CAMBRIDGE, UK – The conductive ink business is on the cusp of rapid and comprehensive change, says IDTechEx. Changing business dynamics has forced many suppliers to change strategy, focusing on many emerging and nascent applications in the hope some will grow in the future to compensate for the commoditization and/or decline in core markets, the firm says.
The perennial trend to narrow the bezel has reduced the L/S (linewidth over spacing) of edge electrodes to 20µm/20µm or lower. This means standard screen printing and polymer thick films can no longer meet the performance requirements, according to IDTechEx. In turn, this has ushered in new conductive ink technologies.
The photosensitive types with spherical particles came first. Here, a wider conductive line is first printed before being narrowed down using photo-patterning. Laser-cut inks with flake particles with average diameters around 1µm came next. Here too, a wide line is first printed before being narrowed down by laser cutting. The flake particles can give rise to higher conductivity provided good particle packing is achieved. Stable printing with constant line height is critical for precise laser cutting. The latter process is gaining traction in China, where the laser cutting machines are also made at moderate prices.
The pressure to narrow the bezel will not cease. Indeed, companies have already demonstrated 15/15 and even 10/10. This means printing processes, and not just inks, will also need to change to enable narrower lines; otherwise the etching-based process will increase their market share.
3D printed electronics promises to bring about a breath of fresh air to 3D printing. This is because 3D printing in plastics has to date been limited to forming “dumb” mechanical objects. 3D printed electronics can dramatically change that; it can structurally integrate the circuitry into the object, thus enabling the prototyping of customized, intelligent, electronic objects.
Nascent Objects was a good example we highlighted previously. In fact, IDTechEx gave it a score of 9/10 for value proposition, medium term commercial opportunity and competitive landscape.
Nascent Objects developed a modular platform that enabled 3D printed electronics. Here, users could design an object in Nascent Object’s software, place the electronic modules (e.g. camera or microphone) at the desired locations, and click to 3D print. The software would plan the metallization paths inside the object, and the printing process would structurally embed the interconnects.
While Nascent Objects did not use printed conductive inks, its approach highlighted the potential. In fact, conductive inks can be an enabling technology here. Material challenges, however, remain. Most important, the printed conductive inks need to provide higher conductivity at much lower annealing temperatures. They also require faster annealing; otherwise this will become the speed-limiting step in the prototyping process.
In-mould electronics is gaining momentum. This trend is well and alive, despite the initial product recall setback suffered in the automotive industry. Several leading suppliers around the world are now offering inks specifically formulated to be in-mould compatible.
In particular, they are changing the formulation to make the inks chemically compatible with polycarbonate substrates and to make the inks more stretchable under thermoforming conditions. The latter is achieved by changing the solvent and binder materials (e.g., polyester-based formulation).
The in-mould inks currently command a substantial price premium compared to standard PTFs. The value chain is also still not yet fully formed. The moulding capability currently exists mostly at a local level only. Nonetheless, the industry is making strong progess with the inks having been launched recently in a white good appliance and having been qualified for use in an automotive part.
There is renewed interest globally in conductive ink-based metal mesh transparent conductive films. This is because technology and application developments are making this approach more competitive. Capacitive touch technology is reaching the large-sized end of the market, with many touch tables and touch TVs now being prototyped or sold. This changes the technology requirements because such touch tables and TVs are likely to be heavily used in public spaces. This means the users may tolerate seeing visible metal mesh linewidths, thereby relaxing the linewidth requirements to a range easily achievable using direct printing.
In parallel, gravure offset printing can now semi-commercially product metal mesh films with linewidths as narrow as 5µm. This makes these metal mesh solutions highly performance competitive with many approaches currently commercialized such as hybrid embossing or photo-patterning.