Stability of Multilayered Ag/Ag3Sn/Sn Films Noncyanide Electroplateded for high-reflective back-electrode

Due to the problems of environmental pollution and energy consumption, the design of high-reflective back-electrode (HRBE) was proposed and applied to flip-chip and verticalpackaged high-power LED packaging processes. The working reliability of the Ag-based reflective electrode material is a key technical bottleneck in the development of a HRBE that has a simple structure, a low manufacturing cost, and a high reliability in a complicated working environment. In this work, multilayered Ag/Ag
₃
Sn/Sn films were prepared by non-cyanide electrodeposition and annealing and we studied their properties. Multilayered Ag/Ag
₃
Sn/Sn exhibited superior high specular reflectance compared to pure Ag films. After immersing in 2 ml/L (NH
₄
)
₂
S
_x
solution for 60min, the multilayered Ag/Ag
₃
Sn/Sn films still maintained the initial reflectivity, and the pure Ag film decreased significantly. In addition, the contact resistance of the pure Ag film increases significantly with the increase of the immersing time and eventually fails. These results show that Ag/Ag
₃
Sn/Sn films have excellent reflectivity and sulfidation resistance, paving the way for the preparation of efficient HRBE.