电化学抛光铜的实验研究

Experimental Study on Electrochemical Polishing of Copper

目的提高铜的表面质量,并将铜的去除量控制在适用范围,研究铜电化学抛光的溶液配比和最佳工艺参数。方法使用自行搭建的电化学抛光系统对工件进行电化学抛光,并使用3D表面轮廓仪和精密电子天平测量工件加工前后的表面粗糙度和质量。采用单因素和正交实验结合的方法设计了实验方案,研究了磷酸浓度、电解液温度、电压、占空比、频率和加工时间对铜表面粗糙度的影响,以及添加剂对实验结果的影响。结果得到磷酸浓度和温度对表面粗糙度的影响曲线。通过极差分析得到了电压、占空比、频率和加工时间对表面粗糙度的影响趋势以及最优参数。在溶液中加入抗坏血酸后,材料去除率可以降低到1000 nm/min以下,但表面粗糙度最高达到75 nm。同时加入抗坏血酸和乙烯硫脲后,材料去除率为400 nm/min,表面粗糙度最低达到17 nm。结论电化学抛光铜的最优参数为:电压10 V,占空比23%,频率23 k Hz,加工时间11~14 min,溶液配比为55%磷酸+0.3%抗坏血酸+0.2%乙烯硫脲。抗坏血酸可以有效地控制材料去除率,抗坏血酸与乙烯硫脲同时作用又可以降低铜的表面粗糙度。

The work aims to improve surface quality of copper,control copper removal in scope of application,and study electrochemical polishing solution ratio and optimum process parameters.The electrochemical polishing was applied to workpiece in a self-assembled electrochemical polishing system.Surface roughness and mass of the workpiece before and after processing were measured and recorded with a 3D surface profiler and precision electronic balance,respectively.Experimental scheme was designed in the combined method of single factor experiment and orthogonal experiment.The effects of phosphoric acid concentration,electrolyte temperature,voltage,duty cycle,frequency and processing time on surface roughness of copper,and the effects of additives on experimental results were studied.Influence curve of phosphoric acid concentration and temperature on surface roughness was obtained.Influence trend of voltage,duty cycle,frequency and processing time on surface roughness,and also optimal parameters were obtained by means of range analysis.After ascorbic acid was added into the solution,material removal rate was reduced to below 1000 nm/min while surface roughness was up to 75 nm.After ascorbic acid and ethylene thiourea were added simultaneously,material removal rate was 400 nm/min and surface roughness was as low as 17 nm.Optimal parameters of electrochemical polishing were:voltage 10 V,duty ratio 23%,frequency 23 kHz,processing time 11~14 min,and solution ratio was as follows:55%phosphoric acid,0.3%ascorbic acid and 0.2%ethylene thiourea.The material removal rate can be effectively controlled by adding ascorbic acid,and the surface roughness of copper can be reduced by adding ascorbic acid and ethylene thiourea simultaneously.