Fabrication of a metallic roll stamp with low internal stress and high hardness for large area display applications by a pulse reverse current electroforming process

Abstract

With the increasing demand for large scale micro/nano components in the fields of display, energy and electrical devices, etc, the establishment of a roll imprinting process has become a priority. The fabrication of a roll stamp with high dimensional accuracy and uniformity is one of the key issues in the roll imprinting process, because the roll stamp determines the properties of the replicated micro/nano structures. In this study, a method to fabricate a metallic roll stamp with low internal stress, high flatness, and high hardness was proposed by a pulse reverse current (PRC) electroforming process. The effects of PRC electroforming processes on the internal stress, hardness, and grain size of the electroformed stamp were examined, and the optimum process conditions were suggested. As a practical example of the proposed method, various micro-patterns for electronic circuits were fabricated via the roll imprinting process using a PRC electroformed stamp.

Manufacturing microstructured tool inserts for the production of polymeric microfluidic devices

“…The hardness of Ni shim formed at a lower current is 257 ± 10 HV5, which is much higher compared to that formed at a high current (160 ± 7 HV5). This observation is consistent with reports on the effect of current on microstructure and hardness [30,33,34]. Overall, the Ni insert is composed of features and a bottom supporting layer.…”

“…Although a lower current density eliminates or reduces the size of voids, electroforming time increases significantly. Pulse reverse current electroplating has been successfully used to eliminate voids in high aspect ratio (~4.5) submicron features by dissolving the deposited metal material according to the anodic reaction [30][31][32]. The effect of current on the microstructure of a feature is shown in Figure 13.…”

High-Resolution, High-Aspect-Ratio Printed and Plated Metal Conductors Utilizing Roll-to-Roll Microscale UV Imprinting with Prototype Imprinting Stamps

“…To improve the mechanical performance further, changing the stamp material is another possibility, , but Sylgard 184 has key advantages for the current work. First, this silicone is readily available at low cost to facilitate economical stamp fabrication as new circuits and features are under development.…”

“…A key advance is the development of a roll-to-roll UV-imprinting process with custom-made, rapidly produced, and easily exchanged prototype imprinting stamps. Most methods for fabricating stamps for roll-to-roll UV imprinting require complex or high-cost processing or are not capable of molding structures that are much higher than they are wide (high aspect ratio). ,, In the process described here, stamps are fabricated from a silicon wafer master pattern using liquid casting of low-cost silicone. A series of stamps is then bound to a poly­(ethylene terephthalate) (PET) film to form a stamp assembly.…”

Advances in precision micro/nano-electroforming: a state-of-the-art review

“…It was also possible to obtain cracked layers of superior quality via PRC, as shown in figure 19(B). Kim et al [124] compared the internal stress of the electroformed stamp by DC and PRC at various pulse frequencies. The internal stress of the stamp was effectively reduced by PRC electroforming compared to DC electroforming, as shown in figure 20, especially when the process used a high current density and low pulse frequency.…”