Effect of Lead and Cadmium-Free Glasses on Reliability and Microstructural Development of Pb-Free Silver End Termination for MLCC Application

摘要

The Waste from Electrical and Electronic Equipment (WEEE) and Restriction of Hazardous Substances in Electrical and Electronic Equipment (RoHS) directives will require elimination of lead and cadmium from silver end termination for MLCC businesses. Metech Electronic Materials, a division of Lord Corporation has developed a new silver end termination paste based on glass composition that does not contain lead and cadmium to replace its existing lead and cadmium based silver end termination. The discrete chips were terminated employing ESI-Palomar Model 2007 termination equipment and using the newly developed lead and cadmium free silver end termination paste. The paste was dried at 150℃ for 10 minutes and fired at 750℃ for 10 minutes at the peak temperature for all the different part types terminated. As fired ship were tested for high temperature and high humidity IR degradation by steaming the parts. The aged reliability of the steam parts was tested for more than 700 hours. The fired chips were also plated using the standard plating bath for nickel and tin. The plated chips were characterized for physical properties such as land, corner and crown coverage, plating thickness of nickel and tin, mechanical properties like peel strength, electrical properties such as capacitance and dissipation factor, and reliability using highly accelerated life test (HALT), and load-humidity board mount test (BMT). The results obtained for the newly developed lead-free silver termination paste were compared with those of standard Metech lead based silver paste and the commercially available lead and cadmium-free silver termination pastes from competitors in the market. The results obtained for the new lead-free and other silver termination pastes studied along with discussion and conclusions are presented in this paper.