涂覆速度和热处理对直接镀Pd键合Cu线性能的影响

Effect of coating speed and annealing on properties of direct Pd-coated copper bonding wire

利用扫描电镜、强度测试仪研究了键合铜线无卤直接镀钯工艺及镀钯键合铜线性能,分析了涂覆速度、热处理及张力对直接镀钯铜线拉断力、伸长率和表面质量的影响。结果表明：无卤直接镀钯工艺可获得镀层均匀的镀钯键合铜线;涂覆速度为80～90 m/min时,镀钯铜线具有适当的厚度和良好的表面质量;随热处理温度提高,直接镀钯铜线拉断力降低,伸长率增加;当热处理温度为450℃时,表面钯原子扩散速率加快,线材强度增加,其表面颜色由金属钯色变为灰铜色;当热处理温度为470℃时,镀钯铜线晶粒粗大,力学性能降低;热处理过程中张力小于0.020 N导致线材表面机械损伤,张力大于0.035 N时造成线材表面波浪纹缺陷。当热处理温度为430℃,张力为0.025～0.030 N时,0.020 mm镀钯铜线具有优异的性能。

Direct coating Pd technology and the Pd-coated copper bonding wire were investigated by means of scan electronic microscopy and tensile strength tester.The effects of coating speed,annealing temperature and wire tension on tensile strength,elongation and surface quality of direct Pd-coated copper bonding wire were analyzed.The results show that the Pd thickness is uniform after direct coating Pd.When the coating speed is 80-90 m/min,the Pd thickness can meet the industrial demand and the surface is bright and uniform.The tensile strength will decrease with annealing temperature increasing,while the elongation increases.When annealing temperature reaches 450 ℃,the diffusion rate between Pd to copper wire increases,then the strength increase and the color of the Pd-coated copper wire becomes bronze color from metal palladium color.The grains of the Pd-coated copper wire are coarsened when the annealing temperature is 470 ℃,then the mechanical properties decrease.During annealing process,the mechanical damage is presented on Pd-coated copper wire when wire tension less than 0.020 N and the ripple defect occurs when wire tension more than 0.035 N.It is concluded that the 0.020 mm Pd-coated copper bonding wire has preferable properties when the annealing temperature is 430 ℃ and the wire tension is 0.025-0.030 N.