A study on design optimization of high-performance composites for portable devices

Lightweight housings for portable and aerospace electronics require materials that combine low density, high tensile strength and reliable electromagnetic interference (EMI) shielding. Here, basalt fiber-reinforced polymer (BFRP) laminates incorporating conductive networks formed by carbon nanotubes (CNTs), copper powder and copper mesh were developed and their mechanical and shielding properties were evaluated. X-band (8–12[Formula: see text]GHz) shielding effectiveness (SE) was measured using a coaxial transmission-line cell, and tensile behavior was characterized on the same laminates. The neat basalt composite showed very low SE ([Formula: see text]5[Formula: see text]dB) but the highest tensile strength. Adding 3[Formula: see text]wt.% CNTs increased SE to [Formula: see text]30[Formula: see text]dB while maintaining strength above that of typical aluminum alloys. A laminate with 15 wt.% copper powder reached [Formula: see text]20[Formula: see text]dB SE but exhibited substantial strength loss due to particle agglomeration and weak interfaces. Copper mesh laminates offered the best balance; two mesh plies achieved [Formula: see text]40[Formula: see text]dB SE while retaining tensile strength within the range of aluminum housing alloys. An Ashby-type [Formula: see text]–SE map using aluminum alloy 5052 as a reference showed a strength-dominated region with insufficient shielding and a high [Formula: see text]-SE region occupied by the 3[Formula: see text]wt.% CNT and symmetric two-ply copper-mesh laminates. These results indicate that effective EMI-shielding BFRP laminates require co-optimization of conductive-network geometry, continuity, stacking symmetry and metal fraction rather than simply increasing the amount of conductive material.