Cu–CoNiFe multilayered stack for low- and intermediate-frequency magnetic shielding

Electromagnetic interference (EMI) shielding has been a fundamental challenge because of the low wave impedances with monolithic metallic shields at low frequencies. Multilayered structures are considered an alternative to traditional monolithic shielding materials. This paper investigates such multilayered conductors of cobalt–nickel–iron alloy (CoNiFe) and copper (Cu) to illustrate their superiority over conventional monolithic shields. Modeling, simulations, and measurements demonstrate improved shielding when multilayered stacks are used against magnetic field sources. Furthermore, the stack-ups have excellent shielding even with a thickness of 5 µm. At least 40 dB of additional shielding effectiveness is achieved across 30–1000 MHz as compared to single-layer shielding from monolithic Cu of the same thickness. These innovative stack-ups also exhibit superior shielding when compared to multilayered stacks and shielding materials in literature. Additionally, these stack-ups are fabricated using standard substrate processes such as electroplating. Consequently, this approach becomes commercially viable and applicable to future electronic systems.