Abstract
Recently, Sn-Ag-Cu solders have been widely used as lead-free candidates for the Ball-Grid-Array (BGA) interconnection in the microelectronic packaging industry. However, widely used Sn-Ag-Cu solders such as with 3.0-4.0 wt% Ag in microelectronics exhibit significantly poorer drop test reliability than SnPb solder due to the low ductility of Sn-Ag-Cu solder bulk. The brittle failure of solder joints occurs at intermetallic compound (IMC) layer after drop test. Because the brittle nature of IMC or defects around IMC transfers a stress to the interfaces as a result of the low ductility of solder bulk. For the improvement of the drop test reliability by solder alloys, the low ductility of solder bulk and the IMC control at the interface are needed. In this paper, the bulk property of solder alloys and interfacial reactions with ENIG of Sb-added Sn-Ag-Cu solder were studied and finally, drop test was performed. Low Ag solder such as Sn1.0Ag0.5Cu and Sn1.2Ag0.5Cu0.5Sb showed higher ductility than high Ag solder such as Sn3.0Ag0.5Cu. In the interfacial reaction, all of the solders had (Cu,Ni) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> Sn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> IMCs and P-rich Ni layer, however, Sn1.2Ag0.5Cu0.5Sb solder showed the lowest P-rich Ni layer thickness, because less Ni participated in the formation of (Cu,Ni) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> Sn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> IMCs. In the drop test, the longer lifetime was in order of Sn1.2Ag0.5Cu0.5Sb, Sn1.0Ag0.5Cu, and Sn3.0Ag0.5Cu. Sn1.2Ag0.5Cu0.5Sb solder showed the best drop test reliability compared with other two solders due to the thinnest P-rich Ni layer. The failures of all packages occurred along P-rich Ni layer which is the most brittle phase at the solder/ENIG interface.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
