Research Of Hihg Performance Sn42Bi57Ag1 Low Temperature Solder Paste

With the development of electronic packaging towards lower temperature,Sn42Bi57Agl solder is widely used as soldering material in the field of low temperature packaging due to its low melting point,excellent mechanical properties and spreading performance.However,most low temperature solder paste mainly have problems such as low activity and high post-solder residue.Therefore,the development of high active Sn42Bi57Agl solder paste has important reference value and practical application value.In this paper,the high active Sn42Bi57Ag1 solder paste is taken as the research materials,taking spreading rate and post-solder residue as the main evaluation indicators,active agent,solvent,film-former,thixotropic agent and the content of solder power in solder paste are selected and optimized by reflow soldering experiment.Meanwhile,the effect of the reflow soldering process on the wetting properties of Sn42Bi57Agl solder paste and the post-solder residue was studied by adjusting the parameters of the reflow soldering process(heating zone,heat preservation zone,reflow zone).The main research results are as follows.(1)When the mass ratio of four organic acids of methyl succinic acid,adipic acid,salicylic acid and succinic acid is 5:3:5:2,the solder paste was high activity and the spreading rate can reach 86.58%,and adding 3%mass fraction of triethanolamine can greatly improve the spreading performance of solder paste.(2)The solvent is compounded of glycol ethylene ether,tetrahydrofurfuryl alcohol and diethylene glycol monoethyl ether at a mass ratio of 1:2:2.The solder paste has good auxiliary welding performance during the reflow soldering process.(3)When acrylic modified rosin(KE-604)is compounded with ice-white rosin at a mass ratio of 1:2:2 as a film-forming agent for Sn42Bi57Ag1 solder paste,the spreading rate of solder paste is 87.38%,the minimum post-solder residue is 52.06%,and the minimum non-bridge gap is 0.15mm.(4)The combination of thixotropic agent hydrogenated castor oil(T)and ethylene bisstearic acid amide(ZHH)has no significant effect on the spreading performance of solder paste.When the mass ratio of the two is 4:1,solder paste has excellent storage performance and thixotropy.(5)The content of alloy powder has little effect on the spreading performance of solder paste.With the increasing of alloy content,the storage property of solder paste was enhanced,and the thixotropy was not significantly changed.when the mass fraction of alloy powder is 88%,solder paste has excellent anti-collapse performance,the minimum non-bridge gap is 0.06mm.(6)When the heating rate is 1.75?/s,the holding time is 75s,the peak temperature is 170?,the reflow heating rate is 0.6?/s,and the spreading performance of the solder paste is excellent.