Modelling electroforming process under constant bias voltage conditions

In order to understand changes in defect concentration during the electroforming process, we modelled the electroforming process in Ta/HfO2/Pt under constant bias voltage. For this purpose, kinetic Monte-Carlo and finite element methods were utilized. Vacancy profiles were obtained for forming voltages from 3 V to 5 V; modelling of lower stresses is time-consuming. It was found that with decreasing voltage, vacancies begin to accumulate near the inert electrode. When the voltage was dropped from 5 to 3 V, the thickness of such a layer increased by 1 nm, and electroforming time exponentially increase.

Electroforming In Space And Ground Telescopes

In the last 25 years, electroforming process has been extensively optimized to produce grazing incidence optics for the X-ray space telescopes, enabling the renown observatories Beppo-SAX for the Italian Space Agency, SWIFT for NASA, XMM Newton for ESA, eROSITA for MPE. These optics are made of thin Nickel mirrors that are grown by electroforming process in an electrolytic bath on a Gold coated mandrel.Electroforming has also been adopted for production of large reflector panels for sub-millimeter radio telescope applications. Between 2006 and 2016, 3000 mirror panels for 25 antennas of the ALMA radio-telescope array of ESO and 1600 mirror panels for the 50-m diameter Large Millimeter Telescope (LMT) “Alfonso Serrano” of INAOE were designed, produced and tested.

Microfabrication of Ni-Fe Mold Insert via Hard X-ray Lithography and Electroforming Process

In this research, a Ni-Fe mold insert for the efficient replication of high aspect-ratio microstructure arrays was fabricated via hard X-ray lithography and an electroforming process. For the X-ray exposure on a photoresist, a gold-based X-ray mask was prepared with conventional UV photolithography. The gold thickness was designed to be over 15 μm to prevent development underneath the absorber and to enhance the adhesion strength between the photoresist and substrate. By using the X-ray mask, a positive-type photoresist was selectively exposed to X-ray under an exposure energy of 4 kJ/cm3. Thereafter, the exposed region was developed in a downward direction to effectively remove the residual photoresist from the substrate. During the evaporation process, deionized water mixed with a surface additive prevented the bending and clustering of the photoresist microstructure arrays by lowering the capillary force, resulting in a defect-free mother structure for electroforming. Lastly, the mother structure was uniformly Ni-Fe electroformed on a conductive substrate without the formation of any pores or detachment from the substrate. Based on the proposed microfabrication process, a Ni-Fe mold insert with a 183 μm pattern size, 68 μm gap size, 550 μm height, 2116 microcavities and a hardness of 585 Hv was precisely manufactured. It can be utilized for the mass production of high aspect ratio metal and ceramic microstructure arrays in micro molding technologies.

Fabrication of a Metal Roller Mold with Nanoimprinted Pattern Using Thermal Nanoimprint Lithography

In this work, fabrication of a metal roller mold with nanoimprinted pattern was demonstrated. To get metal nanopattern on a metal roller mold, thermal nanoimprint lithography (TNIL) and subsequent electroforming process were conducted. A poly(methyl methacrylate) (PMMA) nanopattern was fabricated by TNIL process using a polydimethylsiloxane (PDMS) soft stamp on a bare PMMA film. An optimal experimental condition of TNIL process was investigated for large area, uniform PMMA nanopatterning. As a result, large area PMMA line patterns with 200 nm linewidth were fabricated by large-area TNIL process. Electroforming process on the PMMA nanopatterned film resulted in nickel (Ni) nanopattern with a linewidth of 200 nm from the PMMA line pattern. A large area (360 mm by 730 mm in width and length) Ni stamp for a roller mold was fabricated by laser cutting and tiling process of the multiple electroformed Ni stamps. We successfully fabricated a Ni roller mold with feature size of 200 nm in linewidth by attaching the large area Ni stamp to the surface of a roller body.

Facile Fabrication of Highly Perforated Hollow Metallic Cylinder with Changeable Micro-Orifices by Electroforming-Extrusion Molding Hybrid Process

A seamless thin-walled hollow metallic cylinder with array of micro-perforations is one of the key components for some products. Normally, these micro-perforations are formed by removing material from the given metallic hollow cylinder (pipe or tube) one by one or row by row. To efficiently and flexibly manufacture such a highly perforated hollow cylinder, this paper proposed a hybrid technique combining extrusion moulding process and electroforming process. In the hybrid technique, the extrusion moulding process was used to create polymer extrusion patterns on the outside surface of the given stainless steel (SS) pipe, and then the electroforming process was carried out using the SS pipe as the mandrel. The formation of the polymer extrusion patterns was simulated and extruding molding experiments were carried out to examine the feasibility of the various mandrels. Electroforming experiments were implemented to verify the achievement of the seamless perforated thin-walled hollow cylinder. It was found that five different types of polymer extrusion pattern were able to be obtained on the same extruding pipe just by adjusting some extruding conditions and parameters, and correspondingly four types of perforated hollow cylinder with different tapered orifices are produced after the electroforming process. The obtainable perforations are: perforation with double conic-orifices, perforation with hemispheric orifice and conic orifice, unidirectionally tapered perforation, and straight-walled perforation. The geometric profile of the extrusion patterns is highly dependent on the processing conditions and parameters. The proposed hybrid process represents a promising alternative process to fabricate seamless thin-walled perforated hollow metallic cylinder efficiently, flexibly, and with low cost.