| With the size of the chip gradually approaching the physical limits,three-dimensional integration and packaging interconnect technology will become the future of small,highdensity,highly integrated microelectronic devices to achieve the key technology,and is expected to break the current technical bottlenecks,making Moore law continues.The interconnection between the metal and solder bumps is the key to realize the threedimensional stacking of the chip.In order to improve the reliability of the chip threedimensional stacked package,it is necessary to develop a new type of metal / solder bump with high interconnection reliability.In this paper,the micro-bumps of Sn-Zn alloy solders were prepared by electrodeposition on Cu substrates.The effects of electroplating process parameters on Sn-Zn alloy solder coatings and the electrochemical mechanism of Sn-Zn alloy on Cu substrates were investigated.The interfacial reaction of Sn-Zn alloy solder bumps and Cu bump interconnects,the growth and evolution of intermetallic intermetallic compounds,and the effect of interface IMC growth on the shear strength of interconnected joints.The main results are as follows:(1)The electrochemical workstation was used to study the relationship between the transient current and time of the cathode surface of the Sn-Zn alloy solder on the copper substrate.It was found that the electrochemical mechanism of the Sn-Zn alloy solder on the Cu substrate was transient nucleation,The nucleus is heavily controlled by proliferation.(2)The interfacial reaction of Sn-Zn alloy solder bumps with Cu substrate shows that Cu5Zn8 intermetallic compounds(IMCs)are formed at the interface after reflow of Sn-Zn alloy solder with Cu-containing Cu and Cu No Cu6Sn5 intermetallic compound was found,indicating that the Sn element in the solder did not participate in the interfacial reaction.The production of the interface IMCs was controlled by the alloying element Zn in the solder.(3)The aging test of the interconnection joint showed that the IMCs at the interface between the pure Sn solder and the Cu substrate changed from Cu6Sn5 to Cu6Sn5 and CuSn3 as the aging time was prolonged.Sn-Zn alloy Cu substrate interface is always Cu5Zn8 layer,and no significant phase change occurred.(4)The shear strength of the interconnection joint between the solder alloy and the Cu substrate decreases with the increase of the aging time,and the shear strength of the Sn-Zn alloy solder and Cu substrate interconnection with a small amount of Zn is higher than that of the pure Sn solder In the Sn-Zn alloy solder,the Sn-Zn alloy solder and the Zn content in the Sn-Zn alloy solder are increasing,but the strength of the interconnection joint decreases when the Zn content in the Sn-Zn alloy solder is too large,and the Sn-Cu substrate interconnection joints of the largest shear strength. |
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