Modeling of time-pressure fluid dispensing processes

Chen, Daniel; Schoenau, Greg; Zhang, W.J.

doi:10.1109/6104.895075

Cited by 48 publications

(28 citation statements)

References 8 publications

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“…Pressures above this range (lower vacuum) led to rapid bulging of the initial droplet with no line formation, whereas pressures below this range (higher vacuum) led to failure of the printed lines through a necking type phenomenon (see Figure S2a,b, Supporting Information). The insensitivity of the dispensing pressure to the printing speed can be explained through the well-established time-pressure dispensing model [39] that can be applied in this case. Here, we assume (1) Newtonian flow of EGaIn following the findings in the literature [40] and (2) laminar flow considering the expected low flow rates and apply Bernoulli's equation with the corresponding frictional head losses [41] to obtain the following relation between the dispensing pressures and flow velocity …”

Section: Wileyonlinelibrarycommentioning

confidence: 99%

Freeze‐Printing of Liquid Metal Alloys for Manufacturing of 3D, Conductive, and Flexible Networks

Gannarapu

Gozen

2016

Adv Materials Technologies

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liquid metal alloys including injection of liquid metals into elastomeric channel networks, [10][11][12][13][14] freeze-casting, [15] surface patterning using lithographic techniques, [16][17][18][19] laser engraving, [20] or additive approaches including flow-based direct-writing, [21,22] droplet-by-droplet deposition, [23] heated roller-pen printing, [24,25] ink-jetting, [26] deposition at microscale in the nanoparticle ink form, followed by sintering, [27] or combination of direct-writing and transfer printing. [28] These methods have been utilized to realize various flexible electronic components including interconnects, [10,29] passive circuitry, [11] diodes and memristors, [30,31] antennas for wireless communication, [21,32,33] and wearable force and pressure sensors. [12,34] Despite their demonstrated success, the 3D geometric capability of these methods is still limited. The geometric capability of the injection and lithography is determined by that of the 2D methods used to fabricate the elastomeric channel networks, stencils or stamps. The additive manufacturing methods provide a higher level of geometric capability, however, still are mostly limited to 2D planar designs since the liquid metal cannot maintain its mechanical stability as complex 3D structures. Using these methods, obtaining a limited range of 3D designs still require a number of rigorous process steps including molding, metal injection and vacuuming, as well as layer bonding. In a recent study, Ladd et al. showed that the moldability of liquid metal alloys can be utilized to form vertically extended structures in mm-level sizes, [22] demonstrating the promise for true 3D-printing using liquid metals. However, as also demonstrated in this work, the structural stability of the oxide skin is not sufficient to form complex 3D networks of liquid metal alloys in practical size scales. A number of recent studies combined liquid metal and elastomer printing to build multilayer planar networks of liquid metals where the printed elastomer essentially used as the support material. [35][36][37] Even though these studies improved the geometric capability of additive manufacturing of EGaIn networks, printing of EGaIn along truly 3D paths in a continuous fashion has not been realized. Realization of such a printing method will enable high-density 3D interconnect networks, antennae, and passive circuitry for flexible electronics with substantially increased design complexity.In this paper, we present the freeze-printing method to address this need. This method is schematically described in Figure 1a-d. Here, the liquid metal alloy, EGaIn is dispensed from a nozzle on a substrate, the temperature of which is kept below the melting point of the alloy. As the nozzle is translated in 3D, more liquid is added to the printed structure along the translation path and maintains its cylindrical shape owing to the spontaneous formation and deformation of the oxide skin. In the meantime, the printed structure starts freezing from the substrate generating a moving f...

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Section: Wileyonlinelibrarycommentioning

confidence: 99%

Freeze‐Printing of Liquid Metal Alloys for Manufacturing of 3D, Conductive, and Flexible Networks

Gannarapu

Gozen

2016

Adv Materials Technologies

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“…Pressurised air is supplied to the syringe through a transmission line, and a controller regulates the solenoid valve to drive a desirable amount of fluid out of the syringe needle. It is clear that in such a process the flow rate of the fluid dispensed depends not only on the air pressure and the dispensing time, which is clearly indicated by the conceptual approach [12], but also on the dynamics of the valve as well as the dynamics of the transmission line and syringe [4]. As a result, it is essential to understand the process dynamics of the dispensing system in order to accurately control the fluid dispensing.…”

Section: Introductionmentioning

confidence: 99%

Integrated modelling of a time-pressure fluid dispensing system for electronics manufacturing

Zhao

Ding

et al. 2004

Int J Adv Manuf Technol

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In electronics manufacturing the time-pressure dispensing system has been widely used to squeeze adhesive fluid in a syringe onto boards or substrates with pressurised air. For accurate control of the fluid volume, it is vital to have a thorough understanding of the whole process. However, the complexity of the process, which includes air-fluid coupling and their nonlinear uncertainties, makes it difficult to obtain an accurate process model. Using the spectral method, an approximate fluid flow model for both the Newtonian and non-Newtonian fluid can be developed. By taking into account nonlinear flow passing through the valve, attenuation and time delay in the pneumatic lines, syringe chamber dynamics and fluid flow dynamics, a simple but effective model is derived to describe the whole dispensing system with reasonable accuracy. Experiments performed thereafter validate the model.

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“…The parameters are the shape and size of the dispensed material. Chen et al [4] have characterized the shape and spreading of the fluid on the board by solving a free-boundary problem. Consequently, this paper does not address the shape of the material after the dispensing process.…”

Section: Introductionmentioning

confidence: 99%

“…However, many of the equations cited are not applicable in modeling of non-Newtonian fluids such as adhesives, solder pastes and encapsulants. As presented by Chen et al [4], three models can be used for modeling rheological behaviors of dispensing fluids. They are Power Law, Generalized Power Law and TimeDependent Herschel-Bulkley Law which are respectively given by:…”

Section: Introductionmentioning

confidence: 99%

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Design and characterization of a precision fluid dispensing valve

Nguon

Jouaneh

2004

Int J Adv Manuf Technol

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Precision fluid dispensing is a complicated but yet relevant process where fluid is dispensed in a controlled manner. It is important and applicable in an array of applications ranging from dispensing of food products, biomedical applications to dispensing of adhesive and encapsulants in the semi-conductor industry. This paper discusses the design and characterization of a precision fluid dispensing hybrid valve based on the time-pressure, positive displacement pump, and adhesive jetting technologies. The main advantage of this dispensing method is that the amount of fluid dispensed is independent of the standoff height and does not rely on surface tension between the substrate and the fluid for clean dispensation. Specifically, the dispensed fluid is jetted from a fixed needle height, and hence, repeatability and accuracy is improved while eliminating vertical travel. A prototype valve was built and tested for precision and accuracy of milligrams over a range of pressures and time. The test results are promising, indicating high repeatability and accuracy for low to medium viscous materials and are comparable to existing commercially available precision dispensing systems.

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Modeling of time-pressure fluid dispensing processes

Cited by 48 publications

References 8 publications

Freeze‐Printing of Liquid Metal Alloys for Manufacturing of 3D, Conductive, and Flexible Networks

Freeze‐Printing of Liquid Metal Alloys for Manufacturing of 3D, Conductive, and Flexible Networks

Integrated modelling of a time-pressure fluid dispensing system for electronics manufacturing

Design and characterization of a precision fluid dispensing valve

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