ABSTRACT
Although many electronic functionalities can be realized by printed or organic electronics, short-term marketable products often re-quire robust, reproducible, and nondisturbing technologies. In this chapter we show how hybrid electronics, a combination of printed circuitry, thin-film electronics, and classical silicon-based electro-nics, may give rise to new ways of realizing electronic products. 11.1 IntroductionToday, companies, both small and large, have become increasingly interested in printed electronics, often drawn by the promise of cheap manufacturing technologies and hence cheap products. They expect the technology to deliver at least the same quality at lower cost with improved functionality. Interviews conducted within
the framework of the COLAE project (FP7-ICT-2011-7, grant no. 288881, www.colae.eu) indicated that the typical application areas companies are interested in are lighting (organic light-emitting diode [OLED] lighting), packaging (sensors and lighting elements in labels for product and medical packaging), energy harvesting, and heating elements. This is very much in line with the type of projects that are run at research institutes and the customer requests we encounter. The main driver for companies to consider printed electronics in these application areas is foremost cost reduction, improved reliability, added functionality, and an improved form factor. In addition, they are looking for a technology that allows them to do something that could not be done before, thereby giving them a competitive edge. The current research on flexible electronics focuses mainly on components (OLEDs, organic photovoltaics [OPVs], displays, for instance) rather than providing a complete solution. Such research is predominantly driven by combinations of academic groups such as universities, start-ups, and research institutes, as well as large-scale enterprises. From an application point of view flexible electronics is a promising enabling technology to small and medium enterprises (SMEs) by simply improving upon existing products. A major challenge, however, for SME companies is their requirement of short-term integration of new technologies, typically within a year. This means that to succeed, sets of technologies are required that are relatively mature and reliable and can be introduced without disturbing the overall manufacturing methods and supply chain. At the same time they should bare the general advantages of printed electronics, namely low cost, simple manufacturing, thinness, light weight, etc. Hybrid electronics, a mixture of state-of-the-art printed and thinfilm electronics, combined with classic electronics, may offer this. The manufacturing can mostly be done on existing infrastructure and simultaneously it offers exciting possibilities for new and improved products. This chapter will explore the most common technologies used today to achieve functional products and prototypes based on hybrid printed electronics (HPE). This includes the printing of circuitry, the assembly of components, and some typical finishing techniques, where meaningful technologies that are less common, or
more disruptive, in the manufacturing world will be discussed. This will be followed by a case study and a discussion of the design rules and the challenges that industry may face adopting this technology. 11.2 Basic Technologies
At a high level, the basic process flow for HPE consists of three important groups of processes, as depicted in Fig. 11.1. After preparation of the substrates, the manufacturing typically starts with printing electronic circuitry on a flexible substrate. This is followed by the assembly of passive and active components, and finally the product is finished, for instance, encapsulated or packaged.
