SMaRT Stacking: A Methodology to Produce Optimally Layered EMI Shields with Maximal Green Index Using Fused Deposition Modeling

Abstract Effective electromagnetic interference (EMI) shielding requires structures that are both highly effective and absorption‐dominant, qualities that are often in conflict. Achieving strong shielding typically comes at the expense of secondary electromagnetic pollution, as most conventional shields reflect incoming waves rather than absorbing them. To address this issue, current research is shifting toward asymmetrically layered and gradient multilayer shields, aiming to achieve both high shielding and strong absorption. However, no systematic method exists to determine the layer ordering that maximizes absorption for a given set of materials, and contemporary EMI shields still rely heavily on expert intuition and trial‐and‐error approaches. This work proposes a generalizable optimization method based on gray‐box modeling techniques from system identification to design the optimal stacking sequence of ten additively manufactured layers, producing a 4 mm thick, absorption‐dominant EMI shield for the X‐band. Using fused deposition modeling (FDM) to process polylactic acid (PLA) with varying loadings of multiwalled carbon nanotubes (MWCNT), shields are fabricated with optimized layer orders tailored to different shielding requirements. To illustrate, the resulting EMI shields demonstrate exceptionally high absorption while maintaining high overall shielding performance. A green index, or absorption to reflection ratio, ≈100 is obtained for the optimal layer order requiring 25 dB of shielding.