Hybrid in-mould integration

Next generation of electronic modules and systems in different application areas such as automotive, medical and home appliances will utilize various electronic, optical and mechanical functions integrated in freeform intelligent products with benefits such as decreased volume and weight, lower costs and higher freedom of design when compared to currently available electronics manufacturing and packaging methods. The hybrid in-mould integration technology concept is based on combination of roll-to-roll (R2R) printed electronics, discrete component assembly, film forming and injection overmoulding/in-mould labelling (IML) processes. In this study, compatibility and feasibility of the technology for low-cost disposable healthcare sensor applications, especially pulse oximeters, was investigated. Flexible printed circuit (FPC) substrates for pulse oximeter applications were manufactured in high-volume and low cost fashion by R2R printing and etching processes. Surface mount technology (SMT) and leadframe components were assembled on FPCs by using adhesive bonding technology. The assembly process was also demonstrated using automated, high-volume capable machine. It was proven that SMD components and their interconnections on flex withstand the injection overmoulding process and can thus be embedded seamlessly inside plastic parts. By the use of the same injection moulding process it was also demonstrated that rigid mechanical locking features manufactured by film overmoulding can be combined with the flexibility of FPC. In order to speed up the iteration cycles of the hybrid integration design flow, a new method was developed for rapid prototyping of in-mould integrated products. In the method, 3D printing was used to create a master for a silicone mould, and assembled FPC was overmolded in vacuum casting process with polyurethane material. This paper presents also other research activities at VTT Technical Research Centre of Finland in the field of hybrid system integration carried out in various collaborative projects with companies and research institutes in Europe. The demonstrators realised in these projects include autonomous, intelligent lighting and signaling systems for automotive and traffic signs, in-molded optical touch panel and flexible printed organic light-emitting diode (OLED) embedded into 3D plastic structure using IML-like process in which active OLED foils are used instead of graphic foils. The demonstrators prove that hybrid in-mould integration could be a feasible technology enabling seamless integration of optical, electrical and mechanical features into 3D plastic products.