Papers by Keyword: Solder Bump

Abstract: In this study, the effects of interfacial crack on thermal mechanical behavior of solder bump only induced by current for flip-chip package are investigated by numerical analysis. In the numerical model, the properties of solder bump are dependent on temperature. First, the crack length effects on thermal mechanical behavior of solder bump is examined, with the parameters of temperature, von Mises stress, shear stress and plastic strain. Second, the influence of current density is also numerically examined. It is demonstrated that the increasing current density and the crack length will induce more plastic strain in the solder bump. This study may be helpful for the fabricated technique of the die-solder bump-substrate system.

Abstract: The effect of SiC nanoparticle dispersion was investigated for microstructure change and mechanical properties of Sn-Bi electroplated alloys. The diameters of SiC nanoparticle in this study were 45-55 nm. The SiC nanoparticles were mixed with Sn-Bi electroplating and then the nanoparticles were dispersed with ultrasonic vibrator. After the dispersion, the SiC dispersed Sn-Bi alloys were electroplated on Cu deposited Si wafer. The microstructure and mechanical properties of the sample were evaluated by FE-TEM, FE-SEM, EDS, and shear tester. For TEM observation, the specimens were prepared by ultramicrotome and FIB. The SiC nanoparticles were well-dispersed in Sn-Bi alloy. SiC particles were located near grain boundaries or grain inside. The average grain size of the solder alloy was decrease about 30% compared with the grain size of Sn-Bi alloy prepared in the same condition. Due to the grain refinement and dispersion hardening by SiC nanoparticles, the SiC dispersed Sn-Bi alloy is expected to obtain high reliability and joining strength when it applied to interconnection materials.

Abstract: The focus of this study was on discussing the novel reflow method ISHR (Induction spontaneous heat reflow) used for high-density area array packaging and assembly. Multi-layer under bump metallization (UBM) and Sn3.5Ag lead-free solder ball were laid in the high frequency electromagnetic field. Because of the induction heating, solder balls melted and spread onto the UBM to form solder bumps. The solder bumps could be formed within 2 seconds through this method; meanwhile, the infrared temperature measurement results showed that the rosin substrate temperature was lower. The shear test indicated that the solder bumps made by ISHR can satisfy the mechanical requirement. Finally, the feasibility experiment was performed to demonstrate the application feasibility of this ISHR technology. Through all these experiments, conclusion can be made that the ISHR as a novel reflow method can be applied in microelectronics packaging.

Abstract: The interfacial reactions and shear properties of Sn-37Pb (wt.%) solder bumps with two different under bump metallizations (UBMs), Cu and Ni, were investigated after high temperature storage (HTS) tests at 150
C for up to 65 days. Two different intermetallic compounds (IMCs), Cu6Sn5 and Cu3Sn, were formed at the bump/Cu interface, whereas only a Ni3Sn4 IMC layer was formed at the bump/Ni interface. The thicknesses of these IMCs increased linearly with the square root of duration time. The IMC growth rate at the bump/Cu UBM interface was much greater than that at the bump/Ni UBM interface. The shear properties of the bumps with the Cu UBM were greatly decreased with increasing duration time, compared with those with the Ni UBM.