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NOVEMBER 2024 I SMT007 MAGAZINE 61 to generate objective evidence that the assem- bly will not fail when exposed to harsh envi- ronments. e ROSE (resistivity of solvent extract) test, which measures the conductivity of solvent extracts from a circuit assembly, is widely used to assess the level of ionic residues. IPC now requires ionic contamination testing on production assemblies as a process moni- toring protocol. Conclusion As electronic devices operate in increasingly harsh environments, the tolerance for contam- ination on circuit assemblies becomes ever more critical. Humidity, temperature extremes, corrosive gases, and pollutants all contribute to the risk of electrochemical migration, par- ticularly in the presence of ionic residues. In these conditions, even minimal levels of con- tamination can lead to the formation of con- ductive pathways and dendritic growth, result- ing in catastrophic system failures. e reducing tolerance for residues on circuit assemblies requires a multifaceted approach, including advanced cleaning processes, care- ful material selection, and rigorous testing and monitoring. As the demands on electron- ics reliability continue to grow, particularly in safety-critical industries, the ability to manage residue and mitigate the risks of electrochem- ical migration will be paramount to ensuring the long-term performance and reliability of electronic systems. By understanding the interplay between harsh environments and residue tolerance, manufacturers can take proactive steps to safe- guard their products against the risks of ECM and maintain their competitive edge in a rap- idly evolving industry. SMT007 Mike Konrad is founder and CEO of Aqueous Technologies, and vice president of communi- cations for SMTA. To read past columns, click here. By Beth Turner MacDermid Alpha Electronics Solutions Chapter 4: Sustainability I like to think that anyone con- sidering using encapsulation res- ins to ruggedize electronics is contributing in some way towards sustainability targets. The thing all ruggedizing materials have in common is that they work to extend the lifetime and improve performance; surely that ensures fewer defects, fewer recalls and ultimately less waste? When it comes to encapsulation resins, we can do better than that, and the future looks both optimistic and exciting. Bio-based Supply Chain Many of the traditional raw material feedstocks for encapsulation resins rely on the use of fossil fuels. Today, there are a plethora of opportunities within this supply chain to source bio-based raw materials. Bio-based materials are completely or partially derived from living organisms, for example crops. As they come from renewable resources, bio-based products can help reduce CO 2 emis- sions and offer other advantages such as lower toxicity. Ultimately, reducing supply chain reli- ance from fossil fuels towards bio-based renew- able feedstocks could be one way of helping to reduce the impact of climate change. It is possi- ble, and easy, to procure bio-based epoxy res- ins, modifiers, and cure agents. There are a huge number of opportunities to source bio-based poly- ols, crosslinkers, as well as modifiers. The emer- gence of bio-based additives for use with these cross-linking chemistries is also on the rise. Com- panies often use regulated certification systems to ensure sustainability within the supply chain; one example is the ISCC plus certification scheme that aims to prove no deforestation has occurred to produce the biomaterial. From my experience, there is a general concern that bio-based materials must have some compro- mise when it comes to performance. Continue reading... BOOK EXCERPT: The Printed Circuit Assembler's Guide to... Encapsulating Sustainability for Electronics, Chapter 4