High Performance Package-Level EMI shielding of Ag Epoxy Composites with Spray method for High Frequency FCBGA package Application

We studied and demonstrated high-performance Ag epoxy composites. A variety of shaped Ag particles were teste to optimize the electrical properties and mechanical reliability. The resulting Ag epoxy composites containing flake-shaped Ag particles showed less than $5 \times 10 ^{-7} \Omega \cdot \mathrm {m}$ electrical conductivity and about $20\mathrm {m} \Omega $ series-resistance of PKG daisy chain, which directly corresponded to the excellent shield effectiveness. The shield effectiveness of resulting EMI shielding layer made of Ag and matrix is as high as 60dB, 65dB, 70dB at 5 $\mu {\mathrm{ m}}$, 10 $\mu {\mathrm{ m}}$, 20 $\mu {\mathrm{ m}}$-thick film, respectively by ASTM standard. We studied that how various factors, such as curing temperature, Ag contents, and film thickness, effects the electrical properties of shielding material and FCBGA package. It was found that the resistivity of conductive shielding material and the series-resistance were affected by the curing temperature than the curing time. Additionally, we demonstrated the electrical properties of AgCu epoxy composites.