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JULY 2018 I SMT007 MAGAZINE 49 times over 250°C. This is the step that has the most influence on the quality of the final product. Active flux residues are chief among processing residues and come from a lot of indi- vidual soldering processes. When using water soluble fluxes, any residue left behind will be conductive and corrosive. It isn't as easy to determine the ionic activity level when using a no-clean flux. By design, no-clean flux residue is left behind and assumed to be near benign after thermal excursion, but that's not always the case. Throw in the heavily requested aque- ous cleaning of no-clean flux and you have yet another contributor of contamination. The thinking behind the request to clean is well intentioned, but without knowledge of how no-clean fluxes work, the request can prove detrimental to quality. The reason behind this is when the cleaning process isn't 100% effective, the protective outer shell is removed and material that was intended to be bound will instead be exposed and easily absorb moisture. Think of it as ripping off the bandage and leaving the wound exposed to the elements. So far, the information I have given only scratches the surface when discussing process residues, and I haven't discussed testing options at all. There are lots of choices to be made when building a PCBA, and within each of those choices, there are a lot of ways to do it wrong. In the end, the idea behind this column is to learn from others' mistakes. It's a whole lot less expensive. SMT007 by Dan Thau MILLENNIUM CIRCUITS LTD In today's highly competitive environment, global sourcing is no longer a competitive strategy; it is a stan- dard practice. Understanding what it takes to truly do this successfully separates the industry leaders from the pretenders. When the "Asian shift" in PCBs really began to take hold a few decades ago, it began with Japan, which was soon replaced by Taiwan, which was finally replaced by China. As this dynamic continues, one thing is certain: This international sourcing evolution will continue. To stay in the game, companies need to develop a global sourcing strategy to remain relevant and sustainable. The challenges of developing a robust domestic PCB supply chain is daunting enough but moving onto the international stage presents a whole new degree of diffi- culty that most companies are not equipped to manage. Typically, only the biggest companies have the resources to do this on their own. Identifying potential global suppliers, traveling to audit the suppliers, and the ongo- ing supplier management is not only cost prohibitive for smaller organizations, but they usually don't have the expertise to manage this in-house. This is where the value of selecting a global sourcing partner becomes crystal clear. Read the full article here. The Value of a Global Sourcing Partner

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