Silver nanoparticle technology has been in the semi or full commercialization mode for well more than a decade now. In this time, however, commercial success has proved elusive time and again. Despite its clear value propositions, this technology regularly failed vis-to-vis the strength of the incumbent traditional pastes in performance, scale and cost. The industry efforts however are finally paying off and the market is swinging into success territory.
In this article we will describe the dynamics of a series of key target markets for silver nano inks. These applications are listed in no particular order of importance. This analysis is drawn from our report «Conductive Ink Markets 2018-2028: Forecasts, Technologies, Players». This report provides the most comprehensive and authoritative view of the 2370 tpa conductive inks and paste market, giving detailed ten-year market forecasts segmented by more than 25 applications. The market forecasts are given in tonnage and value at the ink level.
Metal mesh transparent conductors: Transparent conductive layers are employed in diverse applications such as touch displays, OLED lighting and various thin film photovoltaics. ITO (on film or glass) is currently the dominant technology but for years other technologies have sought to replace or complement it to address issues such as price fluctuations, limited conductivity and flexibility. Metal mesh is one such technology option. It can be produced using a variety of processes such as etching, embossing or direct printing.
The latter two approaches require conductive inks. In the embossing approach, a drum embosses trenches into the film substrate that are subsequently filled using nano or sub-micron conductive paste. This approach has been in commercialization mode (using nano inks) for several years, although sales became lukewarm as embedded touch rose in prominence and as ITO film prices were slashed to protect their share in add-on touch. Given their high conductivity, this approach is now also in use for small-sized transparent antenna production for consumer electronics.
The other approach is based on direct printing. Despite its attractiveness on paper, it failed to gain traction mainly because it could not reliably achieve sufficiently narrow linewidths. Direct printing however is making a comeback with multiple approaches such as gravure offset, inkjet printing, etc. In particular, gravure offset printing is often used to create fine line metal mesh (5um linewidth). This is already transitioning into the commercialization mode with first producers running slow and narrow web lines. This trend is likely to continue in the coming years, creating a market for silver nanoparticle inks (and may be special sub-micron ones too).
Printed metal mesh has long also targeted non-touch application. For example, it sought adoption in R2R produced flexible OLED lighting panels. Here, its purpose was to boost the conductivity of the transparent conducting layer. It needed high conductivity at low annealing temperatures, but linewidth was not such as issue. The challenge however was that R2R production of OLED lighting has proved complex and it is yet to enter the market. This setback however appears not to have been a showstopper. Indeed, playing a similar role, printed Ag nano-based metal mesh is on the cusp of multi-tonne success in thin film photovoltaics.
Conformal coatings: On-chip conformal EMI shielding has already been adopted by leading smart phone makers. Here a metal line is conformally coated directly on the chip to minimize EMI interference to and from that are all packed in close proximity. The current method is based on sputtering. This is a known process that achieves highly conducting and thus thin and effective coatings.
Ink-based sprayable solutions are however emerging with a compelling proposition: deposition using non-vacuum, low-CapEx, and high throughput equipment over large areas and with excellent side wall coverage. The challenge here however is that conductive inks are not as conductive and thus not as thin as sputtered coatings.
This is where pure or hybrid nano inks come in: they can offer a higher performance compared with micron-sized pastes, thus helping narrow the performance gap with sputtering. Suppliers are addressing sedimentation and adhesion issues, and end users are now actively testing sprayed EMI shielding, seeking to find that optimal ink and particle size composition and the sweet spot in cost and performance. This is a space to closely monitor.
In parallel, aerosol deposition has also opened the door to the sales of nano inks. This is because the number of installed industrial-scale printers has increased, particularly in Asia, for applications such as antenna printing for consumer electronics devices. This technology enables 3D conformal disposition using a digitally-controlled and low-foot-print equipment. The role of nano materials here is several folds: (1) ensure computability with the nozzle; (2) achieve high conductivity at low annealing temperatures on the substrates; and (3) create uniform coatings when jetted out by the virtue of their near monodispersity.
High temperature die-attach paste: Power electronics is growing, riding the rise of smart grid and electric vehicles. This creates new demand across the material supply chain for thermal management materials. This is because these devices generate/handle high currents (thus high heat) and will also often operate in high temperature.
A particular need is around die attach materials connecting the die to the substrate. These materials must provide strong adhesion as well as high electrical and thermal conductivity. A high-performing option is around sintered silver-based die attach pastes. Traditional versions are composed of micron-sized particles. They are sintered at high temperature (250-300C) and under the application of external pressure.
A new generation of pastes is now being commercialized that are based on nano materials or are a hybrid. These materials have the advantage of being able to be sintered at low temperatures without the assistance of external pressure. These materials are now in the final qualification phases for use in electric vehicles and imminent success is expected in North America.
View larger image here. Pictures of examples of Ag NP ink applications covering EMI shielding, metal mesh, PCB printing, conformal coating, high-temperature die-attach, and so on. These pictures, in no particular order, are from O-Film (I took in 2013), Agfa, Henkel, Asahi Kasei (I took in 2017), NanoDimension (I took in 2017), Optomec, DIC (I took in 2017), Shashin Kagaku (I took in 2017), and so on.
PCB printing: Desktop amateur and professional PCB printers are emerging. The target market for the amateur versions is often DIY or hobbyists. These can often do one or two layered PCBs. They look like a passing trend. The professional ones are more able, capable of doing multi-layer PCBs. Both approaches are slow and unproductive, however they are well suited to low-volume in-house prototypes. The professional ones are based on inkjet printers and are thus employing nanoparticle inks. The machines have now moved beyond beta versions and full industrial versions have already been launched and ordered, whilst at the same time lower-cost and lower-spec versions are also emerging. These developments will also benefit Ag nano ink sales although the volumes and revenue will remain small.
The seed-and-plate approach has also, for years, been in the development phase. The technology itself has been demonstrated but the cost advantage is not yet compelling enough to force a transition. Others have also developed a technique to use uniformly-coated silver nanoparticles as the seed layer for plating smooth copper films on polyimide to create FCCL (flexible copper clad layers). Despite the good results, it is unlikely that this approach will succeed, at least in the short term.
Others: There are numerous other target markets. These are detailed in our report «Conductive Ink Markets 2018-2028: Forecasts, Technologies, Players». Just as examples here will outline a few potential applications. Digitizers are yet another target market. Here, a board with pattered conductive lines is placed behind the screen or whiteboard. Sputtering/etching is the obvious solutions, but some are seeking to replace it with nano inks. Silicon photovoltaics, years ago, were a primary target market. The idea was to replace screen printed pastes with the print seed-and-plate approach. Here, non-contact inkjet printing would print a narrow seed layer on thinned (thus fragile) wafers. This approach failed to gain commercial traction, mainly because wafers did not become as thin as originally predicated due to their falling costs. Printed transistors are also another application that requires nano inks. Printing transistors is however one of the most complex tasks in printed electronics and is still far off commercial success despite excellent recent technology demonstrations in Japan.
Overall, the market for Ag nano inks is swinging into success territory. Several promising applications on the cusp of imminent success. Despite this however, silver nano inks will very much remain the junior partner in the conductive paste business with traditional pastes continuing to achieve sales that are orders of magnitude larger.
For further information please visit our report page. This report «Conductive Ink Markets 2018-2028: Forecasts, Technologies, Players» provides the most comprehensive and authoritative view of the conductive inks and paste market, giving detailed ten-year market forecasts segmented by application and material type. The market forecasts are given in tonnage and value at the ink level. This report includes critical reviews of all the competing conductive inks and paste technologies including firing-type pastes, PTFs, laser-cut or photo-patterned pastes, nanoparticles, stretchable inks, in-mould inks, copper, copper/silver alloys, nanocarbons, and more. It also provides a detailed assessment of more than 25 existing and emerging application sectors.