Lead-free Solder With Halogen-free Flux Studies

In this thesis, Sn-0.7Cu alloys were investigated as lead-free solders. Given consideration to the requirements of halogen-free flux and property of each composition in flux, chosen spreading propert as the scale index to filter each composition of flux and then optimize it. Rosin-core flux for lead-free solder wire and no-clean liquid flux were developed according to optimized fomulation, then the property of these fluxs were test in accordance with correlative standard. The results showed that:(1)Activators with different melting point and boiling point as composite activators indicated excellent fluxing capacity. Composite activators of organic acid and organic amine indicated low corrosion. Chosen TX-10 ester as surfactant of rosin-core flux for solder wire and BYK333 as surfactant of no-clean liquid flux.(2)Problems were found from comprehensive performance test. Sloved these problems by optimizing the formulation. For example, the flux with C oil and peppermint camphor were able to reduce spitting of flux and improve odor respectively. Amount of spitting was from 0.7% low to 0.3%.The optimal amounts content of C oil and peppermint camphor were not more than 5 wt% and 3 wt% respectively.(3)Contrasted the comprehensive performance of self-made flux with the same type commercial flux which were made in domestic and foreign country.(4)Examined practical effects of flux by simulating actual usage. For example, apply the solder wire with rosin-core flux to the heated soldering iron tip and apply the halogen-free flux to the wave soldering machine. The result indicated that welding ability of fluxes were good.