Fabrication of Low-Cost Molds for Manufacturing of High Precise Micro Parts By Electroforming
Authors: Aghili Sayed MohammadAli , Zheng Zhaohan , Wüthrich Rolf 
Published: May 2020

Technology push and market pull lead to an intensification of micro molding processes development which have variety of applications such as micro-gears, micro-pumps, micro optical components, connectors, wave-guides, optical gratings and mass production of polymer micro parts and structures with high aspect ratios [1][2]. In these recent years, broad range of microfabrication technologies including, laser ablation, photolithography, lithography, electroplating, and molding (LIGA), chemical etching have been developed [3]. Most of these technologies have been developed for mass production. Manufacturing industry is however more and more facing the problem of producing personalized parts, resulting in low volume production. New technologies to allow economical fabrication of low volume micro-parts become a need.
In this work, to address the issue of manufacturing high precise 3D micro-metallic parts for small series, we propose 3D printing of micro-molds followed by electroforming to produce micro 3D metallic parts. Advances in additive manufacturing allow for economical and costly manufacturing of polymer micro-molds with high-resolution to fabricate three-dimensional structures which enables the fabrication of personalized microproducts with virtually any shape. This combination of processes can highly decrease fabrication costs for low volume production.
The process starts by printing a mold in Acrylonitrile Butadiene Styrene (ABS). A conductive layer must be included to allow subsequent copper electroforming. Dissolving the ABS part allows in the last step the creation of ultra-light micro-metal parts with a high-quality surface finish and accurate dimensions. Several applications can benefit from a technology able to produce micro dimensional metal parts with thin features like watch industry, medical devices [3] or aerospace and space applications where weight and fraction play key factor.
To include the conductive layer into the mold, a two steps process was developed. First step consists in making an ABS substrate with a conductive layer and printing of the ABS mold. Second step is to bond both elements together (Figure, a). The challenge faced is how to bond the substrate with the conductive layer and the upper mold. The developed solution is to thermally bond the substrate’s conductive surface and the upper mold’s surface by apply an appropriate temperature and pressure.

Refences

[1] L. Weber, W. Ehrfeld, H. Freimuth, M. Lacher, H. Lehr, and B. Pech, “Micromolding: a powerful tool for large-scale production of precise microstructures,” Proc. SPIE - Int. Soc. Opt. Eng., vol. 2879, no. September 1996, pp. 156–167, 1996.
[2] T. Katoh, R. Tokuno, Y. Zhang, M. Abe, K. Akita, and M. Akamatsu, “Micro injection molding for mass production using LIGA mold inserts,” Microsyst. Technol., vol. 14, no. 9–11, pp. 1507–1514, 2008.
[3] M. Vaezi, H. Seitz, and S. Yang, “A review on 3D micro-additive manufacturing technologies,” Int. J. Adv. Manuf. Technol., vol. 67, no. 5–8, pp. 1721–1754, 2013.

Figure 1