Thermal gradient in solder joints under electrical-current stressing

Shao, T. L.; Chiu, S. H.; Chen, Chih; Yao, Da‐Jeng; Hsu, C. Y.

doi:10.1007/s11664-004-0164-0

Cited by 33 publications

(24 citation statements)

References 5 publications

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“…For thermal simulation, we used an infrared microscope to measure the temperature in the solder bumps during current stressing, 8 and then adjusted the simulation parameters so that the simulated temperature in the solder matched the one measured by the infrared microscope under the same applied current.…”

Section: Simulationmentioning

confidence: 99%

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Three-Dimensional Thermoelectrical Simulation in Flip-Chip Solder Joints with Thick Underbump Metallizations during Accelerated Electromigration Testing

Liang

Chang

Chen

2007

Journal of Elec Materi

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Section: Simulationmentioning

confidence: 99%

“…6,7 In addition, serious Joule heating may occur in the solder joints when stressed at high current. 8 Therefore, solder near the entrance point may be migrated away and voids thus form there. 9 The current crowding effect plays a crucial role in the failure of joints.…”

Section: Introductionmentioning

confidence: 99%

Three-Dimensional Thermoelectrical Simulation in Flip-Chip Solder Joints with Thick Underbump Metallizations during Accelerated Electromigration Testing

Liang

Chang

Chen

2007

Journal of Elec Materi

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“…The model used in this study was SOLID69 8-node hexahedral coupled field element using Ansys simulation software (Ansys Inc., PA). For thermal simulation, we used an infrared microscope to measure the temperature in the solder bumps during current stressing 12 and then adjusted the simulation parameters so that the simulated temperature in the solder matched the one measured by the infrared microscope under the same applied current. The threedimensional (3D) schematic solder joint with meshes is shown in Fig.…”

Section: Simulationmentioning

confidence: 99%

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

et al. 2006

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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 × 10 5 A/cm 2 to 7.54 × 10 3 A/cm 2 when a 20-m-thick Cu UBM was used. It could be lowered by a factor of seven, say to 1.55 × 10 4 A/cm 2 , when a 0.7-m UBM of 14770 ⍀ 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 ⍀ cm were applied by 0.2 A.

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“…Nevertheless, the resistance of a solder bump was estimated to be on the order of a few milliohms, whereas the resistance of the metallization trace ranges from several hundred to several thousand milliohms, depending on its dimensions. Thus, the bump resistance is quite small compared with the resistance of the metallization traces, 14 and the daisy-chain structure cannot detect the slight changes in resistance due to void formation in the solder joint. Kelvin probes have recently been implemented in flip-chip solder joints for electromigration study.…”

Section: Introductionmentioning

confidence: 99%

Effect of Migration and Condensation of Pre-existing Voids on Increase in Bump Resistance of Flip Chips on Flexible Substrates during Electromigration

Liang

Chang

Chen

et al. 2008

Journal of Elec Materi

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In Pb-free solder joints formed by reflowing a bump of solder paste, voids are formed within the solder due to the residue of flux in the reflow process. These voids migrate toward the cathode contact during electromigration under current stressing. Accompanying the electromigration, resistance jumps of a few 100 mX were observed. It was postulated that a jump occurs when a void touches the cathode contact. This study investigated the effect of the void migration and condensation on the change in bump resistance using threedimensional (3D) simulations and finite element analysis. It was found that there was negligible change in bump resistance during void migration towards the high-current-density region before touching the cathode contact opening. When a small void condensed on the contact opening and depleted 18.4% of the area, the bump resistance increased only 0.4 mX. Even when a large void depleted 81.6% of the opening, the increase in bump resistance was 3.3 mX. These values are approximately two orders of magnitude smaller than those reported in the literature for the change in resistance due to void migration in flip chips on flexible substrates. We conclude that the reported change in resistance was most likely that of the Al or Cu interconnection in the flip-chip samples.

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Thermal gradient in solder joints under electrical-current stressing

Cited by 33 publications

References 5 publications

Three-Dimensional Thermoelectrical Simulation in Flip-Chip Solder Joints with Thick Underbump Metallizations during Accelerated Electromigration Testing

Three-Dimensional Thermoelectrical Simulation in Flip-Chip Solder Joints with Thick Underbump Metallizations during Accelerated Electromigration Testing

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

Effect of Migration and Condensation of Pre-existing Voids on Increase in Bump Resistance of Flip Chips on Flexible Substrates during Electromigration

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