The research project aimed to create a fully integrated, highly automated LED lighting system that could be manufactured in Germany without the many separate steps that currently drive production to low‑wage countries. By combining novel manufacturing technologies with new materials, the team sought to eliminate the conventional sequence of housing fabrication, LED soldering, optical lens assembly, and heat‑sink mounting. The core innovation is an integrated metal‑plastic injection moulding (IMKS) process that embeds conductive traces and LED contacts directly into a thermally conductive, electrically insulating plastic housing. This allows the LED board and contact pins to be placed inside a three‑dimensional moulded case, after which a low‑melting solder (Sn100Ni+ or Sn96Ag+) is injected to form the electrical connections. An optical component with free‑form geometry can then be moulded over the LED and sealed in a single step, removing the need for separate lens handling and alignment.

Material selection was a key part of the study. The optical component was evaluated using polycarbonate (PC, Makrolon LED2245) and polymethyl methacrylate (PMMA, Plexiglas 7N). Mechanical testing of bonded specimens showed that PMMA consistently exhibited higher tensile strength than the optical PC, a benefit attributed to its lower melt temperature. For housings, several polycarbonate variants were examined, including standard Makrolon 2405 and thermally conductive grades Makrolon TC110 and TC210. Tensile tests of bonded pairs revealed that increasing the proportion of thermally conductive additive reduced the interfacial strength, indicating a trade‑off between heat dissipation and mechanical robustness.

Electrical performance of the IMKS traces was measured by applying 10 A and 20 A currents. Conductivities of 4–5 × 10⁶ S/m were achieved for the soldered traces. Temperature monitoring with an infrared camera showed that the thermally conductive housings effectively limited heat rise: with Sn100Ni+ solder and a 400 bar injection pressure, the maximum temperature reached about 100 °C for Makrolon TC110 and 97 °C for Makrolon TC210, whereas Makrolon 2405 reached a higher 117 °C. The lower‑melting Bi58Sn42 solder could only be tested at 10 A because it melted at higher currents, confirming the importance of selecting a solder with an appropriate melting point for the integrated process.

The project was carried out over four phases from December 2018 to November 2022. Phase 1 focused on material selection and demonstrator geometry, supported by injection‑moulding simulations that optimized gate positions. Phase 2 involved laboratory studies on simplified test parts, including mechanical, optical, and hermeticity tests. In Phase 3, full demonstrators were produced at the Institute for Plastic Processing (IKV) and at Heiform GmbH, then subjected to mechanical, thermal, and electrical analyses by IKV and Mentor GmbH & Co. Phase 4 identified optimization opportunities and outlined future work.

Collaboration was extensive. The lead institution was the Chair for Plastic Processing at RWTH Aachen, with Prof. Dr.-Ing. Christian Hopmann as project coordinator. Key partners included Covestro AG (Leverkusen), Innolite GmbH (Aachen), Heiform GmbH (Herford), Mentor GmbH & Co. Präzisions‑Bauteile KG (Erkrath), Felder GmbH Löttechnik (Oberhausen), Röhm GmbH (Darmstadt), Engel Austria GmbH (Schwertberg), and Motan Holding GmbH. Funding was provided by the German Federal Ministry of Education and Research under grant number 13N14627. Contributions from students at RWTH Aachen were documented in a student thesis, and the results are available in the IKV library. The project demonstrates that a single, highly integrated injection‑moulding cell can produce a complete LED lighting module, reducing process steps, material waste, and logistical complexity while maintaining performance comparable to conventional manufacturing.