Whitney Gaynor | Sinovia Technologies: How do you prevent "viscous fingering" from ruining printed OLED layers?
00:08:17.925 - 00:09:28.895
Other snippets from this talk
Summary of the clip:
How do you prevent "viscous fingering" from ruining printed OLED layers?
Unlike non-contact methods like inkjet or slot-die coating, flexography is a contact printing technology where ink transfer relies on fluid splitting. As the ink separates from the printing plate to the web, physical phenomena like viscous fingering create ribbing and non-uniformities at a specific wavelength, frequency, and amplitude.
For OLEDs, which require ultra-thin organic layers on the nanometer scale, these surface perturbations are highly detrimental and must dry perfectly flat. Mitigating this challenge requires precise co-optimization of flexographic plate materials, ink formulation, and anilox cylinder volumes to ensure self-leveling before curing.
In this short video, you can learn:
* The physics of ink splitting and the root causes of viscous fingering in roll-to-roll contact printing.
* Why thickness uniformities on the nanometer scale are uniquely challenging for printed electronic layers.
* The critical parameters—such as plate materials and anilox volumes—used to manage film topography.
📋 **Clip Abstract** Contact-based flexographic printing introduces fluid-splitting defects like viscous fingering, which cause nanometer-scale thickness variations in wet films. Sinovia manages these hydrodynamic instabilities by co-optimizing ink chemistry, plate properties, and anilox volumes to achieve flat layers.
#ViscousFingering, #FlexographicPrinting, #AniloxCylinders, #PrintedOLEDs, #PrintedElectronics, #RollToRollManufacturing
This is a highlight of the presentation:
More Highlights from the same talk.
00:03:15.025 - 00:04:37.655
How can you print nanoscale-smooth OLED anodes on flexible substrates without damaging the barrier layers?
How can you print nanoscale-smooth OLED anodes on flexible substrates without damaging the barrier layers?
Sinovia Technologies' core innovation is a silver nanowire-based, transparent, conductive film that can be printed roll-to-roll at 100-micron resolution directly onto an ultra-barrier. This serves as the foundational anode layer for bottom-emitting OLED displays, eliminating the need for laser patterning (which produces particles) or photolithography (which can damage the underlying barrier film).
By controlling the structure and utilizing nanoscale-smooth films, subsequent thin organic transport and emitter layers can be deposited uniformly on top. This approach allows high-yield, flexible, segmented, or passive matrix displays to be fabricated continuously from roll to roll.
In this short video, you can learn:
* How silver nanowire networks form a smooth, high-resolution anode directly on flexible ultra-barriers.
* Why roll-to-roll printing avoids the barrier damage typical of photolithography and laser patterning.
* The spatial resolution limit of flexographic printed anodes and its implications for display density.
📋 **Clip Abstract** Sinovia Technologies uses roll-to-roll flexography to print silver nanowire anodes directly on ultra-barrier films at 100-micron resolution. This avoids the defect risks of laser patterning and lithography, creating a nanoscale-smooth foundation for subsequent OLED layers.
#SilverNanowires, #RollToRollFlexography, #PrintedAnodes, #UltraBarrier, #FlexibleOLED, #PrintedElectronics
00:07:55 - 00:09:01
How do you prevent microscale ink splitting from ruining nanometer-scale OLED layers?
How do you prevent microscale ink splitting from ruining nanometer-scale OLED layers?
When transitioning flexographic printing to optoelectronic devices, the physics of ink transfer presents a critical barrier. As ink separates from the flexo plate to the substrate, the liquid meniscus splits, triggering the formation of viscous fingers in the cross-web direction.
In standard graphic arts, this surface perturbation is harmless; however, for OLED architectures, these sub-micron periodic thickness variations propagate directly through the entire device stack. This non-uniformity alters the local electric field, leading to spatial variations in light emission and premature device degradation.
Overcoming this requires modeling and controlling multiple coupled variables. The ink's viscoelastic properties, printing speed, and roll surface textures must be precisely engineered to force the printed film to level before drying.
In this short video, you can learn:
* The fluid dynamics of liquid meniscus splitting and the formation of cross-web viscous fingers.
* Why periodic thickness variations cause non-uniform emission and shorter device lifetimes.
* The multi-variable approach needed to eliminate mechanical print features in thin-film optoelectronics.
📋 **Clip Abstract** This clip details the fluidic challenges of adapting high-speed contact printing to nanometer-scale electronic devices. It explains how viscous fingering during ink transfer damages OLED uniformity and the strategy required to resolve it.
🔗 Link in comments 👇
#ViscousFingering, #FlexographicPrinting, #InkSplitting, #OLEDManufacturing, #PrintedElectronics, #FlexibleElectronics
00:15:16.775 - 00:16:01.075
Why does a higher ink viscosity produce a smoother printed OLED film?
Why does a higher ink viscosity produce a smoother printed OLED film?
During high-speed roll-to-roll printing at 18 meters per minute, the dwell time inside the inline dryers is less than one second, leaving no time for conventional gravity-driven leveling. Consequently, lower viscosity formulations tend to stretch and form severe ribbing during splitting that gets locked in place, reflecting heavily in the light-emission profile.
To achieve a uniform emission pattern, Sinovia utilizes higher viscosity formulations that split cleanly, alongside complex solvent blends that leverage the Marangoni effect. This chemical engineering approach forces the nanoscale layers to rearrange and level dynamically before rapid UV or thermal curing.
In this short video, you can learn:
* Why the lack of leveling time on high-speed presses makes high-viscosity formulations split cleaner and dry flatter.
* How the Marangoni effect is leveraged via solvent blending to force surface reorganization.
* The severe constraints of sub-second drying and curing windows in production-scale flexography.
📋 **Clip Abstract** At production speeds of 18 m/min, the sub-second drying window prevents printed liquid films from leveling naturally, making higher viscosity formulations crucial for clean splitting. Sinovia employs solvent mixtures and high-viscosity inks to exploit surface-tension gradients and achieve uniform light emission.
#MarangoniEffect, #InkRheology, #Flexography, #RollToRollPrinting, #PrintedOLED, #FlexibleElectronics