will exhibit its newest product innovations at Productronica 2023 and highlight its sustainable, high-performing replacements for the soon-to-be discontinued 3M Novec specialty cleaning fluids. Due to emerging regulations on PFAS (per-and polyfluoroalkyl substance) manufacturing, 3M will cease manufacturing fluoropolymers, fluorinated fluids, and PFAS-based additive products by the end of 2025, which includes popular Novec variants like 7100, 71DE, 7200, 72DE, 72DA, and 73DE. MicroCare is stepping up to offer outstanding alternatives. These replacement fluids deliver superior performance in removing various soils encountered during manufacturing processes, including oil, grease, particulate, inks, and fingerprints while prioritizing sustainability. Among the portfolio highlights are the Tergo HDF (Heavy Duty Fluid) and Tergo GCF (General Cleaning Fluid). Both solutions have low GWP (Global Warming Potential) and zero ODP (Ozone Depleting Potential) ratings, ensuring compliance with strict environmental regulations. Additionally, their azeotropic properties make them chemically stable and nonflammable in vacuum and vapour degreasers, providing a reliable and safe cleaning process. These fluids are the perfect replacement for products under scrutiny or being discontinued. “Productronica presents an exceptional platform for us to engage directly with industry professionals, enabling us to showcase our cutting-edge cleaning fluids and tools,” said Scott Wells, General Manager. Productronica, Booth A4–101 www.microcare.com Source: MicroCare Due to regulations on PFAS manufacturing, 3M will cease manufacturing fluoropolymers, fluorinated fluids, and PFASbased additive products by the end of 2025 Low-temperature solder (LTS) materials Low temperature ball attachment process solutions Source: Shenmao PF734-S, built upon an improved low-temperature alloy PF734, outperforms conventional low-temperature alloys like 42% Sn and 58% Bi, says the company Shenmao America has introduced a range of low-temperature solder (LTS) materials in response to the growing demand for ultra-thin packages in the electronics industry. The company says its (LTS) materi- als are specially engineered to reduce reflow temperatures, mitigating PCB and substrate deformation, saving energy, reducing thermal stability requirements of substrates and components, and ultimately enhancing yield rates. PF734-S, built upon an improved lowtemperature alloy PF734, outperforms conventional low-temperature alloys like 42 % Sn and 58 % Bi. The low-temperature flux solutions, SMF-80 and SMF- WC63, deliver excellent workability and are formulated with special activators that optimize wettability and solderability. The no-clean flux SMF-80 eliminates the need for post-reflow cleaning while maintaining high reliability and insulation with minimal flux residue. On the other hand, the water-soluble flux SMF- WC63 offers outstanding cleanability, and any flux residue left after reflow can be easily cleaned with water, ensuring exceptional surface cleanliness. www.shenmao.com Productivity. Profitability. We Connect Munich Trade Fair, November 14-17 Hall B4, Booth 119 EPP Europe » 11 | 2023 43
