Modelling of a vacuum metallization patterning method for organic electronics

Abstract

The high throughput roll-to-roll patterning of metal thin films could be used to create organic functional devices. In this paper we present research into the compatibility of an invacuum selective metallization technique, which uses a sacrificial oil to define the metal electrode pattern for functional devices. The exact mechanism of the sacrificial oil masking, pattern definition and oil vaporization, due to the radiant heating from the thermal evaporation source, is described from previous research and experimental findings. The thermal modeling of this process develops further the requirements for the masking oil. It is found that in this particular system the oil thickness must be 1.63±0.31μm to match the radiative energy, and not be evaporated prior to leaving the metallization zone or to remain, as excess, after metallization is complete. The temperatures required are low and compatible with heat sensitive functional organic materials. The definition of the metal pattern edges is found to be like the liquid oil but thermal modelling still supports the theory of the oil vapor having the largest masking effect and concludes that the pattern definition quality does not depend on the sacrificial oil masking or vaporization effects but on the flexography patterning.

Linear Electron Beam Assisted Roll-to-Roll in-Vacuum Flexographic Patterning for Flexible Thermoelectric Generators

“…Continuous R2R patterning is achieved by flexographic oil masking onto flexible substrates followed by deposition of materials, resulting in simultaneous oil removal, leaving behind the patterned deposited material. Three possible theories can be used to describe the oil masking mechanism: (i) radiative heating of the oil by the thermal deposition source increases the oil vapour pressure to produce an imparting and repelling vapour cloud from the oil mask surface to selectively prevent deposition [10]; (ii) heat of condensation of the depositing material on the oiled regions vaporises the oil and ablates the depositing material, selectively preventing deposition; (iii) the depositing material is unable to nucleate on the oil surface and condenses elsewhere [15]. f-TEGs will be used as device demonstrators to assess the viability of using LEB as a surface cleaning technique in an R2R environment.…”

“…During deposition of thin films via PVD, the oil mask is simultaneously evaporated or ablated, removing the mask and leaving behind the patterned thin film. However, complete removal of the oil during this process is challenging, often with oil residue left behind, thus creating potential contamination and cleanliness problems for subsequent fabrication steps, possibly compromising the function of devices [4,10].…”

Roll-to-roll manufacture of flexible thin-film thermoelectric generators using flexography with vacuum vapour deposition

“…However, nanostructured TEGs give the prospect of significantly improved device performance. Recent advance in a combination of flexography oil masking technique and thermal evaporation (the so-called selective metallisation technique, SMT [17]) raises the prospect of means to fabricate in-line patterns of nano-thick metals in a fast (e.g. ~25 m min -1 in line speed) R2R process for flexible electronics.…”

“…~25 m min -1 in line speed) R2R process for flexible electronics. In SMT, an oil mask is printed onto a polymer web, then the metal vapour is deposited by evaporation during which the oil is simultaneously evaporated by source radiative heating and metal condensation [17].…”

Dynamics of Liquid Transfer from Nanoporous Stamps in High-Resolution Flexographic Printing

“…High-throughput printing of electronic materials is critical to mass production of devices including thin film transistors, − RFID tags, and transparent electrodes, for use in applications such as smart packaging, − asset tracking, and photovoltaics. , Typically, the desired formats of printed electronics contrast those of wafer-based semiconductor fabrication, demanding lower manufacturing cost and large-area compatibility. ,,− Many traditional printing technologies, including inkjet, flexography, gravure, slot die coating, and screen printing, have been adapted to the printing of inks suited as precursors to functional thin films. The performance of devices, such as printed transistors and the resolution of printed display pixels, is in particular limited by the performance of extant printing methods.…”