Evaluation of an Anisotropic Conductive Epoxy for Interconnecting Highly Stretchable Conductors to Various Surfaces

Al-Haidari, Riadh; Garakani, Behnam; Alhendi, Mohammed; Somarathna, Udara S.; Poliks, Mark D.; Tabor, Christopher E.; Yuen, Michelle C.; Stemmermann, Madhu; Stoffel, Nancy

doi:10.1109/ectc51906.2022.00228

Cited by 10 publications

(5 citation statements)

References 28 publications

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“…An alternative solution is using Anisotropic Conductive Adhesive (ACA) material that is conductive only on the z-axis. The most recent research proved ACA materials to be very reliable and mechanically strong 34 . However, for the FDM printed substrate used in this paper, the uneven surface pattern makes it impossible for ACA to reach the uniform pressure condition to generate joints (small silver balls).…”

Section: Flexible Wearable 5g/mmw Phased Array Module With Integrated...mentioning

confidence: 99%

Additively manufactured flexible on-package phased array antennas for 5G/mmWave wearable and conformal digital twin and massive MIMO applications

Zhou

Sitaraman

et al. 2023

Sci Rep

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This paper thoroughly investigates material characterization, reliability evaluation, fabrication, and assembly processes of additively manufactured flexible packaging and reconfigurable on-package antenna arrays for next-generation 5G/mmWave wearable and conformal applications. The objective is to bridge the technology gap in current Flexible Hybrid Electronics (FHE) designs at mmWave frequencies and address the challenges of establishing future design standards for additively manufactured flexible packages and System-on-Package (SoP) integrated modules. Multiple 3D printed flexible materials have been characterized for their electrical and mechanical properties over the 5G/mmW frequency band (26–40 GHz), and the inkjet printed interconnects on 3D printed Polypropylene (PP) substrates demonstrated excellent electrical and mechanical performance during a 10,000-time cyclic bending test over typical wearable flexible radii down to 1 inch. A proof-of-concept flexible on-package phased array with an integrated microfluidic cooling channel on 3D printed substrates was fabricated and measured, demonstrating $$\pm 37^{\circ }$$ ± 37 ∘ beam steering capability with efficient cooling. The proposed reconfigurable design and low-temperature fabrication approach using additive manufacturing can be widely applied to next-generation highly-complex on-demand FHE, flexible multi-chip-module integration, and on-package phased-array modules for 5G/mmWave wearable and conformal smart skin, digital twin and massive MIMO applications.

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Section: Flexible Wearable 5g/mmw Phased Array Module With Integrated...mentioning

confidence: 99%

Additively manufactured flexible on-package phased array antennas for 5G/mmWave wearable and conformal digital twin and massive MIMO applications

Zhou

Sitaraman

et al. 2023

Sci Rep

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“…In many laboratory-scale devices, electrical connections between the liquid metal and the outside world are realized by simply contacting the liquid metal with a solid metal. A simple example would be sticking a copper wire into the liquid metal . Another approach would be implementation of liquid metal-based contacts such as creation of nanotips from liquid metals for soft and conductive junctions .…”

Section: Introductionmentioning

confidence: 99%

“…A simple example would be sticking a copper wire into the liquid metal. 51 Another approach would be implementation of liquid metal-based contacts such as creation of nanotips from liquid metals for soft and conductive junctions. 52 In either case, the wire and the junction would need to be mechanically secured to ensure long-term reliability.…”

Section: Introductionmentioning

confidence: 99%

Flexible-to-Stretchable Mechanical and Electrical Interconnects

Erlenbach

Mondal

et al. 2023

ACS Appl. Mater. Interfaces

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Stretchable electronic devices that maintain electrical function when subjected to stress or strain are useful for enabling new applications for electronics, such as wearable devices, human−machine interfaces, and components for soft robotics. Powering and communicating with these devices is a challenge. NFC (near-field communication) coils solve this challenge but only work efficiently when they are in close proximity to the device. Alternatively, electrical signals and power can arrive via physical connections between the stretchable device and an external source, such as a battery. The ability to create a robust physical and electrical connection between mechanically disparate components may enable new types of hybrid devices in which at least a portion is stretchable or deformable, such as hinges. This paper presents a simple method to make mechanical and electrical connections between elastomeric conductors and flexible (or rigid) conductors. The adhesion at the interface between these disparate materials arises from surface chemistry that forms strong covalent bonds. The utilization of liquid metals as the conductor provides stretchable interconnects between stretchable and non-stretchable electrical traces. The liquid metal can be printed or injected into vias to create interconnects. We characterized the mechanical and electrical properties of these hybrid devices to demonstrate the concept and identify geometric design criteria to maximize mechanical strength. The work here provides a simple and general strategy for creating mechanical and electrical connections that may find use in a variety of stretchable and soft electronic devices.

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“…When creating elastic printed circuit boards (E-PCBs), liquid metal can flow into another circuit line because of high surface tension . Other methods, such as using stretchable ACFs for device connections, require high pressure or temperature for strong bonding . Recently, research on the formation of nanomaterials (such as Au nanoparticles) within elastomers has been conducted for more effortless electrical connectivity .…”

mentioning

confidence: 99%

“…19 Other methods, such as using stretchable ACFs for device connections, require high pressure or temperature for strong bonding. 20 Recently, research on the formation of nanomaterials (such as Au nanoparticles) within elastomers has been conducted for more effortless electrical connectivity. 21 However, this method faces manufacturing challenges, particularly in achieving a vertical electrical conductivity.…”

mentioning

confidence: 99%

Stretchable Electrodes for Interconnects in Soft Electronics

Jeon,

Park

2024

Nano Lett.

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Soft electronics have significantly enhanced user convenience and data accuracy in wearable devices, implantable devices, and human− machine interfaces. However, a persistent challenge in their development has been the disconnection between the rigid and soft components of devices due to the substantial difference in modulus and stretchability. To address this issue, establishing a durable and flexible connection that smoothly links components of varying stiffness to signal-capturing sections with a lower stiffness is essential. In this study, we developed a novel stretchable interconnect that strongly adheres to various materials, facilitating electrical connections effortlessly by applying minimal finger pressure. Capable of stretching up to 1000% while maintaining electrical integrity, this interconnect proves its applicability across multiple domains, including electrocardiogram (ECG), electromyography (EMG), and stretchable light-emitting diode (LED) circuits. Its versatility is further demonstrated through its compatibility with various manufacturing techniques such as 3D printing, painting, and spin coating, highlighting its adaptability in soft electronics.

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Evaluation of an Anisotropic Conductive Epoxy for Interconnecting Highly Stretchable Conductors to Various Surfaces

Cited by 10 publications

References 28 publications

Additively manufactured flexible on-package phased array antennas for 5G/mmWave wearable and conformal digital twin and massive MIMO applications

Additively manufactured flexible on-package phased array antennas for 5G/mmWave wearable and conformal digital twin and massive MIMO applications

Flexible-to-Stretchable Mechanical and Electrical Interconnects

Stretchable Electrodes for Interconnects in Soft Electronics

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