When you turn on your computer, TV or phone, you are using a photonic device – something that creates, manipulates and detects light. But their manufacture is not as efficient, flexible or economically and environmentally sustainable as it could be. “The manufacturing processes are inherited from microelectronics and so still involve manual assembly, especially at the later stages,” says Nerea Otero-Ramudo, coordinator of the EU-funded FLOIM project. FLOIM has developed a new automated manufacturing technology for optoelectronic devices. Based on thermoplastic injection overmoulding, it embeds components straight onto a device, which the team demonstrated by establishing a pre-industrial pilot line capable of producing fully functional devices. “The competitiveness of our solution was assessed by different techno-economic analyses and showed significant improvements on current approaches, in terms of costs, quality, flexibility and eco-efficiency,” adds Otero-Ramudo from the AIMEN Technology Centre, the project host.
With FLOIM’s innovation, the features for the desired optoelectronic component are inscribed into the mould surface or the surface of a metallic insert attached to the mould. The cavity is then filled with molten polymer. Once this solidifies, it retains the desired optical features, while also encasing all the individual components. “This provides excellent flexibility, as the optical features can be changed by swapping the mould insert with another of a different pattern. Substituting thermosets and glass with thermoplastics materials is also greener, cheaper and easier to work with,” explains Otero-Ramudo. Before building the moulds, the team performed several optical simulations to optimise its design. The project’s technique was validated by two demonstrators. The team created an optical encoder head (OEH) – a compact device that converts light to electrical signals – with its housing also created from injection moulding. A fibre optic transceiver (FOT), designed for high-volume data exchange, was also chosen to demonstrate a pilot assembly line. “We manufactured hundreds of units, successfully demonstrating full functionality with excellent optical and electrical performance,” remarks Otero-Ramudo.
The demonstration samples were assessed by an in-mould optical coherence tomography (OCT) system to detect misalignment between the mould and the components. To complement this, a mechatronic module was developed to reposition the mould and correct deviations. The OCT can also detect defects on samples after the injection process, such as cracks or bubbles. The team also created a module, based on a fibre optic sensor, to monitor the mould cavity filling process in real time, while a station to assess the quality and performance of the manufactured devices was integrated into the pilot line. “We have also developed predictive quality assurance based on neural networks and fed by data provided by other injection moulding manufacturing chains,” says Otero-Ramudo.
Increased European competitiveness and security
FLOIM’s results will help boost European production of photonic devices. This will not only increase revenue for European companies but also help establish a reliable European supply chain of components. “Validating injection moulding for optoelectronic device manufacturing opens the door to more available and affordable custom devices – such as innovative lighting systems. And our demonstrators could directly benefit daily life, providing faster communications and higher quality products,” notes Otero-Ramudo. The pilot line for the FOT will now be upgraded to ensure operational reliability at industrial scale. And with the various components of the OEH now separately validated, efforts continue to integrate them within a single injection process. “Project partners already have potential customers and so are ready to start using both demonstrators,” concludes Otero-Ramudo.
FLOIM, overmoulding, injection moulding, photonic, optoelectronic, LED, thermoplastic, polymer, fibre optic transceiver, optical encoder head