naa a22 4500 510803954 CHVBK 20180411083408.0 cr unu---uuuuu 180411e20130401xx s 000 0 eng 10.1007/s11664-012-2389-7 doi (NATIONALLICENCE)springer-10.1007/s11664-012-2389-7 Effect of Ag on the Microstructure of Sn-8.5Zn- x Ag-0.01Al-0.1Ga Solders Under High-Temperature and High-Humidity Conditions [Elektronische Daten] [T. Yeh, K. Lin, U. Mohanty] The effect of Ag on the microstructure and thermal behavior of Sn-Zn and Sn-8.5Zn-xAg-0.01Al-0.1Ga solders (x from 0.1wt.% to 1wt.%) under high-temperature/relative humidity conditions (85°C/85% RH) for various exposure times was investigated. Scanning electron microscopy (SEM) studies revealed that, in all the investigated solders, the primary α-Zn phases were surrounded by eutectic β-Sn/α-Zn phases, in which fine Zn platelets were dispersed in the β-Sn matrix. SEM micrographs revealed that increase of the Ag content to 1wt.% resulted in coarsening of the dendritic plates and diminished the Sn-9Zn eutectic phase in the microstructure. Differential scanning calorimetry (DSC) studies revealed that the melting temperature of Sn-8.5Zn-xAg-0.01Al-0.1Ga solder decreased from 199.6°C to 199.2°C with increase of the Ag content in the solder alloy. Both ZnO and SnO2 along with Ag-Zn intermetallic compound (IMC) were formed on the surface when Sn-8.5Zn-0.5Ag-0.01Al-0.1Ga solder was exposed to high-temperature/high-humidity conditions (85°C/85% RH) for 100h. The thickness of the ZnO phase increased as the Ag content and exposure time were increased. Sn whiskers of various shapes and lengths varying from 2μm to 5μm were extruded from the surface when the investigated five-element solder with Ag content varying from 0.5wt.% to 1wt.% was exposed to similar temperature/humidity conditions for 250h. The length and density of the whiskers increased with further increase of the exposure time to 500h and the Ag content in the solder to 1wt.%. The Sn whisker growth was driven by the compressive stress in the solder, which was generated due to the volume expansion caused by ZnO and Ag-Zn intermetallic compound formation at the grain boundaries of Sn. TMS, 2013 Lead-free solder nationallicence intermetallic compound nationallicence microstructure nationallicence Sn-Zn-Ag-Al-Ga nationallicence temperature and humidity exposure nationallicence Yeh T. Department of Materials Science and Engineering, National Cheng Kung University, 701, Tainan, Taiwan, ROC aut Lin K. Department of Materials Science and Engineering, National Cheng Kung University, 701, Tainan, Taiwan, ROC aut Mohanty U. Department of Materials Science and Engineering, National Cheng Kung University, 701, Tainan, Taiwan, ROC aut Journal of Electronic Materials Springer US; http://www.springer-ny.com 42/4(2013-04-01), 616-627 0361-5235 42:4<616 2013 42 11664 https://doi.org/10.1007/s11664-012-2389-7 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11664-012-2389-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Yeh T. Department of Materials Science and Engineering, National Cheng Kung University, 701, Tainan, Taiwan, ROC aut NATIONALLICENCE 700 1- Lin K. Department of Materials Science and Engineering, National Cheng Kung University, 701, Tainan, Taiwan, ROC aut NATIONALLICENCE 700 1- Mohanty U. Department of Materials Science and Engineering, National Cheng Kung University, 701, Tainan, Taiwan, ROC aut NATIONALLICENCE 773 0- Journal of Electronic Materials Springer US; http://www.springer-ny.com 42/4(2013-04-01), 616-627 0361-5235 42:4<616 2013 42 11664 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer