摘要
仿真模拟预测电铸过程中铸造层的厚度变化是指导生产降低成本、提升电铸质量的重要方式。微型探针针管由于尺寸小、表面及理化性能要求高,一直是材料制备过程的难点。通过电化学测试确定模型输入参数,利用COMSOL软件电镀模块对电铸沉积过程进行了仿真,模拟电铸阴极表面电流密度(I)分布,探究了不同电流密度下铸层达到相同厚度时的沉积时间,并计算了模拟沉积速率。利用扫描电镜(SEM)和白光干涉仪研究了实际制备过程中样品的表面形貌和粗糙度,并与模拟过程进行了对比,结果表明:在焦磷酸盐电铸铜的体系下,当反应温度为35℃,体系pH为8.6±0.1时,I取3.5 A·dm^(-2),预测厚度达到90μm时,电铸过程中铸层厚度误差和反应时间误差最小,分别为0.55%和5.00%,此时样品铸层表面最为致密,放大后表面晶粒细小、结合紧密,且粗糙度最小、表面质量最高。模拟结果与实验结果具有良好的一致性,表明利用COMSOL模拟电铸过程铜沉积制备微型探针是可行的。
Simulation of the thickness change of the casting layer during the electroforming process is an important way to guide production to reduce costs and improve the quality of electroforming.Micro-electroforming technology is a metal micro-structure preparation technology.Compared with ordinary mechanical processing,it can obtain high-purity micron products with precise dimensions and smooth surface.Due to its small size,high surface and physical and chemical performance requirements,the micro-probe has always been a difficult point in the material preparation process.It is feasible to prepare the probe tube by the micro-electroforming process,but the uneven current density distribution leads to the difference in the thickness of the electroforming layer which restricts the improvement of the quality of the probe tube.A combination of simulation and experiment is used to explore the preparation process of the micro copper tube.After demolding,a probe tube with a certain strength that can support the probe is obtained,the surface is flat and compact,the roughness meets the requirements of use,and the signal transmission is not hindered.Choose copper as the electroforming deposition metal,and configure the electroforming liquid with copper pyrophosphate as the main salt.Determine the polarization curve through electrochemical tests and determine the model input parameters.Use the COMSOL electroplating module to use the"secondary current distribution"interface to establish the electroforming flow field and electric field model,and simulate the flow field mass transfer in the electroforming copper process.The current density distribution on the surface of the electroforming cathode was simulated,and the deposition time when the cast layer reached the same thickness under different current densities was explored.Under the same exploration process,the micro-probe needle tube was prepared through experiments,and the surface morphology and roughness of the samples in the actual preparation process were studied by scanning electron microscope(SEM)and Micro XAM white light interferometry.The electroforming process conditions with high dimensional accuracy and low surface roughness were obtained and compared with the simulation results.The results showed that under the system of pyrophosphate electroforming copper casting solution,when the reaction temperature was 35℃and pH of the system was 8.6±0.1,the result of copper deposition in the electroforming experiment was consistent with the physical model established by simulation.The boundary value of the simulated electroforming time was 300 min,and the target value of the predicted thickness was set to 90μm.When the current density was in the range of 2.0~4.5 A·dm^(-2),with the increase of current density(I),the simulated deposition time distribution range was 270~125 min,while the electrodeposition rate increased from 0.333 to 0.720μm·min^(-1).The simulation showed that the electric force lines gather at the tip where the cathode intersected on the bottom surface of the cylinder,and the current density was relatively high.The experimental process under the same conditions showed that the I was 3.5 A·dm^(-2),and when the predicted thickness reached 90μm,the thickness error and reaction time error of the electroforming layer during the electroforming process were the smallest,which were 0.55%and 5.00%,respectively.The experimental electrodeposition rate was basically consistent with the deposition rate calculated by simulation.When other electroforming conditions remained unchanged and I was set to 3.5 A·dm-2,the surface of the electroforming layer of the sample is the densest,the surface grains are fine after SEM image was enlarged,and the surface quality was the highest.Under this process condition,the surface of 3D topography of the cast layer is also the smoothest and uniform,with a minimum roughness of 297nm,which met the requirements of the probe.The simulation results were in good agreement with the experimental results,indicating that it was feasible to use the model to simulate the copper deposition in the electroforming process to prepare micro-probes.Aiming at the phenomenon of uneven thickness of micro-electroforming,COMSOL could be used for simulation.By changing the peripheral electroforming diagram of the target graphic as a current collecting ring,setting different current densities and observing the current distribution,as a result uniform conditions were feasible.In addition,the use of ultrasonic vibration could strengthen the convection of the solution near the cathode surface and reduced the thickness of the diffusion layer,thereby weakening the saddle shape due to diffusion and improving the uniformity of the casting layer.It had broad application value in the subsequent field of micro and small material preparation.Regarding this study,we could discuss the electroforming process under different electroforming time,temperature and ultrasonic conditions in the later stage.These factors affected the thermodynamic and dynamic parameters of the reaction process.By improving the reaction thermodynamics and kinetic conditions,the electroforming rate and forming uniformity were accelerated.For multilayer electroforming,exploring the bonding properties and mechanical properties between casting layers would also be very meaningful work.At the same time,other cast metal could be selected for electroforming process exploration.The above-mentioned research could be carried out under the optimal conditions of COMSOL simulation to provide support for exploring the universality and accuracy of COMSOL.
作者
杨西荣
王苗
刘晓燕
李兆
罗雷
何晓梅
Yang Xirong;Wang Miao;Liu Xiaoyan;Li Zhao;Luo Lei;He Xiaomei(School of Metallurgical Engineering,Xi'an University of Architecture and Technology,Xi'an 710055,China;Key Laboratory of Gold and Resources of Shaanxi Province,Xi'an 710055,China;School of Materials Engineering,Xi'an Aeronautical University,Xi'an 710077,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2024年第3期388-397,共10页
Chinese Journal of Rare Metals
基金
国家自然科学基金项目(51474170)
陕西省教育厅重点实验室项目(20JS075)资助。
关键词
电铸铜
微型探针针管
COMSOL
铸层厚度
组织形貌
electroforming copper
miniature probe needle
COMSOL
layer thickness
micro morphology
作者简介
杨西荣(1971-),男,陕西西安人,博士,教授,研究方向:材料过程制备与性能调控,电话:029-82202923,E-mail:lazy_yxr@qq.com。
