Abstract: Electroless nickel/electroless palladium/immersion gold（ENEPIG） is an important process for surface treatment of circuit boards and microelectronic chips to improve soldering performance. The thickness of Ni（P） in the traditional ENEPIG system is relatively thick（4-7 μm）, which contributes to large resistance, electrical signal degradation and potential bridging problems in the application. Therefore, the development of thin ENEPIG to replace traditional ENEPIG has become an emerging issue in packaging applications. At present, the overall performance of Sn-3.0Ag-0.5Cu（SAC305） solder is good, and it is the most widely used commercial lead-free solder. However, in the interface reaction of SAC305/thin ENEPIG, the Ni（P） layer will be depleted after reflow, and the IMCs grow fast, which reduces the conductivity and mechanical reliability of the solder joints. This review introduced the interface reaction mechanism of SAC305/thin ENEPIG,and the effect of Ni（P） thickness, Pd（P） thickness and P content on the interface structure and morphology of the solder joint was summarized. Finally, the electrical conductivity and impact resistance of SAC305/thin ENEPIG solder joints were analyzed to provide reference for the development of thin ENEPIG.