Title :
Evolutions in Microstructure and Property of Sn-Ag-Cu Lead-free Solders with Trace Addition of Magnesium
Author :
Lu, Sheng ; Wang, Baohua ; Chen, Jing
Author_Institution :
Jiangsu Univ. of Sci. & Technol., Zhenjiang
Abstract :
Sn-Ag-Cu-Mg (SACM) lead-free solders based on near eutectic Sn-Ag-Cu alloys were designed and prepared in this work. Experiments were carried out to explore the effect of trace addition of Mg on microstructure, and property. The microstructure observation and phase identification were carried out by means of optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) respectively. The melting characteristic, wettability and thermal stability of SACM solders with 0.1 to 0.7 wt% Mg were evaluated and compared with Sn-4.0Ag-0.5Cu and Sn-0.7Cu solder alloys by differential thermal analysis (DTA), X-ray diffraction (XRD) and microhardness tester. It is found that only the SACM solder with 0.1 wt.% addition of Mg kept the typical microstructure of near eutectic Sn-Ag-Cu. With more than 0.1 wt.% addition of Mg, the eutectic network was coarsened and the fraction of eutectic microstructure decreased. Especially, with 0.7 wt.% Mg, platelet (AgMg)3Sn eutectic phase and bulk-like SnAgCuMg-rich phases emerged in SACM solder. The melting temperature decreased obviously when trace Mg was added into the ternary Sn-Ag-Cu solder alloy systems while the wettability was inferior to those of Sn-4.0Ag-0.5Cu and Sn- 0.7Cu. After aging treatment, the results of XRD and microhardness testing showed that the SACM solders with trace Mg addition demonstrated nearly the same thermostablization as Sn-4.0Ag-0.50Cu..
Keywords :
X-ray chemical analysis; X-ray diffraction; ageing; copper alloys; differential thermal analysis; eutectic alloys; magnesium alloys; materials preparation; microhardness; optical microscopy; scanning electron microscopy; silver alloys; solders; thermal stability; tin alloys; wetting; EDS; SEM; Sn-Ag-Cu-Mg; X-ray diffraction; XRD; aging treatment; differential thermal analysis; energy dispersive X-ray spectroscopy; eutectic alloys; lead-free solders; melting characteristics; microhardness tester; microstructure observation; optical microscopy; phase identification; scanning electron microscopy; thermal stability; wettability; Dispersion; Electron optics; Environmentally friendly manufacturing techniques; Lead; Magnesium; Microstructure; Optical microscopy; Scanning electron microscopy; Testing; X-ray scattering;
Conference_Titel :
Electronics Packaging Technology Conference, 2007. EPTC 2007. 9th
Conference_Location :
Singapore
Print_ISBN :
978-1-4244-1323-2
Electronic_ISBN :
978-1-4244-1323-2
DOI :
10.1109/EPTC.2007.4469835