Comparative Study of Pressurized and Capillary Underfill Flow Using Lattice Boltzmann Method

Gan, Z. L.; Abas, Aizat; Ishak, M. H. H.; Abdullah, M. Z.; Ngang, Jin Loung

doi:10.1007/s13369-019-03866-y

Cited by 8 publications

(9 citation statements)

References 28 publications

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“…Alternatively, there are few modifications that were proposed on the conventional underfill process to accelerate the flow by applying external driving forces, for instance, forced/pressurized [10][11][12], vacuum-assisted [13,14], raised-die, substrate hole [3], rotational-assisted [15], and thermocapillary [16]. However, these creative iterations of underfill process were less popular as there is almost no application.…”

Section: Types Of Underfill Encapsulation Processmentioning

confidence: 99%

Underfill Flow in Flip-Chip Encapsulation Process: A Review

Abas

2021

Journal of Electronic Packaging

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The scope of review of this paper focused on the pre-curing underfilling flow stage of encapsulation process. A total of 80 related works has been reviewed and being classified into process type, method employed, and objective attained. Statistically showed that the conventional capillary is the most studied underfill process, while the numerical simulation was mainly adopted. Generally, the analyses on the flow dynamic and distribution of underfill fluids in the bump array aimed for the filling time determination as well as the predictions of void occurrence. Parametric design optimization was subsequently conducted to resolve the productivity issue of long filling time and reliability issue of void occurrence. The bump pitch was found to the most investigated parameter, consistent to the miniaturization demand. To enrich the design versatility and flow visualization aspects, experimental test vehicle was innovated using imitated chip and replacement fluid, or even being scaled-up. Nonetheless, the analytical filling time models became more accurate and sophiscasted over the years, despite still being scarce in number. With the technological advancement on analysis tools and further development of analytic skills, it was believed that the future researches on underfill flow will become more comprehensive, thereby leading to the production of better packages in terms of manufacturing feasibility, performances, and reliability. Lastly, few potential future works were recommended, for instance, microscopic analysis on the bump-fluid interaction, consideration of filler particles and incorporation of artificial intelligence.

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Section: Types Of Underfill Encapsulation Processmentioning

confidence: 99%

Underfill Flow in Flip-Chip Encapsulation Process: A Review

Abas

2021

Journal of Electronic Packaging

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“…This equation can be deciphered in such a way that the difference of f a between t and t 1 Dt would be zero if no collisions occur (X = 0). Due to the complicated nature of the collision term in the LBM, the collision operator can be expressed using the Bhatnagar-Groos-Krook (BGK) model, as represented in equation ( 2) (Gan et al, 2019):…”

Section: Lattice Boltzmann Formulationmentioning

confidence: 99%

“…Ball grid arrays (BGA), being a type of SMT, use small solder balls to form connections between the electronic components and the PCB. BGA technology outshines other SMT counterparts like pin grid array (PGA), as it allows for higher interconnection density, better performance due to shorter leads, and better heat conduction (Abas et al, 2016a(Abas et al, , 2016b(Abas et al, , 2016cGan et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, a Ushaped dispensing method has achieved the shortest filling time compared to I-shaped and L-shaped methods (Abas et al, 2016a(Abas et al, , 2016b(Abas et al, , 2016c. A force-induced process such as pressurized underfill is also reported to have a faster filling time compared to the conventional capillary method (Gan et al, 2019). A truncated solder bump is the most common shaped being used in industry, compared to others such as cylindrical and hourglass/concave.…”

Section: Introductionmentioning

confidence: 99%

“…LBM has been extensively used in microscale approaches since the medium is made up of particles that represent the particle velocity distribution function at each of the grid points that are continuously colliding with each other. LBM's best feature, compared to other approaches, is its ability to take into account the microscopic particle to particle interaction forces (Gan et al, 2019). Although simulation results obtained from finite volume method (FVM) simulations are in close agreement with experimental results in most cases, visualization details like void formation cannot be accurately predicted due to the complicated particle interactions that occur during underfill flow (Abas et al, 2016a(Abas et al, , 2016b(Abas et al, , 2016c.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of hourglass shape solder joints on underfill encapsulation process: numerical and experimental studies

Nashrudin

Gan

Abas

et al. 2020

SSMT

Self Cite

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Purpose In line with the recent development of flip-chip reliability and underfill process, this paper aims to comprehensively investigate the effect of different hourglass shape solder joint on underfill encapsulation process by mean of experimental and numerical method. Design/methodology/approach Lattice Boltzmann method (LBM) numerical was used for the three-dimensional simulation of underfill process. The effects of ball grid arrays (BGA) encapsulation process in terms of filling time of the fluid were investigated. Experiments were then carried out to validate the simulation results. Findings Hourglass shape solder joint has shown the shortest filling time for underfill process compared to truncated sphere. The underfill flow obtained from both simulation and experimental results are found to be in good agreement for the BGA model studied. The findings have also shown that the filling time of Hourglass 2 with parabolic shape gives faster filling time compared to the Hourglass 1 with hemisphere angle due to bigger cross-sectional area of void between the solder joints. Practical implications This paper provides reliable insights to the effect of hourglass shape BGA on the encapsulation process that will benefit future development of BGA packages. Originality/value LBM numerical method was implemented in this research to study the flow behaviour of an encapsulation process in term of filling time of hourglass shape BGA. To date, no research has been found to simulate the hourglass shape BGA using LBM.

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