Plastics Get Flexible for Electronics...Plastics Get Flexible for Electronics _____ T o streamline electronic devices by reducing the need for rigid circuit boards, DuPont Microcircuit

Plastics Get Flexible for ElectronicsIntegrated circuitry, “wraparound” electronics, and other conductiveapplications are being made possible using plastics

COVER STORY

14 | PLASTICS ENGINEERING | FEBRUARY 2016 | www.4spe.org | www.plasticsengineering.org

By Geoff Giordano

This molded reference design demonstrates the integrated, molded-in printed circuitry enabled by DuPontMicrocircuit Materials’ in-mold electronic inks. (See also the sidebar article on p. 18; photo courtesy of themolder TactoTek.)

14-21 Cover Story_046854 IndustryNews.QXD 1/20/16 7:58 AM Page 14

Whether plastics are in electronics—or even are the elec-tronics—in consumer and industrial applications, novelconductive polymers and processing methods are helping21st-century plastics engineers realize new performance andaesthetics benchmarks.

In particular, the skyrocketing popularity of portable, per-sonal, or more visually pleasing electronics is driving industryinnovation across the board—from flexible electronics usedin wearable, automotive, or appliance displays, to high-impact plastics for protecting sensitive electronics on thego. conductive inks for in-mold use and polymers modifiedwith conductive metal nanoparticles are also spurring search-es for commercial uses of novel materials.

At least one forecast illustrates the level of activity in thismarket segment. For example, the global market for “elec-troactive” (shape-changing and conductive) polymers isexpected to reach $6.38 billion in value by 2022, accordingto a 2015 report by california-based grand View Research—with an expected compound annual growth of 9.7% from2015 to 2022.

With the plastics electronics market poised for such vig-orous growth, here’s a look at some notable advances thatare changing the way manufacturers think about productdesign and performance, for meeting or exceeding cus-tomers’ desires for cutting-edge goods.

Thin-Film TransistorsFlexEnable of cambridge, UK, is a pioneer in developingorganic transistor technology that allows electronics to bemanufactured on flexible plastic film “the thickness of asheet of paper,” the company says.

“FlexEnable has developed a unique way of manufactur-ing electronics on plastic substrates which will createrevolutionary products whilst challenging conventional man-ufacturing economics,” says technical director MikeBanach. “Plastic electronics enables the development of

ultra-thin, shatterproof, and flexible products includingmobile devices, wearables, surface displays, and imagingsystems.

the company’s production process mimics the approachused to make flat-panel displays on glass, he says, “exceptwe laminate a plastic film to the glass that can easily bedetached at the end.” their production process uses muchlower process temperatures than conventional transistors,enabling the use of cost-effective plastic substrates anddemount mechanisms that allow the glass to be recycled,he continues.

www.plasticsengineering.org | www.4spe.org | FEBRUARY 2016 | PlAstIcs EngInEERIng | 15

Imagine an entire smartphone wrapped around your wrist.Or, how about a smartphone that doubles in size thanks toa wraparound display? Imagine the freedom in being able

to design electronic displays around even the most complexcontours of a car’s interior.

Flexible-display product concepts like this wristphone show how new levels of utility might beunlocked for smart watches and other wearabledevices (this and other flexible-display photos in thisarticle courtesy of FlexEnable Ltd.).


“the most efficient manufacturing approach would be toremove the glass carrier altogether and process circuitsdirectly on the plastic using a roll-to-roll approach,” heexplains. “this is very much the target for the team—andour low-temperature processing approach on flexible sub-strates give us a great head start on the conventionaltechnology.”

the company has optimized a manufacturing processcompatible with the ubiquitous resin PEt, Banach explains,“to take advantage of the economy of scale present in themarket. the temperature profile of our manufacturingprocess (sub-100°c) is also compatible with [cellulose triac-etate], which is widely used to make lcD displays becauseof its ultralow birefringence.”

FlexEnable’s technology can activate surfaces to input oroutput information through flexible sensors and displays,without constraining the design of the product, says companystrategy director Paul cain. “For wearables, the ability to

wrap a display around the wrist or body means significant-ly larger display areas are possible, bringing higher levels ofutility [and] better comfort and user experience, as well asmaking the device rugged and lightweight. the thinness offlexible displays also leaves more room for a battery in theproduct.”

in the automotive realm, cain cites three reasons forflexible displays: “today, the only flat surface in the vehi-cle is the display, and the car has to be designed aroundthe flat constraint of the glass display. Flexible displaysmean the display can be designed around the car, ratherthan the other way round. secondly, curved (concave) dis-plays reduce reflections from the driver’s perspective, andincrease visibility [and] readability of displays. Finally, flex-ible displays open completely new uses … for displays incars—for example, for activating surfaces such as the ‘a’pillar, thereby removing blind spots from the driver’s per-spective by making solid objects see-through.”

16 | Plastics EnginEEring | FEBrUarY 2016 | www.4spe.org | www.plasticsengineering.org

Plastics Get Flexible for Electronics ___________________________________________

This concept shows a smartphone with a wraparound display that opens out into a tablet, doubling the size ofthe device.


FlexEnable’s success has reportedly caught the eye of theprinted electronics industry, with the company fielding offersto discuss its technology at various conferences. “The coremessage we have been conveying at those events is thatthe ability to seamlessly integrate electronics with everydayobjects can only be achieved with flexible electronics,” Cainnotes. “Our organic transistor technology platform can acti-vate surfaces for wearables and ‘everywhere-ables’” in manyindustries, he adds, including “mobile, automotive, aero-space, biometrics, and health care.”

Glass-Free, Flexible DisplaysPlastic Logic of Dresden, Germany, which licenses FlexEn-able’s technology, develops and manufactures shatterproof,glass-free EPDs, or electrophoretic displays. Available in awide range of sizes, these EPDs are being used in smartcards, wearables, mobile devices, and signage.

www.plasticsengineering.org | www.4spe.org | FEBRUARY 2016 | PLASTICS ENGINEERING | 17

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An example of FlexEnable’s OLCD (organic liquid crystaldisplay) curved around a coffee cup.


“Our displays are unique, being extremely robust andshatterproof,” says Rachel Trovarelli, head of marketing com-munications for Plastic Logic. “The award-winning technologyand manufacturing process was developed in-house and isbacked by over 100 patents, applied [for] and granted. Wewere the first to industrialize a process for the manufactureof flexible displays using polymers. Our production processis proven with a high yield, comparable with LCD, and wealready have product in the market.”Compared to glass-based EPD, she says, “our flexible,

glass-free EPD technology is comparable to standarddevices currently available in the market with respect topower use—no power is needed unless the display is updat-ed.” She says it’s “truly e-paper”—the display is readablein sunlight. “However, the fact that we use plastic as a sub-strate instead of silicon on glass, as is the case withtraditional EPDs, provides our displays with unique char-acteristics like true flexibility, thinness (of less than 1 mm),light weights (a few grams depending on the size), and,naturally, robustness.”


Plastics Get Flexible for Electronics ___________________________________________

To streamline electronic devices by reducing the needfor rigid circuit boards, DuPont Microcircuit Materialslaunched a range of in-mold electronic inks in October

that allow circuits to be directly printed onto plastic sub-strates.These inks, which the company says “offer important

design, manufacturing, weight, and cost advantages,” allowtouch controls like buttons, switches, and slides to be seam-lessly integrated into high-value items like cars and homeappliances.“Twenty years ago, washers and dryers were big white

boxes in the basement,” says John Voultos, segment managerfor DuPont Microcircuit Materials. “Today, they have madetheir way upstairs, and as they have become more visible,their style and design has become more important. At thesame time, consumers have become comfortable usingtouch screens and touch buttons with the growth of smartphones and tablets. Consumers no longer require physicalbuttons to feel comfortable using a device of any kind—fromphones to washing machines.”However, printed circuit boards (PCBs) have continued to

limit designers to flat shapes and a standard palette of designsand complex assemblies, he says, meaning “next-genera-tion touch designs have not yet flourished.”DuPont’s in-mold electronic inks “allow designers to print

electronics in plastic,” he explains. “Functions such as touchcontrols and lighting can be directly embedded inside plas-tic parts by printing circuits directly onto plastic sheets, whichare thermoformed and injection molded. This means elec-tronic controls can take on almost any shape, while movingcloser to the surface for the strongest signal.”What differentiates DuPont’s inks is that they’re “capable

of stretching over 70% while providing consistent perform-ance through the aggressive thermoforming and injectionmolding processes,” he explains. “Our third-party teardownsand internal analysis show that in-mold electronics will reducecost by up to 50% and weight by up to 70% versus traditionalbuttons. And in-mold electronics offers simpler assembly,up to 20% cost savings, more curvature, and better per-formance than PCB-based capacitive touch solutions.”Potential applications include appliances like washers, dry-

ers, and refrigerators, as well as automotive overheadconsoles and instrument panels, he continues. “We havebeen working closely with various companies in the applianceand automotive industries, and there is strong interest inthis technology to reduce weight, improve aesthetics, andeliminate manufacturing steps.”

In-Mold Electronic Inks

An example of in-mold circuits printed with DuPontconductive inks.


In terms of producing their EPDs, Plastic Logic obtainspolymers—organic semiconductors and dielectrics—“engi-neered to meet our specifications, which include parametersfor electrical performance, but other aspects like, e.g., vis-cosity [and] degree of purity, as well as standardenvironmental, health, and safety aspects,” she explains.Beyond design and performance benefits, Plastic Logic’s

manufacturing method of printing on a plastic substrate“allows up-scalability and economy of scales with cost effi-ciency,” she continues. Meanwhile, the low temperature ofthe company’s processes—all below 100°C—“implies envi-ronment-friendly industrial production compared with thetraditional silicon semiconductor industry.”Plastic Logic sees several market segments with great

potential with respect to market share and revenue in thefirst two quarters of this year. “You will see more and moreproducts coming on the market enabled by our displays,”Trovarelli asserts.

“The main market segments are mobile devices, forinstance: a secondary screen for a mobile phone, embed-ded either on the back or in a protective cover; smart cardslike ID, security, or bank cards with embedded displays; sig-nage, such as displays for … bus, tram, and train stops; andwearables like smart wristbands, bracelets, and intelligentjewelry. We see also demand for our technology to be usedin sensors—for instance, as a backplane for a portable X-ray detector, which is currently under development.”

Nanomodifier Breakthrough?For Mackinac Polymers, based in Fort Myers, Florida, an acci-dental discovery led to a remarkable advance in electroactivepolymers: a process that inserts transitional nanometalsinto the chemical backbone of materials like polyester poly-ols, copolyesters, and olefins to produce conductivepolymers. Mackinac’s creation earned the company a patent


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in July, and it says its commercialization is on the horizon. Infact, when the company gave a presentation at NASA inNovember, the aerospace agency claimed to have numer-ous applications for Mackinac’s material and called thescience “revolutionary,” the company says.In the process of seeking to create a heavier, glass-like

acrylic, “We thought we could achieve this by inserting somemetal nanoparticles into the formulation,” explains Mack-inac chief chemist Ralph Locke. “During experimentation,we noticed several key indicators that something was hap-pening with these particles that was of significance. After acouple of more experiments and testing, we concluded andproved that we were actually getting the nanoparticles intothe chemical backbone of the polymer. This was our ‘eure-ka moment’.”Mackinac’s new non-traditional synthesis process “differ-

entiates us from other producers because we are not dopingor compounding,” Locke explains. “We are creating homo-geneously conductive polymers that are consistent,repeatable, and controllable without the need to compoundwith additives or fillers. We are not aware of any other com-panies who are utilizing this new synthesis process. We arethe true pioneers of this technology.”The transitional metal nanoparticles Mackinac is insert-

ing into polymer backbones are transitional metal salts,“preferably with particle sizes between 30 and 50 nm,” Lockenotes. “They are readily available.”In terms of performance, “the conductivity and surface

resistivity of our materials are very similar to those of exist-ing compounded materials,” Locke says. “We can creatematerials with a surface resistivity anywhere from 1012 ohm-sq. to 10-4 ohm-sq. “One difference with our materials, however, is that we

can create highly conductive materials without sacrificingthe physical properties of the base polymer. Compound-ed materials typically have a hard time getting to the lowend of the surface resistivity chart without sacrificing thesephysical characteristics, due to the heavy loading required.Because we are using nanomaterials and at significantlower levels, physical characteristics can be maintained.Our nanoparticles are also locked into the backbone andthus will not leach out of the polymer. Our materials aremuch more stable.”Development of the technology did not present signifi-

cant challenges or hurdles, Locke continues. “Once we figuredout what we had, we were able to repeat it with various tran-sitional metal nanoparticles. We then started working withnew polymers and metal combinations and found that our

process was working across the board. Looking back, weare [wondering], ‘Why hasn’t this been done before?’”The findings led Mackinac to search for how to apply its

technology. “We initially focused on electroactive polymers,because the market currently consumes a lot of these mate-rials,” says Don Phillips, Mackinac’s president. “Thesematerials are also created by compounding methods withmetals in various forms. Knowing the limitations of com-pounding, we thought a homogeneously conductive materialwould be of value. It turns out that we were correct, as weare getting a lot of interest in our materials.”Phillips feels the need for electroactive materials “will con-

tinue to grow in various industries as consumers andmanufacturers continue to look for more functionality fromtheir materials and to streamline their processes. Addition-ally, in the automotive and aerospace markets, they’re alsoconcerned with weight reduction. By combining the elec-troactive characteristics into a polymer, weight can be savedby switching from metal components to a polymer-basedcomponent. Or weight can be saved by using nanosized par-ticles instead of other larger materials.”

“Homogenous, Controllable, andRepeatable”“Additionally, our materials are homogenous, controllable,and repeatable,” Phillips adds. “Compounded materials varybatch to batch. The repeatability [of our material] alone willlead to superior performance compared to compoundedmaterials.“Also, compounded materials are sometimes overloaded

to ensure functionality. As a result, the integrity of the orig-inal polymer is diminished while the cost is increasedconsiderably. We feel that our materials are basically a drop-in replacement for current compounded materials with theaddition of superior performance at a reduced price.”The flexibility of Mackinac’s process provides a valuable

spin on traditional methods. “The current process for creatinga conductive material is to take a virgin PP, for example, andmix it with 20% to 40% … carbon black, carbon nanotubes,or some other conductive material,” Locke says. “With ourmaterials, the same spec can typically be achieved by using3% to 10% nanomaterials.”The compounding process, he says, also involves pur-

chasing the raw material from one supplier, purchasing theconductive material from another supplier, mixing the twotogether and then shipping the final product. “With ourprocess, the homogenous conductive material comes straight


Plastics Get Flexible for Electronics _______________________________


out of the reactor ready to ship. The post-processing sup-pliers, mixing steps, and transportation are eliminated.” As far as cost goes, “our process does create a modest

or very small increase in the polymerization cost,” Phillipsnotes. “However, this small incremental cost increase in thepolymerization process is typically less than the currentcompounding process. We feel that we have a very strongvalue proposition for converters who are looking for func-tionalized polymers. In fact, recent business case analysishas proven that we can save significant dollars.”Mackinac says its materials should also save wear and

tear on processing equipment because they “have far lessmetal in them, and the sizes are much smaller,” Locke says.“This should increase the life of the equipment and reducemaintenance costs.”Based on initial business-case analyses, Phillips says “the

compounding step can increase material costs anywherefrom 150% to 700% over the base polymer cost, due to theadditional costs for the conductive additive material andthe processing costs of compounding. We’re finding thatour materials, on the other hand, only have a marginalincrease over the base polymer cost, depending on theapplication.”Mackinac sees a prime opportunity to sell to “existing

raw-material providers and convertors,” Phillips projects.“Convertors can contact us direct for functionalized mate-rials, which we can supply or develop for them, while the rawmaterials suppliers have the ability to license the technol-ogy to create their own materials. Additionally, we’respeaking with compounders who are looking to master-batch our functionalized materials into their compoundedproducts.”



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Plastics Get Flexible for Electronics...Plastics Get Flexible for Electronics _____ T o streamline electronic devices by reducing the need for rigid circuit boards, DuPont Microcircuit