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Roll-to-Roll Coating Technology: It’s a Different Ball of Wax

Compiled and edited by Jeff Dorsch, Contributing Editor

Manufacturing flexible electronics and coatings for a variety of products has some similarities to semiconductor manufacturing and some substantial differences, principally roll-to-roll fabrication, as opposed to making chips on silicon wafers and other rigid substrates. This interview is with Neil Morrison, senior manager, Roll-to-Roll Coating Products Division, Applied Materials.

1. What are the leading market trends in roll-to-roll coating systems?

Neil Morrison: Several market trends are driving innovations in roll-to-roll technology and barrier films.  One is the flexible electronics market where we see the increasing use of film-based components within displays for portable electronic devices such as smartwatches, smartphones, tablets and laptops.

The majority of these passive applications are for anti-reflection films, optical polarizers and hard coat protected cover glass films.

Examples of active device applications include touch sensors. Roll-to-roll vacuum processing dominates this segment through the use of low-temperature deposited, optically matched layer stacks based on indium tin oxide (ITO). Roll-to-roll deposition of barrier film is also increasing with the emergence of quantum dot-enhanced LCD displays and the utilization of barrier films in organic light-emitting diode (OLED) lighting.

In addition to the electronics industry, roll-to-roll technology is used for food packaging and industrial coatings. What’s new today for food packaging is consumers want to be able to view the freshness of the food inside the packaging. Given this, the use of both aluminum foil and traditional roll-to-roll evaporated aluminum layers is slowly being phased into vacuum-deposited aluminum oxide (AlOx) coated packaging.

Within the industrial coatings market segment, significant growth is being driven by the use of Fabry-Perot color shift systems for “holographic” security applications, such as those used to protect printed currency from counterfeiting. This requires the use of electron-beam evaporation tooling to deposit highly uniform, optical quality dielectric materials sandwiched between two metallic reflector layers.

2. What are the leading technology trends in roll-to-roll coating systems?

Neil Morrison: Roll-to-roll coating is being extended to the display industry through the use of higher optical performance substrates with enhanced transmission, optical clarity and color neutrality. These materials are typically more difficult to handle than traditional polyethylene terephthalate (PET) substrates due to inherent properties and the properties of the primer and/or hard coat layers used to treat or protect their surface.

The majority of displays used in mobile applications are moving to thinner substrates, to reduce the “real estate” within the display and enable thinner form factor products and more space for larger batteries.

At the technology level, roll-to-roll sputter tooling dominates the touch panel industry with continual improvements in substrate handling, pre-treatment and inline process monitoring and control. Roll-to-roll chemical vapor deposition (CVD) equipment has also entered the marketplace to address high barrier requirements and to reduce cost compared with traditional sputter-based solutions. Roll-to-roll CVD technology is still in its infancy but is expected to become more prevalent in the near future within the barrier and hard coat market segments.

In the display industry, defect requirements are becoming more and more stringent and are moving towards metrics previously unseen in the roll-to-roll industry.

3. How would you best and briefly describe the Applied SmartWeb, Applied TopBeam, and Applied TopMet systems?

Neil Morrison: The Applied SmartWeb roll-to-roll modular sputtering or physical vapor deposition tool is used to deposit metals, dielectrics and transparent conductive oxides on polymeric substrates for the touch panel and optical coating industry. Its high-precision substrate conveyance system permits winding of polymeric substrates down to thickness levels of ~23 microns at speeds of up to 20 meters/minute depending upon the application. Up to six process compartments with separate gas flow control and pumping allow the deposition of complex layer stacks within a single pass.

Our Applied TopBeam system is a roll-to-roll e-beam evaporation tool used to deposit dielectrics on substrate thicknesses as low as 12 micron and at speeds up to approximately 10 meters/second.  Key to the tool is Applied’s unique electron-beam steering and control system, which provides excellent layer deposition and uniformity at exceptionally high processing speeds by permitting uniform and stable heating of the evaporant material  over the entire width of the substrate.

The Applied TopMet is a high-productivity roll-to-roll thermal evaporation platform available for depositing Al and AlOx layers on substrates down to 12 microns in thickness and is used primarily for food and industrial packaging.

Applied SmartWeb (Source: Applied Materials)

4. Who are Applied’s leading competitors in this market?

Neil Morrison: Other companies in the roll-to-roll market include Von Ardenne, Leybold Optics (Buehler), Schmid, Ulvac and Kobelco.

5. How big is the worldwide market on annual basis?

Neil Morrison: It is difficult to accurately size the entire roll-to-roll market because of the wide variety of applications across multiple industries from flexible electronics to food packaging. Just estimating the size of the market within the flexible electronics category alone is tough because there are three areas that combine to make up the current flexible electronics market – OLEDs for flexible displays, flexible printed circuit boards, and flexible touch panels for phones and tablets. And with applications continuing to grow, it is difficult to provide a specific market size.



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