Stress Analysis and Optimization of a Flip Chip on Flex Electronic Packaging Method for Functional Electronic Textiles

Li, Menglong; Tudor, John; Torah, Russel; Beeby, Steve

doi:10.1109/tcpmt.2017.2780626

Cited by 14 publications

(9 citation statements)

References 15 publications

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“…Since the diameter of the tube was fixed, the volume of resin dispensed, in addition to the size of the component, determined the finished length of the encapsulation. One method of incorporating complex electronic circuits into a yarn is to use flexible Kapton strips as a substrate (as recently reported in the literature [31,32]). This would require micro-pods with lengths from 10 mm up to at least 50 mm.…”

Section: Discussionmentioning

confidence: 99%

A Novel Method for Embedding Semiconductor Dies within Textile Yarn to Create Electronic Textiles

Nashed

Hardy

Hughes‐Riley

et al. 2019

Fibers

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Electronic yarns (E-yarns) contain electronics fully incorporated into the yarn’s structure prior to textile or garment production. They consist of a conductive core made from a flexible, multi-strand copper wire onto which semiconductor dies or MEMS (microelectromechanical systems) are soldered. The device and solder joints are then encapsulated within a resin micro-pod, which is subsequently surrounded by a textile sheath, which also covers the copper wires. The encapsulation of semiconductor dies or MEMS devices within the resin polymer micro-pod is a critical component of the fabrication process, as the micro-pod protects the dies from mechanical and chemical stresses, and hermetically seals the device, which makes the E-yarn washable. The process of manufacturing E-yarns requires automation to increase production speeds and to ensure consistency of the micro-pod structure. The design and development of a semi-automated encapsulation unit used to fabricate the micro-pods is presented here. The micro-pods were made from a ultra-violet (UV) curable polymer resin. This work details the choice of machinery and methods to create a semi-automated encapsulation system in which incoming dies were detected then covered in resin micro-pods. The system detected incoming 0402 metric package dies with an accuracy of 87 to 98%.

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Section: Discussionmentioning

confidence: 99%

A Novel Method for Embedding Semiconductor Dies within Textile Yarn to Create Electronic Textiles

Nashed

Hardy

Hughes‐Riley

et al. 2019

Fibers

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“…Further adaptions will enable use insulated copper wire, so that multi-terminal dies can be added into E-yarn using the automated process. The process can also be adapted for incorporation of circuitry populated on Kapton strip into E-yarn (Li et al 2018). Enclosing electronics within the core of yarns could be useful to the process of extracting electronics from electronic textiles, so further investigation of the feasibilities of this can be investigated, to ensure that sustainable recycling and disposal of electronic textiles is at the forefront of development of this technology (McLaren et al 2017).…”

Section: Further Developmentsmentioning

confidence: 99%

Automated insertion of package dies onto wire and into a textile yarn sheath

et al. 2019

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Wider adoption of electronic textiles requires integration of small electronic components into textile fabrics, without comprising the textile qualities. A solution is to create a flexible yarn that incorporates electronic components within the fibres of the yarn (E-yarn). The production of these novel E-yarns was initially a craft skill, with the inclusion of package dies within the fibres of the yarn taking about 90 min. The research described here demonstrated that it is possible to produce E-yarns on an industrial scale by automating the manufacturing process. This involved adapting printed circuit board manufacturing technology and textile yarn covering machinery. The production process started with re-flow soldering of package dies onto fine multi-strand copper wire. A carrier yarn was then placed in parallel with the copper wire to provide tensile strength. The package die and adjacent carrier yarn were then encapsulated in a polymer micro-pod to provide protection from moisture ingress and from mechanical strain on the die and solder joints. The process was then completed by surrounding the micro-pod and copper interconnects with additional fibres, held tightly together with a knitted fibre-sheath. This prototype, automated production process reduced the time for embedding one micro-device within a yarn to 6 min, thus increasing the production speed, demonstrating that automation of the E-yarn production process is feasible. Prototype garments have been created using E-yarns. Further developments can include automated transfer of the yarn components from one stage of production to the next, enabling greater increases in speed of manufacture of E yarns.

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“…An electronic textile (etextile) is a textile with integrated electronic functionality. E-textiles can be applied in many areas such as in clothing, for medical application or in home furnishings (Li 2017a;Meoli and May-Plumlee 2002). We aim to produce electronic textiles by directly mounting electronic components, in die form, within the yarn of the textile on a miniature flexible substrate.…”

Section: Introductionmentioning

confidence: 99%

Finite element analysis (FEA) modelling and experimental verification to optimise flexible electronic packaging for e-textiles

Torah

Liu

et al. 2020

Microsyst Technol

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In this paper a three-dimensional model of a novel electronic package has been developed using Finite element analysis to evaluate the shear load, tensile, bending and thermal stresses. Simulations of a complete flexible flip chip electronic packaging method are performed to minimize stresses on the packaged electronic device to improve robustness and reliability. Three component under-fill adhesives (Loctite 4860, Loctite 480 and Loctite 4902) and three circuit substrate materials (Kapton, Mylar and PEEK) are compared and the optimal thickness of each is found by shear load, tensile load, bending test and thermal expansion simulations. A fixed die size of 3.5 mm 9 8 mm 9 0.53 mm has been simulated and evaluated experimentally under shear and bending load. The shear and bending experimental results show good agreement with the simulation results and verify the simulated optimal thickness of the adhesive layer. The Kapton substrate together with the Loctite 4902 adhesive were identified as the optimum in the simulation. The simulation of under-fill adhesive and substrate thickness identified an optimum configuration of a 0.045-0.052 mm thick substrate layer and a 0.042-0.045 mm thickness of the Loctite 4902 adhesive. The bending simulation has also been used to determine the neutral axis of the encapsulated electronic package in this paper, thus identifying the optimal material and thickness for the encapsulation layer of the package.

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Stress Analysis and Optimization of a Flip Chip on Flex Electronic Packaging Method for Functional Electronic Textiles

Cited by 14 publications

References 15 publications

A Novel Method for Embedding Semiconductor Dies within Textile Yarn to Create Electronic Textiles

A Novel Method for Embedding Semiconductor Dies within Textile Yarn to Create Electronic Textiles

Automated insertion of package dies onto wire and into a textile yarn sheath

Finite element analysis (FEA) modelling and experimental verification to optimise flexible electronic packaging for e-textiles

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