This paper presents research activities carried out at VTT Technical Research Centre of Finland in the field of hybrid
integration of optics, electronics and mechanics. Main focus area in our research is the manufacturing of electronic
modules and product structures with printed electronics, film-over-molding and polymer sheet lamination technologies
and the goal is in the next generation of smart systems utilizing monolithic polymer packages. The combination of
manufacturing technologies such as roll-to-roll -printing, injection molding and traditional component assembly is called
Printed Hybrid Systems (PHS).
Several demonstrator structures have been made, which show the potential of polymer packaging technology. One
demonstrator example is a laminated structure with embedded LED chips. Element thickness is only 0.3mm and the
flexible stack of foils can be bent in two directions after assembly process and was shaped curved using heat and
pressure. The combination of printed flexible circuit boards and injection molding has also been demonstrated with
several functional modules. The demonstrators illustrate the potential of origami electronics, which can be cut and folded
to 3D shapes. It shows that several manufacturing process steps can be eliminated by Printed Hybrid Systems
technology. The main benefits of this combination are small size, ruggedness and conformality. The devices are ideally
suited for medical applications as the sensitive electronic components are well protected inside the plastic and the
structures can be cleaned easily due to the fact that they have no joints or seams that can accumulate dirt or bacteria.
The gravure printing technique is currently under investigation as a possible method for the roll-to-roll production of OLEDs in the 6th framework EU funded project entitled ROLLED - "Roll-to-roll manufacturing technology for flexible OLED devices and arbitrary size and shape displays". The objective in the project is to fabricate an entire OLED structure by using roll-to-roll manufacturing methods and to examine, how the commercial production could be set up and integrated into an existing printing process. In order to attain a roll-to-roll compatibility, all the materials, inks and device structures need to be suitable for printing. Since, such OLED device structures are very sensitive to moisture and oxygen, high barrier materials to be applied as wet chemical coatings on transparent polymer films such as PET by common roll-to-roll coating techniques have been investigated. The barrier films on their respective substrates act as front and back side encapsulation materials, where the front side encapsulation material is to be used as a transparent and flexible substrate for OLED fabrication. The transmission rates to be achieved for both front and back side encapsulation for oxygen and water vapour are 5 mg m-2day-1 (corresponding to 7 cm3m-2day-1 for O2). In this paper, we show how light-emitting devices manufactured by gravure printing operate compared to the ones manufactured by traditional methods. Furthermore, we present recent results on the development of ITO nanoparticle coatings, cathode inks and flexible barrier materials.
Embedding of optoelectrical, optical, and electrical functionalities into low-cost products like product packages and printed matter can be used to increase their information content. For these purposes, components like displays, photodetectors, light sources, solar cells, battery elements, diffractive optical elements, lightguides, electrical conductors, resistors, transistors, switching elements etc. and their integration to functional modules are required. Also the need of rapid and reliable di-agnostic systems for wellness and healthcare applications is apparent. Today the time from sampling to result can take hours or even several days. In future the target is to analyze the sample within a few minutes for further action. Additionally, the price of the components for low-end products and disposable sensors has to be in cent scale or preferably below that. Therefore, new, cost-effective, and volume scale capable manufacturing techniques are required. Recent developments of liquid-phase processable electrical and optical polymeric, inorganic, and hybrid material inks together with biocompatible materials have made it possible to fabricate functional components by conventional roll-to-roll techniques such as gravure printing on flexible paper and plastic like substrates. In this paper, we show our current achievements in the field of roll-to-roll fabricated electronics, optoelec-tronics and biosensors. With examples of light guiding structures, organic light emitting diodes, biocompatible materials etc., we demonstrate the huge potential of roll to roll fabrication as a low cost mass production technology for future low end electronic products.