辅助阴极对电铸微模芯厚度均匀性的影响

Effect of auxiliary cathode on thickness uniformity of micro-electroformed mold insert

用Ansys有限元软件对微透镜阵列模芯电铸过程中的电场线分布进行模拟分析,研究了辅助阴极的尺寸对电流密度分布的影响,预测了电铸模芯厚度均匀性的变化趋势。分析发现,辅助阴极能提高电铸模芯厚度的均匀性,当框形辅助阴极与母板阴极的边长之比为1.5时,模芯表面的电流密度相对偏差由无辅助阴极时的82.8%降低至10.1%。通过电铸实验对模拟结果进行验证。结果表明,所得铸层厚度偏差可降低到18.89%,与模拟分析结果较为一致。电铸成型所得1 mm厚的微透镜阵列模芯厚度均匀,微观形貌与母板一致,可应用于微注塑成型工艺。

The distribution of electric field lines on microlens array mold insert during the elecl^oforming process was simulatively analyzed using Ansys finite element software. The effect of the size of auxiliary cathode on current density distribution was studied, predicting the variation of thickness uniformity of electroformed mold insert. It was found that auxiliary cathode can improve the thickness uniformity of electroformed mold insert. When the length ratio of auxiliary cathode frame to backplane cathode is 1.5, the relative deviation of current density on the surface of mold insert is decreased from 82.8% without auxiliary cathode to 10.1%. The simulation results were verified through electroforming experiment. The results showed that the thickness deviation of the obtained electroformed coating can be decreased to 18.89%, which is in good accordance with the simulation analysis results. The electroformed microlens array mold insert with a thickness of 1 mm has uniform thickness and the same micromorphology as backplane and can be applied to microinjection molding process.