The Research Of Composition Design And Performance On No Clean Low Silver SAC Lead-Free Solder Paste

As the rapid development of electronic products which change into more finer,smaller,lighter,and thinner,surface mount technology(Hereinafter referred as SMT)gradually become one of the most common and important technology in the electronics industry.Solder paste is the most crucial materials of SMT,therefore,the research on no clean low silver Sn-Ag-Cu lead-free solder paste has important practical significance.This experiment firstly investigated the optimal choice of the matrix and the main components of flux,afterthat,the excellent flux used by no clean low silver lead-free solder paste was prepared,then SAC0307 solder powder and the optimized flux were mixed in a certain proportion,and then no clean low silver SAC lead-free solder paste was prepared,finally its performances were tested.The main conclusions were as follows:(1)The components of the prepared flux were determined: The solvent component was diethylene glycol: alcohol B: ether C = 6: 1: 3;The rosin was gum rosin B;The active agent was glutaric acid: succinic acid: Acid A: acid B = 2: 3: 1: 2;The surfactant was OP-10;The Lubricants was polyethylene glycol 2000;The antioxidant was hydroquinone;The thixotropic agent was the complex of ST and E;The inhibitor was phenylalanine triazole;The coagent was triethanolamine.The prepared flux was a stable,slightly yellow and translucent paste,no stratification and crystallization during cold storage,the value of pH was 5.52,the non-volatile matter content was 65.83%,halogen-free,without penetrating corrosion,and had good wetting properties.The flux residue after soldering was thin and transparent,low-corrosive,meet to the requirements of dryness,nearly no cleaning after soldering.(2)The mass ratio of flux and 3# SAC0307 solder powder in the prepared solder paste was 89:11,its viscosity was 814 kcp.There were no obvious icicles,bridging and other defects after printing,meanwhile the solder paste also had excellent collapse resistance;The wetting performance test was 1 level,and the spread morphology of the solder joint was full,bright and beautiful;The solder ball test was 1 level;The flux residue after soldering was thin and transparent,so it was no need to clean.(3)The research of the reflow solder joint tests showed that a scalloped IMC was generated in the interface of the solder joint,its thickness was about 2.6?m;The interfacial IMC was pinned into the interface of the solder matrix and the copper substrate,which could improve the strength of the solder joint;Due to the effect of reflow processparameters,a few small voids were founded within the solder matrix of the prepared solder paste,so its shear strength of the solder joint was a bit weaker than the commercial solder paste,which were between 31 Mpa and 44Mpa;The ductile fracture of the reflow solder joints were occurred in the solder matrix.The results of parallel experiment showed that the performance of the prepared solder paste could achieved the commercial levels.