Synthesis Of Nano-SnAgCu Solder By Microemulsion Method

Nowadays,because of the increased awareness of the toxicity of lead to humans and the harm to the environment,lead-free soldering plays an important role in electronic packaging.The high melting point of lead-free tin-based solder leads to high energy consumption during electronics assembly and reduced reliability of devices.The melting point of nano lead-free solder is much lower than the bulk material and it has received increasing attention.The synthesis of nanomaterials by microemulsion can precisely control the particle size and stability of nanomaterials,and limit the processes of nucleation,growth,coalescence and agglomeration of nanomaterials.The microemulsion method has the advantages of cheap raw materials,simple experimental device,easy operation,mild reaction conditions,narrow particle size distribution and controllable size,and can avoid the agglomeration problem of nanoparticles.But so far,there has been no report on the preparation of nano-alloy solder by microemulsion.In this paper,nano Sn3.0Ag0.5Cu solder was prepared by microemulsion method,its melting point and welding performance were tested,and the preparation conditions of stable microemulsion were systematically studied.The prepared alloy has a low melting point and good soldering performance and is expected to replace the conventional tin-lead solder.1.Preparation of stable microemulsionThe composition ratio of the stable microemulsions was successfully obtained by titration,including W/O microemulsion and O/W microemulsion,and the effects of two different titrants on the preparation of stable microemulsion were compared,different titrations has little effect on the formation of microemulsions.The obtained microemulsion component ratio was made into a three-phase diagram,and in the region I of the three-phase diagram,any ratio can form a stable microemulsion.The area of the stabilized microemulsion gradually increases with the increase of the surfactant HLB value,which indicates that the surfactant with larger HLB value is more favorable for forming the O/W microemulsion,and there is no significant difference in the W/O microemulsion three-phase microemulsion region.2.Preparation of microemulsion reactors with different particle sizesA microemulsion prepared by titration in which two mutually incompatible liquids are divided into tiny spaces by a surfactant to form a"microemulsion reactor"whose radius is fixed by changing the type of surfactant and water and surface activity.The mass ratio of the agent was successfully controlled to control the particle size of the microemulsion.It is found that the particle size of the microemulsion,ie the size of the microemulsion reactor,increases with the increase of the mass ratio of water to surfactant.The size of the microemulsion reactor can be controlled at 1-120 nm by selecting different surfactants.Within the range,the particle size of the nanoparticles synthesized by the microemulsion method is controlled to obtain nanoparticles having a narrow particle size distribution and uniform size.3.Synthesis of nano solder powder by microemulsion and the study of its soldering propertyThe Sn3.0Ag0.5Cu nanoparticles were synthesized by microemulsion method.The effects of different experimental conditions on the synthesized nano-SAC particles were investigated.Under the optimal experimental conditions,the average particle size of the synthesized nanoparticles was about 7-9 nm,the particle size distribution was narrow,and the size was uniform.The diffraction peaks of three Ag₃Sn phases were found by XRD diffraction.Microemulsion is capable of synthesizing nanoalloys.From the DSC characterization,it can be seen that the initial melting temperature of the nanoparticles is 183.6?,which is close to the lowest temperature of the traditional tin-lead solder paste.At the same time,by welding and testing the welding strength,the maximum welding strength of the sample is 29.76 MPa,showing Excellent soldering performance,it is expected to replace tin-lead solder paste.