Organization. Of Ce, Sn-based Lead-free Solder, Performance And Interface Effects

Sn-Pb solders have been widely used in electronic packaging industry.This solder and the alloys developed with it have long provided and continue to provide many benefits, such as low cost,ease of handling,low melting temperatures,ductility, and excellent wetting on several substrates.However,in respect of environmental and health concerns,with the ever-increasing awareness of the toxicity of lead,significant pressure has been put on the electronics industry to get the Pb-free solder.Trace rare earth element Ce were added into Sn-3.0Ag-0.5Cu,Sn-7Ag-10Sb and Sn-3.1Ag-8.0Bi-2.1Cu-1.7In solders aiming at examining the effect of different amount of rare earth on the physical properties,spreading property,corrosion p roperty and mechanical properties of the solders,the effect of rare earth on the microstructure was also investigated.The results showed that the trace elements are beneficial to the properties of the solder Pb-free.The content of rare earth element h ad a slight effect on the resistivity, corrosion and melting point.Trace rare earth element improved the spreading area.With the increase of rare earth element content,the microstructure of the solder was from fir-tree crystal to equiaxed crystal and refined.The strength reach the best.According to the testing on the physical,spreading and mechanical properties,the most suitable content of rare earth in the Pb-free solders is 0.3wt%.During soldering,the solder alloy reacts with the substrate to form intermetallic compounds at the joint interface.It is desirable to achieve a good metallurgical bond. However,excessive intermetallic compound growth may have a deleterious effect.In other words,the thick intermetallic growth degrades interface integrity,owing to the brittle nature of intermetallic compounds and also the mismatches in physical properties such as thermal expansion coefficient and elastic modulus.Therefore,it is necessary to understand the factors that control the kinetics of interfacial reaction.Therefore,the objective of this study focuses on the kinetics of the intermetallic compound formation behavior of Sn-3.0Ag-0.5Cu,Sn-7Ag-10Sb and Sn-3.1Ag-8.0Bi-2.1Cu-1.7In solders with addition 0.3wt%rare earth element was investigated for Cu-substrate after soldered.the results show that,The adding of rare earth element can be helpful to reduce the Intermetallic compound in solders.Adding the rare earth element Ce is the best to depress the growth of the intermetallic compound.