Research On Vacuum Soldering Process Of SiC_p/6063Al Composites

SiC_p/Al composites become one of the ideal alternative to traditional electronic packaging materials because of characteristics of high strength,high stiffiness ratio,small density,low coefficient of thermal expansion,ect.However,due to its poor weldability,SiC_p/Al composites will be restricted in practical application of T/R module.By researching the properties and weldability of aluminum composites,Sn-Ag-Cu-Bi fillers applying to soldering SiC_p/6063 Al composites with nickel plating were procuced in this paper.The study investigated the soldering technology between high and low volume SiC_p/6063 Al composites after nickel plating.The paper analyzed the microstructure and composition of solder,soldered joints and shear fracture through DSC,XRD,SEM,EDS and other experimental methods.Intestigation results are as follows:The study successfully smelts 6 groups of Sn-3.0Ag-0.5Cu-xBi new lead-free solders based on Sn-Ag-Cu eutectic solder.By comparing test results of six Sn-3.0Ag-0.5Cu-xBi solder,comprehensive performance of Sn-3.0Ag-0.5Cu-3.0Bi solder is the best,and its solid-liquid phase line temperature are 214 ? and 232 ?.The solder's wettability in SiC_p / 6063 Al composites after nickel plating is the best,and the spreading area is 41.52mm2/0.1g,the wetting angle is 18°.High and low volume SiC_p/6063 Al composites with Ni-plating are vacuum soldered with Sn-3.0Ag-0.5Cu-3.0Bi filler.In the soldering process,the solder and the nickel atoms diffuse and react to each other to generate a continuous IMC at the interface.The solder and the base metal formes a good metallurgical bond and a good quality of soldered joint is obtained.Soldering seam gradually narrows,and IMC layer thickens gradually,and Ni layer gradually becomes thinner with increasing the soldering temperature or prolong the soaking time.When soldering temperature are250 ? and 270 ?,the shear strength of soldered joints improves with prolonging the holding time.The shear strength increases first and then decreases with prolonging the holding time under 290 ?.It reaches the maximum value of 39.89 MPa for 30 min.By analyzing the shear fracture morphology and EDS of soldered joint,fracture mainly occurs in the solder layer or the junction of solder and the nickel layer.In the soldering process,the holding time or brazing temperature increases,scallop-shaped morphology IMC does not change,but the grain size becomes large.The growth of the interface IMC can be suppressed by Bi element of the soldering alloy.The growth of interfacial intermetallic compound can be divided into a faster growth rate stage and a slower growth rate stage.With increasing the soldering time,the growth rate of IMC reduces.Growth mechanisms of IMC are component diffusion and interfacial reaction mixture growth mechanism.Shear strength of vacuum soldered joint shows increasing trend with increasing the thickness of the nickel layer within plating time of 30 min.The nickel layer structure of composite surface is dense and uniform without pores,and the combination of nickel layer and the substrate is good after plating time of 20 min.From the feature region spectrum analysis with 5min electroless nickel,we know that fracture occurrs in the junction of solder and the nickel layer.Combined to shear strength and air tightness test results of soldered joint,using Sn-3.0Ag-0.5Cu-3.0Bi solder high shear strength,good air tightness soldered joint of nickel-plated SiC_p/6063 Al composites can be got under the process of electroless nickel plating time of 30 min,soldering temperature of 290 ?,and holding time of 30 min.