采用金相显微镜、双束离子显微镜、高低温拉力仪及纳米压痕仪对不同真应变条件的金包银复合键合丝的组织和力学性能进行表征,研究了金包银复合键合丝的组织结构演变、力学性能及变形行为特点.结果表明:金包银复合键合丝的银合金芯材沿着拉伸方向从胞状树枝晶演变为纤维组织,靠近界面的过渡层始终保持细小的等轴晶或球状晶粒,金包覆层在变形过程中均匀连续.各组分在变形过程中尺寸变化不一致,拟合后的尺寸变化常数与试样直径的变化不成正比.显微硬度、抗拉强度、延伸率均随着变形量的增加而增大.在单轴拉伸过程中,金包银复合键合丝组分之间相互制约,使单向拉应变变为复杂的二维应力状态,交替变化的应力状态可抑制裂纹的形核,提高材料的塑性和韧性.“,”The microstructure and mechanical property of gold cladding silver composite bonding wire under different true strains were characterized by metallographic microscope,double beam electron microscope,high-low temperature tensile tester and nano-indentor.The results show that the silver alloy core of gold cladding silver composite bonding wire evolves from cellular dendrite to fiber structure along the drawing direction.The gold cladding layer is uniform and continuous and the transition layer near the interface always keeps fine equiaxed or spherical grains during the deformation process.Inconsistent size change among each component is observed during deformation,and the fitted size change constant is not proportional to the change of wire diameter.Microhardness,tensile strength and elongation increase with the increase of deformation amount.During the uniaxial drawing process,the unidirectional tensile strain becomes a complex two-dimensional stress state due to the interaction between each component of the composite wire.Thus the plasticity and toughness of the material can be improved because the alternating stress inhibits the nucleation of crack.