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Flexible Optical Injection Moulding of optoelectronic devices

Periodic Reporting for period 2 - FLOIM (Flexible Optical Injection Moulding of optoelectronic devices)

Okres sprawozdawczy: 2020-03-01 do 2021-02-28

Miniaturized, integrated photonic devices are driving an increasing number of applications, while facing pressure to lower cost and increase flexibility. The production chain is inherited from microelectronics, which is not appropriate for novel, low cost, high efficiency photonic devices. FLOIM concerns a new, automatized manufacturing technology to produce optoelectronic components and the assembly of the corresponding optical system, based on the use of thermoplastic materials and the embedding of all the components into a compact and robust unique device. Improving the cost efficiency, flexibility and environmental footprint of the complete integrated optoelectronics workflow, can provide European industry with a key tool for excelling in advanced applications and differentiating their products, while keeping production, innovation capacity and key Intellectual Property in Europe, which is the main goal of the FLOIM project. FLOIM aims to develop a manufacturing platform that takes into consideration the integration of optical embedding technology for high-precision injection moulding, enabled by multiscale structuring of mould cavity inserts. This platform also includes in line quality assessment methodology and instrumentation to extract information from the process, machinery and produced parts to perform full quality evaluation and prognosis towards a zero-defect paradigm, while providing full process control and automation. The technical goals of the project can be summarized as: Novel manufacturing chains for high quality integrated optical devices, Design new manufacturing equipment for functional optical embedding, Custom optical functions through mould insert machining and structuring, Sustainable production of eco-friendly optoelectronics, Disruptive applications.
General specifications were established for the demonstrators proposed in the project: Fibre Optic Transceiver (FOT), miniaturized scanning head for optical encoders (OEH), and Back Light Units (BLU). Benchmarks were established. Three research lines were developed in parallel: mould inserts micro structuring, injection moulding of optical components, and in line quality control and alignment. Tooling technologies were optimized to better fulfil the industrial requirements; the injection moulding process was optimized for the different demo parts; and the assembly of the pilot line began, including the manufacturing equipment and the measuring, alignment and quality control systems.
For inserts micro structuring, multiple technologies have been studied. The micromilling technology used for generating optical quality surfaces was also studied to manufacture gratings within the micrometric scale, obtaining excellent local homogeneity. Laser direct writing, Ion Implant Lithography (IIL), and multi-photon polymerization (MPP) have been used for generating specific patterns on steel mould inserts, which were later transferred to the optics by injection moulding, providing advanced optical functionalities without increasing the size of the final part or the processing steps. The proposed technologies have been validated and will be further improved within the demonstration activities.
As for injection moulding of the optical components, different trials have already been performed in the demonstrators: Multiple FOT samples have already been successfully injected without damaging the bonded wires. The diffraction grating in the OEH has been reproduced in small areas, demonstrating good replication capabilities. Large areas of the BLU have been over moulded with different materials, showing the challenge of guaranteeing either perfect adhesion on the LED units or the existence of an air gap between them and the injected polymer.
Optical Coherence Tomography (OCT) and fibre optic interferometry have proven to be suitable technologies for the injection moulding process monitoring and quality assessment. The OCT system has been built and tested with real FOT samples, proving its usefulness to detect anomalies within the injected material and check if the bonding wires have been damaged during the injection process. Fibre optic interferometry was tested for measuring small displacements of a polymer, achieving resolutions better than one micron.
A mechatronic device for assuring the automatic alignment of the components during the injection process, was designed and built. This system, along with the OCT control system, will be integrated in a mock-up mould for industrial validation.
The pilot line will be used for the manufacturing of FOT demonstrator due the stronger requirements in cycle time, alignment and repetitiveness. Most of the equipment required for the front-end part have already been purchased and installed, where they are being customized to fulfil the manufacturing line requirements. The automated cell for the back-end processes of the FOT manufacturing has been assembled and is currently being validated before its shipment the final facilities.
Regarding dissemination and communication, at the beginning of the project efforts were put onto raising awareness of the project among target audiences, later, the first results of the project have been presented on scientific publications, congresses and exhibitions.
The project has already reached multiple advances beyond the state of the art at this stage. Resolution of under a micron has been achieved and the tooling technologies are suitable for the injection moulding process. The work will continue to optimize the patterning of the inserts, especially on large areas, as well as the replication process by injection moulding. Replication accuracy and less induced stresses in the structured surfaces will be guaranteed by combining injection compression moulding and injection moulding, increasing reliability, adhesion and performance. OCT and fibre optical interferometry have already proved to be valuable technologies to achieve the required in line and in mould quality control. In the future, these technologies will be implemented along with the alignment system for process monitoring. Process control, system optimization and quality prediction will be supported by near real-time inspection data analysis and prognosis. The demonstrators chosen in FLOIM project will benefit from a shorter lead-time, reduced cost and higher productivity yield; due to the reduction of manufacturing steps, automation of the process, use of thermoplastic materials and the 100 % in-line quality assessment. The manufacturing steps have already been reduced thanks to the patterns generated on the mould inserts, which remove the necessity of adding further functional optical elements, while enabling higher compactness of the product and reducing energy losses in the injected optical component, thus increasing the overall energy efficiency of the device.
Detailed financial projections are envisaged for later stages of the project, when the project has a clearer and more advanced product, market characterisation and market analysis in order to define a realistic and reasonable scenario. At this moment, First Market Uptake estimations by involved industrial partners are presented in the “Impact table” submitted as an image.
MPP Glass
Diffusive pattern
4 point diagram
FlexEnable - 12.1-inch Conformable OLCD
SEM image of IIL structures made by ADAMA
OCT laboratory setup for future in mould quality control at RECENDT
Impact Table
FLOIM logo
Mechatronic alignment device concept
Laser micro and nanostructured mould insert processed at Ceit with a high repetition femtosecond las
Overmoulded BLU
OCT reconstructed 3D image of a measure sample by RECENDT
FLOIM target - Masssive manufacturing of optoelectronic devices