Ink-jetted Functional Circuits
Ink-jet printing techniques have been recently gaining attention because of their advantageous features, such as simplicity of fabrication, which makes it the ideal technique for the realization of prototypes and customized products. Such technique with a simple modification, proposed by an Italian supplier, can be applied to a wider variety of materials, including polymers, adhesives, metal alloys, ferromagnetic nanomolecules, passivation and encapsulation materials.
Ink-jet printing is a very widespread method used everywhere to transfer computer data to paper or transparencies. Ink-jet priniting techniques have been recently gaining renewed attention because of their advantageous features, such as simplicity of fabrication (that makes it the ideal technique for the realization of prototypes, small industrial production and customized products), compatibility with different substrates, feasibility of non-contact and no-mask patterning, low temperature processing and low cost.
This technology with a simple modification can be applied to a wide variety of materials, including polymers, adhesives, metal alloys, ferromagnetic nano-molecules, passivation and encapsulation materials. The printer deposits small ink droplets, containing the conductive material, directly on the substrate; in this way it is possible to realize electrical paths free of discontinuity on - even 3D - surfaces. In addition, vertical connections can be easily realized by superimposing the drops in appropriate place, without the aid of mechanical drilling systems or a laser, therefore the final circuit can be composed by different layers. Obviously in the case of a metallic substrate it will be necessary to previously apply a dielectric layer or treatment, in order to ensure proper functionality to conductive ink.
The ink-jet printed circuit does not need a photo-mask or a matrix to reproduce a circuit layer: the added value of the technology resides, indeed, in the fact that the image you want to print is digital and resides within a computer. In this regard this technology is particularly effective in the real time software compensation of eventual errors due to deformation and narrowing of organic materials caused by heat, or any positioning errors.
Innovations & Advantages
The ink-jet technology has a strong innovation impact in different fields; in fact it possesses immense potentiality to expand beyond printing, to applications in manufacturing and deposition, as ink-jet heads have the ability to deposit small drops of any kind of fluid (both inks and non-inks) in a precise, well-defined, and repeatable format, as in the case of printed electronics.
The market for an ink-jet print-head in printed electronics is still in the nascent stages, as the field would need further technological advancements. However the use of Ink-jet technology in the field of electronics, would be a potential low-cost alternative to the traditional manufacturing process, thereby resulting in the manufacture of low cost electronics. Furthermore, the rapid technological changes and the increasing miniaturization and complexity of electronic equipments in different sectors, such as Aerospace and Defense, telecommunications, automotive and industrial markets are expected to drive demand for ink jet circuits.
Direct printing of functional circuitry on the selected substrate would reduce the steps between the electronic drawings and the assembled circuit down to two: printing on the insulated substrate and subsequent drying up. Though such technology may be complex and require multidisciplinary skills, ink-jet application offers important advantages: it could be used to apply coating, to accurately deposit precise amounts of materials and to build micro/nano electro mechanical systems, directly on the substrate component. In summary, benefits of ink-jet technology include:
• Reduction of manufacturing costs
• Provision of higher quality output
• The new ability to process components and implement functional circuitry directly on the substrate
• Mass saving
• Less galvanic treatments
• Less waste production
• Future possibility to move from 2D to 3D printing
The potential applications have been grouped into five clusters by the OEA (Organic Electronic Association). These clusters are Organic Photovoltaics, Flexible Displays, Lighting, Electronics and Component and Integrated Smart Systems. What makes them so versatile are characteristics such as reduced thickness, less weight, and the ability to take any form, besides reliability and functionality. These are driving requirements in various innovative end-use applications, such as
Aerospace and Defense: Satellites, Launchers, Space Transportation Vehicles, Instrumentation panels, Plasma display, Radar Systems, Jet engine controls, Night vision systems, Radio communication systems, Power converters, Power supplies, LED lighting systems, Instrumentation, Control tower systems, Temperature sensors, Audio interface applications, APU (Auxiliary Power Units), Smart weapons, Laser gyroscopes, Torpedoes, Electronic shielding, Radio communications Surveillance systems.
Automotive: Instrument panels, Under-hood circuits, Headliner circuits, ABS systems.
Industrial Controls: Laser measuring, Inductor coil pickups, Copy machines, Heater coils.
Computer and Peripherals: Dot matrix print heads, Disk drives, Ink-jet print heads, Printer head cable.
Medical: Hearing aids, Heart pace-makers, Defibrillators, Ultrasound probe heads.
Instruments: NMR analyzers, X-ray equipment, Particle counters, Infrared analyzers.
Telecom: Cell phones, High speed cables, Base stations, Smart cards & RFID.
This technique proves to be extremely versatile; different equipment can be manufactured by this process. The Aerospace industry makes extensive use of printed circuits that need to have high reliability in extreme conditions. In this regard, this technology is particularly indicated for active thermal management electronic devices, such as heaters or strain-gauges applications. In fact it limits mechanical shocks and vibration influence of and is resilient over a wide temperature range.
Current and Potential Domains of Application
Currently used by the technology proposer for the aerospace field, particularly for thermal control in the aerospace sector, for satellites and launchers.