Study On Preparation And Performance Of SAC0307 Tin - Based Low Silver And Lead - Free Solder Paste

With the development of surface mount technology (SMT), solder paste is playing an increasingly critical role in surface mount technology. According to the defects about the solder paste from original laboratory, on the basis of the flux component in optimizing, a type of solder paste with excellent performance which is suitable for Sn0.3Ag0.7Cu low-silver lead-free solder has been developed by changing the components.(1) Thorough adjusting each component types, content and ratio of the flux, the final formulation of the flux:the content of rosin, solvent, surfactant, surface active agent, a thixotropic agent and triethanolamine were40%,40%,4%,2%,5%,1%.KE-604rosin and Fully hydrogenated rosin were selected as the rosin and those mass ratio is1:1; X ether and diethylene glycol hexyl ether complex as solvent whose mass ratio is1:1; Selection succinate, AK-218, adipic acid were selected as the active agent, the ratio of the complex of2.93:41.61:5.64; MF-200A was selected as a surface active agent; castor oil and hydrogenated castor oil were selected as thixotropic agent, whose content is5%.(2) By the rheological properties of the paste, the Sn0.3Ag0.7Cu lead-free solder powder which has moderate oxygen content, Smaller particle size, narrow distribution range and good roundness was selected and when the ratio of the flux and the solder powder was11.5:88.5, the paste has moderate viscosity, thixotropic index and the non-recovery rate of viscosity were relatively high, with good printing properties and rheological properties.(3) The Sn0.3Ag0.7Cu low silver lead-free solder was developed to test the performance, including halogen content, tin beads, collapse, expansion rate, copper corrosion, surface insulation resistance testing, and compared with Sn0.3Ag0.7Cu low silver lead-free solder paste of the commercial Senju company.The result showed that homemade paste is halogen free low silver lead-free solder paste, solder ball test has reached the first grade; both at25℃and150℃collapse is0.06mm, better than commercially solder paste; after welding, the residues has no corrosion on copper, expansion rate and surface insulation resistance are relatively high.