Foil-to-Foil System Integration Through Capillary Self-Alignment Directed by Laser Patterning (original) (raw)
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Capillary self-alignment of mesoscopic foil components for sensor-systems-in-foil
Journal of Micromechanics and Microengineering, 2012
This paper reports on the effective use of capillary self-alignment for low-cost and time-efficient assembly of heterogeneous foil components into a smart electronic identification label. Particularly, we demonstrate the accurate (better than 50 μm) alignment of cm-sized functional foil dies. We investigated the role played by the assembly liquid, by the size and the weight of assembling dies and by their initial offsets in the self-alignment performance. It was shown that there is a definite range of initial offsets allowing dies to align with high accuracy and within approximately the same time window, irrespective of their initial offset.
Towards reel-to-reel integration of ultra-thin chips to polymer foils
2012 4th Electronic System-Integration Technology Conference, 2012
The EU FP7 funded project Chip2Foil aims to realise a technology platform allowing a radically different implementation of the assembly process for ultra-thin chips (UTCs) to polymer foils. The process is based on redistribution of the tolerance budget, and consists of two major steps: self-assembly supported chip placement followed by an adaptive circuitry approach for realising the electrical interconnects. The concept accepts non-contact, low precision presentation of a UTC to the self-assembly force field, which brings the chip to a final position with moderate precision. Next, in an adaptive interconnection process the chip position is measured with respect to the circuitry on the foil and interconnects are created on an individual chip and IO basis. The main technology building blocks are described and the current performance is demonstrated, including chip thinning, fast UTC release from wafer tape, self-assembly supported chip placement using magnetic forces and adaptive electrical interconnection by laser scribing of a screen-printed silver patch.
Novel methodology to integrate ultra-thin chips on flexible foils
The placement and integration of ultra-thin chips (UTCs) on low-cost polymer foils is a key challenge in the realization of large-area flexible electronic products. Such products, are for cost reasons, preferably fabricated on low cost polyester foils like PET/PEN. A disadvantage of these materials is that they have a low thermal stability. As a consequence of this, the majority of existing chip integration technologies cannot be used. A novel approach for placement and interconnection of UTCs is presented in this paper. This approach, which involves face-up bonding of UTC and its subsequent interconnection, is compatible with low-cost polymer foils. The key process steps involved in UTC integration using the proposed methodology are discussed in detail. The fabrication of a technology demonstrator to validate the proposed concept is also detailed.
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.
Micromachines, 2011
New surface mounting and packaging technologies, using self-assembly with chips having cavity structures, were investigated for three-dimensional (3D) and hetero integration of complementary metal-oxide semiconductors (CMOS) and microelectromechanical systems (MEMS). By the surface tension of small droplets of 0.5 wt% hydrogen fluoride (HF) aqueous solution, the cavity chips, with a side length of 3 mm, were precisely aligned to hydrophilic bonding regions on the surface of plateaus formed on Si substrates. The plateaus have micro-channels to readily evaporate and fully remove the liquid from the cavities. The average alignment accuracy of the chips with a 1 mm square
Hybrid microassembly of chips on low precision patterns assisted by capillary self-alignment
Proceedings of the ... IEEE/RSJ International Conference on Intelligent Robots and Systems. IEEE/RSJ International Conference on Intelligent Robots and Systems
this paper discusses capillary self-alignment assisted hybrid microassembly of chips on low precision patterns, in both the precision of the dimension and the precision of the edge smoothness. Special segmented patterns having jagged edges have been purposely designed and fabricated to mimic some real-world RFID antennas. Experimental tests have been carried out to investigate influence of the dimension and the edge jaggedness on the yield and accuracy of the self-alignment, using 730 × 730 × 70 µm RFID chips as the test samples. The results show that the self- alignment occurs reliably with releasing bias less than 300 µm in both horizontal axes, despite the variation in size of the segmented pattern and edge jaggedness. However, both the dimension and the edge jaggedness affect the alignment accuracy.
Precision Engineering
Self-assembly of components using liquid surface tension is an attractive alternative to traditional robotic pick-and-place as it offers high assembly accuracy for coarse initial part placement. One of the key requirements of this method is the containment of the liquid within a designated binding site. This paper looks to expand the applications of self-assembly and investigates the use of topographical structures applied to 3D printed micro components for self-assembly using liquid surface tension. An analysis of the effect of edge geometry on liquid contact angle was conducted. A range of binding sites were produced with varying edge geometries, 45-135°, and for a variety of site shapes and sizes, 0.4 - 1 mm in diameter, and 0.5 × 0.5–1 × 1 mm square. Liquid water droplets were applied to the structures and contact angles measured. Significant increases in contact angle were observed, up to 158°, compared to 70° for droplets on planar surfaces, demonstrating the ability of these ...
Investigation of the capillary self-alignment of complex geometrical chips
Capillary self-alignment (CSA) of mesoscopic objects has emerged in the 2000s [1,2]. It has been recently widely investigated for applications such as 3D microelectronics [3] and assembly of optical components [4]. It is now thought that it could be a solution for packaging technologies [5] (Fig.1). For 3D microelectronics, it has been found to be an efficient technique if specific precautions are taken [6]. However, the case of the alignment of complicated plate shapes is still a challenge, even if encouraging first experiments have been recently performed [5], and a model for the shift-restoring force has been published [7]. In this text, we investigate re-alignment of several complex plate shapes used in microsystem packaging.
Microfluidics on foil: state of the art and new developments
The concept of microfluidics on foil opens up new opportunities for combining the advantages of having a flexible substrate with reel-to-reel processing, which has the potential to be the basis for extremely cheap micro products. To reach this goal, foil substrates must be combined with micro-manufacturing technologies that are well adapted to these substrates. Some technologies are already available, some are the subject of current research, and some still have to be conceived. In the current paper, technologies such as reel-to-reel embossing, reel-to-reel laminating, and laser ablation/cutting as well as laser welding will be discussed. The discussions include a brief review of the state of the art as well as a report on latest research results stemming from research by the present authors. Furthermore, this paper shows the vision of what can be achieved if foil-based technologies, such as polymer (opto-)electronics and microfluidics are combined. A polymer electronics-based alcohol sensor is presented as an example system.
Design of interfaces with lithographically patterned adhesive pads for gluing at the microscale
2018
The creation of small adhesive pads by traditional dispensing methods is technically limited. However, the miniaturisation of micromechanical components requires the parallel development of adhesive pads with sizes in the sub-50 µm range combining good geometrical confinement and mechanical strength. Therefore, a new design of interfaces with adhesive pads of 32–8 µm are presented through local deposition of a liquid adhesive by means of “top-down” or “bottom-up” patterning. Using lithography and photochemical process, the shape of the adhesive pads is first stabilized by partial cross-linking and effective adhesive bonding with a counterface subsequently takes place during full cross-linking. The parameters for photochemical cross-linking of the adhesive pads are optimised and the mechanical performance of the patterned adhesive interfaces is evaluated. For “top-down” patterned adhesive interfaces, the geometrical stabilisation of the adhesive pads requires relatively long cross-li...