Characterization of woven electromagnetic shielding thermoplastic-fiber composites compared to non-woven electromagnetiv shielding concepts

As a result of necessary weight reductions and increasing proportions of functionally integrated, modular systems, the construction and production methods are becoming increasingly compact and complex. Thus, in addition to metallic materials, plastics are increasingly being used. In contrast to metallic materials, fiber-reinforced plastics have significantly lower densities with comparably high strength characteristics. Consequently, fiber-reinforced plastics offer a high, specific lightweight construction potential with regard to possible applications in electromobility concepts. At the same time, however, high demands are placed on the functional and component safety of housings for electronic devices and systems that contain sensitive sensors, applied and conductive elements. Undesirable electromagnetic couplings between the electrical modules must be avoided. Plastics are dielectric, however, so magnetic and electric fields can pass through the plastics attenuated. This can cause stray fields to emanate from the individual electrical components, which in turn can cause interference in neighboring circuit parts and even lead to significant failures of the electronics. The aim of this research is to develop glass fiber composite semi-finished products with integrated, cost-effective protection against electromagnetic influences based on unidirectional tapes and commercially available metal-coated polymer woven materials. These composites are to be compared with already explored composites with a metal-coated non-woven polymer fabric EMI layer. For this purpose, glass fiber thermoplastic composites with various functional layers to form metallized woven fabric were produced by hot pressing. The samples were analyzed and, based on this, the processing procedure was optimized to achieve optimum consolidation of the hybrid composite. A particular challenge is that the shielding component must remain intact in all process steps in order to ensure the highest possible shielding effectiveness over a wide frequency range. The subsequent comparison of the specially analyzed quasi-static and dynamic properties of the hybrid composite concepts by means of quasi-static tensile and 3-point-bending tests as well as shear load tests complete the investigation portfolio. From this, a comparison of the two concepts of non-woven vs. woven fabric is derived with regard to the composite properties. This research and development project is funded by the German Federal Ministry of Education and Research (BMBF) within the “Forschungscampus” program (funding number 02P18Q750) and implemented by the Project Management Agency Karlsruhe (PTKA).