Issue link: https://iconnect007.uberflip.com/i/1140547
82 DESIGN007 MAGAZINE I JULY 2019 The microprocessor LGA package was at- tached to the printed substrate using the Sn42/ Bi57.6/Ag0.4 low-temperature solder reflow process with a peak temperature at 155 o C. Fig- ure 13 shows a printed substrate with the LGA package attached. Further work is underway to evaluate the quality of the solder joints and further optimize the attach process. Summary and Conclusions Development of a flexible hybrid system was presented in this article. A two-layer intercon- nect structure was developed to accommodate the high-density, fine-pitch routing for the mi- croprocessor package, through screen printing of conductive ink and filled microvias. Differ- ent approaches to attach the components to the printed substrates are being explored. Ini- tial feasibility of using low temperature solder Sn42/Bi57.6/Ag0.4 was demonstrated to sol- der the LGA packages to the substrates printed with solderable ink. Further development and evaluation are underway. FLEX007 Acknowledgments The authors would like to acknowledge the contributions from Robert Penning, Dr. Jie Lian and Dr. Francoise Sarrazin of the com- pany Advanced Manufacturing Engineering (AME) Lab, and Lipika Bhattacharya, Glenn Henriquez, Hien Tran, Arnold Andreas, Bruce Thompson, and Raj Dhesikan of the company Innovation Lab. References 1. E. Forsythe, B.J. Leever, "NextFlex: Flexible Hybrid Electronics Manufacturing," Defense AT&L, pp. 32–36, September–October 2016. This paper was first presented at the IPC APEX EXPO 2019 Technical Conference and published in the 2019 Technical Conference Proceedings. Weifeng Liu, Ph.D., is engineering manag- er, Advanced Manufacturing Engineering Group, Flex, Milpitas, California. William Uy is program manager, Advanced Manufacturing Engineering Group, Flex, Milpitas, California. Dennis Willie is director of engineering, Advanced Manufacturing Engineering Group, Flex, Milpitas, California. Dongkai Shangguan, Ph.D., is vice president , Flex, Milpitas, California. Alex Chan is no longer with the company. Figure 12: Printed substrate: (a) top side, (b) bottom side. Figure 13: Printed substrate with components attached using low-temperature soldering process.