Periodic Reporting for period 1 - MULTIMOLD (Multi-functional In-Mold Electronics)
Reporting period: 2024-01-01 to 2025-06-30
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.
In the first 18 months of the project 6 working streams were running in parallel to evaluate the proposed MULTIMOLD solutions in order to overcome the current limitations of the in-mold electronics technology. The technical developments were carried out based on three 1st GEN demonstrators and 2 technology testbeds each including different technological innovations. An automotive HMI has been designed and fabricated including piezoelectric sensors and illuminated touch buttons showing the successful user interaction even at the exterior of a car and in highly humid conditions. An industrial HMI has been prepared integrating haptic actuation and a 3D formed flex PCB allowing for a high integration density of LEDs and integrated piezoelectric sensing in a confined space. The 1st GEN condition monitoring demonstrator showed the successful overmolding of sensitive electronic components like solar cells and batteries. Additionally, the overmolded system did survive lab and field testing w.r.t the harsh environmental conditions present on the rotor blade of a wind turbine. Possible end of life scenarios have been explored with a testbed allowing different material combinations to be evaluated in IME recycling trials to effectively separate the plastics from the electronics. The production of the testbed in parallel delivered a full set of LCA data for the production phase of in-mold electronic products for different approaches. In order to increase process reliability and reproducibility FEM simulation and optical simulation supported the injection molding and mold fabrication process and a tailor made data storage providing cloud access to production data for further data analysis as well as a framework for the digital product passport have been established in order to enhance process yield and detection of critical failure mechanisms in the process chain. Advanced possibilities of light management using microstructural elements have been evaluated together with different approaches of fabrication of microstructured molds using direct laser writing and gray scale laser lithography processes.
MULTIMOLD showed the feasibility to use piezoelectric sensing in injection molded parts providing touch sensing even in underwater conditions, or in operation with gloves or objects. Additionally, overmolding of sensitive electronics like batteries and solar cells has been demonstrated for the first time, showing the possibility to protect autonomous sensor systems in harsh environmental conditions. With the use of 3D formed flexPCBs MULTIMOLD demonstrated the feasibility to achieve highly integrated electronics and printed sensors in confined space using IME technology. Different material combinations suitable for IME have been investigated w.r.t their recycling potential and the circular use. Innovative laser processing of microstructures for fabrication of molds for injection molding was implemented for improvement of light management and will be further utilized for promoting adhesion and improving the haptic user interaction.