Martins Luís C, Silva Cátia S, Fernandes Leandro C, Sampaio Álvaro M, Pontes António J
Institute of Polymers and Composites, Department of Polymer Engineering, Campus de Azurém, University of Minho, 4800-058 Guimarães, Portugal.
DONE Lab-Advanced Manufacturing of Polymers and Tools, Campus de Azurém, University of Minho, 4800-058 Guimarães, Portugal.
Polymers (Basel). 2023 Dec 8;15(24):4649. doi: 10.3390/polym15244649.
Electronic devices are sensitive to electromagnetic (EM) emissions, and require electromagnetic shielding protection to ensure good operation, and prevent noise, malfunctioning, or even burning. To ensure protection, it is important to develop suitable material and design solutions for electronic enclosures. Most common enclosures are made with metal alloys using traditional manufacturing methods. However, using thermoplastic composites combined with additive manufacturing (AM) technologies emerges as an alternative that enables the fabrication of complex parts that are lightweight, consolidated, and oxidation- and corrosion-resistant. In this research, an AM technique based on material extrusion was used to print 2 mm-thick specimens with a multi-material made of micro-carbon fiber (CF)-filled polyamide that was reinforced at specific layers using continuous carbon fibers stacked with a 90° rotation to each other. The specimens' electromagnetic shielding effectiveness (EMSE) was evaluated in the frequency band of 0.03-3 GHz using the coaxial transmission line method. Depending on the number of CF layers, the EM shielding obtained can be up to 70 dB, with a specific shielding up to 60 dB.cm/g, predominantly by the absorption mechanism, being 22 times higher than without the CF layers. These findings promote this innovative approach to lightweight customizable solutions for EM shielding applications.
电子设备对电磁辐射敏感，需要电磁屏蔽保护以确保良好运行，并防止噪声、故障甚至烧毁。为确保防护，开发适用于电子外壳的材料和设计解决方案很重要。大多数常见外壳采用传统制造方法用金属合金制成。然而，使用热塑性复合材料与增材制造（AM）技术相结合成为一种替代方案，能够制造出重量轻、结构紧凑且抗氧化和耐腐蚀的复杂零件。在本研究中，基于材料挤出的增材制造技术用于打印2毫米厚的试样，该试样由微碳纤维（CF）填充的聚酰胺制成的多材料制成，并在特定层使用相互旋转90°堆叠的连续碳纤维进行增强。使用同轴传输线法在0.03 - 3 GHz频段评估了试样的电磁屏蔽效能（EMSE）。根据CF层的数量，获得的电磁屏蔽可达70 dB，比吸收率高达60 dB.cm/g，主要通过吸收机制实现，比没有CF层时高22倍。这些发现推动了这种创新方法在电磁屏蔽应用中实现轻质可定制解决方案。
