Study On The Relationship Between Corrosion Behavior And Storage Stability Of Solder Paste

Our country's electronic industry started late.At present,as an advanced technology,longterm storage of solder paste at room temperature has been set up a high technical barrier by foreign countries.The problem of long-term storage at room temperature is still puzzling our solder paste industry.In recent years,storage stability has gradually become a domestic research hotspot for solder paste,especially focusing on the research direction of solder powder and active ingredient corrosion.However,the research on the essential mechanism of solder paste viscosity increase and the systematic research on the internal corrosion and viscosity of solder paste were not sufficient.In this paper,the influence of corrosion inhibitor on the corrosion behavior of solder alloy and the direct relationship between corrosion inhibitor and solder paste storage stability were studied by electrochemical method and weight loss method.The electrochemical behavior of the solder alloy in the alcohol-ether solvents of the flux was studied.The interfacial reaction was analyzed by impedance spectroscopy,and the solder paste properties of different solvents were evaluated.Finally,an organic acid intercalated hydrotalcite material is prepared and added to the solder paste in order to improve the storage stability of the solder paste.Obtained the following main research results:(1)The corrosion rate of SAC305 solder alloy in diethylene glycol monobutyl ether solution of succinic acid will be increased when 5 different inhibitors,such as 2-MI,2-EI,BTA,2-PI and 2-MBI added in.Under the system of this experimental formula,the effect of different inhibitors on the viscosity stability of solder paste was from good to bad: 2-PI> Blank > 2-MBI > BTA > 2-MI >2-EI.The solderability of solder paste with different inhibitors was from good to bad: 2-MI > blank > 2-EI > 2-PI > BTA > 2-MBI.(2)In the alcohol-ether solvent(EE,DEGEE,DEG,TEG),the electrochemical corrosion process of SAC305 alloy was controlled by charge transfer resistance and adsorption film resistance.In polyethanol ether solvents(m PEG200,m PEG400),the electrochemical corrosion process is only controlled by the resistance of the adsorbed film.(3)The results of solder paste made of different alcohol-ether solvents showed that: in terms of weldability,the alcohol-ether solvents with monohydroxy(EE,DEGGEE)in the molecule had better weldability.The welding performance of binary hydroxy alcohol-ether solvents(DEG,TEG)and polymerized alcohol-ether solvents(m PEG200,m PEG400)were poor.(4)The precursor hydrotalcite was composed from magnesium nitrate and aluminum nitrate,and the succinic acid intercalated hydrotalcite(Su Ac-LDH)was modified by organic acid.The hydrotalcite material intercalated with succinic acid failed to improve the storage stability of solder paste.