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Recently, the dimensions of the flip-chip solder bumps reduce to about 20-30 micrometers, also known as "micro-bumps" sandwitched between two Si chips. In such a structure, electromigration and thermomigration behaviors in the micro-bumps are not clear now. In this study, the temperature map distribution of Al traces and Al pads in CoC and C4 structures during current stressing was directly...
The ultra fine pitch micro bump became the future trend due to the development of 3D IC. In this research, three-dimensional simulation was employed to examine the temperature distribution in micro SnAg solder bumps. According to the result, the temperature distribution in solder bump of micro bump is nearly uniform. In addition, the hot side is near the substrate side, whereas the cold side is near...
In this study, the temperature map distribution in the Sn3.0Ag0.5Cu solder bump with Cu column under current stressing is directly examined using infrared microscopy. It is the radiance changes between the different materials of the surface that cause the unreasonable temperature map distribution. By coating a thin layer of black optical paint which is in order to eliminate the radiance changes, we...
The requirement for smaller devices but with much greater performance leads to a boost in current density and damage caused by electromigration. Recently, some researches show that the grain orientation changes during current stressing. In this study, the solder of SnAg2.6 with 2 um-thick UBM layer of Ni and 20 um-thick copper pad is used. Electron Backscattered Diffraction (EBSD) is applied to investigate...
Several simulation studies reported that a hot spot exists in flip-chip solder bumps under accelerated electromigration. Yet, there are no experimental data to verify it. In this paper, the temperature distribution during electromigration in flip-chip SnAg3.5 solder bumps is directly inspected using infrared microscopy. Two clear hot spots are observed in the bump. One is located at the region with...
This study investigates electromigration study of eutectic SnPb flip-chip solder joints on ceramic substrates. The under bump metallization (UBM) structure consists of 5-mum Cu / 3-mum Ni under bump metallization (UBM). Under the current stressing by 0.9 A at 150degC, we did not find void formation but a large amount of intermetallic compound (IMC) of Cu6(Sn,Ni)5 were formed when the bump resistance...
In this paper, the temperature distribution during electromigration in flip-chip SnAg3.5 solder bumps is directly examined using infrared microscopy. Two clear hot spots are observed in the bump. One is located at the region with peak current density, and the other one is at the bump edge under the current-feeding metallization on the chip side. Under a current stress of 1.06 times 104 A/cm2, the...
In flip-chip solder joints, Cu has been used as a under-bump metallization (UBM) for its excellent wettability with solders. In addition, electromigration has become a crucial reliability concerns for fine-pitch flip chip solder joints. In this paper, 3D finite element method was employed to simulate the current density distribution for the eutectic SnPb solder joints with 5 mum, 10 mum, and 20 mum...
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