High precision self-alignment using liquid surface tension for additively manufactured micro components (original) (raw)
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Self-assembly of microsystem components with micrometer gluing pads through capillary forces
Journal of Manufacturing Processes, 2020
The self-alignment of microparts based on capillary forces and micrometer adhesive pads was evaluated through experimental evidence, analytical modelling and simulation. The local deposition of adhesive pads in the range of 2000 to 20 μm was realized by photo-lithographical patterning of an acrylate adhesive interlayer, followed by the spontaneous assembly with glass counterfaces that have a complementary array of hydrophobically modified gold structures. The design rules for self-alignment of microparts were studied from calculations of the capillary force and displacement as a function of the adhesive pad dimensions, pad heights and offset length. In all cases, the self-alignment induced by capillary forces is driven by a minimization of the surface energy, leading to an equilibrium position. The analytical results provided good qualitative understanding of the alignment process: larger dimensions, smaller separation and higher offset values contributed to higher forces and fast alignment. The simulation experiments in Surface Evolver were based on calculated geometries of adhesive pad providing a minimum surface energy and also take into account the local deformation of the adhesive pad together with an additional degree of rotational freedom. Consequently, the latter results indicated a high degree of precision with good correlation to the experiments and analytical results.
Personal and Ubiquitous Computing, 2011
Fluid driven self-alignment is a low cost alternative to fast but relatively inaccurate robotic pickand-place assembly of micro-fabricated components. This fluidic self-alignment technique relies on a hydrophobic-hydrophilic pattern on the surface of the receiving substrate, which confines a fluid to a receptor site. When a micro-component is dropped on the fluid capillary forces drive the assembly process, resulting in accurate
Concept for Fluidic Self-Assembly of Micro-Parts Using Electro-Static Forces
Self-assembly is relatively unused in industrial micro-fabrication, although it offers opportunities to simplify processes and to lower manufacturing costs. A variety of self-assembly procedures have been introduced that take advantage of various forces, e.g. capillary, gravitational, electro-static. In this paper a concept for the alignment of micro-parts on a substrate using fluidic-self-assembly with electro-static attraction is presented. Further, FEM-simulations for the electro-static alignment force are performed and its dependence on several geometric parameters, e.g. the width of the binding sites and the distance between micro-part and substrate at the binding sites, is investigated. Based on results an analytic model is extracted. Furthermore, simulations are also performed to estimate capillary alignment forces, acting on micro-parts that are self-aligned. Finally, the magnitude of electro-static and capillary forces is compared. This novel assembly concept, where the ali...
2010 IEEE 23rd International Conference on Micro Electro Mechanical Systems (MEMS), 2010
This paper presents a novel method to achieve high yield assembly of millimeter-scale thin silicon chips from an air-water interface. Surface functionalized silicon parts (1000!1000!100 !m 3 ) assemble in preprogrammed hydrophilic locations on a wafer substrate with self-alignment. We optimized the process and design factors systematically using DOE (Design of Experiment) that leads to high yield (100 %).
Low-height sharp edged patterns for capillary self-alignment assisted hybrid microassembly
Journal of Micro-Bio Robotics, 2014
This paper studies the hybrid microassembly of 300 μm (L)×300 μm (W)×30 μm (H) microchips on sharp edged patterns with different edge heights. Hybrid microassembly combines the robotic pick-and-place technique and the droplet based surface tension driven selfassembly technique, where the robotic pick-and-place handling tool is used for coarse positioning and the droplet selfassembly technique is used for high-accuracy self-alignment. Spreading of the liquid outside the pattern leads to failure in self-alignment. Sharp edge on a solid surface is known for enabling contact line pinning according to Gibbs inequalities, which prohibits spreading of the liquid. Topological patterns featured with the sharp edge can be used as the receptor site for surface tension driven self-alignment. However, it is unclear how high the sharp edged pattern should be to achieve successful self-alignment in hybrid microassembly. In this paper, sharp edged topological patterns with five different edge heights: 70 nm, 140 nm, 280 nm, 540 nm and 1,050 nm, have been fabricated and tested with water to investigate the influence of the edge height on the hybrid microassembly. The experimental results indicate the edge height affects both the contact line pinning and the selfalignment process. Water droplet can successfully pin at the edge of patterns higher than 280 nm. Self-alignment can reach 100 % success rate on the patterns with edge height of 1 μm when the initial placement error is below 150 μm.
Processes for the Self-assembly of Micro Parts
IFIP Advances in Information and Communication Technology, 2012
The following approach of a fluidic based self-assembly process uses the surface forces for a precise handling and positioning of small devices for a roll-to-roll manufacturing. The surface, on which the device should be positioned, will be functionalized with hydrophile and hydrophobic areas. Thus water droplets can be caught on the hydrophile areas. The devices to be positioned will be placed on these droplets and due to the surface tension moved to their final position. The droplets, a solution of ultrapure water and isopropanol, are evaporating residue-free within seconds [1].
Self-alignment in the stacking of microchips with mist-induced water droplets
Journal of Micromechanics and Microengineering, 2011
This paper reports a novel and versatile water droplet self-alignment technique where the water is delivered in mist form onto the assembly site. The droplet forming process has been carefully investigated using machine vision, where each individual droplet on the microchip surface can be identified and the volume per surface area can be calibrated at a specific time. The result reveals that the volume of water droplets on the assembly surface grows linearly as a function of time. Self-alignment based on the mist-induced droplets has been studied, where a robotic microgripper is used to deliver the microchips on the assembly site. The paper also investigates the maximum tolerance of the initial placement error in stacking SU-8 chips 200 × 200 × 70 μm in size, and the possibility of stacking two SU-8 chips of different dimensions using the proposed self-alignment technique. Moreover, self-alignment of chips on hydrophilic/hydrophobic patterns covered by mist-induced water droplets has been studied. The experimental results indicate that this novel self-alignment technique is very promising. Furthermore, a statistical model has been used to validate the experimental results.
Electrostatic attraction and surface-tension-driven forces for accurate self-assembly of microparts
Microelectronic Engineering, 2010
Self-assembly is not widely used in industrial micro-fabrication, although it can potentially involve assembly processes that are considerably less complex. A variety of procedures for self-alignment of parts have been introduced and investigated lately. These procedures mainly utilise capillary, gravitational or electrostatic forces in the micro-scale. This paper investigates two different concepts for accurate selfassembly of parts. One is well described in the literature by third parties and involves the alignment of parts by utilising the surface tensions of micro-scaled adhesive films, which are selectively coated on hydrophobic alignment structures. In the present publication the influence of the dimensions of such structured alignment sites on the process flow is discussed. The second concept is a novel approach to accomplish self-alignment of micro-structures with electrostatic attraction. Several complementary and electrically conductive micro-structured patterns serve as binding sites for the alignment of parts in this approach. In order to obtain knowledge of how these two approaches operate, they have been modelled and simulated. Additionally, in order to analyse the feasibility of these procedures and to verify simulation results experiments have been performed on micro-structured parts and substrates. In particular, the layout of the alignment structures and the size of the parts were identical for both described concepts in the experimental work; therefore, these two methods were compared. With the self-assembly procedure that utilises electrostatic attraction, high alignment accuracies and forces, affecting the part over large distances, were observed. Finally, parts with micro-structured binding sites, which were as small as 10 Â 10 lm 2 , could accurately be self-aligned with electrostatic attraction.