Underfill of flip chip on laminates: simulation and validation

Nguyen, Luu; Quentin, C.; Fine, P.; Cobb, B.; Bayyuk, Sami; Yang, Hong; Bidstrup-Allen, S.A.

doi:10.1109/adhes.1998.742047

Cited by 9 publications

(6 citation statements)

References 6 publications

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“…Experimental and numerical studies have been carried out on this problem (Han et al, 1996;Khor et al, 2010;Chang and Young, 2014), which showed that implementation with model strategies based on similar assumptions used in this work are very effective. It was in particular shown that if the gap height is significantly smaller than the gap width, and that the solid elements within the gap are cylindrical rather than spherical, neglecting pressure gradients and fluxes in the height direction in the simulation still allows to model the experiments very well (Nguyen et al, 1999). All the previous works were performed without accounting for air pockets that may remain in the system even during adhesive injections.…”

Section: Significance Of Air Entrapments In Adhesivesmentioning

confidence: 99%

Towards the efficient modelling of trapped air pockets during squeeze flow

Müller

Willenbrock

Stahl

et al. 2022

Exp. Comput. Multiph. Flow

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In most bonding processes, an adhesive is applied to a substrate in a specific pattern before the second substrate is subsequently pressed against it. During this, the adhesive flows in such a way that, ideally, it completely fills the joint. In practice, however, areas with entrapped air frequently remain in the bonded adhesive layer. Within the scope of a research project, these flows are systematically analyzed in order to identify optimal initial application patterns for the adhesive and substrate geometry to minimise such risks. For this purpose, the authors use an efficient flow model, the partially filled gaps model (PFGM), extended in this study to include the functionality of trapped air pockets. Depending on the volume fractions of air and adhesive, the flow of both phases is computed. Therefore, the model is introduced and fully described, benchmarked with respect to its plausibility and functionality, and results obtained are compared with a CFD calculation. Thereafter, the functionality of openings and closings of the pockets are analyzed. Lastly, the model is then applied to a real scenario created with a Hele-Shaw cell measurement. The benchmark as well as the comparison with the measurement results show the high potential of this technique.

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Section: Significance Of Air Entrapments In Adhesivesmentioning

confidence: 99%

Towards the efficient modelling of trapped air pockets during squeeze flow

Müller

Willenbrock

Stahl

et al. 2022

Exp. Comput. Multiph. Flow

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show abstract

“…Only a handful of underfill experiments have been conducted to investigate underfill flow during the flip-chip encapsulation process. In the earlier years, actual flip-chips of industrial standard were adopted for use in underfill experiments (Han and Wang, 1997;Nguyen et al, 1999). However, the underfill experimentation gradually shifted towards the use of imitation chips that were made of a transparent material such as glass (Lee et al, 2010;Kim et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Filling efficiency of flip-chip underfill encapsulation process

Abas

Abdullah

2019

SSMT

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Purpose This paper aims to introduce a new indicative parameter of filling efficiency to quantify the performance and productivity of the flip-chip underfill encapsulation process. Additionally, the variation effect of the bump pitch of flip-chip on the filling efficiency was demonstrated to provide insight for flip-chip design optimization. Design/methodology/approach The filling efficiency was formulated analytically based on the conceptual spatial and temporal perspectives. Subsequently, the effect of bump pitch on filling efficiency was studied based on the past actual-scaled and current scaled-up underfill experiments. The latter scaled-up experiment was validated with both the finite volume method-based numerical simulation and analytical filling time model. Moreover, the scaling validity of scaled-up experiment was justified based on the similarity analysis of dimensionless number. Findings Through the scaling analysis, the current scaled-up experimental system is justified to be valid since the adopted scaling factor 40 is less than the theoretical scaling limit of 270. Furthermore, the current experiment was qualitatively well validated with the numerical simulation and analytical filling time model. It is found that the filling efficiency increases with the bump pitch, such that doubling the bump pitch would triple the efficiency. Practical implications The new performance indicative index of filling efficiency enables the package designers to justify the variation effect of underfill parameter on the overall underfill process. Moreover, the upper limit of scaling factor for scaled-up package was derived to serve as the guideline for future scaled-up underfill experiments. Originality/value The performance of underfill process as highlighted in this paper was never being quantified before in the past literatures. Similarly, the scaling limit that is associated to the scaled-up underfill experiment was never being reported elsewhere too.

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“…Zheng et al (2008) also conducted two-dimensional underfill flow modelling to study the effect of large dies with nonuniform bump arrangements with two different flow models. Moreover, Wan et al (2009) conducted another numerical study on underfill flow front predictions and compared their results with the experimental work of Nguyen et al (1999). They used power law distribution to represent the non-Newtonian fluid behaviour of underfill epoxy.…”

Section: Introductionmentioning

confidence: 99%

Effects of Aspect Ratio in Moulded Packaging Considering Fluid/Structure Interaction: A CFD Modelling Approach

Ishak

Abdullah

Aziz

et al. 2017

JAFM

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The fluid/structure interaction (FSI) investigations of stacked chip in encapsulation process of moulded underfill packaging using the two-way Coupling method with ANSYS Fluent and ANSYS Structural solvers are presented. The FSI study is executed with different aspect ratio of stacked chip on the mould filling during the encapsulation process. The simulation results in the FSI study is well validated with experimental setup. The epoxy moulding compound (EMC) and structure (chip) interaction is analyzed for better understanding the FSI phenomenon.Von Mises stresses experienced by the chip also be monitored for risk of chip cracking. The proposed analysis is anticipated to be a recommendation in the chip design and improvement of 3D integration packages.

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Underfill of flip chip on laminates: simulation and validation

Cited by 9 publications

References 6 publications

Towards the efficient modelling of trapped air pockets during squeeze flow

Towards the efficient modelling of trapped air pockets during squeeze flow

Filling efficiency of flip-chip underfill encapsulation process

Effects of Aspect Ratio in Moulded Packaging Considering Fluid/Structure Interaction: A CFD Modelling Approach

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