本研究探討添加0~1.5wt%Cu對Sn-3Ag-2Sb無鉛銲料之熔點與微結構的影響，以及與Cu基板銲接後界面IMC層之變化；同時利用單邊搭接(Single Lap)試件及高溫儲存來評估Cu添加量對銲點剪切強度與抗熱性的影響。

　　實驗結果顯示Sn-3Ag-2Sb-xCu銲料熔點隨著Cu的添加而下降， Sn-3Ag-2Sb的熔點為224.8℃，添加0.5、1.0及1.5%Cu銲料的熔點分別降低為220.1、219.8及219.7℃，隨著Cu添加量的增加固、液相區間有縮小之趨勢。Sn-3Ag-2Sb添加0.5%Cu時，Cu固溶於-Sn中，微結構仍與Sn-3Ag-2Sb相似，為Ag3Sn與-Sn所組成的環狀結構，但整體組織變細。當Cu添加量超過1.0%時，在β-Sn中生成Cu6Sn5化合物。Cu6Sn5有兩種形貌，在1.0%Cu時，形貌為片狀組織；Cu含量高達1.5%，Cu6Sn5則為柱狀，其中粗大的柱狀Cu6Sn5成兩端封閉空心管狀，細小Cu6Sn5為實心棒狀。在Sn-3Ag-2Sb/Cu與Sn-3Ag-2Sb-1.5Cu/Cu的界面上均有長條狀化合物，經深腐蝕分別為板狀Ag3Sn與柱狀Cu6Sn5化合物且經長時間熱儲存均會粗大化。Sn-3Ag-2Sb-xCu銲料與Cu接合，Cu會快速反應融入銲料，界面上Sn與Cu反應生成扇貝狀之Cu6Sn5化合物，隨著Cu添加量的增加，IMC會增厚，且Cu6Sn5晶粒較大。在Sn-3Ag-2Sb-1.5Cu/Cu之界面IMC層經625小時高溫熱儲存厚度大幅增加，由3.2μm成長至6.9μm，而Cu6Sn5晶粒數目由多變少，晶粒大小由3μm成長至7μm左右，造成界面層粗糙度變大。

　　剪切測試顯示Sn-3Ag-2Sb未經儲存之剪切強度為58.5MPa，添加0.5、1.0及1.5%Cu分別為66.3、91.8及115.5MPa，剪切強度隨Cu添加量的增加而升高。高溫儲存後，所有銲點的強度隨時間增加而下降。625小時熱儲存後，Sn-3Ag-2Sb強度為46.1MPa，添加0.5、1.0及1.5%Cu分別為52.3、76.5及78.1MPa。未經儲存之銲點破壞面大多發生在銲料中，隨儲存時間增加則傾向在界面發生；破裂面在銲料時強度最高，其次為破裂面在部分銲料、部分界面，破裂面在界面強度最低。綜合銲點剪切強度、抗熱性與延展性而言，添加1.0% Cu則具有較佳的性質表現。

　The effects of adding 0~1.5wt% Cu into Sn-3Ag-2Sb lead-Free solder on the melting point and microstructure as well as the interfacial IMC（Intermetallic Compound） layer are studied in this reseach. The Single Lap specimens and high temperature storage evaluate the influences of different Cu addition for the shear strength of solder joint and thermal resistance.

　Experimental results show that melting points of the Sn-3Ag-2Sb-xCu solder are decreased with Cu additions. The melting points are 224.8˚C(Sn-3Ag-2Sb)、220.1˚C(adding 0.5%Cu)、219.8˚C(adding 1.0%Cu)and 219.7˚C(adding 1.5%Cu)respectively. Cu solved into -Sn matrix when Cu addition is lower than 0.5%. The microstructures are composed of Ag3Sn and -Sn in form of circular structure. When Cu addition is more than 1.0%, Cu6Sn5 compounds can be found in the solder. Cu6Sn5 has two kind of shape, the platelet-type as can be found by 1.0%Cu addition; Cu content is up to 1.5%, Cu6Sn5 is column, among them coarse column Cu6Sn5 both ends and seal the hollow tube, thin Cu6Sn5 is needle-like. When Sn-3Ag-2Sb-xCu solder combine with Cu substrate, Cu solve into solder fastly, due to Sn atoms react with Cu atoms to form scallop shape Cu6Sn5 compounds. The compounds at the interfacial surface of Sn-3Ag-2Sb/Cu and Sn-3Ag-2Sb-1.5Cu /Cu appear plate Ag3Sn and column Cu6Sn5 respectively by deep etching. Both compounds become coarse after high temperature storage. The IMC layer thickness can be raised with the Cu addition increasing.

　The shear strength results show that the average shear strength of as-soldering Sn-3Ag-2Sb solder joint is 58.5MPa. The shear strength can be raised with the Cu addition increasing. The strength of 0.5, 1.0, 1.5%Cu, are 52.3, 76.5, 78.1 MPa respectively. The shear strength of the whole solder joint decrease distinctly after 150℃ thermal storage. After 625 hours storage the Strength of Sn-3Ag-2Sb solder is 46.1MPa. The strength of adding 0.5, 1.0, 1.5%Cu are 52.3、76.5、78.1MPa. The fracture position of solder joints at as-soldered occurred at the inside of solder. However, the fracture position tended to occur at the interfacial surface with storage time increasing. It is highest in intensity to break at the inside of solder, secondly break at the surface on some solder , some interface, it is lowest in intensity to break at the interfacial surface. According to the shear strength and thermal resistance and ductility, the solder adding 1.0%Cu has better behaviors.

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