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JUNE 2025 I SMT007 MAGAZINE 61 • Control Level 2A: For low critical appli- cations, where tin whiskers are considered infrequent and acceptable • Control Level 2B: For non-critical appli- cations, where mitigation protocols are in place, including the avoidance of Pb-free tin finishes • Control Level 2C: For critical applica- tions with limited system redundancy, and completely prohibits the use of Pb- free tin finishes For most military and aerospace applica- tions, Control Levels 2B and 2C offer the most comprehensive mitigation strategies to man- age tin whisker risks. A more effective and reli- able solution, particularly for aerospace appli- cations, is robotic hot solder dip (RHSD) pro- cessing. is involves removing 100% of the pure tin plating from component leads and ter- minations, replacing it with a tin-lead alloy, eliminating the risk of tin whisker forma- tion. Robotic hot solder dip processing can be applied to a wide range of components, includ- ing through-hole and surface-mount devices, axial and radial components, connectors, and discrete electronic devices. e RHSD process has several advantages over manual dipping methods for electronic components, particularly in reducing the effects of tin whisker development. It offers greater precision and control over solder appli- cations, ensuring a uniform coating that min- imizes imperfections conducive to whisker growth. It also allows for improved tempera- ture management during soldering, resulting in a consistent intermetallic layer that miti- gates conditions favorable to tin whiskers. By automating the process, human error is sig- nificantly reduced, leading to enhanced qual- ity assurance and lower contamination risks. Furthermore, the RHSD process enables higher throughput while maintaining quality across a vast array of components, making it an optimal choice for applications requiring reliable performance. Conclusion e mitigation of tin whiskers is crucial for ensuring the reliability and longevity of elec- tronic assemblies, especially in critical appli- cations like aerospace. While traditional man- ual dipping methods may appear cost-effec- tive, they oen introduce challenges not pres- ent when performed robotically. For optimal results, manufacturers should utilize an RHSD process because it effectively mitigates tin whiskers, minimizes contamination risk, and ensures consistently high-quality intermetallic bond formation. By employing these advanced solutions, adhering to industry standards, and using the proper equipment, aerospace manufactur- ers can significantly enhance the solderabil- ity and reliability of their components. is leads to more dependable electronic devices and assemblies. As technology develops, con- tinued advancements in mitigation techniques are crucial in addressing the complexities of tin whisker growth. Future columns will delve further into the robotic hot solder dip process, providing insights and best practices to enhance the qual- ity and performance of electronics assembly in high-reliability sectors. SMT007 Nash Bell is president of BEST, Inc. To read past columns, click here. " A more effective and reliable solution, particularly for aerospace applications, is robotic hot solder dip (RHSD) processing. "