Film insert molding and in-mold decoration are standard processes in injection molding allowing to generate 3D-shaped objects with seamlessly integrated graphics and high freedom in design. With the functional printing of electronic circuits and sensors, the field of in-mold electronics (IME) has now emerged. This technology embeds lighting and capacitive sensors for human interaction in injection molded products, thus allowing to prepare 3D-shaped human machine interfaces (HMIs) with a smooth surface and an appealing design. The interest in HMIs based on in-mold electronics technology has been taken up especially by the automotive industry and in control panels for consumer products. In the past the different functions in HMIs (shape, light, electronics, haptic sensation) were realized by assembling different components separately. By integrating the electronics in the IME process these functions are integrated in one plastic product in a single injection molding process. Thus, the entire complexity of the product manifests in the increasingly complex mold fabrication and injection molding process, finally resulting in a simple-to-use multifunctional product. Despite these decisive advantages, the market uptake is currently hindered by several limitations of the technology. The goal of MULTIMOLD is thus to overcome the current challenges of IME products which are: 1) the overall manufacturing process in IME typically involves multiple sub-processes like printing, component assembly, lamination, forming and injection molding. Although most of the sub-process yields are around 99%, the combination of many sub-processes currently results in a high drop-out rate. 2) the IME product becomes a multi-material compound that is difficult to recycle and thus does not meet the requirements of European society and policy on sustainability and circularity. 3) the embedding of complex electronics (microcontrollers, ICs) requires multilayer PCBs with high resolution interconnection lines and contact pads not easily achieved with functional printing used in IME so far. 4) the currently used capacitive sensors are not usable with cold fingers or gloves and do not provide haptic feedback, thus leading to an unsatisfactory user experience. 5) the direct lighting by LEDs placed in the vicinity of capacitive sensors generates a substantial heat inside the injection-molded part, leading to bad user experience in the HMI. In addition, low durability due to cracked interconnection lines often occurs next to the rigid LED parts, in particular in 3D-formed areas. 6) the humidity resilient integration of sensors and electrical components has not yet been established in IME processes. By introducing the next generation manufacturing process of products with complex geometries and microstructures based on in-mold electronics establishing a robust, weather-resistant material concept that provides inherent recyclability by design. Piezoelectric sensing, improved light management and high integration density open up innovative solutions for the targeting industries (i.e. technology and tools manufacturers, integrators, OEM, and end users) in the automotive HMI (market size USD 23 billion in 2023), industrial HMI (market size USD 5.3 billion in 2023) and Condition Monitoring (market size USD 3.1 billion in 2024) sectors. The innovations (i.e. simulations, skills development strategies and LCA / recycling results) developed in MULTIMOLD are also expected to have impact on the scientific community and on the environment.
