Effect of Minor Mg on the Various Properties of Sn-Cu Lead-Free Solder Alloys

• Main Authors: Yu-Chang Peng, 彭育彰
• Other Authors: Her-Yueh Huang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/sb7b2b

碩士 === 國立虎尾科技大學 === 材料科學與綠色能源工程研究所 === 100 === The research was focused on the effects of Mg additions to Sn-0.7Cu lead-free solder on the melting point, microstructure, mechanical property, and joint performance. Results of differential scanning calorimeter analysis showed that alloying of Mg to Sn-0.7Cu decreased the melting temperature slightly where the melting temperature was 227.88 °C. The microstructures of Sn-0.7Cu and Sn-0.7Cu-0.01Mg solders could be clearly divided into two regions, it was identified that the dendrite arm was primary β-Sn phase while the interdendritic eutectic was the Cu6Sn5/β-Sn eutectic phase. However, the eutectic regions of ternary eutectic Sn-3Ag-0.5Cu solder were a mixture of fine intermetallic particles of Cu6Sn5 and Ag3Sn in the β-Sn matrix. The wetting property was improved by addition of Mg element into the Sn-0.7Cu solder alloy. The addition of Mg enhanced the elongation of the solders but decreased their tensile strength. The intermetallic compounds thickness gradually increased with the increase of aging time. The tensile strength of the joints decreased with the increase of aging time while the fracture site was moved from solder alloy to intermetallics interface.