Change in electrical conductivity of electrically conductive adhesives during curing process

Fukumoto, Shinji; Makimoto, Kazuhiro; Ohta, Kengo; Nakamura, Toshio; Matsushima, Michiya; Fujimoto, Kozo

doi:10.1007/s10853-022-07305-6

Cited by 7 publications

(13 citation statements)

References 16 publications

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“…However, for high conductivity, these contacts must be of low resistance . The electrical path is affected by the thickness of any organic resin films between the particles − ,, and also the surface condition of the particles themselves, for example, the presence of high-resistivity oxides. In the ODT-SAM-Cu system presented here, the addition of an ODT-SAM onto the surface of the Cu particles also presents the possibility of additional interfacial layers that may affect conduction. − , …”

Section: Discussionmentioning

confidence: 99%

“…In the ODT-SAM-Cu system presented here, the addition of an ODT-SAM onto the surface of the Cu particles also presents the possibility of additional interfacial layers that may affect conduction. [55][56][57]60 From Figure 2, the high electrical conductivity of the cured Cu-ICAs made with ODT-SAM-Cu clearly demonstrates the effectiveness of the initial etching procedures and removal of the native oxides from the Cu. Short-term storage of the ODT-SAM-Cu in the freezer led to a small increase in surface oxide, but the Cu-ICAs made from these powders were still highly conductive.…”

Section: Contact Resistance and Surface Oxide Levelsmentioning

confidence: 92%

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The Role of Self-Assembled Monolayers in the Surface Modification and Interfacial Contact of Copper Fillers in Electrically Conductive Adhesives

Wang,

Zhou,

Goulas

et al. 2023

ACS Appl. Mater. Interfaces

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Printing of electrical circuits and interconnects using isotropic conductive adhesives (ICAs) is of great interest due to their low-temperature processing and compatibility with substrates for applications in sensors, healthcare, and flexible devices. As a lower cost alternative to silver (Ag), copper (Cu)filled ICAs are desirable but limited by the formation of highresistivity Cu surface oxides. To overcome this limitation, selfassembled monolayers (SAMs) of octadecanethiol (ODT) have been demonstrated to reduce the oxidation of micrometer-scale Cu powder particles for use in ICAs. However, the deposition and function of the SAM require further investigation, as described in this paper. As part of this work, the stages of the SAM deposition process, which included etching with hydrochloric acid to remove pre-existing oxides, were studied using X-ray photoelectron spectroscopy (XPS), which showed low levels of subsequent Cu oxidation when ODT coated. The treated Cu powders were combined with one-or two-part epoxy resins to make Cu-ICAs, and the effect of the Cu surface condition and weight loading on electrical conductivity was examined. When thermally cured in an inert argon atmosphere, ICAs filled with Cu protected by ODT achieved electrical conductivity up to 20 × 10 5 S•m −1 , comparable to Ag-ICAs, and were used to make a functional circuit. To understand the function of the SAM in these Cu-ICAs, scanning and transmission electron microscopy were used to examine the internal micro-and nano-structures along with the elemental distribution at the interfaces within sections taken from cured samples. Sulfur (S), indicative of the ODT, was still detected at the internal polymer−metal interface after curing, and particle-to-particle contacts were also examined. XPS also identified S on the surface of cured Cu-ICAs even after thermal treatment. Based on the observations, electrical contact and conduction mechanisms for these Cu-filled ICAs are proposed and discussed.

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Section: Discussionmentioning

confidence: 99%

Section: Contact Resistance and Surface Oxide Levelsmentioning

confidence: 92%

The Role of Self-Assembled Monolayers in the Surface Modification and Interfacial Contact of Copper Fillers in Electrically Conductive Adhesives

Wang,

Zhou,

Goulas

et al. 2023

ACS Appl. Mater. Interfaces

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“…Generally, resin matrix and conductive fillers are two essential components of ECAs. The resin matrix grants the physical and mechanical properties of the ECAs through the heat or light curing to form a 3D network structure and conductive fillers with high electrical conductivity can provide the shortest channels of electronic conductance as the volume percentage of conductive particles exceeds the percolation threshold of ECAs [2,3] …”

Section: Introductionmentioning

confidence: 99%

“…The resin matrix grants the physical and mechanical properties of the ECAs through the heat or light curing to form a 3D network structure and conductive fillers with high electrical conductivity can provide the shortest channels of electronic conductance as the volume percentage of conductive particles exceeds the percolation threshold of ECAs. [2,3] Silver particles are the most commonly used fillers of ECAs because of their unique properties in chemistry such as high inoxidizability and physics such as excellent electrical and thermal conductivity. Furthermore, silver particles of various sizes and shapes are easily manufactured, and silver spheres, flakes, rods, and wires in the micrometer and nanometer scale have been used in ECAs for electronic packaging.…”

Section: Introductionmentioning

confidence: 99%

Electrolytic Synthesis and Tolyltriazole Modification of Dendritic Silver Powders for High‐performance Electrically Conductive Adhesives

Lei

Wang

et al. 2023

ChemistrySelect

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Dendritic silver particles (DSPs) were synthesized by a facile electrolysis method based on the self-made silver methanesulfonic as an electrolyte and the surface of DSPs was coated with methyl-1H-benzotriazole to prepare the surface-modified DSPs. Dendritic feature with a trunk and nano-branches is confirmed by scanning electron microscopy. At temperatures above 200 °C, the sintering phenomenon is discovered at the nano-branches of DSPs. As the prepared DSPs are introduced into the commercial micron-scale silver particles-based electrically conductive adhesives (ECAs), the electrical resistivity can be significantly reduced to 5.63 × 10 À 5 Ω cm, which is superior to the traditional conductive adhesives derived from the pure micron-scale silver particles, implying the high application value of DSPs for high-performance conductive adhesive.

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“…However, Lu et al reported thermal decomposition behavior of the Ag flake lubricant and proposed a mechanism of thermal decomposition of the Ag flake lubricant, in which decomposition of the lubricant includes the release of the fatty acid, formation of short chain acids by decomposition of the hydrocarbon moiety of the fatty acid, and formation of alcohols through decarbonation of the short chain acids. Fukumoto et al believed that the thin fatty acid layer provided insulating properties to the Ag surface; the fatty acids were removed from the particle surface via evaporation during the curing process and the electrical resistivity of the ECAs decreased considerably.…”

Section: Introductionmentioning

confidence: 99%

Surface Functionalization of Micrometer Silver Flakes for Fabricating High-Performance Electrically Conductive Adhesives

Zhang

Líu

Wang

et al. 2022

ACS Appl. Electron. Mater.

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Silver (Ag) flakes are widely used as conductive fillers in the electrically conductive adhesives (ECAs). However, there are organic lubricants on the Ag surface such as oleic acid and stearic acid, a kind of surfactant commonly used in the production of Ag flakes, which will deteriorate the conductivity and mechanical properties of the ECAs. In this study, glutaric acid was used to remove the organic lubricants, which can increase the electrical conductivity and mechanical properties of the ECAs. FTIR, Raman, and XPS tests revealed that the glutaric acid was chemically adsorbed on the Ag surface by single-dentate coordination and then reacted with organic lubricants, explaining the action mechanism by which the glutaric acid enhanced the electrical and mechanical properties of the ECAs. In addition, the effects of glutaric acid on the thermal stability, bulk resistivity, shear strength, and viscosity of the ECAs were investigated. When the glutaric acid reached 0.12 wt %, the minimum bulk resistivity of the ECAs was 1.52 × 10–4 Ω·cm, the shear strength was 24.57 MPa, and the viscosity was 149 Pa·s. This provides a method for fabricating high-performance ECAs.

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Change in electrical conductivity of electrically conductive adhesives during curing process

Cited by 7 publications

References 16 publications

The Role of Self-Assembled Monolayers in the Surface Modification and Interfacial Contact of Copper Fillers in Electrically Conductive Adhesives

The Role of Self-Assembled Monolayers in the Surface Modification and Interfacial Contact of Copper Fillers in Electrically Conductive Adhesives

Electrolytic Synthesis and Tolyltriazole Modification of Dendritic Silver Powders for High‐performance Electrically Conductive Adhesives

Surface Functionalization of Micrometer Silver Flakes for Fabricating High-Performance Electrically Conductive Adhesives

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