Flexible substrate with floating island structure for mounting ultra-thin silicon chips

Takeshita, Toshihiro; Takei, Yusuke; Yamashita, Takahiro; Oouchi, Atsushi; Kobayashi, Takeshi

doi:10.1088/2058-8585/ab7bc3

Cited by 6 publications

(5 citation statements)

References 27 publications

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“…Being flexible makes UTC a great choice when the sample is exposed to bending, folding or twisting. Nonetheless, UTC is susceptible to cracking under tensile stress [29]. As a result, the failure of these samples at 30% strain was attributed to the UTC cracking, which was also verified experimentally (figure 4(b)).…”

Section: Stretchability After Chip Mounting Without Encapsulationsupporting

confidence: 73%

Flip chip bonding on stretchable printed substrates; the effects of stretchable material and chip encapsulation

Malik

Kaczynski

Zangl

et al. 2023

Flex. Print. Electron.

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Stretchable printed electronics have recently opened up new opportunities and applications, including soft robotics, electronic skins, human-machine interfaces, and healthcare monitoring. Stretchable Hybrid systems (SHS) leverage the benefits of low-cost fabrication of printed electronics with high-performance silicon technologies. However, direct integration of silicon-based devices on conventional stretchable substrates such as thermoplastic polyurethane (TPU) and polydimethylsiloxane (PDMS) is extremely challenging due to their restricted low-temperature processing. In this study, a recently developed thermoset, stretchable substrate (BeyolexTM) with superior thermal and mechanical properties was employed to realize HSS via direct flip chip bonding. Here, ultra-thin chips (UTC) with a fine-pitch, daisy-chain structure was flip-chip bonded by using anisotropic conductive adhesives, while the complementary circuitry was facilitated via screen-printed, stretchable silver tracks. The bonded samples successfully passed reliability assessments after being subjected to cyclic 30% stretch tests for 200 cycles. The potential benefits of chip encapsulation after integration with the stretchable substrate to withstand larger strains were demonstrated by both mechanical simulation and experimental results.

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Section: Stretchability After Chip Mounting Without Encapsulationsupporting

confidence: 73%

Flip chip bonding on stretchable printed substrates; the effects of stretchable material and chip encapsulation

Malik

Kaczynski

Zangl

et al. 2023

Flex. Print. Electron.

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“…Additionally, we previously demonstrated that it is possible to reduce the strain transmission using a floating island structure. (23) However, this previous investigation did not consider the sealing of the UTC. As shown in Fig.…”

Section: Introductionmentioning

confidence: 97%

Flexible Hybrid Electronic Device Sealed by Dimethylpolysiloxane with Floating Nested Structure

Takeshita¹,

Yamashita²,

Takei³

et al. 2020

Sensors and Materials

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This paper describes a new sealing structure, a "floating nested structure", for flexible hybrid electronic (FHE) device applications using an ultrathin chip (UTC). In the floating nested structure, the part on which the UTC is mounted is physically connected to the sealing material only with a meander structure. By using the floating nested structure, the tensile strain transmitted to the UTC mounted on a flexible substrate can be reduced markedly. We fabricated a UTC with a thickness of 5 µm using deep reactive ion etching (deep-RIE) technology. The fabricated UTC had flexibility with a radius of curvature of 0.5 mm. Also, we conducted an experiment to demonstrate the effect of the floating nested structure. When the elongation of the test sample used in the experiment was 20%, the strain on the flexible substrate without the floating nested structure was 710 µε. In contrast, the strain was 220 µε when using the flexible substrate with the floating nested structure. This means that the floating nested structure reduced the propagation of strain by 69.0%. From the above results, it is expected that the floating nested structure can be useful in the development of FHE devices with both elasticity and flexibility. This version has been created for advance publication by formatting the accepted manuscript. Some editorial changes may be made to this version.

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“…There have been several attempts at integrating thinned silicon microprocessor dies on to flexible substrates [59,88]. While this hybrid integration can sometimes meet conformality requirements, cost continues to be a limitation [92] due to the high cost of silicon manufacturing (integration costs increase as well).…”

Section: Introductionmentioning

confidence: 99%

FlexiCores

Bleier

Lee

Rodríguez

et al. 2022

Proceedings of the 49th Annual International Symposium on Computer Architecture

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Flexible electronics is a promising approach to target applications whose computational needs are not met by traditional silicon-based electronics due to their conformality, thinness, or cost requirements. A microprocessor is a critical component for many such applications; however, it is unclear whether it is feasible to build flexible processors at scale (i.e., at high yield), since very few flexible microprocessors have been reported and no yield data or data from multiple chips has been reported. Also, prior manufactured flexible systems were not field-reprogrammable and were evaluated either on a simple set of test vectors or a single program. A working flexible microprocessor chip supporting complex or multiple applications has not been demonstrated. Finally, no prior work performs a design space of flexible microprocessors to optimize area, code size, and energy of such microprocessors.In this work, we fabricate and test hundreds of FlexiCoresflexible 0.8 µm IGZO TFT-based field-reprogrammable 4 and 8-bit microprocessor chips optimized for low footprint and yield. We show that these gate count-optimized processors can have high yield (4-bit FlexiCores have 81% yield -sufficient to enable subcent cost if produced at volume). We evaluate these chips over a suite of representative kernels -the kernels take 4.28 ms to 12.9 ms and 21.0 µJ to 61.4 µJ for execution (at 360 nJ per instruction). We also present the first characterization of process variation for a flexible processor -we observe significant process variation (relative standard deviation of 15.3% and 21.5% in terms of current draw of 4-bit and 8-bit FlexiCore chips respectively). Finally, we perform a design space exploration and identify design points much better than FlexiCores -the new cores consume only 45-56% the energy of the base design, and have code size less than 30% of the base design, with an area overhead of 9-37%.

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Flexible substrate with floating island structure for mounting ultra-thin silicon chips

Cited by 6 publications

References 27 publications

Flip chip bonding on stretchable printed substrates; the effects of stretchable material and chip encapsulation

Flip chip bonding on stretchable printed substrates; the effects of stretchable material and chip encapsulation

Flexible Hybrid Electronic Device Sealed by Dimethylpolysiloxane with Floating Nested Structure

FlexiCores

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