Self-alignment of microchips using surface tension and solid edge

Tsai, Chi-Chun; Hsieh, Chin-Hua; Yeh, J. Andrew

doi:10.1016/j.sna.2007.04.019

Cited by 55 publications

(29 citation statements)

References 11 publications

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“…In the former case, surface chemistry is tailored to make the pads more wettable than the surrounding areas 23 , and θ of is set by the advancing contact angle of the surrounding area ( figure 2(b)). In latter case (figure 2(a)) the canthotaxis sector is extended by edge confinement 29,30 , and θ of is imposed by the Gibbs' criterion 12 :…”

Section: A Analytical Modelmentioning

confidence: 99%

Modeling capillary forces for large displacements

Mastrangeli

Arutinov

Smits

et al. 2014

Microfluid Nanofluid

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Originally applied to the accurate, passive positioning of submillimetric devices, recent works proved capillary self-alignment as effective also for larger components and relatively large initial offsets. In this paper we describe an analytic quasi-static model of 1D capillary restoring forces that generalizes existing geometrical models and extends the validity to large displacements from equilibrium. The piece-wise nature of the model accounts for contact line unpinning singularities ensuing from large perturbations of the liquid meniscus and dewetting of the bounding surfaces. The superior accuracy of the generalized model across the extended displacement range, and particularly beyond the elastic regime as compared to purely elastic models, is supported by finite element simulations and recent experimental evidence. Limits of the model are discussed in relation to the aspect ratio of the meniscus, contact angle hysteresis, tilting and self-alignment dynamics.

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Section: A Analytical Modelmentioning

confidence: 99%

Modeling capillary forces for large displacements

Mastrangeli

Arutinov

Smits

et al. 2014

Microfluid Nanofluid

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“…For small displacements, an analytical model to estimate the lateral restoring force developed by a meniscus between two square pads is sketched in (Tsai et al 2007) (see details in Sect. 3.3).…”

Section: State Of the Art And Definition Of The Problemmentioning

confidence: 99%

“…3.3 Square pads Tsai et al (2007) already presented a model to compute the lateral stiffness of a square pad shifted by a distance s along one of its edges. This model is based on the assumption of a prismatic meniscus whose volume is equal to the area of the square pad multiplied by the gap.…”

Section: Circular Padsmentioning

confidence: 99%

“…In the field of 2D positioning, Boufercha reported selfcentering by translation of components (Boufercha et al 2008) while (Sariola et al 2008;Tsai et al 2007) reported on rotational self-positioning as well. Theoretically, these systems evolve toward minimum energy configurations which correspond to the desired positions, defined by the patterns on a substrate (see Mastrangeli et al (2009b) for a study on patterned substrates coating for fluidic self-assembly).…”

Section: Introductionmentioning

confidence: 99%

“…It is worth to note that the viscosity is not thereby mentioned; hence the characterization of the dynamics has not been taken into account. Many fluidic assembly case studies have been studied: micro-electro mechanical systems packaging (Fang 2006), 3D microopto-electro-mechanical systems [where, e.g., a mirror patterned in-plane is rotated out-of-plane thanks to surface tension actuated hinges (Hong and Syms 2006)], arrays of optical fibers onto an optical chip [with misalignment claimed to be in the order of 1 lm (Avital and Zussman 2006)], RFID microchips (Tsai et al 2007). Even biological samples such as drosophila embryos have been self-assembled on patterned sites (Zhang et al 2005).…”

Section: Introductionmentioning

confidence: 99%

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Spectral analysis and experimental study of lateral capillary dynamics for flip-chip applications

Lambert

Mastrangeli

Valsamis

et al. 2010

Microfluid Nanofluid

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This article presents a study on the dynamics of lateral motion of a liquid meniscus confined by a pad and a chip moving parallel to the pad. This problem is a typical flip-chip case study, whose use is widespread in industrial assembly. The proposed model describing this dynamics is built upon two coupled physics: the NavierStokes equation governing the liquid flow between the pad and the chip, and the Newton's law describing the motion of the chip. This coupled problem is solved with a spectral method based on Chebyshev polynomials, by assuming a linear analytical expression of the lateral stiffness of the meniscus in the cases of circular and square pads. The theoretical results are benchmarked with literature results and thoroughly experimentally validated. From these results, we propose a map giving the characteristic time of the chip dynamics according to only two non-dimensional parameters, constructed with the physical (density, surface tension, and viscosity), geometrical (pad area and gap), or dynamical (chip mass) parameters of the problem.

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