SECTOR

Printed electronics have been studied for over 50 years. The conductive inks used in automotive windshield de-icing systems date back to the 50s, while the first printed transistors or OLEDs date back to the 80s. It’s a multidisciplinary field, drawing on skills in chemistry, physics, electronics and the machinery and equipment sector. This combination of new materials and low-cost, large-area production techniques opens up a wide range of electronic functions associated with thin, light, flexible components that can be manufactured and integrated directly into products at low cost.

At present, there are many players in this sector, operating in different sectors.

• French and European R&D skills are relatively dispersed within teams whose core business is not printed electronics, as may be the case in other European countries. Things are changing, platforms are being planned and French players are getting organized.
• Start-ups are developing specific applications and equipment based on research work.

Printed electronics processes develop heating systems, sensors, actuators, antennas, transistors, capacitors, batteries, fuel cells, light-emitting diodes, photovoltaic cells and displays.

To integrate these technologies into the manufacturing processes of electronic systems, and to meet the new challenges of innovation, manufacturers need new skills. This means developing training in the context of printed electronics.

CONTACT NAMES

BORDEAUX INP – Bordeaux
OLEDS, OPV, SENSORS
VIGNAU Laurence – laurence.vignau@ims-bordeaux.fr

EIDD – Paris
OLED, POV, SENSORS, TRANSISTORS
BATTAGLINI Nicolas – nicolas.battaglini@univ-paris-diderot.fr

HEPIA – Geneve
ANTENNA, RF, MEDICAL, SENSORS
Bechevet Delphine – delphine.Bechevet@hesge.ch

GRENOBLE INP – PAGORA – Grenoble
GRAPHIC PRINTING, ELECTRONIC PRINTING, GREEN ELECTRONICS
REVERDY-BRUAS Nadège – nadege.reverdy-bruas@grenoble-inp.fr

Research center for new energy technologies. Based in Grenoble and Chambéry, in the heart of France’s leading energy-producing region, the Laboratoire d’Innovation pour les Technologies des Energies Nouvelles et les nanomatériaux (Liten) is the first European research center entirely dedicated to the energy transition.

Thanks to its position within the CEA, over the past 15 years Liten has become a major player in technological research to meet the challenges of energy and the environment, while supporting economic growth.

IRT ST EXUPERY

Accelerating scientific and technological research and transfer to industry in the aeronautics, space and embedded systems sectors: high-performance multifunctional materials – electric aircraft – systems engineering and modeling – intelligent systems and communications.

GDR OERA

The CNRS GDR 3368 “Organic Electronics” brings together just over forty academic laboratories working in the field of organic electronics.

Substrates

The advantage of organic printed electronics is the use of flexible substrates. The choice of these flexible substrates is dictated by the drying temperatures of the different formulations printed on them.

The most commonly used substrates are PET (Polyethylene Terephthalate), PEN (Polyethylene Naphthalate) for formulations with higher drying temperature solvents. Paper and PVC substrates tend to be used for consumer applications such as tickets, packaging and smart labels.

Ink formulations

There are a number of different formulations currently on the market:

• Metal-based conductive inks: Ag is the most widely used metal, but its prohibitive cost is jeopardizing business models based on this metal. To replace it, formulations based on copper oxide are still being tested,
• Transparent conductors based on organic polymers used to replace transparent conductive deposits such as ITO or ZnO,
• Resistive to obtain resistive functions,
• Dielectrics to obtain capacitors, bridges, insulating zones, etc…
• piezoresistive for direct piezoresistive sensors.

Other organic polymers are also doped with p and n to produce transistors; the most commonly used are polythiophene (PEDOT-PSS), polyaniline (PANI) and polypyrrole (PP).

These different formulations have rheologies adapted to the various deposition technologies used (screen printing, flexography, inkjet, etc.).
Research is currently underway into nanoparticle-based formulations incorporating metal or graphite particles. Ongoing research is looking into the possibility of replacing transparent conductors with graphite nanotube or graphene-based formulations.

To ensure good continuity in the deposition of the ink or polymer film, the surface properties of the substrate to be printed (particularly its roughness) are of prime importance.

Encapsulants

Organic materials are particularly sensitive to water, steam and high temperatures, which means they need to undergo certain (often costly) treatments in order to be encapsulated. There is still a great deal of progress to be made in this field in terms of treatments and deposition techniques, in order to optimize the performance of organic applications over time.

Screen printing

This process deposits a film of ink between 20 and 100 µm thick, and achieves good conductivity results on a wide variety of substrates. While it guarantees excellent repeatability, it is a slow process, cost-effective for small quantities with low resolution.

Flexography

Flexography allows a linearity of 60 lines per centimeter, with a thin plate of high hardness, making it ideal for electronic printing. The thickness of the ink film deposited can reach 6 to 8 µm. The disadvantage of this process lies in the profile of the deposited ink film, which creates a halo at the edges, leading to a thickness irregularity that can disrupt printing.
Flexography is used to produce RFID antennas on labels using silver inks, as well as for printed batteries. The progress made in recent years and the improved conductivity of the inks used make flexography one of the most promising techniques.

Rotogravure

Rotogravure is an intaglio printing process. This process deposits a relatively thick film of ink, ideal for electronic component applications.

Vacuum evaporation

Vacuum evaporation and spin-coating techniques are regularly employed. However, their low yield (75% of the polymer solution is lost) and high cost make them unsuitable for continuous production.

Slot Die

This deposition process is a non-contact direct transfer process compatible with all inks.

Offset printing

Offset printing is a well-established process for a multitude of substrates (paper, cardboard, metal, plastics). The resolution achieved is excellent, production speed is attractive and, last but not least, recto/verso printing produces circuits on both sides of a substrate. However, offset also has its drawbacks. To compensate for the lack of conductivity due to the thinness of the ink film (2 to 3 µm), it is generally necessary to apply several layers. In addition, a conductive ink with a viscosity of between 5 and 50 Pa.s is required, which is difficult to achieve with conductive polymers. This is why conductive metallic inks are still the main choice.

AFELIM’s EQUIPMENT & SERVICES working group brings together equipment manufacturers and service companies involved in printed electronics. The aim is to anticipate the needs of laboratories and manufacturers, and to develop the complementarities of equipment suppliers in major projects, with a view to rapidly supplying innovative new products.

The working group is preparing a booklet presenting the different functions of the printed electronics process and the know-how of equipment manufacturers and service companies.

To meet these technological challenges, a number of private and academic research centers, sometimes in symbiosis or under contract with manufacturers, are developing and testing new processes and equipment. And to bring value-added products to market in a short space of time, start-ups need technical resources and industrial processes that are often beyond their capabilities.

This is why France has set up several technology platforms to develop synergies around the integration of intelligent objects. These complementary platforms cover the entire sector (materials, formulations, processes, components, systems), providing specific processes and equipment for pre-production testing.

A TECHNOLOGICAL PLATFORMS working group has been set up within AFELIM.

This group supports the development of these platforms and technical centers, and federates resources for rapid application development.

The first AFELIM booklet lists skills and know-how, resources and access to five French platforms: ELORPRINTTEC in Bordeaux, CTP in Grenoble and Douai, CT IPC in Oyonnax, SPRINT IM2NP in Marseille, PTIC CEA LITEN in Grenoble.

Le savoir-faire et la maturité technologique des plateformes :

TRL 1 Observation of the basic principle
TRL 2 Technological concept formulation
TRL 3 Experimental proof of concept
TRL 4 Technology validation in the laboratory
TRL 5 Technology validation in real-life environment
TRL 6 Technology demonstration in real environment
TRL 7 Prototype-scale system demonstration in operational environment
TRL 8 Qualification of a complete system
TRL 9 Real system demonstrated in operational environment

Printed electronics provide opportunities for innovation and differentiation for new generations of functions and products.

Production processes, at ambient temperature and air, are based on additive deposition of very thin materials, and involve a reduced number of steps. This industry generally uses clean rooms that consume very little electrical energy and water.

Printed electronics contribute to environmental impact in all market sectors :

• in transport, less weight and therefore less consumption, more functionality in a reduced volume.
• in construction, easy integration into existing environments.
• in agriculture, flexible photovoltaic films that can be integrated into greenhouses.
• in luxury goods, intelligent, recyclable packaging.
• in healthcare, traceability of medicines at lower cost.

Companies manufacturing products based on organic electronics attach great importance to environmental aspects.

A CIRCULAR ECONOMY working group has been set up within AFELIM

AFELIM schools, laboratories and industrialists are now meeting on a regular basis to work on the subject of the circular economy in the printed electronics value chain. More than twenty members took part in this first meeting.

The expectations of this CIRCULAR ECONOMY working group are essentially to exchange information in order to provide concrete solutions, federate the common interests of AFELIM members and develop collaborative projects.

The aim is to structure a global approach and rapidly establish an inventory of recycling and life-cycle analysis of the value chain: materials, substrates, processes, products (end-of-life, recyclability, reuse of materials and substrates, etc.) in order to introduce the circular economy right from the product design stage.