Direct Measurement of Hot-spot Temperature in Flip-chip Solder Joints With Cu Columns Under Current Stressing using Infrared Microscopy

2010 ◽  
Vol 1249 ◽  
Author(s):  
Chih Chen ◽  
Yu Chun Liang ◽  
D. J. Yao
Keyword(s):  
Thin Layer ◽  
Flip Chip ◽  
Solder Bump ◽  
Hot Spot ◽  
Infrared Microscopy ◽  
Column Temperature ◽  
Current Stressing ◽  
Large Current ◽  
Spot Temperature ◽  
A Current

AbstractIn 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 got the corrected temperature map distribution. Under a current stress of 1.15 × 104 A/cm2 at 100℃C, the hot-spot temperature is 132.2℃ which surpasses the average Cu column temperature of 129.7℃C and the average solder bump temperature of 127.4 ℃. Thermomigration in solder may still occur under a large current stressing.

Direct measurement of hot-spot temperature in flip-chip solder joints under current stressing using infrared microscopy

2008 ◽  
Vol 104 (3) ◽  
pp. 033708 ◽  
Author(s):  
Hsiang-Yao Hsiao ◽  
S. W. Liang ◽  
Min-Feng Ku ◽  
Chih Chen ◽  
Da-Jeng Yao
Keyword(s):  
Direct Measurement ◽  
Flip Chip ◽  
Solder Joints ◽  
Hot Spot ◽  
Infrared Microscopy ◽  
Current Stressing ◽  
Spot Temperature

Investigation of Joule Heating Effect in Various Stages of Electromigration in Flip-chip Solder Joints by Infrared Microscopy

2010 ◽  
Vol 1249 ◽  
Author(s):  
Hsiang Yao Hsiao ◽  
Chih Chen ◽  
D. J. Yao
Keyword(s):  
Joule Heating ◽  
Flip Chip ◽  
Solder Bump ◽  
Solder Joints ◽  
Void Nucleation ◽  
Heating Effect ◽  
Infrared Microscopy ◽  
Joule Heating Effect ◽  
Last Stage ◽  
A Current

AbstractThe Joule heating effect at various stages under electromigration of flip-chip Sn3.5Ag solder joints was investigated under a current of 0.5 A at 100°C. During various stages of electromigration, voids may form and propagate and Joule heating effect may vary at different void sizes. To verify the void nucleation and propagation on Joule heating effect during electromigration process, the solder bump was stressed for different lengths of time and then examined by Kelvin bump probes and infrared microscopy. We found that voids started to form at approximately 1.2 times of the initial bump resistance. Then the voids propagated when the bump resistance increased. In addition, the temperature of the solder joints increased with the bump resistance and the increase of current stressing time. It increased very slowly in initial stages. In the last stage, the temperature of the solder bump increased rapidly due to the increase of the bump resistance and the local Joule heating effect.

Electromigration Reliability of 96.5Sn–3Ag–0.5Cu Flip-Chip Solder Joints With Au/Ni/Cu or Cu Substrate Pad Metallization

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Yi-Shao Lai ◽  
Ying-Ta Chiu ◽  
Chiu-Wen Lee
Keyword(s):  
Flip Chip ◽  
Solder Joints ◽  
Average Current Density ◽  
Cross Sectional ◽  
Cu Substrate ◽  
Cu Metallization ◽  
Substrate Side ◽  
Current Stressing ◽  
Average Current ◽  
A Current

Designed experiments were conducted in this paper to study the effect of Au/Ni/Cu or Cu substrate pad metallization on the electromigration reliability of 96.5Sn–3Ag–0.5Cu flip-chip solder joints with Ti/Ni(V)/Cu under bump metallurgy (UBM) under a current stressing condition with an average current density of around 5 kA/cm2 at an ambient temperature of 150°C. Cross-sectional observations on current-stressed solder joints indicate that although Cu metallization results in severe voiding compared with Au/Ni/Cu metallization on the substrate side of the solder joint, the dominant failure has been identified as UBM consumption, and test vehicles with Cu metallization exhibit better electromigration reliability than those with Au/Ni/Cu metallization. The stronger durability against current stressing for test vehicles with Cu metallization may attribute to the lower UBM consumption rate due to the continuous Cu diffusion toward UBM as a result of the concentration gradient. The consumption of UBM is faster for test vehicles with Au/Ni/Cu metallization because Cu diffusion from the substrate pad is retarded by the Ni barrier.

Effect of aluminum trace dimension on electro-migration failure in flip-chip package

2017 ◽  
Vol 31 (07) ◽  
pp. 1741002
Author(s):  
Peisheng Liu ◽  
Guangming Fan ◽  
Yahong Liu ◽  
Longlong Yang ◽  
Xiaoyong Miao
Keyword(s):  
Temperature Gradient ◽  
Joule Heating ◽  
Current Density ◽  
Flip Chip ◽  
3D Model ◽  
Hot Spot ◽  
Electrical Coupling ◽  
Migration Mechanism ◽  
Spot Temperature

A 3D model of flip-chip package is established and thermal–electrical coupling is analyzed. The effect of the width of Aluminum (Al) trace on electro-migration mechanism is also studied. Reducing rates of the hot-spot temperature, the max Joule heating, the max temperature gradient and the max current density are defined to research the effects of the Al trace thickness and the UBM thickness on electro-migration.

Orientation transformation of Pb grains in 5Sn–95Pb/ 63Sn–37Pb composite flip-chip solder joints during electromigration test

2008 ◽  
Vol 23 (7) ◽  
pp. 1877-1881 ◽  
Author(s):  
Ying-Ta Chiu ◽  
Kwang-Lung Lin ◽  
Yi-Shao Lai
Keyword(s):  
Electron Microscopy ◽  
Driving Force ◽  
Flip Chip ◽  
Solder Bump ◽  
Solder Joints ◽  
Electron Backscatter Diffraction ◽  
Current Stressing ◽  
Electron Backscatter ◽  
Backscatter Diffraction ◽  
Scanning Electron

Microstructural evolution occurred in 5Sn–95Pb/63Sn–37Pb composite flip-chip solder bump during electromigration. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) observations for 5Sn–95Pb/63Sn–37Pb composite flip-chip solder joints subjected to 5 kA/cm2 current stressing at 150 °C revealed a gradual orientation transformation of Pb grains from random textures toward (101) grains. We proposed that the combination of reducing the surface energy of Pb grain boundaries and resistance of the entire polycrystalline system are the driving force for the orientation transformation of Pb grains during an electromigration test.

scholarly journals Relieving the current crowding effect in flip-chip solder joints during current stressing

2006 ◽  
Vol 21 (1) ◽  
pp. 137-146 ◽  
Author(s):  
S.W. Liang ◽  
T.L. Shao ◽  
Chih Chen ◽  
Everett C.C. Yeh ◽  
K.N. Tu
Keyword(s):  
Flip Chip ◽  
Solder Bump ◽  
Solder Joints ◽  
Three Dimensional ◽  
Current Crowding ◽  
Crowding Effect ◽  
Average Temperature ◽  
Current Stressing ◽  
Underbump Metallization ◽  
Overall Resistance

Three-dimensional simulations for relieving the current crowding effect in solder joints under current stressing were carried out using the finite element method. Three possible approaches were examined in this study, including varying the size of the passivation opening, increasing the thickness of Cu underbump metallization (UBM), and adopting or inserting a thin highly resistive UBM layer. It was found that the current crowding effect in the solder bump could be successfully relieved with the thick Cu UBM or with the highly resistive UBM. Compared to the solder joint with Al/Ni(V)/Cu UBM, for instance, the maximum current density in a solder bump decreased dramatically by a factor of fifteen, say from 1.11 × 105 A/cm2 to 7.54 × 103 A/cm2 when a 20-μm-thick Cu UBM was used. It could be lowered by a factor of seven, say to 1.55 × 104 A/cm2, when a 0.7-μm UBM of 14770 μΩ cm was adopted. It is worth noting that although a resistive UBM layer was used, the penalty on overall resistance increase was negligible because the total resistance was dominated by the Al trace instead of the solder bump. Thermal simulation showed that the average temperature increase due to Joule heating effect was only 2.8 °C when the solder joints with UBM of 14770 μΩ cm were applied by 0.2 A.

Damages and Microstructural Variation of High-lead and Eutectic SnPb Composite Flip Chip Solder Bumps Induced by Electromigration

2005 ◽  
Vol 20 (8) ◽  
pp. 2184-2193 ◽  
Author(s):  
Yeh-Hsiu Liu ◽  
Kwang-Lung Lin
Keyword(s):  
Flip Chip ◽  
Solder Bump ◽  
Electron Flow ◽  
Electron Probe Microanalyzer ◽  
Current Stressing ◽  
Solder Bumps ◽  
Underbump Metallization ◽  
Current Polarity ◽  
High Lead ◽  
Eutectic Snpb

The electromigration behavior of the high-lead and eutectic SnPb composite solder bumps was investigated at 150 °C with 5 × 103 A/cm2 current stressing for up to 1711 h. The diameter of the bumps was about 125 μm. The underbump metallization (UBM) on the chip side was sputtered Al/Ni(V)/Cu thin films, and the Cu pad on the board side was plated with electroless Ni/Au. It was observed that damages occurred in the joints in a downward electron flow (from chip side to the substrate side), while those joints having the opposite current polarity showed only minor changes. In the case of downward electron flow, electromigration damages were observed in the UBM and solder bumps. The vanadium in Ni(V) layer was broken under current stressing of 1711 h while it was still intact after current stressing of 1000 h. The electron probe microanalyzer (EPMA) elemental mapping clearly shows that the Al atoms in the trace migrated through the UBM into the solder bump during current stressing. Voids were found in the solder bump near the UBM/solder interface. The Sn-rich phases of the solder bumps showed gradual streaking and reorientation upon current stressing. This resulted in the formation of uniaxial Sn-rich phases in the middle of the solder bump, while the columnar and fibrous Sn-rich phases were formed in the surrounding regions. The formation mechanism of electromigration-induced damage to the UBM structure and solder bump were discussed.

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