This study proposed and demonstrated the feasibility of adopting metallization method of bottom-up Damascene process (seed layer over entire patterned surface) in LIGA electrodeposition process to fabricate void-free submilimeter scale metallic components. Single additive (PEG of molecular weight, Mw 10,000) rather than complicated mixture of multiple additives is studied in order to simplify the additives concentration monitoring process. Hydrodynamic flow pattern and concentration distribution of additive in the electrolyte flowing across trenches of various aspect ratio were studied by using fluid kinetics simulation. Simulation results showed the shear flow of the agitated electrolyte across the top surface caused the formation of a concentration gradient of inhibitor (PEG) within the cavity, in which the concentration of inhibitor at the top surface was consistently maintained at a higher level as compared to the bottom part of cavity. The studies on the influence of PEG concentration on electrodeposition profile showed a relatively low concentration of 10 ppm has exhibited a remarkable difference in the electrodeposition rate at the top and inner surfaces of submillimeter cavity (bottom-up electrodeposition) which subsequently eliminated the formation of void/seam-like defects associated with conventional electrodeposition. Underfilling issue was identified and a two-step electrodeposition method was proposed to mitigate the underfilling effect. Nickel component electrodeposited by PEG-added electrolyte shows higher Vickers hardness of approximately 20% as compared to additive-free sample. Flat and thin surface layer that has been electrodeposited using this technique suggested a low risk of parts’ peel-off. This resulted in the simplified process of surface polishing, planarization and demolding. This approach provides an insight into fabrication techniques for void-free multilayer, millimeter-scaled components like watch parts.

这项研究提出并证明了在LIGA电沉积工艺中采用自下而上的金属镶嵌工艺（整个图案化表面上的种子层）的金属化方法来制造无空隙的亚毫米级金属部件的可行性。为了简化添加剂浓度监测过程，研究了单一添加剂（分子量为10,000 Mw的PEG）而不是多种添加剂的复杂混合物。通过流体动力学模拟研究了流过不同长宽比的沟槽的电解质中的流体动力流型和添加剂的浓度分布。模拟结果表明，搅动过的电解质在顶表面上的剪切流导致空腔内抑制剂（PEG）浓度梯度的形成，其中，与空腔的底部相比，抑制剂在顶表面的浓度始终保持较高的水平。对PEG浓度对电沉积轮廓的影响的研究表明，相对较低的10 ppm浓度在亚毫米腔的顶部和内表面的电沉积速率（自下而上的电沉积）表现出显着差异，从而消除了空隙的形成与常规电沉积相关的/缝状缺陷。确定了底部填充的问题，并提出了一种两步电沉积方法来减轻底部填充的影响。与不含添加剂的样品相比，由添加了PEG的电解质电沉积的镍组分具有更高的维氏硬度，约为20％。使用此技术进行电沉积的平坦且薄的表面层表明部件脱落的风险很小。这样就简化了表面抛光，平面化和脱模的过程。这种方法提供了对无空隙的多层毫米级部件（如钟表部件）制造技术的深入了解。