Dynamic flow measurements of capillary underfill through a bump array in flip chip package

Lee, Seok-Hwan; Sung, Jaeyong; Kim, Sarah Eunkyung

doi:10.1016/j.microrel.2010.07.001

Cited by 29 publications

(42 citation statements)

References 17 publications

(15 reference statements)

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“…The functions of underfill encapsulation include to relief the residual stress due to thermal mismatch, to serve as a protective layer and to promote the package's reliability [2][3]. There are various researches conducted to optimize the underfill process through package design [4][5][6][7] as well as to resolve the issues of incomplete filling [8] and void defect [7,9]. The most common and straightforward approach in underfill research is through experiment [2][3][5][6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Symmetrical Unit-Cell Numerical Approach for Flip-Chip Underfill Flow Simulation

Chong¹,

Zawawi²,

Hao³

et al. 2020

CFDL

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Underfill process is a critical manufacturing process to safeguard and enhance the package reliability of flip-chip devices. In most underfill researches, the underfill flow was primarily investigated through numerical simulation. Nonetheless, the numerical simulation required a tremendously long time to complete. This paper presents a new symmetrical unit-cell approach to simulate the flip-chip underfill encapsulation process. The current numerical simulation is based on the finite volume method scheme. By exploiting the repetitive symmetry of bump array in flip-chip, the computational domain was simplified into a long array of unit-cells of one-pitch thick while the symmetrical walls between adjacent unit-cells were modelled using the periodic boundary condition. Accordingly, the computational costs can be greatly reduced. Alongside with the introduction of a new numerical approach of flip-chip underfill, the variation effect of bump pitch was studied by considering four flip-chip cases with bump pitches ranging from 0.08 mm to 0.16 mm. The numerical findings were found to in great consensus to the referencing experimental data, with the discrepancy, not more than 14.54%. Additional validation with the analytical filling time model revealed that both the numerical and analytical filling progressions are comparable. It is found that the increases in bump pitch can reduce the filling time at a particular filling distance, such that the filling time was halved within the investigated range of bump pitch. This new numerical approach is particularly useful for the simulation works of underfill process, especially the design and process optimization.

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Section: Introductionmentioning

confidence: 99%

Symmetrical Unit-Cell Numerical Approach for Flip-Chip Underfill Flow Simulation

Chong¹,

Zawawi²,

Hao³

et al. 2020

CFDL

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“…Khor et al [16] have reported the solder bump arrangement effect using numerical simulations. Lee et al [17] have investigated the dynamic flow and meniscus during the underfill process using a bump array in flip chip packaging by microparticle image velocimetry. The development of compact, highly reliable portable devices such as the iPod, iPhone, and iPad requires a small and thin silicon chip to suit space constraints without affecting performance.…”

Section: Introductionmentioning

confidence: 99%

Underfill process for two parallel plates and flip chip packaging

Khor

Abdullah

Ani

2012

International Communications in Heat and Mass Transfer

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“…As a quantitative visualization technique, a particle image velocimetry (PIV) system (Keane and Adrian 1992) has been widely used to measure the whole flow field in macro and micro scale flows (Kim et al 2008;Meinhart et al 1999). In our previous study (Lee et al 2010) using a high-speed micro particle image velocimery (lPIV) system, the velocity fields and the variations of meniscus and contact angle were measured for the first time in the capillary underfill flows. Then, the filling time was compared with analytical models at a given bump pitch, and the breakdown of equilibrium contact angle was observed when the meniscus passed through the bump array.…”

Section: Introductionmentioning

confidence: 99%

“…It is a problem that the contact angle does not remain in equilibrium under the flowing status, so that it should be measured by in situ experiments. The present study adopted the in situ measurement technique for the dynamic contact angle, which was developed in our previous study (Lee et al 2010). Figure 3 shows the raw image recorded and geometrical interpretation of the contact angle between parallel plates, respectively.…”

Section: Introductionmentioning

confidence: 99%

Micro-PIV measurements of capillary underfill flows and effect of bump pitch on filling process

Kim

Sung

Lee

2011

J Vis

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This study is devoted to investigate the effects of the bump pitch on the capillary underfill flow. A micro particle image velocimetry (lPIV) system was used to visualize the flows and the shape of meniscus. Transparent flip chip specimens with quadrilateral bump arrangements were fabricated by etching silicon on glass wafer. Six bump pitches from 60 to 160 lm were tested and glycerin was dispensed to fill into the flip chip specimens. From the present experiments, it is shown that the overall filling speed becomes faster at larger bump pitch and changes abruptly when the bump pitch is twice the bump diameter. The detailed meniscus movement also has different behavior if the bump pitch gets smaller and larger than twice the bump diameter. The variation of dynamic contact angle is synchronized with that of the meniscus velocity throughout the whole process. During the interaction with the flip chip bumps, the contact line of the meniscus becomes concave or convex. The curvature of the concave and convex lines is larger at the smaller bump pitch.

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Dynamic flow measurements of capillary underfill through a bump array in flip chip package

Cited by 29 publications

References 17 publications

Symmetrical Unit-Cell Numerical Approach for Flip-Chip Underfill Flow Simulation

Symmetrical Unit-Cell Numerical Approach for Flip-Chip Underfill Flow Simulation

Underfill process for two parallel plates and flip chip packaging

Micro-PIV measurements of capillary underfill flows and effect of bump pitch on filling process

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