Shape Synergy of Ag@Cu Chip Packaging Nano-Paste and Its Sintering Reliability

Electrochemical migration of Ag can result in failure of power chips, thus affecting the application of nano-Ag paste as packaging material. In this study, a novel sintered material is developed using shape-synergistic Ag-coated Cu (Ag@Cu) particles, aiming at establishing a highly reliable connection between the chips and the substrates. The sintering behavior of Ag@Cu particles is examined, elucidating the role of skeleton-wetting synergism in enhancing the strength of the sintered layer from a structural perspective. Two distinct shapes of Ag@Cu particles serve as a skeleton support, providing electrical conductivity, and nano-Ag particles enhance wettability. Ag as a coating layer can slow down the oxidation of Cu, despite that oxidation still occurs in the sintered layer during the high-temperature tests, initially weakening the strength of the sintered layer, but eventually stabilization is achieved. The presence of Cu effectively inhibits electrochemical migration of Ag. The reliability of the sintered layer is enhanced by the novel shape of Ag@Cu particles and the interaction between Ag and Cu, thereby ensuring the stability of the power chips.