Prepartion Of New Water-soluble Flux For Low Temperature Aluminum And Study Of Soldering Process Behavior

With the vigorous development of the electronic packaging industry,person have better requirements for low-temperature soldering performance of aluminum alloy,and the soldering performance of aluminum alloy depends on the performance of solder and flux.Sn-Zn solder has the advantages of low melting point,low cost and good soldering performance,making it the best choice for electronic package soldering.However,the Sn-Zn based solder has a disadvantage of poor wettability due to the presence of Zn.In order to improve this deficiency,the Sn-9Zn solder was modified by micron SiC particles,and its melting characteristics,heat dissipation performance,microstructure and mechanical properties were analyzed.At the same time,the oxide film composition on the surface of 6061 aluminum alloy was analyzed by XPS and XRD,and the corresponding low-temperature aluminum water-soluble flux was prepared for the composition of the oxide film.The water-soluble flux was used to investigate the wetting properties between the composite solder and the aluminum alloy,the wetting mechanism was analyzed.Studies have shown that the addition of a certain amount of SiC microparticles in the Sn-9Zn solder has a decrease in the melting point of the solder,but the decrease is not large.The melting point of Sn-9Zn-1SiC??m?composite solder is 198.16?,which is 0.41? lower than Sn-9Zn solder.A finer round cake-like Sn-Zn eutectic was found on the microstructure of composite solder,which greatly improved the microhardness and tensile strength of the composite solder.When the SiC particle content is 0.75%,the tensile strength reaches a maximum of 105 MPa,which is 146.9%higher than campared to Sn-9Zn.Sn-9Zn solder.When the content of SiC microparticles is 1%,the microhardness of the composite solder is 45.43Hv0.3,which is 96.9%higher campared to Sn-9Zn.At the same time,the heat dissipation rate of Sn-9Zn-1SiC??m?composite solder is 4.48?/min,and the heat dissipation rate is improved compared with Sn-9Zn solder.At 240?,the main component of the surface oxide film of 6061 aluminum alloy is enriched with magnesium in addition to?-Al₂O₃,forming a thin layer of MgAl₂O₄ oxide on the surface.The low temperature flux with NH₄BF₄ as matrix has high activity at 240? and can remove the oxide film on the surface of 6061aluminum alloy.The mechanism of membrane rupture:HF is decomposed in the flux at 240? to produce HF,HF chemically reacts with the MgAl₂O₄ oxide layer on the surface of the aluminum alloy to generate cracks,providing channels for HF infiltration,and further infiltrating HF with?-Al₂O₃ reacts to break the oxide film on the surface of the aluminum alloy.The flux rupture mechanism is a combination of dissolution reaction and chemical reaction to remove the membrane mechanism.Sn-9Zn-xSiC?x=0.25,0.5,0.75,1wt.%?four kinds of composite solders spreading well on the surface of 6061 aluminum alloy and have good soldered joint properties.The wetting and spreading mechanism of SiC particle modified Sn-9Zn composite solders and 6061 aluminum alloy.The formation mechanism of precursor film were analyzed.The spreading area of Sn-9Zn-0.75SiC??m?composite solder on the surface of aluminum alloy is 113mm²,and the soldered joint strength is up to 87MPa.Compared with Sn-9Zn solder,the spread area increased by 189.7%,Joint strength increased by 196%.As the content of SiC particles in the composite solder increases,the thickness of the solid solution at the interface of the soldering joint decreases.In the microstructure of the Sn-9Zn-1SiC composite solder and the 6061 aluminum alloy brazed joint,the thickness of the solid solution is 0.73?m.The solid solubility thickness is reduced by 223%compared with Sn-9Zn-0.25SiC??m?.The fractures of the four composite solders all exhibited typical ductile fracture morphology.