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The continuing trend of miniaturization has brought many challenges to PCB assembly. Amid shrinking component sizes and increasing interconnect densities with smaller and smaller board real estate, manufacturers are facing a myriad of issues in processes such as soldering, cleaning, and inspection, to name a few.
Focusing on the cleaning aspect, Zestron recently held a technical workshop in Alabang, Muntinlupa City in the Philippines to help users address their cleaning challenges amid the advancements in semiconductor device packaging.
First to present was Guan Tatt Yeoh, senior application engineer for Zestron South Asia, who discussed how the standoff height—the clearance between the underside of a soldered SMD and the surface of the board—and geometry of LGA, MLC, LCC, and flip-chip devices are impacting the cleaning process in PCB assemblies.
Yeoh discussed parameters to consider, such as wash temperature and exposure time, types of nozzles, and spray pressure and angles, to optimize the cleaning process to improve the quality and reliability of the boards. He also discussed a case study that involves flip-chip defluxing, and how the cleaning chemistry also helps address cleaning challenges under low standoffs.
Jack Haiyang Nie, marketing director of KEDtech Co. Ltd., presented on the cleaning process in semiconductor device assembly. He focused on the contaminants in the semiconductor packaging process, the cleaning process considerations, and the latest cleaning systems available for ensuring accurate, effective cleaning.
In most cleaning systems and processes, wash bath contamination always accumulates over time, mainly in the form of flux residues. To address this issue, it is important to have an analytic tool to properly monitor and maintain stability in the cleaning process. Yeoh’s next presentation focused on this issue, and highlighted cleaning parameters to monitor and control to ensure a reliable, repeatable and cost-effective cleaning process. He also talked about the differnt bath concentration monitoring methods—the advantages and disadvantages of each—and why automated systems are a way to go to ensure the consistency and stability of the cleaning process.
Now in its second year, the full-day workshop also included a group discussion, with participants presenting specific cleaning challenges and how they were able to solve them.