ead-free Sn3.5Ag and Sn3.5Ag0.5Cu solder balls were reflowed by laser to form solder bumps. Shear test was performed on the solder bumps, and SEM/EDX （scanning electron microscopy/energy dispersive X-ray spectrometer...ead-free Sn3.5Ag and Sn3.5Ag0.5Cu solder balls were reflowed by laser to form solder bumps. Shear test was performed on the solder bumps, and SEM/EDX （scanning electron microscopy/energy dispersive X-ray spectrometer） was used to analyze the formation of intermetallic compounds （IMCs） at interface region. A finite element modeling on the temperature gradient and distribution at the interface of solder bump during laser reflow process was conducted to elucidate the mechanism of the IMCs growth direction. The results show that the parameters window for laser reflow bumping of Sn3.5Ag0.5Cu was wider than that of Sn3.5Ag. The shear strength of Sn3.5Ag0.5Cu solder bump was comparable to that of Sn3.5Ag solder bump, and was not affected obviously by laser power and irradiation time when appropriate parameters were used. Both laser power and heating time had a significant effect on the formation of IMCs. A continuous AuSn4 intermetallic compound layer and some needle-like AuSn4 were observed at the interface of solder and Au/Ni/Cu metallization layer when the laser power is small. The formation of needle-like AuSn4 was due to temperature gradient at the interface, and the direction of temperature gradient was the preferred growth direction of AuSn4. With increasing the laser power and heating time, the needle-like AuSn4 IMCs dissolved into the bulk solder, and precipitated out once again during solidification along the grain boundary of the solder bump.展开更多
A novel electroplating indium bumping process is described,as a result of which indium bump arrays with a pitch of 100μm and a diameter of 40μm were successfully prepared.UBM（under bump metallization） for indium b...A novel electroplating indium bumping process is described,as a result of which indium bump arrays with a pitch of 100μm and a diameter of 40μm were successfully prepared.UBM（under bump metallization） for indium bumping was investigated with an XRD technique.The experimental results indicate that Ti/Pt（300（？）/200（？）） has an excellent barrier effect both at room temperature and at 200℃.The bonding reliability of the indium bumps was evaluated by a shear test.Results show that the shear strength of the indium bump significantly increases after the first reflow and then changes slowly with increasing reflow times.Such a phenomenon may be caused by the change in textures of the indium after reflow.The corresponding flip-chip process is also discussed in this paper.展开更多
基金supported by the National Natural Science Foundation of China under grant No.50475031/E052104.
文摘ead-free Sn3.5Ag and Sn3.5Ag0.5Cu solder balls were reflowed by laser to form solder bumps. Shear test was performed on the solder bumps, and SEM/EDX （scanning electron microscopy/energy dispersive X-ray spectrometer） was used to analyze the formation of intermetallic compounds （IMCs） at interface region. A finite element modeling on the temperature gradient and distribution at the interface of solder bump during laser reflow process was conducted to elucidate the mechanism of the IMCs growth direction. The results show that the parameters window for laser reflow bumping of Sn3.5Ag0.5Cu was wider than that of Sn3.5Ag. The shear strength of Sn3.5Ag0.5Cu solder bump was comparable to that of Sn3.5Ag solder bump, and was not affected obviously by laser power and irradiation time when appropriate parameters were used. Both laser power and heating time had a significant effect on the formation of IMCs. A continuous AuSn4 intermetallic compound layer and some needle-like AuSn4 were observed at the interface of solder and Au/Ni/Cu metallization layer when the laser power is small. The formation of needle-like AuSn4 was due to temperature gradient at the interface, and the direction of temperature gradient was the preferred growth direction of AuSn4. With increasing the laser power and heating time, the needle-like AuSn4 IMCs dissolved into the bulk solder, and precipitated out once again during solidification along the grain boundary of the solder bump.
基金Project supported by the State Key Development Program for Basic Research of China(No.2006CB0N0802)the Shanghai Basic Research Project(No.08JC1422000)
文摘A novel electroplating indium bumping process is described,as a result of which indium bump arrays with a pitch of 100μm and a diameter of 40μm were successfully prepared.UBM（under bump metallization） for indium bumping was investigated with an XRD technique.The experimental results indicate that Ti/Pt（300（？）/200（？）） has an excellent barrier effect both at room temperature and at 200℃.The bonding reliability of the indium bumps was evaluated by a shear test.Results show that the shear strength of the indium bump significantly increases after the first reflow and then changes slowly with increasing reflow times.Such a phenomenon may be caused by the change in textures of the indium after reflow.The corresponding flip-chip process is also discussed in this paper.
