Performances of Wafer-Level UnderFill with 50&amp;#x00B5;m pitch interconnections: Comparison with conventional underfill

Taluy, Alisee; Lhostis, S.; Jouve, A.; Garnier, G.; Dezandre, Emilienne; Farcy, A.; Chéramy, S.; Sillon, N.; Sylvestre, Alain

doi:10.1109/eptc.2011.6184400

Cited by 6 publications

(1 citation statement)

References 9 publications

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“…For the assembly of wafer grades of 50 microns or less, the influence of capillary UF on the electrical functions of Cu pillars under thermomechanical stresses should be considered. The rounded-corner shape and coverage issues of Si-to-Si stacks can be also suppressed [ 22 ]. In this study, we aimed to investigate damage modes in Cu-Cu joints with different dielectrics under thermal cycling.…”

Section: Introductionmentioning

confidence: 99%

Failures of Cu-Cu Joints under Temperature Cycling Tests

et al. 2022

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In this study, the failure mechanisms of Cu-Cu joints under thermal cycling were investigated. Two structures of dielectrics (PBO/underfill/PBO and SiO2) were employed to seal the joints. Stress gradients induced in the joints with the different dielectrics were simulated using a finite element method (FEM) and correlated with experimental observations. We found that interfacial voids were forced to move in the direction from high stress regions to low stress ones. The locations of migrated voids varied with the dielectric structures. Under thermal cycling, such voids were likely to move forward to the regions with a small stress change. They relocated and merged with their neighboring voids to lower the interfacial energy.

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Section: Introductionmentioning

confidence: 99%

Failures of Cu-Cu Joints under Temperature Cycling Tests

et al. 2022

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Coarse-grained molecular dynamics simulation of wettability and bleed out of capillary underfill

et al. 2021

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Coarse-grained molecular dynamics simulations were performed to elucidate the capillary flow process of liquid state capillary underfill (CUF), a sealing resin material. First, we ran a wettability simulation with the CUF consisting of a monomer with small and large fillers. We observed that a certain amount of the monomer spreads ahead on the substrate, while many fillers are left inside the droplet. This was confirmed by subsequent mean square deviation (MSD), which showed that the monomer had a higher MSD, 25–45 σ2, than the small and large fillers, which were 0.4–1.4 σ2 and 0.02–0.2 σ2, respectively. When one part of large fillers was replaced with small fillers, small fillers helped accelerate the wetting dynamics because they could move fast. However, when the small filler ratio was high (20%), the MSD of small fillers decreased. Next, we performed a capillary flow simulation in which the CUF flowed between parallel walls and observed that it formed a ridgeline at the upper wall edge. Small fillers contributed to a decreased flow time. However, when the small filler ratio was even higher, the flow time increased. Then, the small fillers slowed themselves down, as shown in the MSD. This is due to an increase in monomer interactions and less space to move. We also found that the bleed length decreased with an increase in the small filler ratio. This study clarified the effects of filler usage on the flow time and bleed length and contributed to new insight into the capillary actions and material design relevant to CUF.

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