本研究主要探討添加鎂對Sn-3Ag-0.5Cu-4Ti活性無鉛銲錫之鹽水腐蝕行為的影響。在Sn-3Ag-0.5Cu無鉛銲錫中添加4 wt.% 鈦及1 wt.%鎂可使固相線與液相線分別由218.4°C及221.8°C降至215.3°C及216.7°C。隨著添加4 wt.%鈦、1 wt.%鎂及0.1 wt.%混合稀土元素(Re)於Sn-3Ag-0.5Cu銲錫合金中，Sn-3Ag-0.5Cu-4Ti-1Mg-0.1Re合金電阻及硬度值均微幅增加，片電阻值約0.0244Ω/□，而硬度值約22.46Hv。同時添加4 wt.% 鈦、1 wt.% 鎂及0.1wt.%稀土元素之Sn-3Ag-0.5Cu-4Ti-1Mg-0.1Re合金在25°C 之3.5wt%NaCl水溶液中具有最高的腐蝕電位-859.7mV。Sn-3Ag-0.5Cu-4Ti-1Mg及Sn-3Ag-0.5Cu-1Mg-0.1Re合金之腐蝕電位分別-1227.2mV及-1245.5mV。腐蝕電流密度Sn-3Ag-0.5Cu-4Ti-1Mg-0.1Re、Sn-3Ag-0.5Cu-4Ti-1Mg及Sn-3Ag-0.5Cu-1Mg-0.1Re分別為1.02x10-6A/cm2、3.72 x10-6A/cm2及1.38 x10-6A/cm2。顯示Sn-3Ag-0.5Cu-4Ti-1Mg-0.1Re具最佳的耐蝕性，由金相顯微組織觀察亦具最小的反應層厚度12.96μm。幾種添加鎂之活性無鉛銲錫合金經電化學極化後其反應生成物主要為SnO、SnO2、及Sn3O(OH)2Cl2。

The effect of magnesium on the corrosion behavior of Sn-3.0Ag-0.5Cu-4Ti active solder alloys was investigated in NaCl solution. The addition of 4 wt.% Ti and 1 wt.% Mg in Sn-3Ag-0.5Cu lead free solder decreased both solidus and liquids from 218.4°C and 221.8°C to 215.3°C and 216.7°C, respectively. The addition of 4 wt.% Ti, 1 wt.% Mg and 0.1 wt.% mixed rare earth element (Re) in Sn-3Ag-0.5Cu solder alloy significantly increased both resistance and hardness. The sheet resistance and hardness of Sn-3Ag-0.5Cu-4Ti-1Mg-0.1Re alloy were 0.0244Ω/□ and 22.46Hv, respectively. Polarization studies indicated that the Sn-3Ag-0.5Cu-4Ti-1Mg-0.1Re alloy with 4 wt.% Ti, 1wt.% Mg and 0.1 wt.% mixed rare earth element (Re) had the highest corrosion potential -859.7mV in 3.5 wt.% NaCl solution at 25°C. The corrosion potentials of Sn-3Ag-0.5Cu-4Ti-1Mg and Sn-3Ag-0.5Cu-1Mg-0.1Re were -1227.2mV and -1245.5mV, respectively. The corrosion current densities of Sn-3Ag-0.5Cu-4Ti-1Mg-0.1Re, Sn-3Ag-0.5Cu-4Ti-1Mg and Sn-3Ag-0.5Cu-1Mg-0.1Re were 1.02x10-6A/cm2, 3.72 x10-6 A/cm2 and 1.38 x10-6A/cm2, respectively. The results revealed that the Sn-3Ag-0.5Cu-4Ti-1Mg-0.1Re alloy had the best corrosion resistance. Moreover, the metallographic observation indicated the corrosion scale thickness on Sn-3Ag-0.5Cu-4Ti-1Mg-0.1Re alloy was 12.96μm. The corrosion products were mainly SnO, SnO2 and Sn3O(OH)2Cl2 on the polarized surface of magnesium containing active lead free solders.