Inkjet printing and IR sintering optimization for flexible electronic applications

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Volume Title
School of Chemical Technology | Doctoral thesis (article-based) | Defence date: 2019-02-01
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Author
Date
2019
Department
Kemian ja materiaalitieteen laitos
Department of Chemistry and Materials Science
Major/Subject
Mcode
Degree programme
Language
en
Pages
74 + app. 38
Series
Aalto University publication series DOCTORAL DISSERTATIONS, 18/2019
Abstract
The main focus of this thesis work was to develop mass manufacturing compatible fabrication processes for flexible electronic devices, using paper either as an active layer or as a substrate. Combining common printing techniques with low temperature sintering processes was the key to develop and optimize the production of such simple devices on flexible substrates, mainly paper. The use of paper as a flexible substrate has highly attractive characteristics, being its low cost, wide availability and environmental friendliness, some of the more appealing. Together, they make paper substrates exceptionally interesting for printed electronics, when compared with more traditional substrates, such as polymers. Nevertheless, functional printing of simple components or complex devices on paper is extremely challenging, mainly due to the porosity of the substrate or low heat resistance. Aditionally, commercial inks are developed mainly for non-porous substrates, as polymers, and need a specific range of sintering time and temperatures, to be functional. That makes them immensely defiant to use in porous substrates or be compatible with mass manu-facturing processes, where cost and speed are main restrictions in the industry. In this thesis work, inkjet printing and sintering optimization parameters have been tuned in order to obtain good conductivity on various commercial paper substrates. Multicoated paper Lumi silk from StoraEnso was chosen as the optimal substrate for printed electronics. This was mainly because of its smoothness, which promoted good line uniformity, non-disruptive and less ink penetration into the substrate, without the need for additional coatings. More, this substrate was able to endure slightly higher sintering temperatures than the other paper substrates, for the same period of sintering time. The use of photonic sintering methods reduces drastically the sintering time, allowing a more localized heating, for a very short, sometimes almost instantaneous, period of time. Infrared sintering was then the sintering method of choice, allowing fast sintering of silver layers, under 10 minutes. It is compatible with roll-to-roll fabrication, enabling low-cost mass manufacturing of devices. We demonstrate various devices fabricated by inkjet printing techniques: an OFF/ON switch with semiconducting active layer, a capacitive humidity sensor with a response time of about 5 minutes, and a paper microfluidic device with conductivity detection for protein analysis.
Description
Supervising professor
Franssila, Sami, Prof., Aalto University, Department of Chemistry and Materials Science, Finland
Thesis advisor
Smolander, Maria, Dr., VTT Technical Research Centre of Finland Ltd, Finland
Keywords
photonic sintering, paper substrate, switch, humidity sensor, interdigitated electrode, isoelectric focusing, paper microfluidics
Other note
Parts
  • [Publication 1]: Cate, Tessa; Gaspar, Cristina; Virtanen, Heini; Stevens, Ralph; Koldeweij, Robin; Olkkonen, Juuso; Rentrop, Corné; Smolander, Maria. 2014. Printed electronic switch on flexible substrates using printed microcapsules. ©Springer International Publishing AG. Journal of Materials Science, volume 49, issue 17, pages 5831-5837. ISSN 0022-2461 (Print) 1573-4803 (Online).
    DOI: 10.1007/s10853-014-8271-7 View at publisher
  • [Publication 2]: Gaspar, Cristina; Passoja, Soile; Olkkonen, Juuso; Smolander, Maria. 2016. IR-sintering efficiency on inkjet-printed conductive structures on paper substrates. Elsevier B.V.. Microelectronic Engineering, volume 149, pages 135-140. ISSN 0167-9317.
    DOI: 10.1016/j.mee.2015.10.006 View at publisher
  • [Publication 3]: Gaspar, Cristina; Olkkonen, Juuso; Passoja, Soile; Smolander, Maria. 2017. Paper as active layer in inkjet-printed capacitive humidity sensors. Sensors. Sensors, volume 17, issue 7, pages 1464. ISSN 1424-8220.
    DOI: 10.3390/s17071464 View at publisher
  • [Publication 4]: Gaspar, Cristina; Sikanen, Tiina; Franssila, Sami; Jokinen, Ville. 2016. Inkjet-printed silver electrodes on macroporous paper for a paper based isoelectric focusing device. AIP (American Institute of Physics). Biomicrofluidics, volume 10, issue 6, pages 064120. ISSN 1932-1058.
    DOI: 10.1063/1.4973246 View at publisher
  • [Publication 5]: Hakola, Liisa; Gaspar, Cristina; Ilmonen, Anu; Lehtinen, Kaisa; Smolander, Maria. 2014. Printed Intelligence for consumer products. IEEE. Proceedings of the 5th Electronics System-Integration Technology Conference (ESTC), pages 1-4.
    DOI: 10.1109/ESTC.2014.6962774 View at publisher
Citation
Permanent link to this item
https://urn.fi/URN:ISBN:978-952-60-8399-5
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[diss] Kemian tekniikan korkeakoulu / CHEM