Is Thin Film MEMs the Future of Inkjet Heads? Or is this a case of the Emperor’s new clothes?

In this article, Richard Darling proposes that despite the incredible potential of thin film inkjet heads, this development could be a case of the Emperor’s new clothes. It sounds super exciting, but in reality, does it make commercial sense?

is thin-film truly solving the right problem or addressing real market needs now? Does the high cost attached to thin-film development prohibit most to take it on?

Firstly, to properly extol the virtues of new technology I think it is important to understand what it is and how it potentially can deliver benefit.

What is a ‘thin film’ MEMS inkjet head?

MEMs stand for ‘microelectronic mechanical systems’

A printhead structure is made in semi-conductor material such as silicon and the piezoelectric material deposited in a thin film. Bulk piezo uses relatively large blocks of the piezo-electric material. Thin-film can enable certain significant printing performance advantages that are seen as superior to bulk piezo inkjet, and this is why many people believe it to be the future.

However, this involves a very expensive production process that requires FAB labs. These labs cost on average a $ Billion to make and a lot to run, so unsurprisingly, therefore, there are under 200 worldwide occupied in a wide array of product manufacturing in high volumes. However, they are great for producing consistent quality at low cost should there be a market demand for high volumes of product output.

Volume is key. The significant downside of this exciting technology is the indisputable fact that there is a huge cost attached to manufacture unless printheads are to be produced in very high quantities.

So, what are the exact benefits of thin-film for inkjet?

Thin-film promises uniform precision manufacturing with high yield, low cost per nozzle with high volume production, small and highly complex optimised structures to deliver fluids with even pressure distribution and highly controlled jetting performance at previously unseen firing frequencies.

This is a clever and exciting technology development for the Inkjet industry. Traditional ‘Print snobs’ might even be impressed. Suddenly, the previously impenetrable markets that offset and flexo have dominated may now be open to seduction by the charms of thin-film Inkjet.

This enables higher nozzle counts with tighter packing densities plus smaller drop sizes. The benefits these deliver can include highly defined imaging, small text in superb quality, photo-imaging and tonal gradients that have only so far been achieved by traditional printing. Printing with thin-film technology could take place at break-neck speeds by inkjet standards, though still relatively slow by analogue standards. Some regard offset speed and image quality as a critical requirement for industrial production

Could this breakthrough to enable the wholesale conversion from analogue to digital, overcoming the perennial insistence on offset image quality and high throughput speeds for single-pass inkjet to be adopted for multiple industries. But this is in itself a debatable point as in fact I raised in his recent talk at the FuturePrint Virtual Summit. Others have questioned the assumptions behind “digital-analogic” philosophy.

This begs the question: Does thin-film inkjet solve a problem so large that it can justify the gargantuan investment in production? Does the commercial argument for thin-film inkjet really stack up?

From basic research and anecdotal observation, it’s difficult to escape the maths, although may not be the focus of those who may already be commercially, technically and perhaps emotionally invested in its success.

If a printhead manufacturer spends $250m to develop thin-film capability and a SiMEMS printhead and then sells 250,000 of these printheads over a period of time, then R&D expense alone would need an allocation of $1,000 per printhead. This figure is simple but overlooks associated costs of such an investment for the period from spending to payback which maybe 5, 10 or more years. We could, though we should not, put aside the opportunity cost and significant risk factors, both technical and commercial. Thin-film inkjet is a big, expensive and risky venture.

To expect sufficient traction such that market demand tops 250,000 units within a reasonable payback period is ambitious. It also assumes no interference from multiple competitors sharing similar ideas and ambitions, i.e. no producer can expect to monopolise.

What is wrong with bulk piezo?

I am an evangelist of innovation, but not innovation for the sake of it.

Many forms of bulk piezo printheads already meet the needs of many industries. Everyone would be interested in possibilities for lower cost and better imaging quality at greater speed.

In reality, a printhead is an imaging ‘paintbrush’. The print swathe has a hardware cost. Per inch of swathe, a 1200dpi printhead has more nozzles (double that of a 600dpi printhead) so even if the nozzle cost of a 1200dpi SiMEMS is half that of a 600dpi bulk piezo device, the print swathe capability costs the same.

Firing tiny drops at high frequencies is more problematic, and risk of nozzles failing to fire increases. Commonly, SiMEMS operation needs to provide nozzle redundancy and error correction for most single-pass processes. Necessarily some nozzles are therefore not fully utilised but are held back as error correction back-up. Is this compromising reliability for cost-effectiveness or cost-effectiveness for reliability?

Either way, it’s a trade-off.

Nothing new is perfect: For thin film, this is the case but, sure, this is exciting and very clever technology. However, progress in the adoption of this exciting technology hasn’t been fast. My view is that bulk piezo Inkjet should not be quaking in its boots just yet. Before the Emperor begins parading his new clothes, there are plenty of industrial applications that can already be readily addressed by tried-and-tested bulk piezo inkjet. Taking a new tech gamble based on digital-analogic may not be such a good bet, particularly during 2020/21, an era of such uncertainty.

Is this technology travelling through a hype cycle? Has it already transcended the peak of inflated expectations and is now descending into the trough of despair? I wouldn’t dare to suggest that this innovation is doomed to fall into the chasm, without hope of crossing, but it may take some time for it to find its place, to gain the necessary traction that will make it a mainstream choice. And it must be a mainstream choice to make printhead manufacturing viable.

Thin-film inkjet may yet find its particular purpose and may well yet ascend the slope of enlightenment. However, one might think right now given the commercial pressures placed upon the business and industrial landscape, this could well be some way off.

But what do you think? Do you agree?

A longer-form discussion paper on this theme is available now for anyone interested.

Please email here and a white paper will be sent shortly.