Recent advances in reverse offset printing: an emerging process for high-resolution printed electronics

Abstract

Mechanisms, materials, and processes of high-resolution printing techniques dedicated to printed electronics are reviewed. Advanced printing methods, including reverse offset printing and adhesion contrast planography, use absorption of ink solvents by polydimethylsiloxane (PDMS) to semi-solidify inks before ink-transfer. The patterning principle transforms from wetting to adhesion and fracture; resolution problems encountered during the patterning of liquid inks (e.g. spreading, splitting, coalescence, bulges, and coffee ring shapes) can be avoided, and single-μm features can be achieved. After summarizing the fundamentals of reverse offset printing, details on the patterning mechanism and contact mechanics encountered during the process are shown together with the design concept of the ink formulation. Complementary processes for multilayered electronic devices (e.g. wet-on-wet for high-throughput production, buried electrode formation, taper formation, and vertical interconnections) and the prediction of pattern size integrity are presented.

Reverse-Offset Printing of Polymer Resist Ink for Micrometer-Level Patterning of Metal and Metal-Oxide Layers

“… 22 The three polymers were dissolved at various weight loadings in various solvents (1-butanol, 2-methoxyethanol, cyclohexanone, ethyl acetate, ethyl lactate, and toluene) that were considered suitable for ROP in terms of their physical properties and absorption to PDMS ( Table S1 ). 4 In the initial printing tests using the inks, PVP dissolved in 1-butanol and PVPh dissolved either in ethyl acetate or ethyl lactate produced good patterns, whereas PMMA failed to produce patterns ( Table S2 and Figure S1 ). The result of the patterning tests for evaporated Al films is shown after lift-off for 3 wt % PVPh in ethyl lactate and 5 wt % in 1-butanol in Figure S1g and Figure S1h , respectively.…”

“…From these high-resolution printing methods, ROP in particular shows great promise for the fabrication of electronic components and circuits as it can deliver high-quality patterns with a submicrometer printing resolution, 5 micrometer-level overlay printing accuracy, 6 uniform layer thickness, and rectangular cross section with steep sidewalls, thus producing features resembling those obtained with photolithography. 4 However, there is a fundamental dearth in the availability of electronic materials as printable inks, which limits the more universal utilization of printing methods in electronics manufacturing. For example, many low work function metals such as Al and Ti cannot be formed as stable, printable nanoparticle (NP) solutions due to their rapid oxidation in air.…”

Stretchable Light-Emitting Device Using a Film/Elastomer Bilayer System with Electrodes Patterned by Printed Electronics Technique

“…Concerning the luminosity of the device, the intensity of the electric field depends on the gap between the electrodes. Technically, reverse offset printing enables line and space on the level of single-micrometer [17,18]. Although the breakdown voltage of the Parylene and PEDOT:PSS layers should be considered, the device has room for improvement with respect to its luminosity, which can be done by narrowing the gap of the electrodes and amplifying the intensity of the electric field between them.…”

Tunable Reverse Offset Printing with a Stretchable Blanket for Fabricating Flexible Printed Electronics

“…[ 43 ] An ideal cliché should be chosen based on specifications such as the minimum resolution, registration errors, aspect ratio of reliefs, pattern area, reusability, mechanical robustness, and cost. [ 34 ] When new structures are designed to meet the requirements of specific device applications, clichés with new features are required for fabrication via photolithography or e‐beam lithography, followed by reactive ion etching, or replica by the NIL process, all of which are quite time‐consuming and costly processes. If we can tune the blanket material containing the printing ink before the off‐step, which is brought into contact with the cliché to remove unnecessary regions of the ink, we can infer that several new structures can be conveniently created based on the same cliché.…”

“…[17][18][19] Among the various techniques such as inkjet printing, [20][21][22][23][24][25][26] screening printing, [27][28][29] and flexographic printing, [30][31][32][33] the reverse offset printing (ROP) method is able to print fine pattern with a minimum achievable resolution of 0.5-5 μm. [34,35] ROP has been currently extensively developed for inks, offset materials, processes, machinery, and applications mainly in academia and industries. For example, Choi et al [36] investigated the mechanism of ROP and presented a criterion for successful printing considering the adhesion and cohesion strengths.…”