Enabling flexible electronics from the roll
August 17, 2016
Roll to roll printing has been long considered the ultimate approach to the cost-effective manufacture of electronics over large and small areas.
There was an interesting article in a The Economist a few weeks back called ‘Printed Electronics: On a Roll’. It was a timely reminder of the potential of printing to transform the economics of making electronics. Simply stated, the argument is that if you make electronics with the same manufacturing infrastructure, similar materials, and at the same speed in which you can print newspapers, costs will tumble. Of course this is true, but the reality is that the printers need to be more sophisticated, materials need to be engineered, and slow web speeds are required to achieve operational devices. Innovations are required throughout the supply chain to make the roll to roll manufacturing of electronics happen and it was really encouraging to read about the substantive developments that are occurring on the equipment and the materials. However, an integrated process still remains elusive.
Roll to roll: existing challenges
There are three attributes to the current process for making transistor-based electronics that are incompatible with roll to roll printing. The first attribute, which usually gains the most attention, is the fact that electronics are made in wafer or sheet-fed factories. FlexEnable, like many others, uses glass as a reusable carrier for thin plastic substrates during manufacturing. This is not a showstopper because it can easily be substituted for a web held in tension. The second attribute which is often noted in these discussions is the process temperatures. Lower temperatures are required for high yielding web processing and FlexEnable’s approach of using organic TFTs made below 100°C has a big advantage over ceramic-based technologies. However, it is the final attribute that often gets missed. Electronics are almost exclusively made with masked-based photolithographic processes. It is the replacement of these that will really usher in the revolution of roll to roll manufacturing of electronics.
Roll to roll: the future
At FlexEnable we take a practical view on how to replace lithographic steps. Printing, in the conventional sense, means direct deposition of materials to produce the pattern required. This additive approach can be used to replace some lithographic steps and is especially beneficial when expensive materials are required. However, for the foreseeable future these techniques will lack the accuracy and resolution to replace all lithographic steps. At FlexEnable we can employ laser direct imaging and ablation when higher patterning resolution is required. The first fully integrated roll to roll process line for electronics will be a mixture of those process techniques that are optimised for a specific application.
This brings me to my last observation from the Economist article. What was intriguing was how the author found contrast between the manufacturing revolution that is currently occurring with the 3D printing of mechanical components to the expected journey of electronics with ‘conventional printing’. In my blog post this time last year on changing the manufacturing paradigm for electronics, I shared my view that it is similarities with the 3D printing manufacturing paradigm that will define printed electronic innovations in the next few years. I believe a highly customisable processing approach for electronics that greatly reduces the mask costs for lower volume runs is achievable within the next two years. This will become the workshop in which a fully integrated roll to roll process is developed.
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