Copper pastes using bimodal particles for flexible printed electronics

Tam, Sze Kee; Fung, Ka Yip; Ng, Ka Ming

doi:10.1007/s10853-015-9498-7

Cited by 41 publications

(15 citation statements)

References 21 publications

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“…The sub-10-nm nanoparticles are known to have further reduced melting temperatures, 34 and the introduction of copper flakes enhances flexibility and suppresses crack formation. 35 Higher temperatures result in oxidation but are also required to reduce oxide formation and, in some cases, produce nanoparticles chemically.…”

Section: ■ 3d Printing Of Conductive Pastesmentioning

confidence: 99%

“…Curing under a nitrogen atmosphere allowed for lower temperatures and higher conductivities (1.9 × 10 4 S/cm at 80 °C and 1.2 × 10 5 S/cm at 120 °C). The sub-10-nm nanoparticles are known to have further reduced melting temperatures, and the introduction of copper flakes enhances flexibility and suppresses crack formation . Higher temperatures result in oxidation but are also required to reduce oxide formation and, in some cases, produce nanoparticles chemically.…”

Section: D Printing Of Conductive Pastesmentioning

confidence: 99%

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Highly Conductive 3D Printable Materials for 3D Structural Electronics

Baker

Bao

Kim

2021

ACS Appl. Electron. Mater.

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3D printing will be one of the key technologies in the next industrial revolution. It will usher us into an era of decentralized manufacturing, empowering individuals to manufacture in their communities. One area in particular that can benefit from 3D printing is the production of electronics. 3D printing allows for the fabrication of structural electronics, which have their components embedded in the 3D structured object. Recently spotlighted 3D structural printing technologies include fused filament fabrication and direct-ink writing to prepare 3D conductive traces. Highly conductive traces are imperative for achieving reliable 3D structural electronics. This Spotlight will overview highly conductive 3D printable materials available from several prominent methods of producing conductive traces. Key conducting materials demonstrated by 3D deposition, photocuring, and electrochemical approaches have been reviewed and discussed.

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Section: ■ 3d Printing Of Conductive Pastesmentioning

confidence: 99%

Section: D Printing Of Conductive Pastesmentioning

confidence: 99%

Highly Conductive 3D Printable Materials for 3D Structural Electronics

Baker

Bao

Kim

2021

ACS Appl. Electron. Mater.

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“…The 3:1 (micro/nano, wt%) mixed paste was found to have the most substantial synergistic effect. Tam et al also prepared mixed paste with Cu nanoparticles (60.8 nm) and Cu flakes (9.3 μm) [ 124 ]. The optimal formulation of mix pastes for the screen printing was determined to be 20 wt% Cu flakes and 80 wt% Cu nanoparticles, leading to a resistivity of 29 μΩ·cm for the sintered Cu film on PET at 120 °C under a 5% H 2 atmosphere for 3 h, which was a lower resistivity (59 μΩ·cm) than the sintered Cu film from the paste with only Cu nanoparticles without Cu flakes.…”

Section: Formulation Designs In Cu-based Mixed Inks/pastesmentioning

confidence: 99%

Surface and Interface Designs in Copper-Based Conductive Inks for Printed/Flexible Electronics

Tomotoshi

Kawasaki

2020

Nanomaterials

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Silver (Ag), gold (Au), and copper (Cu) have been utilized as metals for fabricating metal-based inks/pastes for printed/flexible electronics. Among them, Cu is the most promising candidate for metal-based inks/pastes. Cu has high intrinsic electrical/thermal conductivity, which is more cost-effective and abundant, as compared to Ag. Moreover, the migration tendency of Cu is less than that of Ag. Thus, recently, Cu-based inks/pastes have gained increasing attention as conductive inks/pastes for printed/flexible electronics. However, the disadvantages of Cu-based inks/pastes are their instability against oxidation under an ambient condition and tendency to form insulating layers of Cu oxide, such as cuprous oxide (Cu2O) and cupric oxide (CuO). The formation of the Cu oxidation causes a low conductivity in sintered Cu films and interferes with the sintering of Cu particles. In this review, we summarize the surface and interface designs for Cu-based conductive inks/pastes, in which the strategies for the oxidation resistance of Cu and low-temperature sintering are applied to produce highly conductive Cu patterns/electrodes on flexible substrates. First, we classify the Cu-based inks/pastes and briefly describe the surface oxidation behaviors of Cu. Next, we describe various surface control approaches for Cu-based inks/pastes to achieve both the oxidation resistance and low-temperature sintering to produce highly conductive Cu patterns/electrodes on flexible substrates. These surface control approaches include surface designs by polymers, small ligands, core-shell structures, and surface activation. Recently developed Cu-based mixed inks/pastes are also described, and the synergy effect in the mixed inks/pastes offers improved performances compared with the single use of each component. Finally, we offer our perspectives on Cu-based inks/pastes for future efforts.

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“…The second category of ink formulation is bimodal hybrid Cu inks which can be divided into two groups of Cu micro- or nanoparticles mixed with another nanomaterial. − The addition of the nanomaterial improves the microstructure of the printed trace by filling the pores of the pattern, resulting in improved packing density with less susceptibility to mechanical failure. It also improves the conductivity of the pattern by providing low effective sintering temperature that could be easily achieved by faster sintering methods, such as microwaves, IPL, and laser beam.…”

Section: Introductionmentioning

confidence: 99%

Highly Conductive Copper–Silver Bimodal Paste for Low-Cost Printed Electronics

Zareei

Gopalakrishnan

Mutlu

et al. 2021

ACS Appl. Electron. Mater.

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Printed electronics are circuits that are additively manufactured using conductive pastes composed of micro-/nanoconductive metal particles. Silver-based compounds are the most widely used metals for such pastes due to their superior conductivity and oxidation stability. However, the high cost of silver (Ag) has demanded its replacement with more cost-effective and abundant metals such as copper (Cu). Despite its cost-effectiveness and abundance, Cu suffers from high oxidation tendency and sintering temperature that have limited its widespread utilization in printed electronics. In this work, we have developed a low-cost hybrid bimodal paste composed of Cu microparticles (1–5 μm) and Ag nanoparticles (20–30 nm) (CuMPs/AgNPs) via nondestructive photonic sintering. The concurrent melting of AgNPs and catalytic reduction of CuMPs allow the paste to be sintered at considerably low temperatures using an intense-pulsed light (IPL) source. The required light energy density for effective sintering of different mixing ratios of AgNPs and CuMPs was systematically measured using electrical, optical, and mechanical characterization techniques. These analyses revealed that a minimum of 16 wt % AgNPs in the bimodal CuMP/AgNP paste with an IPL irradiation energy of 10.6 J/cm2 and pulse duration of 5 ms achieved a minimum sheet resistance of 0.072 Ω/□ that results from localized melting of AgNPs between adjacent CuMPs. Furthermore, the CuMP/AgNP films with a minimum of 6 wt % AgNPs showed significantly improved oxidation stability characteristics even after 7 days of incubation in accelerated oxidation conditions [70 °C and 100% relative humidity (RH)]. As a proof of concept, we demonstrated an application of the developed paste (CuMPs-6 wt % AgNPs) by directly printing a wireless resonant moisture sensor onto the interior region of a cardboard package box, which is capable of performing in situ monitoring of the moisture ranging from 30 to 85% RH with an average linear sensitivity of −3.08 % RH/MHz.

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Copper pastes using bimodal particles for flexible printed electronics

Cited by 41 publications

References 21 publications

Highly Conductive 3D Printable Materials for 3D Structural Electronics

Highly Conductive 3D Printable Materials for 3D Structural Electronics

Surface and Interface Designs in Copper-Based Conductive Inks for Printed/Flexible Electronics

Highly Conductive Copper–Silver Bimodal Paste for Low-Cost Printed Electronics

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