With fine pitch assemblies, the accuracy and repeatability of the pick & place equipment become more critical to achieving an acceptable process yield. In order to establish the requirements for the pick & place accuracy, the self-alignment capability of the components during reflow has to be known. Self-alignment depends on many factors including at least the wetting force of the solder, the ratio of component weight versus soldering area and the surface tension of the solder. 

This article originally appeared in Global SMT & Packaging magazine 6.6 - June/July 2006.

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Dongkai Shangguan received his BS degree in Mechanical Engineering from Tsinghua University, China, Ph.D. degree in Materials from the University of Oxford, U.K., and MBA degree from the San Jose State University. He conducted post-doctoral teaching and research at the University of Cambridge and then at The University of Alabama. He lectured at the Wayne State University as Adjunct Faculty and is currently a guest professor at Shanghai University, China. Dongkai worked for 10 years at Ford Motor Co. / Visteon Corporation as Senior Technical Specialist, Supervisor of Advanced Electronics Manufacturing, and Manager of Supplier Quality, before he joined Flextronics International in 2001 where he is currently Senior Director with the Corporate Technology Group, responsible for advanced assembly technology, environmental technology, design/manufacturing collaboration and DFX, industrialization, etc. Dongkai has published 2 books and about 200 papers (including many journal publications and  several book chapters), and has given numerous technical presentations and keynotes. He has 20 U.S. and international patents issued and a number of U.S. and international patents pending. Dongkai is a senior member of IEEE and SME, and a member of the IEEE CPMT Society Board of Governors. He actively participates in professional organizations and consortia, and has chaired technical sessions and panels at numerous conferences. He is currently a regular columnist for the ‘Global SMT & Packaging’ magazine, and serves on the editorial/advisory board of several technical journals. Dongkai has received a number of recognitions for his contributions to the industry, including the ‘President’s Award’ from IPC, ‘Total Excellence in Electronics Manufacturing Award’ from the Society of Manufacturing Engineers (SME), and the ‘Soldertec Lead-Free Soldering Award’. He is listed in ‘American Men & Women of Science’ and ‘Who’s Who in America’.

Keywords : component self-alignment, lead-free, accuracy, repeatability, placement, pick & place, fine pitch

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