Search Results (4)

Thickness nonuniformity is a bottleneck in the micro electroforming process of micro-metal devices. In this paper, a new method of fabricating a layered auxiliary cathode is proposed to improve the thickness uniformity of a micro-electroforming layer. In order to analyze the general applicability of the proposed method, four basic microstructures, namely circular, square, regular triangular, and regular hexagonal were used to study the effect of a layered auxiliary cathode on thickness uniformity through simulation and experimentation. The simulation results showed that with the help of the proposed auxiliary cathode, the thickness nonuniformity of four microstructures should decrease due to the reduced edge effect of the current density. The experimental results showed that the thickness uniformity of four microstructures fabricated via the proposed method was improved by 190.63%, 116.74%, 80.43%, and 164.30% compared to that fabricated via the traditional method, respectively. Meanwhile, the micro-gear was fabricated and the nonuniformity was reduced by 101.15% using the proposed method. Full article

Metal interconnects with a vertical wavy structure have been studied to realize high-density and low-electric-resistance stretchable interconnects. This study proposed a new method for fabricating vertical wavy structured metal interconnects that comprises the pre-stretch method and the micro-corrugation process. The pre-stretch method is a conventional method in which a metal film is placed on a pre-stretched substrate, and a vertical wavy structure is formed using the return force of the substrate. The micro-corrugation process is a recent method in which a metal foil is bent vertically and continuously using micro-gears. In the proposed method, the pitch of the vertical wavy structured interconnect fabricated using the micro-corrugation process is significantly narrowed using the restoring force of the pre-stretched substrate, with stretchability improvement of up to 165%, which is significantly higher than that of conventional vertical wavy structured metal interconnects. The electrical resistance of the fabricated interconnect was low (120–160 mΩ) and stable (±2 mΩ or less) until breakage by strain. In addition, the fabricated interconnect exhibits durability of more than 6500 times in a 30% strain cycle test. Full article

Compared to alternative production methods, cold forming offers technological, economic and ecological potential for the mass production of microgears. Within the current boundaries of the technology, the cold forming of modules m < 0.2 mm is not possible due to size effects, high tool stresses and handling problems. The investigations of this contribution present a novel process chain for the multi-step forming of microgears with a module of m = 0.1 mm. For this purpose, a numerical model of the first two steps of the process chain is set up and confirmed based on experimental forming tests. The results have proven the feasibility of the process chain by a complete forming of the gear teeth. Full article

A numerical analysis using FE (finite element) analysis was performed to clarify the shearing mechanism in the process of extrusion-type fine blanking (FB) for a thin foil of JIS SUS304 in this study. Extrusion-type FB, in which a negative clearance between the punch and the die has been developed and investigated experimentally to improve the quality of the sheared surface in the blanking of thin foils. The resultant sheared surface for extrusion-type FB indicated an almost completely sheared surface, and the fracture portion on the sheared surface was much smaller than that in conventional FB, the so-called finish-type FB. The material flow and fracture criteria in extrusion-type FB were analyzed in comparison with those in finish-type FB. The differences in material flow and so-called critical fracture value were verified for the two processes. The principal stress near the shearing surface has mostly compressive components in extrusion-type FB due to its negative clearance, and the critical fracture value was also less than that in finish-type FB, in which the principal stress near the shearing surface has mostly tensile components. Furthermore, SEM observation with EBSD (electron back-scatter diffraction) analysis of the shearing surface was performed to verify the phenomena. Reductions in deformation-induced crystal orientation rotation and martensite transformation in extrusion-type FB were confirmed in comparison with those in finish-type FB from the analysis results. Full article