Study On Isothermal Electromigration Behavior Of Sn2.5Ag0.7Cu0.1RExNi/Cu Solder Joint

Drive integrated circuit continues to decrease in size of miniaturization and high performance of electronic products,as micro solder bumps connected with the conductive bridge size also decreases sharply,resulting in continued growt h in the current density of solder joints,meet or exceed the solder joints can occur within the electromigration critical current density.Electromigration results in the thickening of the intermetallic compound(Intermetallic,compound,between,interfaces)at the interface of the solder joint,as well as holes and cracks in the cathode,which seriously reduces the reliability of the brazed joint.Among the lead-free solder,SnAgCu solder is considered to be one of the most promising substitute of SnPb solder products,carry out the reliability of solder joints especially of electromigration reliability problem has become a research topic is more active in recent years.This paper takes Sn2.5Ag0.7Cu0.1RExNi/Cu brazing joint as the research object,to explore the temperature electromigration factors and occurrence conditions,then study the environmental conditions of current density,temperature and composition of solder electromigration effect of welding head on Microstructure and proper ties of Sn2.5Ag0.7Cu0.1RExNi/Cu steel,the growth activation energy of Sn2.5Ag0.7Cu0.1REx Ni/Cu solder joint interface IMC calculation,discusses the formation of electromigration the mechanism.The results show that In the Sn2.5Ag0.7Cu0.1RExNi/Cu brazing joint electromigration orthogonal test,current density head migration tests the greatest impact on the Sn2.5Ag0.7Cu0.1RExNi/Cu braze welding,followed by temperature,the minimum impact factors for power;without considering the interaction of the case to the anode interface thickness of IMC increases exponentially as the main migration organization representation,when the current the density is higher than 7.5 ×10~3A/cm~2 Sn2.5Ag0.7Cu0.1REx Ni/Cu brazing joint can present electromigration.When the current density is less than 7×10~3A/cm~2,the IMC thickness of the interface anode and cathode side is slightly increased and decreased when the Sn2.5Ag0.7Cu0.1RE/Cu brazed head is in constant temperature electromigration.When the current density is 7×10~3A/cm~2,The thickness of the anode IMC at the interface increases exponentially,The thickness of the cathode IMC is rapidly thinned and voids and microcracks are formed,with typical electromigration phenomena in organization feature is obvious.With the increase of Sn2.5Ag0.7Cu0.1RE/Cu brazing current density,anode side interface IMC growth activation energy decreased gradually,joint shear fracture by brazing seam / cathode side near the interface of brazing seam mixed fracture zone of dimple and cleavage of the IMC interface to th e coexistence of the cathode side to the cleavage brittle fracture transition,corresponding to the joint shear strength reduction.When the current density is 104A/cm~2,with the increase of temperature,the Sn2.5Ag0.7Cu0.1RE/Cu solder joint interface of anode side IMC is thickened by Scallop in Shell shaped gradually into the lamellar boundary;the morphology of IMC cathode side gradually thinning,by Scallop in Shell shape changed to jagged cathode side base material subjected to erosion,high temperature to produce Cu3 Sn the.Sn2.5Ag0.7Cu0.1RE/Cu solder joint shear fracture by brazing / change the cathode side near the interface of brazing seam mixed fracture zone of dimple and cleavage coexist to the cathode side of IMC interface to cleavage brittle fracture,the joint shear strength reduction.When the current density is 104A/cm~2,adding trace Ni can effectively improve the microstructure and properties of Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu brazed joint.Compared with the Sn2.5Ag0.7Cu0.1RE/Cu brazed joint,After welding,the thickness of the interface of Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu brazed joint increases smaller,The cathode thickness decreases less,The corresponding Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu of brazed joint interface of anode side IMC growth activation energy i s higher,the cleavage joint shear fracture by brazing seam zone to ductile fracture of the interface to the cathode side of IMC and dimple mixed fracture transition,corresponding to the joint shear strength reduction.