Effect of Ag content on soldering ability of Sn-Ag-Cu solders

The influences of Ag content on melting temperature and wettability of Sn-xAg-0.5Cu(x=0.3,0.5,0.7,0.9) lead-free solder alloys were studied.The melting temperatures of alloys were compared by DSC(differential scanning calorimetry) curves and the wettability was compared by the area and rate of wetting on Cu substrate.The experimental results indicate that alloys with higher Ag content have lower melting points and melting range,and the content of Ag in solder alloys has a significant impact on the distribution and profile of the DSC curves.However,with the Ag content increasing,the wettability of the alloys degrades.By combining the two key properties of solder alloy,melting temperature and wettability,Sn-0.7Ag-0.5Cu shows higher performance.