View source for Printed electronics

{{Short description|Electronic devices created by various printing methods}}
{{distinguish|Printed circuit board}}
[[File:Elektronikdruck.jpg|thumb|Gravure printing of electronic structures on paper]]

'''Printed electronics''' is a set of [[printing]] methods used to create electrical devices on various substrates. Printing typically uses common printing equipment suitable for defining patterns on material, such as [[screen printing]], [[flexography]], [[gravure]], [[offset lithography]], and [[inkjet]]. By electronic-industry standards, these are low-cost processes. Electrically functional electronic or optical inks are deposited on the substrate, creating active or passive devices, such as [[thin film transistors]], capacitors, coils, and [[resistors]]. Some researchers expect printed electronics to facilitate widespread, very low-cost, low-performance electronics for applications such as [[flexible display]]s, [[smart labels]], decorative and animated posters, and active clothing that do not require high performance.<ref name="Coa09">
Coatanéa, E., Kantola, V., Kulovesi, J., Lahti, L., Lin, R., & Zavodchikova, M. (2009). Printed Electronics, Now and Future. In Neuvo, Y., & Ylönen, S. (eds.), Bit Bang – Rays to the Future. Helsinki University of Technology (TKK), MIDE, Helsinki University Print, Helsinki, Finland, 63-102. {{ISBN|978-952-248-078-1}}. http://lib.tkk.fi/Reports/2009/isbn9789522480781.pdf - "Moreover, PE technology could provide a number of enabling factors like flexibility and robustness, allowing incorporation of electronics functions into objects that do not yet contain any active electronic components, e.g. toy applications, printed advertising material or electronic labels [...]."</ref>

The term ''printed electronics'' is often related{{by whom|date=May 2021}} to [[organic electronics]] or [[plastic electronics]], in which one or more inks are composed of carbon-based compounds.<ref>{{Cite web|title= Printed & Flexible Electronics - IDTechEx Research Reports and Subscriptions|url= https://www.idtechex.com/en/reports/printed-and-flexible-electronics/1|access-date=2020-09-21|website=www.idtechex.com|language=en}}</ref>{{request quotation|date=May 2021}} These other terms refer to the ink material, which can be deposited by solution-based, vacuum-based, or other processes. Printed electronics, in contrast, specifies the process, and, subject to the specific requirements of the printing process selected, can utilize any solution-based material. This includes [[organic semiconductor]]s, [[inorganic]] [[semiconductor]]s, metallic conductors, [[nanoparticle]]s, and [[Carbon nanotube|nanotubes]]. The solution usually consist of filler materials dispersed in a suitable solvent. The most commonly used solvents include ethanol, xylene, Dimethylformamide (DMF), Dimethyl sulfoxide (DMSO), toluene and water, whereas, the most common conductive fillers include silver nanoparticles, silver flakes, carbon black, graphene, carbon nanotubes, conductive polymers (such as polyaniline and polypyrrole), and metal powders (such as copper or nickel). Considering the environmental impacts of the organic solvents, researchers are now focused on developing printable inks using water.<ref>{{cite journal |last1=Khan |first1=Junaid |last2=Mariatti |first2=M |last3=Zubir |first3=Syazana A |last4=Rusli |first4=Arjulizan |last5=Manaf |first5=Asrulnizam Abd |last6=Khirotdin |first6=Rd Khairilhijra |title=Eco-friendly alkali lignin-assisted water-based graphene oxide ink and its application as a resistive temperature sensor |journal=Nanotechnology |date=29 January 2024 |volume=35 |issue=5 |pages=055301 |doi=10.1088/1361-6528/ad06d4|pmid=37879329 |bibcode=2024Nanot..35e5301K |doi-access=free }}</ref><ref>{{cite journal |last1=Khan |first1=Junaid |last2=Mariatti |first2=M |title=In-situ graphene oxide reduction via inkjet printing using natural reducing inks |journal=Flexible and Printed Electronics |date=1 September 2023 |volume=8 |issue=3 |pages=035009 |doi=10.1088/2058-8585/acf143|doi-access=free }}</ref><ref>{{cite journal |last1=Khan |first1=Junaid |last2=Mariatti |first2=M. |title=Effect of natural surfactant on the performance of reduced graphene oxide conductive ink |journal=Journal of Cleaner Production |date=November 2022 |volume=376 |pages=134254 |doi=10.1016/j.jclepro.2022.134254|bibcode=2022JCPro.37634254K }}</ref>

For the preparation of printed electronics nearly all industrial printing methods are employed. Similar to conventional printing, printed electronics applies ink layers one atop another.<ref name="Rot01">{{cite journal | last1 = Roth | first1 = H.-K. | display-authors = et al | year = 2001 | title =  Organische Funktionsschichten in Polymerelektronik und Polymersolarzellen| journal = Materialwissenschaft und Werkstofftechnik | volume = 32 | issue = 10| page = 789 | doi = 10.1002/1521-4052(200110)32:10<789::AID-MAWE789>3.0.CO;2-E }}</ref> So the coherent development of printing methods and ink materials are the field's essential tasks.<ref>{{Cite journal|last= Thomas|first= D.J.|date= 2016|title= Integration of Silicon and Printed Electronics for Rapid Diagnostic Disease Biosensing|journal= Point of Care: The Journal of Near-Patient Testing & Technology|volume= 15|issue=2|pages=61–71|doi=10.1097/POC.0000000000000091|s2cid=77379659}}</ref>

The most important benefit of printing is low-cost volume fabrication.{{citation needed|date=May 2021}} The lower cost enables use in more applications.<ref name="Xu00">
{{cite journal | doi = 10.1016/s0379-6779(00)00291-5 | volume=115 | issue=1–3 | title=Plastic electronics and future trends in microelectronics | journal=Synthetic Metals | pages=1–3 | year=2000| last1=Xu | first1= J.M.(Jimmy) }}</ref> An example is [[RFID]]-systems, which enable contactless identification in trade and transport. In some domains, such as [[light-emitting diodes]] printing does not impact performance.<ref name="Rot01"/> Printing on flexible substrates allows electronics to be placed on curved surfaces, for example: printing solar cells on vehicle roofs. More typically, conventional semiconductors justify their much higher costs by providing much higher performance.

[[File:ComplementaryTechnologies.png|thumb|Printed and conventional electronics as complementary technologies.]]

==Resolution, registration, thickness, holes, materials==
The maximum required resolution of structures in conventional printing is determined by the human eye. Feature sizes smaller than approximately 20&nbsp;μm cannot be distinguished by the human eye and consequently exceed the capabilities of conventional printing processes.<ref name="Bla05">
A. Blayo and B. Pineaux, Joint sOC-EUSAI Conference, Grenoble, 2005.</ref> In contrast, higher resolution and smaller structures are necessary in most electronics printing, because they directly affect  circuit density and functionality (especially transistors). A similar requirement holds for the precision with which layers are printed on top of each other (layer to layer registration).

Control of thickness, holes, and material compatibility (wetting, adhesion, solubility) are essential, but matter in conventional printing only if the eye can detect them. Conversely, the visual impression is irrelevant for printed electronics.<ref name="Fug06">U. Fügmann et al., mstNews 2 (2006) 13.</ref>

==Printing technologies==
The attraction of printing technology for the fabrication of electronics mainly results from the possibility of preparing stacks of micro-structured layers (and thereby thin-film devices) in a much simpler and cost-effective way compared to conventional electronics.<ref name="She04">J. R. Sheats, ''Journal of Materials Research'' 2004; 19  1974.</ref>  Also, the ability to implement new or improved functionalities (e.g. mechanical flexibility) plays a role.  The selection of the printing method used is determined by requirements concerning printed layers, by the properties of printed materials as well as economic and technical considerations of the final printed products.

Printing technologies divide between sheet-based and [[roll-to-roll]]-based approaches. Sheet-based [[inkjet]] and [[screen printing]] are best for low-volume, high-precision work. [[Gravure]], [[offset printing|offset]] and [[flexography|flexographic printing]] are more common for high-volume production, such as solar cells, reaching 10,000 square meters per hour (m<sup>2</sup>/h).<ref name="Bla05"/><ref name="She04"/> While offset and flexographic printing are mainly used for inorganic<ref name="Har02">{{cite journal | last1 = Harrey | first1 = P.M. | display-authors = et al | year = 2002 | title =  Capacitive-type humidity sensors fabricated using the offset lithographic printing process| journal = Sensors and Actuators B | volume = 87 | issue = 2| pages = 226–232 | doi=10.1016/s0925-4005(02)00240-x| bibcode = 2002SeAcB..87..226H }}</ref><ref name="Sid05">J. Siden et al., Polytronic Conference, Wroclaw, 2005.</ref> and organic<ref name="Zie05">{{cite journal | last1 = Zielke | first1 = D. | display-authors = et al | year = 2005 | title =  Polymer-based organic field-effect transistor using offset printed source/drain structures| doi = 10.1063/1.2056579 | journal = Applied Physics Letters | volume = 87 | issue = 12| page = 123508 | bibcode = 2005ApPhL..87l3508Z }}</ref><ref name="Mak05">{{cite journal | last1 = Mäkelä | first1 = T. | display-authors = et al | year = 2005 | title =  Utilizing roll-to-roll techniques for manufacturing source-drain electrodes for all-polymer transistors| journal = Synthetic Metals | volume = 153 | issue = 1–3| pages = 285–288 | doi=10.1016/j.synthmet.2005.07.140}}</ref> conductors (the latter also for dielectrics),<ref name="Hub07">{{cite journal | last1 = Hübler | first1 = A. | display-authors = et al | year = 2007 | title =  Ring oscillator fabricated completely by means of mass-printing technologies| journal = Organic Electronics | volume = 8 | issue = 5| page = 480 | doi = 10.1016/j.orgel.2007.02.009 }}</ref> [[gravure]] printing is especially suitable for quality-sensitive layers like organic semiconductors and semiconductor/dielectric-interfaces in transistors, due to high layer quality.<ref name="Hub07"/> If high resolution is needed, gravure is also suitable for inorganic<ref name="Lep94">S. Leppavuori et al., Sensors and Actuators 41-42 (1994) 593.</ref> and organic<ref name="Mak03">{{cite journal | last1 = Mäkelä | first1 = T. | display-authors = et al | year = 2003 | title =  Roll-to-roll method for producing polyaniline patterns on paper| doi = 10.1016/s0379-6779(02)00753-1 | journal = Synthetic Metals | volume = 135 | page = 41 }}</ref> conductors. Organic [[field-effect transistors]] and [[integrated circuit]]s can be prepared completely by means of mass-printing methods.<ref name="Hub07"/>

===Inkjet printing===
Inkjets are flexible and versatile, and can be set up with relatively low effort.<ref name="Par05">{{cite journal | last1 = Parashkov | first1 = R. | display-authors = et al | year = 2005 | title =  Large Area Electronics Using Printing Methods| journal = Proceedings of the IEEE | volume = 93 | issue = 7| pages = 1321–1329 | doi=10.1109/jproc.2005.850304| s2cid = 27061013 }}</ref> However, inkjets offer lower throughput of around 100&nbsp;m<sup>2</sup>/h and lower resolution (ca. 50&nbsp;μm).<ref name="Bla05"/> It is well suited for low-[[viscosity]], soluble materials like organic semiconductors. With high-viscosity materials, like organic dielectrics, and  dispersed particles, like inorganic metal inks, difficulties due to nozzle clogging occur. Because ink is deposited via droplets, thickness and dispersion homogeneity is reduced. Using many nozzles simultaneously and pre-structuring the substrate allows improvements in productivity and resolution, respectively. However, in the latter case non-printing methods must be employed for the actual patterning step.<ref name="Gan04">{{cite journal | last = de Gans | first = B.-J. | display-authors = et al | year = 2004 | title =  Inkjet Printing of Polymers: State of the Art and Future Developments| doi = 10.1002/adma.200300385 | journal = Advanced Materials | volume = 16 | issue = 3| page = 203 | bibcode = 2004AdM....16..203D }}</ref> Inkjet printing is preferable for organic semiconductors in [[OFET|organic field-effect transistors]] (OFETs) and [[organic light-emitting diode]]s (OLEDs), but also OFETs completely prepared by this method have been demonstrated.<!-- this is illogical--><ref name="Sub05">{{cite journal | last1 = Subramanian | first1 = V. | display-authors = et al | year = 2005 | title =  Progress Toward Development of All-Printed RFID Tags: Materials, Processes, and Devices| doi = 10.1109/jproc.2005.850305 | journal = Proceedings of the IEEE | volume = 93 | issue = 7| page = 1330 | s2cid = 8915461 }}</ref> Frontplanes<ref name="Hol01">
S. Holdcroft, ''Advanced Materials'' 2001; 13  1753.</ref> and [[backplane]]s<ref name="Ari04">{{cite journal | last1 = Arias | first1 = A.C. | display-authors = et al | year = 2004 | title =  All jet-printed polymer thin-film transistor active-matrix backplanes| journal = Applied Physics Letters | volume = 85 | issue = 15| page = 3304 | doi=10.1063/1.1801673| bibcode = 2004ApPhL..85.3304A }}</ref> of OLED-displays, integrated circuits,<ref name="Sir00">{{cite journal | last1 = Sirringhaus | first1 = H. | display-authors = et al | year = 2000 | title =  High-Resolution Inkjet Printing of All-Polymer Transistor Circuits| journal = Science | volume = 290 | issue = 5499| pages = 2123–2126 | doi=10.1126/science.290.5499.2123 | pmid=11118142| bibcode = 2000Sci...290.2123S }}</ref> [[organic photovoltaic|organic photovoltaic cells (OPVCs)]]<ref name="Sha04">
V.G. Shah and D.B. Wallace, IMAPS Conference, Long Beach, 2004.</ref> and other devices can be prepared with inkjets.

===Screen printing===
[[Screen printing]] is appropriate for fabricating electrics and electronics due to its ability to produce patterned, thick layers from paste-like materials. This method can produce conducting lines from inorganic materials (e.g. for circuit boards and antennas), but also insulating and passivating layers, whereby layer thickness is more important than high resolution. Its 50 m<sup>2</sup>/h throughput and 100&nbsp;μm resolution are similar to inkjets.<ref name="Bla05"/> This versatile and comparatively simple method is used mainly for conductive and dielectric layers,<ref name="Boc05">{{cite journal | last1 = Bock | first1 = K. | display-authors = et al | year = 2005 | title =  Polymer Electronics Systems - Polytronics| journal = Proceedings of the IEEE | volume = 93 | issue = 8| pages = 1400–1406 | doi=10.1109/jproc.2005.851513| s2cid = 23177369 }}</ref><ref name="Bao97">{{cite journal | last1 = Bao | first1 = Z. | display-authors = et al | year = 1997 | title =  High-Performance Plastic Transistors Fabricated by Printing Techniques| journal = Chemistry of Materials | volume = 9 | issue = 6| pages = 1299–1301 | doi=10.1021/cm9701163}}</ref> but also organic semiconductors, e.g. for OPVCs,<ref name="Sha01a">{{cite journal | last1 = Shaheen | first1 = S.E. | display-authors = et al | year = 2001 | title =  Fabrication of bulk heterojunction plastic solar cells by screen printing| journal = Applied Physics Letters | volume = 79 | issue = 18| page = 2996 | doi=10.1063/1.1413501| bibcode = 2001ApPhL..79.2996S }}</ref> and even complete [[Organic field-effect transistor|OFETs]]<ref name="Hol01"/> can be printed.

===Aerosol jet printing===
Aerosol Jet Printing (also known as Maskless Mesoscale Materials Deposition or M3D)<ref name="Ren12">M. Renn, US Patent number 7,485,345 B2. Page 3.</ref> is another material deposition technology for printed electronics. The Aerosol Jet process begins with [[Aerosol|atomization]] of an ink, via ultrasonic or pneumatic means, producing droplets on the order of one to two micrometers in diameter. The droplets then flow through a virtual impactor which deflects the droplets having lower momentum away from the stream. This step helps maintaining a tight droplet size distribution. The droplets are entrained in a gas stream and delivered to the print head. Here, an annular flow of clean gas is introduced around the aerosol stream to focus the droplets into a tightly collimated beam of material. The combined gas streams exit the print head through a converging nozzle that compresses the aerosol stream to a diameter as small as 10&nbsp;μm. The jet of droplets exits the print head at high velocity (~50 meters/second) and impinges upon the substrate.

Electrical interconnects, passive and active components<ref name="Cho08">J.H. Cho et al, Nature Materials, 19 October 2008.</ref> are formed by moving the print head, equipped with a mechanical stop/start shutter, relative to the substrate. The resulting patterns can have features ranging from 10&nbsp;μm wide, with layer thicknesses from tens of nanometers to >10&nbsp;μm.<ref name="Kha07">B. Kahn, ''Organic and Printed Electronics'', Volume 1, Issue 2 (2007).</ref> A wide nozzle print head enables efficient patterning of millimeter size electronic features and surface coating applications. All printing occurs without the use of vacuum or pressure chambers. The high exit velocity of the jet enables a relatively large separation between the print head and the substrate, typically 2–5&nbsp;mm. The droplets remain tightly focused over this distance, resulting in the ability to print conformal patterns over three dimensional substrates.

Despite the high velocity, the printing process is gentle; substrate damage does not occur and there is generally minimal splatter or overspray from the droplets.<ref name="Kin09">B. H. King et al, Photovoltaic Specialists Conference (PVSC), 2009 34th IEEE.</ref> Once patterning is complete, the printed ink typically requires post treatment to attain final electrical and mechanical properties. Post-treatment is driven more by the specific ink and substrate combination than by the printing process. A wide range of materials has been successfully deposited with the Aerosol Jet process, including diluted thick film pastes, conducting polymer inks,<ref>{{Cite journal|last1=Fisher|first1=Christine|last2=Warmack|first2=Bruce J.|last3=Yu|first3=Yongchao|last4=Skolrood|first4=Lydia N.|last5=Li|first5=Kai|last6=Joshi|first6=Pooran C.|last7=Saito|first7=Tomonori|last8=Aytug|first8=Tolga|date=2021-04-19|title=All-aerosol-jet-printed highly sensitive and selective polyaniline-based ammonia sensors: a route toward low-cost, low-power gas detection|url=https://doi.org/10.1007/s10853-021-06080-0|journal=Journal of Materials Science|volume=56|issue=22|pages=12596–12606|language=en|doi=10.1007/s10853-021-06080-0|bibcode=2021JMatS..5612596F |osti=1798595 |s2cid=233303736|issn=1573-4803}}</ref> thermosetting polymers such as UV-curable epoxies, and solvent-based [[polymer]]s like polyurethane and polyimide, and biologic materials.<ref name="Gru10">Ingo Grunwald et al, 2010 Biofabrication 2 014106.</ref>

Recently, printing paper was proposed to be used as the substrate of the printing. Highly conductive (close to bulk copper) and high-resolution traces can be printed on foldable and available office printing papers, with 80°Celsius curing temperature and 40 minutes of curing time.<ref>{{cite journal |first1=Yi-Dan |last1=Chen |first2=Vijayasarathi |last2=Nagarajan|first3=David W. |last3=Rosen|first4=Wenwei |last4=Yu|first5=Shao Ying |last5=Huang|title=Wireless Power Transfer via Strongly Coupled Magnetic Resonances |journal=Journal of Manufacturing Processes |volume=58 |date=Oct 2020 |pages=55–66 |doi=10.1016/j.jmapro.2020.07.064}}</ref>

===Evaporation printing===
Evaporation printing uses a combination of high precision screen printing with material vaporization to print features to 5&nbsp;[[μm]]. This method uses techniques such as thermal, e-beam, sputter and other traditional production technologies to deposit materials through a high precision shadow mask (or stencil) that is registered to the substrate to better than 1&nbsp;μm. By layering different mask designs and/or adjusting materials, reliable, cost-effective circuits can be built additively, without the use of photo-lithography.

===Other methods===
Other methods with similarities to printing, among them [[microcontact printing]] and [[nanoimprint lithography|nano-imprint lithography]] are of interest.<ref name="Gat05">{{cite journal | last1 = Gate | first1 = B.D. | display-authors = et al | year = 2005 | title =  New Approaches to Nanofabrication: Molding, Printing, and Other Techniques| doi = 10.1021/cr030076o | journal = Chemical Reviews | volume = 105 | issue = 4| pages = 1171–96 | pmid = 15826012 }}</ref> Here, μm- and nm-sized layers, respectively, are prepared by methods similar to stamping with soft and hard forms, respectively. Often the actual structures are prepared subtractively, e.g. by deposition of etch masks or by lift-off processes. For example, electrodes for OFETs can be prepared.<ref name="Li06">{{cite journal | last1 = Li | first1 = D. | last2 = Guo | first2 = L.J. | year = 2006 | title =  Micron-scale organic thin film transistors with conducting polymer electrodes patterned by polymer inking and stamping| doi = 10.1063/1.2168669 | journal = Applied Physics Letters | volume = 88 | issue = 6| page = 063513 | bibcode = 2006ApPhL..88f3513L | hdl = 2027.42/87779 | url = https://deepblue.lib.umich.edu/bitstream/2027.42/87779/2/063513_1.pdf | hdl-access = free }}</ref><ref name="Lei06">{{cite journal | last1 = Leising | first1 = G. | display-authors = et al | year = 2006 | title = Nanoimprinted devices for integrated organic electronics| doi = 10.1016/j.mee.2006.01.241 | journal = Microelectronics Engineering | volume = 83 | issue = 4–9| page = 831 }}</ref> Sporadically [[pad printing]] is used in a similar manner.<ref name="Kno04">{{cite journal | last1 = Knobloch | first1 = A. | display-authors = et al | year = 2004 | title =  Fully printed integrated circuits from solution processable polymers| journal = Journal of Applied Physics | volume = 96 | issue = 4| page = 2286 | doi=10.1063/1.1767291| bibcode = 2004JAP....96.2286K }}</ref> Occasionally so-called transfer methods, where solid layers are transferred from a carrier to the substrate, are considered printed electronics.<ref name="Hin07">{{cite journal | last1 = Hines | first1 = D.R. | display-authors = et al | year = 2007 | title =  Transfer printing methods for the fabrication of flexible organic electronics| doi = 10.1063/1.2403836 | journal = Journal of Applied Physics | volume = 101 | issue = 2| pages = 024503–024503–9 | bibcode = 2007JAP...101b4503H }}</ref> [[xerography|Electrophotography]] is currently not used in printed electronics.

==Materials==
Both organic and inorganic materials are used for printed electronics. Ink materials must be available in liquid form, for solution, dispersion or suspension.<ref name="Bao00">
Z. Bao, ''Advanced Materials'' 2000; 12: 227.</ref> They must function as conductors, semiconductors, dielectrics, or insulators. Material costs must be fit for the application.

Electronic functionality and printability can interfere with each other, mandating careful optimization.<ref name="Fug06"/> For example, a higher molecular weight in polymers enhances conductivity, but diminishes solubility. For printing, viscosity, surface tension and solid content must be tightly controlled. Cross-layer interactions such as wetting, adhesion, and solubility as well as post-deposition drying procedures affect the outcome. Additives often used in conventional printing inks are unavailable, because they often defeat electronic functionality.

Material properties largely determine the differences between printed and conventional electronics. Printable materials provide decisive advantages beside printability, such as mechanical flexibility and functional adjustment by chemical modification (e.g. light color in OLEDs).<ref name="Mol04">{{cite journal | last1 = Moliton | last2 = Hiorns | first2 = R.C. | year = 2004 | title =  Review of electronic and optical properties of semiconductingπ-conjugated polymers: applications in optoelectronics| journal = Polymer International | volume = 53 | issue = 10| pages = 1397–1412 | doi=10.1002/pi.1587}}</ref>

Printed conductors offer lower conductivity and charge carrier mobility.<ref name="Nob00"/>

With a few exceptions, inorganic ink materials are dispersions of metallic or semiconducting micro- and nano-particles. Semiconducting nanoparticles used include silicon<ref name="UMA01">{{cite journal | last1 = Maennl | first1 = U. | display-authors = et al | year = 2013 | title =  Interfacial and Network Characteristics of Silicon Nanoparticle Layers Used in Printed Electronics| journal = Japanese Journal of Applied Physics | volume =  52| issue = 5S1| pages =  05DA11| doi = 10.7567/JJAP.52.05DA11 | bibcode = 2013JaJAP..52eDA11M }}</ref>  and oxide semiconductors.<ref name ="Fab09">{{cite journal | last1 = Faber | first1 = H. | display-authors = et al | year = 2009 | title =  Low-Temperature Solution-Processed Memory Transistors Based on Zinc Oxide Nanoparticles| doi = 10.1002/adma.200900440 | journal = Advanced Materials | volume = 21 | issue = 30| page = 3099 | bibcode = 2009AdM....21.3099F }}</ref> Silicon is also printed as an organic precursor<ref name ="Shi06">{{cite journal | last1 = Shimoda | first1 = T. | display-authors = et al | year = 2006 | title =  Solution-processed silicon films and transistors| journal = Nature | volume = 440 | issue = 7085| pages = 783–786 | doi=10.1038/nature04613| pmid = 16598254 | bibcode = 2006Natur.440..783S | s2cid = 4344708 }}</ref>  which is then converted by pyrolysis and annealing into crystalline silicon.

[[PMOS logic|PMOS]] but not [[CMOS]] is possible in printed electronics.<ref name="Lee97"/>

===Organic materials===
Organic printed electronics integrates knowledge and developments from printing, electronics, chemistry, and materials science, especially from organic and polymer chemistry. Organic materials in part differ from conventional electronics in terms of structure, operation and functionality,<ref name="Var05">{{cite journal | last1 = Vardeny | first1 = Z.V. | display-authors = et al | year = 2005 | title =  Fundamental research needs in organic electronic materials| doi = 10.1016/j.synthmet.2004.09.001 | journal = Synthetic Metals | volume = 148 | page = 1 }}</ref> which influences device and circuit design and optimization as well as fabrication method.<ref name="Kem01">H. Kempa et al., it 3 (2008) 167.</ref>

The discovery of [[conductive polymer|conjugated polymers]]<ref name="Nob00">
http://nobelprize.org/nobel_prizes/chemistry/laureates/2000/chemadv.pdf Nobel prize in chemistry, 2000</ref>  and their development into soluble materials provided the first organic ink materials. Materials from this class of polymers variously possess [[electrical conduction|conducting]], [[semiconductor|semiconducting]], [[electroluminescence|electroluminescent]], [[photovoltaics|photovoltaic]] and other properties. Other polymers are used mostly as [[insulator (electrical)|insulators and dielectrics]].

In most organic materials, hole transport is favored over electron transport.<ref name="Fac07">{{cite journal | last1 = Fachetti | year = 2007 | title =  Semiconductors for organic transistors| journal = Materials Today | volume = 10 | issue = 3| page = 38 | doi = 10.1016/S1369-7021(07)70017-2| doi-access = free }}</ref> Recent studies indicate that this is a specific feature of organic semiconductor/dielectric-interfaces, which play a major role in OFETs.<ref name="Zau07">{{cite journal | last1 = Zaumseil | first1 = J. | last2 = Sirringhaus | first2 = H. | year = 2007 | title =  Electron and Ambipolar Transport in Organic Field-Effect Transistors| journal = Chemical Reviews | volume = 107 | issue = 4| pages = 1296–1323 | doi=10.1021/cr0501543 | pmid=17378616}}</ref> Therefore, p-type devices should dominate over n-type devices. Durability (resistance to dispersion) and lifetime is less than conventional materials.<ref name="Lee97">{{cite journal | last = de Leeuw | first = D. M. | display-authors = et al | year = 1997 | title =  Stability of n-type doped conducting polymers and consequences for polymeric microelectronic devices| doi = 10.1016/s0379-6779(97)80097-5 | journal = Synthetic Metals | volume = 87 | page = 53 }}</ref>

Organic semiconductors include the conductive [[polymer]]s poly(3,4-ethylene dioxitiophene), doped with poly([[styrene]] [[sulfonate]]), ([[PEDOT:PSS]]) and poly([[aniline]]) (PANI). Both polymers are commercially available in different formulations and have been printed using inkjet,<ref name="Bha06">{{cite journal | last1 = Bharathan | first1 = J. | last2 = Yang | first2 = Y. | year = 2006 | title =  Polymer electroluminescent devices processed by inkjet printing: I. Polymer light-emitting logo| doi = 10.1063/1.121090| journal = Applied Physics Letters | volume = 72 | issue = 21| page = 2660 | bibcode = 1998ApPhL..72.2660B }}</ref> screen<ref name="Boc05"/> and offset printing<ref name="Zie05"/> or screen,<ref name="Boc05"/> flexo<ref name="Mak05"/> and gravure<ref name="Mak03"/> printing, respectively.

Polymer semiconductors are processed using inkjet printing, such as [[polythiophene|poly(thiopene)s]] like poly(3-hexylthiophene) (P3HT)<ref name="Spe01">{{cite journal | last1 = Speakman | first1 = S.P. | display-authors = et al | year = 2001 | title =  High performance organic semiconducting thin films: Ink jet printed polythiophene &#91;rr-P3HT&#93;| journal = Organic Electronics | volume = 2 | issue = 2| page = 65 | doi = 10.1016/S1566-1199(01)00011-8 }}</ref> and poly(9,9-dioctylfluorene co-bithiophen) (F8T2).<ref name="Pau03">{{cite journal | last1 = Paul | first1 = K.E. | display-authors = et al | year = 2003 | title =  Additive jet printing of polymer thin-film transistors| journal = Applied Physics Letters | volume = 83 | issue = 10| page = 2070 | doi=10.1063/1.1609233| bibcode = 2003ApPhL..83.2070P }}</ref> The latter material has also been gravure printed.<ref name="Hub07"/> Different electroluminescent polymers are used with inkjet printing,<ref name="Gan04"/> as well as active materials for [[photovoltaic]]s (e.g. blends of P3HT with [[fullerene]] derivatives),<ref name="Aer08">{{cite journal | last1 = Aernouts | first1 = T. | display-authors = et al | year = 2008 | title =  Polymer based organic solar cells using ink-jet printed active layers| doi = 10.1063/1.2833185| journal = Applied Physics Letters | volume = 92 | issue = 3| page = 033306 | bibcode = 2008ApPhL..92c3306A | url = https://lirias.kuleuven.be/handle/123456789/638267 | url-access = subscription }}</ref> which in part also can be deposited using screen printing (e.g. blends of [[poly(p-phenylene vinylene)|poly(phenylene vinylene)]] with fullerene derivatives).<ref name="Sha01a"/>

Printable organic and inorganic insulators and dielectrics exist, which can be processed with different printing methods.<ref>{{cite web|title=Ion Gel Insulator |url=http://www.license.umn.edu/Products/Ion-Gel-as-a-Gate-Insulator-in-Field-Effect-Transistors__Z07062.aspx |url-status=dead |archive-url=https://web.archive.org/web/20111114011218/http://www.license.umn.edu/Products/Ion-Gel-as-a-Gate-Insulator-in-Field-Effect-Transistors__Z07062.aspx |archive-date=November 14, 2011 }}</ref>

===Inorganic materials===
Inorganic electronics provides highly ordered layers and interfaces that organic and polymer materials cannot provide.

[[Silver nanoparticle]]s are used with flexo,<ref name="Sid05"/> offset<ref name="Har00">{{cite journal|last1=Harrey|first1=P. M.|title=Interdigitated Capacitors by Offset Lithography|display-authors=et al|year=2000|journal=Journal of Electronics Manufacturing|volume=10|pages=69–77|doi=10.1142/s096031310000006x}}</ref>  and inkjet.<ref name="Per06">{{cite journal | last1 = Perelaer | first1 = J. | display-authors = et al | year = 2006 | title =  Ink-jet Printing and Microwave Sintering of Conductive Silver Tracks| url = http://library.tue.nl/csp/dare/LinkToRepository.csp?recordnumber=621662| journal = Advanced Materials | volume = 18 | issue = 16| pages = 2101–2104 | doi=10.1002/adma.200502422| bibcode = 2006AdM....18.2101P | url-access = subscription }}</ref> [[Gold]] particles are used with inkjet.<ref name="Noh07">{{cite journal | last1 = Noh | first1 = Y.-Y. | display-authors = et al | year = 2007 | title =  Downscaling of self-aligned, all-printed polymer thin-film transistors| journal = Nature Nanotechnology | volume = 2 | issue = 12| pages = 784–789 | doi=10.1038/nnano.2007.365| pmid = 18654432 | bibcode = 2007NatNa...2..784N }}</ref>

A.C. [[electroluminescent]] (EL) multi-color displays can cover many tens of square meters, or be incorporated in watch faces and instrument displays. They involve six to eight printed inorganic layers, including a copper doped phosphor, on a plastic film substrate.<ref name="packagingessentials.com">
Mflex UK (formerly Pelikon) and elumin8, both in the UK, Emirates Technical Innovation Centre in Dubai, [[Schreiner]] in Germany and others are involved in EL displays.  Spectrolab already offers commercially flexible solar cells based on various inorganic compounds. [https://archive.today/20070517164819/http://www.packagingessentials.com/indnews.asp?id=2007-03-22-15.57.31.000000]</ref>

[[CIGS cell]]s can be printed directly onto [[molybdenum]] [[coating|coated]] [[glass sheet]]s.

A printed [[gallium arsenide germanium solar cell]] demonstrated 40.7% conversion efficiency, eight times that of the best organic cells, approaching the best performance of crystalline silicon.<ref name="packagingessentials.com"/>

===Substrates===
Printed electronics allows the use of flexible substrates, which lowers production costs and allows fabrication of mechanically flexible circuits. While inkjet and screen printing typically imprint rigid substrates like glass and silicon, mass-printing methods nearly exclusively use flexible foil and paper.  [[polyethylene terephthalate|Poly(ethylene terephthalate)]]-foil (PET) is a common choice, due to its low cost and moderately high temperature stability.<ref>Carey, T., Cacovich, S., Divitini, G., Ren, J., Mansouri, A., Kim, J. M., ... & Torrisi, F. (2017). Fully inkjet-printed two-dimensional material field-effect heterojunctions for wearable and textile electronics. Nature communications, 8(1), 1-11.https://doi.org/10.1038/s41467-017-01210-2</ref> [[Polyethylene naphthalate|Poly(ethylene naphthalate)]]- (PEN) and [[polyimide|poly(imide)]]-foil (PI) are higher performance, higher cost alternatives.  [[Paper]]'s low costs and manifold applications make it an attractive substrate, however, its high roughness and high [[wettability]] have traditionally made it problematic for electronics. This is an active research area,<ref>{{Cite journal|last1=Tobjörk|first1=Daniel|last2=Österbacka|first2=Ronald|date=2011-03-23|title=Paper Electronics|journal=Advanced Materials|language=en|volume=23|issue=17|pages=1935–1961|doi=10.1002/adma.201004692|pmid=21433116|bibcode=2011AdM....23.1935T |issn=0935-9648}}</ref> however, and print-compatible metal deposition techniques have been demonstrated that adapt to the rough 3D surface geometry of paper.<ref>{{Cite journal|last1=Grell|first1=Max|last2=Dincer|first2=Can|last3=Le|first3=Thao|last4=Lauri|first4=Alberto|last5=Nunez Bajo|first5=Estefania|last6=Kasimatis|first6=Michael|last7=Barandun|first7=Giandrin|last8=Maier|first8=Stefan A.|last9=Cass|first9=Anthony E. G.|date=2018-11-09|title=Autocatalytic Metallization of Fabrics Using Si Ink, for Biosensors, Batteries and Energy Harvesting|journal=Advanced Functional Materials|volume=29|issue=1|language=en|pages=1804798|doi=10.1002/adfm.201804798|pmid=32733177|pmc=7384005|issn=1616-301X|doi-access=free}}</ref><ref>{{Cite book |last1=Vicente |first1=António T. |url=https://www.intechopen.com/chapters/53636 |title=Optoelectronics and Bio Devices on Paper Powered by Solar Cells |last2=Araújo |first2=Andreia |last3=Gaspar |first3=Diana |last4=Santos |first4=Lídia |last5=Marques |first5=Ana C. |last6=Mendes |first6=Manuel J. |last7=Pereira |first7=Luís |last8=Martins |first8=Elvira Fortunato and Rodrigo |date=2017-02-22 |publisher=IntechOpen |isbn=978-953-51-2936-3 |language=en}}</ref>

Other important substrate criteria are low roughness and suitable wet-ability, which can be tuned pre-treatment by use of [[coating]] or [[Corona discharge]]. In contrast to conventional printing, high absorbency is usually disadvantageous.

==History==
Albert Hanson, a German by birth, is credited to have introduced the concept of printed electronics. in 1903 he filled a patent for "Printed Wires," and thus printed electronics were born.<ref>{{cite patent|inventor-last=Hanson|inventor-first=Albert|title=Printed Wires|issue-date=1903|number=4681|country=GB}}</ref> Hanson proposed forming a Printed Circuit Board pattern on copper foil through cutting or stamping. The drawn elements were glued to the dielectric, in this case, paraffined paper.<ref>{{cite web|url=https://rostec.ru/en/news/4515084/|title=The printed circuit board is the base of modern electronics|author=<!--Not stated-->|date=November 24, 2014|website=rostec.ru|publisher=Rostec|access-date=November 28, 2018|archive-date=August 28, 2019|archive-url=https://web.archive.org/web/20190828061658/https://rostec.ru/en/news/4515084/|url-status=dead}}</ref> The first printed circuit was produced in 1936 by Paul Eisler, and that process was used for large-scale production of radios by the USA during World War II. Printed circuit technology was released for commercial use in the US in 1948 (Printed Circuits Handbook, 1995). In the over a half-century since its inception, printed electronics has evolved from the production of printed circuit boards (PCBs), through the everyday use of membrane switches, to today's RFID, photovoltaic and electroluminescent technologies.<ref name="Jacobs">{{cite thesis|last=Jacobs|first=John|date=2010|title=An Investigation of Fundamental Competencies for Printed Electronics|publisher=Clemson University}}</ref> Today it is nearly impossible to look around a modern American household and not see devices that either uses printed electronic components or that are the direct result of printed electronic technologies. Widespread production of printed electronics for household use began in the 1960s when the Printed Circuit Board became the foundation for all consumer electronics. Since then printed electronics have become a cornerstone in many new commercial products.<ref>{{Citation|url=https://news.nationalgeographic.com/news/2013/13/130509-paper-printed-circuits-electronics-technology-science/|archive-url=https://web.archive.org/web/20130513194346/http://news.nationalgeographic.com/news/2013/13/130509-paper-printed-circuits-electronics-technology-science/|url-status=dead|archive-date=May 13, 2013|title=Printing Electronics Just|work=National Geographic News|date=10 May 2013|publisher=National Geographic Partners, LLC|access-date=November 30, 2018|ref=none}}</ref>

The biggest trend in recent history when it comes to printed electronics is the widespread use of them in solar cells. In 2011, researchers from MIT created a flexible solar cell by inkjet printing on normal paper.<ref>{{Citation|url=https://news.mit.edu/2011/printable-solar-cells-0711|title=While You're Pp, Print Me a Solar Cell|work=MIT News|date=11 July 2011 |publisher=MIT News Office|access-date=November 30, 2018|ref=none}}</ref> In 2018, researchers at Rice University have developed organic solar cells which can be painted or printed onto surfaces. These solar cells have been shown to max out at fifteen percent efficiency.<ref>{{Citation|url=https://www.printedelectronicsworld.com/articles/15804/stretchy-solar-cells-a-step-closer|title=Stretchy solar cells a step closer |work=Printed Electronics World|date=15 November 2018 |publisher=IDTechEx|access-date=November 30, 2018|ref=none}}</ref> Konarka Technologies, now a defunct company in the US, was the pioneering company in producing inkjet solar cells. Today there are more than fifty companies across a diverse number of countries that are producing printed solar cells.

While printed electronics have been around since the 1960s, they are predicted{{when|date=August 2020}} to have a major boom in total revenue.  As of 2011, the total printed electronic revenue was reported to be at $12.385 (billion).<ref>{{Citation|url=http://thor.inemi.org/webdownload/2014/Printed_Elec_Zhang_051214.pdf|title=Printed Electronics:Manufacturing Technologies and Applications|last=Zhang|first=Chuck|publisher=Georgia Tech|access-date=November 30, 2018|ref=none}}</ref>  A report by IDTechEx predicts the PE market will reach $330 (billion) in 2027.<ref name="Das">{{Citation|url=https://events.hkstp.org/events/Past_AIS/APAC2016/files/Keynote_1_Raghu_Das_Printed_Electronics.pdf|title=Printed Electronics: Markets, Technologies, Trends|last=Das|first=Raghu|publisher=IDTechEx|access-date=November 30, 2018|ref=none}}</ref>  A big reason for this increase in revenue is because of the incorporation of printed electronic into cellphones. Nokia was one of the companies that pioneered the idea of creating a "Morph" phone using printed electronics. Since then, Apple has implemented this technology into their iPhone XS, XS Max, and XR devices.<ref>{{cite press release |url=https://www.printedelectronicsworld.com/articles/15387/new-iphones-models-support-native-background-nfc-tag-read-function |title=New iPhones models support native 'background' NFC tag read function |publisher=Thinfilm |via=IDTechEx |access-date=November 30, 2018}}</ref>  Printed electronics can be used to make all of the following components of a cellphone: 3D main antenna, GPS antenna, energy storage, 3D interconnections, multi-layer PCB, edge circuits, ITO jumpers, hermetic seals, LED packaging, and tactile feedback.

With the revolutionary discoveries and advantages that printed electronic gives to companies many large companies have made recent investments into this technology. In 2007, Soligie Inc. and Thinfilm Electronics entered into an agreement to combine IPs for soluble memory materials and functional materials printing to develop printed memory in commercial volumes.<ref name="Jacobs" />  LG announce significant investment, potentially $8.71 billion in OLEDs on Plastic. Sharp (Foxconn) will invest $570m in pilot line for OLED displays. BOE announce potential $6.8 billion in flexible AMOLED fab. Heliatek has secured €80m in additional funding for OPV manufacturing in Dresden. PragmatIC has raised ~ €20m from investors including Avery Dennison.  Thinfilm invests in new production site in Silicon Valley (formerly owned by Qualcomm).  Cambrios back in business after acquisition by TPK.<ref name="Das"/>

==Applications==
Printed electronics are in use or under consideration include wireless sensors in packaging, skin patches that communicate with the internet, and buildings that detect leaks to enable [[Maintenance (technical)#Preventive maintenance|preventative maintenance]]. Most of these applications are still in the prototyping and development stages.<ref>{{cite web |title=Custom Printed Electronics |url=https://www.almax-rp.com/printed-electronics/ |website=Almax - RP |date=30 December 2016 |access-date=13 August 2021}}</ref> There is a particularly growing interest for [[Flexible electronics|flexible smart electronic systems]], including photovoltaic, sensing and processing devices, driven by the desire to extend and integrate the latest advances in (opto-)electronic technologies into a broad range of low-cost (even disposable) consumer products of our everyday life, and as tools to bring together the digital and physical worlds.<ref>{{Cite journal |last1=Vicente |first1=António T. |last2=Araújo |first2=Andreia |last3=Mendes |first3=Manuel J. |last4=Nunes |first4=Daniela |last5=Oliveira |first5=Maria J. |last6=Sanchez-Sobrado |first6=Olalla |last7=Ferreira |first7=Marta P. |last8=Águas |first8=Hugo |last9=Fortunato |first9=Elvira |last10=Martins |first10=Rodrigo |date=2018-03-29 |title=Multifunctional cellulose-paper for light harvesting and smart sensing applications |url=https://pubs.rsc.org/en/content/articlelanding/2018/tc/c7tc05271e |journal=Journal of Materials Chemistry C |language=en |volume=6 |issue=13 |pages=3143–3181 |doi=10.1039/C7TC05271E |issn=2050-7534|url-access=subscription }}</ref>

Norwegian company [[Thin Film Electronics ASA|ThinFilm]] demonstrated roll-to-roll printed organic memory in 2009.<ref>[http://www.printedelectronicsworld.com/articles/winners_of_the_idtechex_printed_electronics_europe_awards_00001368.asp Thinfilm and InkTec awarded IDTechEx' Technical Development Manufacturing Award] IDTechEx, April 15th 2009</ref><ref>[http://www.eetimes.com/electronics-news/4084606/PolyIC-ThinFilm-announce-pilot-of-volume-printed-plastic-memories PolyIC, ThinFilm announce pilot of volume printed plastic memories] EETimes, September 22nd 2009</ref><ref>[http://www.printedelectronicsworld.com/articles/all_set_for_high_volume_production_of_printed_memories_00002179.asp All set for high-volume production of printed memories] Printed Electronics World, April 12th 2010</ref><ref>[http://www.printedelectronicsnow.com/articles/2010/05/thin-film-electronics-plans-to-provide-memory-ever Thin Film Electronics Plans to Provide ‘Memory Everywhere’] Printed Electronics Now, May 2010</ref>

Another company, Rotimpres based in Spain, has successfully introduced applications on different markets as for instance; heaters for smart furniture or to prevent mist and capacitive switch for keyboards on white goods and industrial machines.<ref>[https://printedelectronics.rotimpres.com/en/heaters-for-industry/ Revolutionize Your Industrial Heating with Rotimpres] Heater, October 14th 2024</ref><ref>[https://printedelectronics.rotimpres.com/en/applications/capacitive-keyboards/ Capacitive keyboards - Rotimpres] Capacitive switch, October 14th 2024</ref>

==Standards development and activities==
[[Technical standard]]s and road-mapping initiatives are intended to facilitate [[value chain]] development (for sharing of product specifications, [[characterization]] standards, etc.) This strategy of standards development mirrors the approach used by silicon-based electronics over the past 50 years.  Initiatives include:
* The [[IEEE Standards Association]] has published [[IEEE]] 1620-2004<ref>{{Cite web |url=http://grouper.ieee.org/groups/1620/ |title=IEEE P1620 Index page |access-date=2006-11-30 |archive-url=https://web.archive.org/web/20110610212227/http://grouper.ieee.org/groups/1620/ |archive-date=2011-06-10 |url-status=dead }}</ref> and IEEE 1620.1-2006.<ref>{{Cite web |url=http://grouper.ieee.org/groups/1620/1/ |title=IEEE P1620.1 Index page |access-date=2006-11-30 |archive-url=https://web.archive.org/web/20110610212235/http://grouper.ieee.org/groups/1620/1/ |archive-date=2011-06-10 |url-status=dead }}</ref>
* Similar to the well-established [[International Technology Roadmap for Semiconductors]] (ITRS), the International Electronics Manufacturing Initiative (iNEMI)<ref>{{Cite web|url=https://www.inemi.org/|title=iNEMI &#124; International Electronics Manufacturing Initiative|website=www.inemi.org}}</ref> has published a roadmap for printed and other [[organic electronics]].
IPC—Association Connecting Electronics Industries has published three standards for printed electronics. All three have been published in cooperation with the Japan Electronic Packaging and Circuits Association (JPCA):
* IPC/JPCA-4921, Requirements for Printed Electronics Base Materials
* IPC/JPCA-4591, Requirements for Printed Electronics Functional Conductive Materials
* IPC/JPCA-2291, Design Guideline for Printed Electronics
These standards, and others in development, are part of IPC's Printed Electronics Initiative.

==See also==
{{Portal|Electronics|Manufacturing}}
{{div col|colwidth=18em}}
* [[Amorphous silicon]]
* [[Anilox]] rolls
* [[Chip tag]]
* [[Coating and printing processes]]
* [[Conductive ink]]
* [[Electronic paper]]
* [[Flexible battery]]
* [[Flexible electronics]]
* [[Laminar electronics]]
* [[Nanoparticle silicon]]
* [[Oligomer]]
* [[Organic electronics]]
{{div col end}}

==References==
{{Reflist|33em}}

==Further reading==
* ''Printed Organic and Molecular Electronics'', edited by D. Gamota, P. Brazis, K. Kalyanasundaram, and J. Zhang (Kluwer Academic Publishers: New York, 2004).  {{ISBN|1-4020-7707-6}}

==External links==
* [http://www.dea.brunel.ac.uk/cleaner/Electronics_Projects/Handbook_1.htm Cleaner Electronics Research Group] - Brunel University
* Printed Electronics conference/exhibition [https://web.archive.org/web/20080915190411/http://printedelectronics.idtechex.com/printedelectronicsasia08/en/ Asia] [https://web.archive.org/web/20080921033814/http://printedelectronics.idtechex.com/printedelectronicsusa08/en/ USA]
* [https://web.archive.org/web/20081009011825/http://www.ferro.com/spotlight/New+Nano+Silver+Powder+Enables+Flexible+Printed+Circuits.htm New Nano Silver Powder Enables Flexible Printed Circuits] ([[Ferro Corporation]])
* Western Michigan University's [https://web.archive.org/web/20101214061056/http://www.wmich.edu/engineer/cape/facilities.php Center for Advancement of Printed Electronics (CAPE)] includes [http://www.printedelectronicsworld.com/articles/western_michigan_university_and_daetwyler_progress_gravure_printing_00001879.asp?sessionid=1 AccuPress gravure printer]
* [http://digitalcommons.calpoly.edu/grcsp/26/ Major Trends in Gravure Printed Electronics June 2010]
* [http://innocreatividad.com/2013/06/19/printed-electronics-avistando-el-futuro Printed Electronics – avistando el futuro. Printed Electronics en Español]
* [https://www.coursera.org/learn/solar-cell Organic Solar Cells - Theory and Practice (Coursera)]

{{Digital electronics}}
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{{DEFAULTSORT:Printed Electronics}}
[[Category:Electronics manufacturing]]
[[Category:Flexible electronics]]