| Using cutting-remelting technology to produce BGA solder balls is a good technological process with the characteristics of easier to be controlled, lower product cost, and simple equipments. By using this method, we can get solder balls with clean surface and good metal gloss, no extraneous component and other pollutants. No collision bruising, rupture, burr, accretion and heavy oxygenize. According to the process flow of the experiment, experimental facility is home-made. Experimental equipment is made up of temperature controller, electric thermo-couple, heating ring, fixed mount, steel pipe. Heating ring is mounted the upper extreme of the steel pipe and the site of heating ring is adjustable. By adjusting the site of the heating ring, the length of zone of heating can be modified. Comparing solder balls produced by castor oil and lube oil, we can concluded that castor oil is more suitable as medium than lube oil because the density and viscosity are bigger. On the base of experiments, the appropriate processing parameters ( heating-up temperature, length of zone of heating, holding time)have been determined. Fitting to lower melting point of tin-lead solder, the length of zone of heating is 150mm; Fitting to higher melting point of non-lead solder, length of zone of heating is 200mm. The heating-up temperature is determined by solder's melting point, that is 210℃,215℃,250℃,255℃for Sn-37Pb, Sn-45Pb, Sn-3.8Ag-0.7Cuand Sn-0.7Cu respectively, and holding time is 20min, 20min, 30min, 30min respectively. According to the processing parameters, the solder Sn-37Pb, Sn-45Pb, Sn-0.7Cu and Sn-3.8Ag-0.7Cu solder balls have been prepared. We observe solder balls by Microscope, picking bad balls. Use SEM to observe the ball surface and microstructure , take the photos and analysis the surface of solder balls finally.
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