Non-Cyanide Thick Silver Electrodeposition Base on Instantaneous Nucleation for 3D Microstructures with High Performance

Abstract

To meet the diversified development of electronics, it is essential to develop 3D metal microstructures with high performance. However, 3D thick silver forming is still a challenge due to high internal stresses and various defects. Here we proposed a method for the thick Ag electrodeposition with low-stress and high chemical stability for 3D Ag-based microstructures. We carried out systematic studies through electrochemical measurements, morphological characterization, micro-texture analysis, internal and stability examination. The results show that the nucleation mechanism of electroplating Ag is transformed from progressive nucleation to instantaneous nucleation through the coordinated control of current density and temperature. Higher temperature and lower deposition potential are preferred to form the large-grained crystallization. Additionally, the external parameters for fabricating Ag coating were optimized, and the correlation between micro-texture and internal stress was also verified. The feasibility of thick Ag preparation process was demonstrated by extending the electroplating time, showing excellent performance. Finally, 3D Ag micropillar arrays with the height of 577 μm and the high aspect ratio close to 3 were fabricated by MEMS processing techniques, displaying satisfied 3D forming ability. This work presents a new approach for manufacturing the 3D Ag microstructures and lays foundation for the multi-functionalization Ag-based devices.