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Industrial Digital Fabrication Using Inkjet Technology
KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Electronics and Embedded systems, Electronic and embedded systems. XaarJet ltd.. (Division of Electronics)
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The use of acoustic waves initiated by the deformation of a microchannel is one method for generating monodisperse, micrometer-sized droplets from small orifices and is employed in piezo-electric inkjet printheads. These printheads are used in both graphical printing and digital fabrication, where functionalities, such as optical, biological, electrical or mechanical, are being produced locally. The processes leading to detrimental artifacts such as satellite droplets or nozzle outages, however, are not fully understood and require profound experimentation. This thesis presents both novel techniques to study jetting for optimal droplet formation and reliability, as well as the post-processing techniques required for solution-based production of a conductive feature on low-cost polymeric substrates.

A multi-exposure imaging system using laser light pulses shorter than 50 ns and a MEMS micro-mirror enabled the imaging of the droplet formation at ten instances on the droplet's  travel towards the substrate. The technique allows for the study of droplet formation, satellite droplet break-up and secondary tail formation allowing for better control and understanding of the process.

Reliability measurement using a linescan camera was introduced to record every droplet ejected from the width of a printhead. The variations in droplet velocity and misalignment of the printhead required the use of a constant background illumination to reliably capture the droplets. The resulting low-contrast images were post-processed using statistical analysis of the graylevel distributions of both, the droplet and background pixels, and were subsequently used in a histogram matching algorithm to enable reliable identification of the threshold value required for unhindered detection of missing droplets based on the printed image. Using temporal oversampling the technique was shown to qualitatively describe droplet velocity variations introduced by the actuation of the printhead.  

The conversion of inkjet-printed metallic nanoparticle inks to conductive structures was investigated with a focus on the applicability to industrial processes. Intense pulsed light (IPL) processing achieved comparable results to convective oven sintering in less than ten seconds. The dynamics of IPL sintering were found to be strongly dependent on the spectral composition of the light resonating in the processing chamber. By implementing a passive filtering concept, thermal runaway was prevented and the line conformation was optimized irrespective of the underlying substrate. Alternatively, pulse-shaping, to tailor the energy flux into the deposit and incorporate drying in the IPL process, was found to generate conductive copper features without pre-drying.

The findings were applied to applications comprising small droplet generation for nanoimprint lithography, the fabrication of conductors for blind via connections to buried LED dies as well as the hybrid generation of hyperbolic ion-trap electrodes for  mass spectrometry applications. The addition of the non-contact and high accuracy of the inkjet process enabled suitable performance that lies beyond that of conventional processes.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2019. , p. 92
Series
TRITA-EECS-AVL ; 2019:82
Keywords [en]
inkjet printing, droplet formation, digital fabrication, sintering, nanoparticles, printed electronics
National Category
Media and Communication Technology Other Electrical Engineering, Electronic Engineering, Information Engineering Fluid Mechanics and Acoustics
Research subject
Industrial Information and Control Systems; Media Technology; Information and Communication Technology
Identifiers
URN: urn:nbn:se:kth:diva-263711ISBN: 978-91-7873-366-8 (print)OAI: oai:DiVA.org:kth-263711DiVA, id: diva2:1369020
Public defence
2019-12-09, Ka-Sal B (Peter Weissglas), Kistagången 16, Kista, 10:00 (English)
Opponent
Supervisors
Funder
EU, FP7, Seventh Framework Programme, CP-TP 228686EU, FP7, Seventh Framework Programme, CP-TP 285045Vinnova, 2013-01473Available from: 2019-11-11 Created: 2019-11-10 Last updated: 2019-11-11Bibliographically approved
List of papers
1. Analysis of Formation of an Individual Droplet Using a High-ResolutionMulti-Exposure Imaging System
Open this publication in new window or tab >>Analysis of Formation of an Individual Droplet Using a High-ResolutionMulti-Exposure Imaging System
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2013 (English)In: International Conference on Digital Printing Technologies and Digital Fabrication / [ed] IS&T, 2013, p. 354-358Conference paper, Published paper (Other academic)
Abstract [en]

Localized dispensing of precious functional materials has attracted considerable interest in the academic as well as the industrial society. While the number of publications show numerous fields of applications in printed electronics, photovoltaics, display technologies and thin functional coatings, the transition into the industrial sector is often hindered by challenges resulting from ink-printhead combinations and their implications on reliability and stability of the process, as well as side-effects such as mist accumulation in heavy duty printing equipment.While measuring equipment to quantify various rheological and interfacial parameters foor fluid optimization has been developed with the accompanying mathematical models, the physical jetting experiment as well as high-duty printing trials cannot yet be substituted by these methods. In order to quantify the generation of a droplet alongside with its tailing behavior and mist formation as well as statistics based on cross-talk effects and relaxation-related effects, high-resolution and high-speed imaging are required.This paper examines the optical setup and outlines the required calculations for establishing sharp, high-resolution images using a combination of a high power laser diode with a resonant MEMS micro mirror with a theoretical resolution of 1.8 μm. The limitations of the setup regarding the achievable resolution as well as potential improvements are assessed. Furthermore, the experimental setup, including repetitive generation of nanosecond-pulses necessary for motion-blur-free images, will be discussed. Additionally, results from imaging a droplet formation process using a Xaar 126 printhead are discussed.

Series
NIP & Digital Fabrication Conference, ISSN 2169-4451
National Category
Fluid Mechanics and Acoustics Media Engineering
Identifiers
urn:nbn:se:kth:diva-263703 (URN)
Conference
NIP & Digital Fabrication Conference, 2013 International Conference on Digital Printing Technologies.
Note

QC 20191115

Available from: 2019-11-09 Created: 2019-11-09 Last updated: 2019-11-15Bibliographically approved
2. Inkjet Printing of Electrical Connections in Electronic Packaging
Open this publication in new window or tab >>Inkjet Printing of Electrical Connections in Electronic Packaging
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2011 (English)In: NIP27 : 27th International Conference on Digital Printing Technologies, October 2-6, 2011, Minneapolis, Minnesota ; Digital Fabrication 2011: technical programs and proceedings, The Society for Imaging Science and Technology, 2011, p. 445-451Conference paper, Published paper (Refereed)
Abstract [en]

Two aspects were evaluated of an approach to produce inkjet printed electrical connections in a roll-to-roll application. In the first part it was demonstrated that inkjet printing with silver nanoparticles allows to connect LED dies embedded in a flexible polymeric substrate by way of electrical via connections and to operate the LED dies at their nominal 20 mA and 3 V driving conditions. A standard convection oven process was used to sinter the inkjet printed tracks. The second part of the work focused on identifying sinter technologies that provide the required fast processing times needed for roll-to-roll applications. IR irradiation, Rapid Electrical Sintering, and Broadband Photonic Curing were evaluated and compared with Convective Oven Sintering as benchmark technique. All these techniques produced similar track conductivities. Fastest operation was obtained with Broadband Photonic Curing, which enabled a total process time of three seconds as compared with 150°C and 30 min in the convection oven.

Place, publisher, year, edition, pages
The Society for Imaging Science and Technology, 2011
Keywords
Convection oven, Driving conditions, Electrical connection, Electronic Packaging, Flexible polymeric substrates, IR irradiation, Process time, Processing time, Roll to Roll, Silver nanoparticles
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-159655 (URN)2-s2.0-84860747196 (Scopus ID)978-089208296-4 (ISBN)
Conference
27th International Conference on Digital Printing Technologies, NIP27 and 7th International Conference on Digital Fabrication 2011, Minneapolis, MN, United States, 2 October 2011 through 6 October 2011
Note

QC 20150206

Available from: 2015-02-06 Created: 2015-02-06 Last updated: 2019-11-10Bibliographically approved
3. Spectrally Enhanced Photonic Sintering
Open this publication in new window or tab >>Spectrally Enhanced Photonic Sintering
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2012 (English)In: NIP28 : 28th international conference on digital printing technologies : technical program and proceedings: Digital fabrication 2012 : September 9-13, 2012, Quebec City, Quebec, Canada, The Society for Imaging Science and Technology, 2012, p. 424-430Conference paper, Published paper (Refereed)
Abstract [en]

Inkjet printing with silver nanoparticle inks is frequently being used to print electrically conductive structures. However, typically slow thermal post-processes are applied to produce metallic contact between the nanoparticles resulting in the high electrical conductivity. In an earlier evaluation a number of different post-process were investigated for their capability to sinter the inkjet printed structures within such short time frame to allow for integration into roll-to-roll or roll-to-sheet machines. Among the different techniques like IR-irradiation, and Rapid Electrical Sintering, Photonic Sintering appeared as the most prominent candidate, and was shown to enable electrical conductivities equal to oven sintering. In that previous investigation the inkjet printed structures were dried and subsequently shipped for off-line post treatment. The hybrid process of inkjet printing of silver nanoparticle inks and photonic sintering was further investigated with the goal to implement both processes on a roll-to-roll machine. Specifically it was attempted to perform the photonic sintering process with a single lamp and without an intermediate drying process. In this paper we investigate the sintering characteristics of an inkjet printed, wet deposit having liquid volumes of 510 pL per 100 μm2 on non-absorbing substrates using a single Xenon Sintering 2000 system. The paper specifically highlights the importance of radiation homogeneity, threshold energy, substrate and track morphology onto the sintering process. The influence of the spectral composition of the light is analyzed. The findings allow for spectral tailoring of the process to successfully work on PI and PET irrespective of the illumination source.

Place, publisher, year, edition, pages
The Society for Imaging Science and Technology, 2012
Keywords
Electrical conductivity, Electrically conductive, High electrical conductivity, Illumination sources, Photonic sintering, Silver nanoparticles, Sintering characteristics, Spectral composition
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-159659 (URN)2-s2.0-84875750030 (Scopus ID)978-089208302-2 (ISBN)
Conference
28th International Conference on Digital Printing Technologies, NIP 2012 and Digital Fabrication 2012, Quebec City, QC, Canada, 9 September 2012 through 13 September 2012
Note

QC 20150206

Available from: 2015-02-06 Created: 2015-02-06 Last updated: 2019-11-10Bibliographically approved
4. Novel developments in photonic sintering of inkjet printed functional inks
Open this publication in new window or tab >>Novel developments in photonic sintering of inkjet printed functional inks
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2013 (English)In: NIP29: Digital fabrication 2013, 29th international conference on digital printing technologies, September 29-October 3, 2013, Seattle, Washington : technical program and proceedings, The Society for Imaging Science and Technology, 2013, p. 476-478Conference paper, Published paper (Refereed)
Abstract [en]

Inkjet printing of electrical tracks in roll-to-roll applications was hampered for a long time since nano-particle inks required thermal sintering at temperatures greater than 120 °C for several minutes. Among a large number of potential R2R compatible techniques, photonic sintering of inkjet-printed metal-based inks was shown to enable very fast sintering times and providing high quality of structural integrity and low electrical resistance [1]. While the above investigations were carried out with a low dutylow frequency irradiation source, novel developments allow for pulse shaping on the timescale of several microseconds and, therefore, the combination of drying and sintering pulses into a single piece of equipment. In this contribution the photonic sintering process was investigated numerically and experimentally for the case of inkjetprinted aqueous copper oxide ink and a Pulse Forge®3200 X2 tool, both implemented onto a NovaCentrix roll-to-roll machine. Our finding support the assumption, that pulse shaping and, therefore, energy tailoring as a function of time, is essential for efficient conversion of wet copper oxide deposits into conductive copper with no impact on the underlying substrate. The paper presents and discusses the resulting electrical resistances of features processed with a conventional hybrid solution using IRradiation for pre-drying as well as a single step drying and sintering using a single radiation source.

Place, publisher, year, edition, pages
The Society for Imaging Science and Technology, 2013
Series
International Conference on Digital Printing Technologies, ISSN 2169-4362
Keywords
Conductive copper, Electrical resistances, Function of time, Hybrid solution, Irradiation sources, Photonic sintering, Single radiation, Thermal sintering, Copper deposits, Drying, Ink, Irradiation, Pulse shaping circuits, Sintering
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-147454 (URN)2-s2.0-84897695629 (Scopus ID)978-089208306-0 (ISBN)
Conference
29th International Conference on Digital Printing Technologies, NIP 2013 and Digital Fabrication 2013, 29 September 2013 through 3 October 2013, Seattle, WA, United States
Note

QC 20140813

Available from: 2014-08-13 Created: 2014-06-27 Last updated: 2019-11-10Bibliographically approved
5. High-Speed, Low-Volume Inkjet and its Role in Jet and Flash Imprint Lithography
Open this publication in new window or tab >>High-Speed, Low-Volume Inkjet and its Role in Jet and Flash Imprint Lithography
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2014 (English)In: NIP & Digital Fabrication Conference, 2014 International Conference on Digital Printing Technologies, The Society for Imaging Science and Technology, 2014, Vol. I, p. 408-412Conference paper, Published paper (Refereed)
Abstract [en]

Imprint lithography is an effective technique for replication of nanoscale features. Jet and Flash™ Imprint Lithography (J-FIL™) uses field-by-field deposition and exposure of a low viscosity resist deposited by inkjet printing onto the substrate. The patterned mask is lowered into the fluid, where capillary action assists to flow the fluid into the relief patterns. Following the filling step, the resist is UV cured, the mask is removed, and a patterned resist is left on the substrate.J-FIL™ is a technique, where the imprint technology provides the nanoscale pattern resolution while the inkjet technology contributes the throughput that is required for industrial applications. The drop volume and drop placement accuracy of the inkjet-printed resist is critical, allowing the volume to be distributed appropriately across the substrate surface to achieve a uniform target thickness and preventing non-filling of the relief patterns. With J– FIL™, it is possible to resolve 28 nm structures with residual layer thickness of 13 and 20 nm on 300 mm and 450 mm Si-wafers.In this study, improvements during the filling step are explored for low droplet volumes at high ejection frequencies when using standard printheads with jetting performance of 12 kHz, <3 pL and modified printheads with jetting performance of 28 kHz, <2 pL.

Place, publisher, year, edition, pages
The Society for Imaging Science and Technology, 2014
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-159664 (URN)
Conference
2014 International Conference on Digital Printing Technologies, Philadelphia, PA, September 2014
Note

QC 20150210

Available from: 2015-02-06 Created: 2015-02-06 Last updated: 2019-11-10Bibliographically approved
6. Electrical through-hole and planar interconnect generation in roll-to-roll LED lighting manufacturing using industrial inkjet printheads
Open this publication in new window or tab >>Electrical through-hole and planar interconnect generation in roll-to-roll LED lighting manufacturing using industrial inkjet printheads
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2011 (English)In: Mater Res Soc Symp Proc, 2011, p. 1-6Conference paper, Published paper (Refereed)
Abstract [en]

Despite the availability of many high-volume and low-cost manufacturing processes for LED-based lighting applications, relying mainly on fixed patterns such as LED-backlights and RGB-pixelated displays, novel applications, such as "mood lighting" or interior wall displays call for more complicated and shaped LED arrangements. The presented work is based of a novel roll-to-roll (R2R) process to adaptively and cost-efficiently generate LED arrangements on RMPD® substrates. Inkjet printing of planar and though-hole electrical interconnections is of high importance to the process, as it provides a fully digital way of interconnecting devices electrically, accounting for the actual position of the component and spatially provide different ink film thicknesses. Xaar's industrial inkjet printheads are used to dispense defined volumes of 50 pL of a silver nanoparticle ink in order to provide high reliability and good positioning accuracy while maintaining low satellite drop densities. Specific printing strategies are investigated at a print speed of 0.1 m/s to allow for a reliable electrical connection in case of up to 50 μm deep via connections to the buried component. Due to the low glass-transition nature of the underlying substrates, low sintering temperatures are required to preserve the mechanical properties of the substrate. Low temperature oven sintering yielding sufficient conductivity to drive a current of 40 mA will be discussed. 

Series
Materials Research Society Symposium Proceedings, ISSN 0272-9172 ; 1340
Keywords
Electrical connection, Electrical interconnections, High reliability, Ink film, Inkjet printheads, Interconnecting device, LED lighting, Lighting applications, Low sintering temperature, Low temperatures, Manufacturing process, Novel applications, Positioning accuracy, Print speed, Roll to Roll, Satellite drops, Silver nanoparticles, Through hole, Wall displays, Digital devices, Electric connectors, Glass transition, Ink, Lighting, Mechanical properties, Silver, Sintering, Substrates, Thermal printing, Light emitting diodes
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-150599 (URN)10.1557/opl.2011.1270 (DOI)2-s2.0-84860648989 (Scopus ID)9781618395399 (ISBN)
Conference
2011 MRS Spring Meeting, 25 April 2011 through 29 April 2011, San Francisco, CA
Note

QC 20140908

Available from: 2014-09-08 Created: 2014-09-08 Last updated: 2019-11-10Bibliographically approved
7. A Hybrid Apprach Combining 3D and Conductive Inkjet Printing for theGeneration of Linear Ion Traps for Mass Spectrometry Applications
Open this publication in new window or tab >>A Hybrid Apprach Combining 3D and Conductive Inkjet Printing for theGeneration of Linear Ion Traps for Mass Spectrometry Applications
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2014 (English)In: 30th International Conference on Digital Printing Technologies (NIP 30): Digital Fabrication and Digital PrintingDesc : Proceedings, 2014, p. 133-136Conference paper, Published paper (Other academic)
Abstract [en]

Printed conductors have attracted strong interest in academia as well as the industry. While first applications using printed conductors on flat as well as curved surfaces are establishing in the market, extensive research still is conducted on the postprocessing technologies needed for high-volume fabrication of solution processed conductors. With regards to the potential low-cost, high-throughput manufacturing of conductors on inexpensive polymeric foils, new applications start to evolve that call for an even more elaborate investigation of the printing and post-processing steps included. This paper assesses the potential of inkjet-printed conductors for the use in low-pressure environments, such as linear ion-traps for mass spectrometry. In these environments remainders of trapped air or organic solvents affect the performance and lifetime of the getter pump systems used. Additionally, high frequency characteristics of the processed conductors are investigated as these are essential for the sensitivity of an ion trap. In this contribution we establish the framework for the application of conductive Inkjet printing on curved surfaces for sensing application in low-pressure environments. Inkjet-deposited nanoparticle inks were investigated with respect to their characteristics under vacuum conditions. The deposits on polymeric foils as well as on DLP processed three-dimensional semi-finished parts were subjected to thermal post-processing and measured with respect to their electrical characteristics as well as their outgassing behavior.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Fluid Mechanics and Acoustics Media Engineering
Identifiers
urn:nbn:se:kth:diva-263706 (URN)9781510814387 (ISBN)
Conference
30th International Conference on Digital Printing Technologies (NIP 30): Digital Fabrication and Digital Printing, 7-11 September 2014, Philadelphia, Pennsylvania, USA.
Note

QC 20191115

Available from: 2019-11-09 Created: 2019-11-09 Last updated: 2019-11-15Bibliographically approved
8. Quantitative Assessment of Inkjet Reliability under Industrial Conditions: Measuring All Drops during Extended High‐Duty Printing
Open this publication in new window or tab >>Quantitative Assessment of Inkjet Reliability under Industrial Conditions: Measuring All Drops during Extended High‐Duty Printing
2018 (English)In: Handbook of Industrial Inkjet Printing / [ed] Werner Zapka, Weinheim: Wiley-VCH Verlagsgesellschaft, 2018, p. 445-458Chapter in book (Refereed)
Abstract [en]

Reliability is one of the key challenges in inkjet technology. Nozzles perform unreliably for a number of reasons, such as drying, clogging through air‐ and inkborne contaminants, ingestion of air, or nozzle plate flooding. To extract quantitative information about the number of missing droplets from the acquired images, suitable algorithms need to be applied. To identify the presence of the droplet, a value derived from the characteristics of the area of interest needs to be compared with the threshold value. The Line Scan approach for the measurement of reliability offers a convenient way to assess reliability of a printhead in a laboratory environment providing quantitative and statistical data about location, duration, and time of misfire events. With the knowledge of the printhead frequency and the hypothetical print resolution applied in the printing experiments, the length of such tic marks as a number of subsequent missing droplets can be calculated.

Place, publisher, year, edition, pages
Weinheim: Wiley-VCH Verlagsgesellschaft, 2018
National Category
Fluid Mechanics and Acoustics Signal Processing Media Engineering
Identifiers
urn:nbn:se:kth:diva-263707 (URN)10.1002/9783527687169.ch24 (DOI)2-s2.0-85052003312 (Scopus ID)9783527338320 (ISBN)9783527687169 (ISBN)
Note

QC 20191111

Available from: 2019-11-09 Created: 2019-11-09 Last updated: 2019-11-11Bibliographically approved

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Citation style
  • apa
  • harvard1
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More styles
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  • de-DE
  • en-GB
  • en-US
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