Printed Electronics Sector Looks for In-Line Inspection and Failure Analysis Tools

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Printed Electronics Sector Looks for In-Line Inspection and Failure Analysis Tools

Analysts see a $500-$600 million market for printed or flexible electronics this year, potentially exploding to a multi-billion dollar market within a few years, once some technical issues get resolved. Printed electronics makers and suppliers at the recent FlexTech Alliance workshop (hosted by SEMI in San Jose, California) highlighted the need for in-line inspection and failure analysis tools, and standard testing protocols, to move printed electronics products into volume production. Suppliers also stressed the need for workshops or roadmaps to communicate clear and common target specifications for barrier and encapsulation films, so they can focus their development effort on the right features for real markets.

One key need is online real-time inspection tools, says Dan Gamota, principal of startup Printovate, Inc., and formerly director of Motorola’s printed electronics effort. He and other producers of printed electronics products at the workshop noted that the rolls of flexible substrates and barrier films they received from suppliers were not uniform enough for producing consistent results for their devices, as subtle difference in surface chemistry both within a roll and from roll to roll turn out to have significant impact on electronic performance. Current testing methods cannot make these spatial distinctions, so the films may meet the specifications macroscopically, but not be uniform across all areas.

The sector also aims to start a collaborative effort on advancing understanding of failure mechanisms and yield killers in printed electronics, by specifying the common kinds and densities of defects that matter in its products, and then looking for what kinds of tools and solutions already exist in university labs and in other sectors— from the IC industry to the high speed film processing world. “Other industries may have already looked at these issues,” notes Gamota. “And transferring solutions from other industries would probably be an easier option for bringing things over faster, since universities can take considerable time to develop tools.” As chair of the large area flexible electronics section of the iNEMI electronics industry roadmap, he’s looking for input from metrology suppliers in all sectors for next year’s edition.

Both users and suppliers argued that better testing standards and systems were also needed, including testing after integration and processing, not just on flat lab samples, as inks on the surface and rolling through presses change performance. Testing also needs to be done with conditions that reflect real conditions of product use, like flexing. Products for solar applications need to be tested under exposure to light and impure water spray, not just the typical heat and humidity. Some suggested a central standard testing lab would be useful for testing films, barriers and adhesives, since different labs tend to get different results even with the same test equipment without standard protocols.

Key Role for Materials, Starting with Low-end and Hybrid Products

So far, some 40% of the total printed electronics market is the value of materials, with inks alone accounting for some $240 million in sales, according to IDTechEx. Nanoparticle technology has made silver and now copper easily printable. Development of better flexible transparent barrier films remain key to the growth of many applications, says CEO Raghu Das. In fact, he notes, the lack of a good UV protection system is the major issue holding back flexible photovoltaics.

Most flexible electronics are currently made on metal foil, with the heat-resistant foils accounting for 84% of the substrate market in 2010, says Nanomarkets analyst Paul Markowitz. He figures polymers will grow to 26% of the market by 2013, as processing temperatures come down, and other materials like paper and flexible glass will become a significant 20% portion by 2016.

The advances in functional inks mean that simpler, relatively low resolution electrical circuits can now be produced with existing off-the-shelf printing equipment with minor customization. These tools, however, are not easy to use for small volumes or prototyping. “A lot of people doing prototyping are using spin coating or inkjet or vacuum processes,” notes Das. “Since the flexo press needs 5 liters of material just to get the tool warmed up, and the nano particle inks sell by the gram.”

Like most radically new technologies, printed electronics are creeping into the industry around the edges. Most first applications are either hybrid approaches that combine new solution processes or organic materials with a more conventional electronics process flow, or very simple devices that do something not otherwise practical without unreasonable cost.

The biggest potential, Das argues, is for printed electronics to enable completely new applications, such as the simple printed battery test strips, or the smart skin patches, shipping more than 1 million units a year. The current applied by smart skin patches sends 10x more cosmetic or drugs into the body than just putting the patch on the skin. Glucose sensor strips for diabetics, a market worth several $100 million a year, can now be printed with silver ink with good yield at lower cost than the conventional sputtered product, so should take over much of that market. There’s also big potential from consumer goods companies looking to capitalize on the “wow factor” of attention-getting new design options to bring curves and backlighting, action and interaction, to their products, packaging, and store displays.

Flexible and solution processed photovoltaics have potential to bring solar costs down low enough to be viable without government subsidies, but most printed or flexible products so far use hybrid solutions. The analysts point to creative options that include vacuum deposition on flexible substrates (Unisolar/Global Solar), or solution-coating on flexible substrates then covered with glass sheets for encapsulation (Nanosolar). Innovalight is printing its solar film on top of silicon wafers to make high performing tandem cells. “It’s faster to get to market to combine printing with conventional processes like sputtering, CVD and lithography,” notes Das.

E-readers and Other Displays Gradually Get More Flexible

Flexible displays were a mere $85 million market in 2008, but will expand to an $8.2 billion opportunity by 2018, says Jennifer Colegrove, director of display technologies at DisplaySearch. The largest part of that market will be electrophoretic displays, using bi-stable low-power frontplanes like those from E-Ink, in everything from big signage two meters on a side to tiny sceens on smart cards. OLEDs will become significant towards the end of the decade, and EL products—already shipping on tee shirts, advertising signage, and curved control panels on automobiles—will also become more significant.

While e-books so far have put printed flexible E-Ink frontplanes on more conventional rigid glass transistor backplanes, new display models coming out will be more purely solution processed, and more purely flexible. Colegrove notes that both Hitachi and Samsung have mobile phones on the market with displays with both flexible front and back planes for low cost and low power, though the units are on rigid handsets. Plastic Logic will introduce its solution-processed e-reader at CES in January. LG Display is close to introduction of an e-book made on metal foil, but apparently using photolithography for backplane resolution. “For new device designs, it’s all about doing whatever works to get to market,” says Colegrove. PVI is reportedly planning introduction of an e-book with a flexible polyimide backplane. Samsung and LG have reported low temperature 120C-150C processes for plastic substrates, though at the demo level with still some defects.

The low-end, low-cost, flexible or printed displays potentially bringing simple new displays to new places have yet to become a big market, in part because the economy has slowed all such investment in new projects. But Display Search still expects demand for displays for smart cards to become 1 million units very quickly once the economy recovers, for security, banking, and transportation tickets. Electronics shelf displays, which do offer clear long-term savings from easy central updating but require upfront investment, are now starting to appear, with bistable displays on glass from ZBD display. These are now in more than 100 stores, mostly in Europe, but also testing in Seattle’s PCC Natural Markets chain. “This is just starting and penetration is slow,” says Colegrove. “But high volume will come, because there’s a big benefit for the stores.”

Markowitz puts the flexible/printed market at $569 million currently, and projects 50%-60% growth for the next couple of years. But once more of the technical issues get solved, he figures growth will really take off, to pass $6 billion in 2014. He figures OLED lighting will be the first big application to take off, as its specialty design applications for unique sheets of lighting will allow premium pricing. But sales of flexible PV, displays, and sensors will shortly follow, with these four leading sectors all becoming roughly equal markets going forward. Displays will do well because the overall display market is so large that even small penetration for flexible units can mean big demand. On the other hand, costs for printed RFID will have to be so low that even billions of units may still add up to revenues of only tens of millions of dollars.

November 3, 2009