Water‐Based Isotropically Conductive Adhesives: Towards Green and Low‐Cost Flexible Electronics

Abstract

This paper reports the first high‐performance water‐based isotropically conductive adhesives (WBICAs) – a promising material for both electrical interconnects and printed circuits for ultralow‐cost flexible/foldable printed electronics. Through combining surface iodination and in situ reduction treatment, the electrically conductivity of the WBICAs are dramatically improved (8 × 10‐5 Ω cm with 80 wt% of silver); moreover, their reliability (stable for at least 1440 h during 85 °C/85% RH aging) meets the essential requirements for microelectronic applications. Prototyped applications in carrying light emitting diode (LED) arrays and radio frequency identification (RFID) antennas on flexible substrates were demonstrated, which showed satisfactory performances. Moreover, their water‐based character may render them more environmentally benign (no volatile organic chemicals involved in the printing and machine maintenance processes), more convenient in processing (reducing the processing steps), and energy economic (thermally sintering the silver fillers and curing the resin is not necessary unlike conventional ICAs). Therefore, they are especially advantageous for mass‐fabricating flexible electronic devices when coupled with paper and other low‐cost substrate materials such as PET, PI, wood, rubber, and textiles.

A comprehensive study of silver nanowires filled electrically conductive adhesives

“…There are two critical issues that currently prohibit ECAs from large scale applications: relatively lower conductivity and adhesive strength [1][2][3][4][5][6][7][8][9][17][18][19][20][21][22][23][24][25]. However, there are always conflicting to two fundamental properties unless the decrease of content of fillers does not cause the decrease of conductance of ECAs.…”

“…One feasible approach to this problem is the establishment of perfect conductive pathways under the low content of conductive fillers. Silver nanostructures are incorporated for the purpose of electrical conductance and adhesive strength improvement of the ECAs [1,[5][6][7][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35].…”

Bio-Organic Electronics—Overview and Prospects for the Future

“…A water-based conductive adhesive for electrical interconnects and printed circuits was published by Yang and co-workers [20]. This environmentally harmless, but not biodegradable, adhesive based on polyether diol was stable for 1440 h at 85 °C and a relative humidity of 85% and can potentially be used for flexible consumer electronics.…”

“…Their dielectric properties fulfil the requirements for the use in OTFTs. Nucleobases such as adenine (20) and guanine (21) can easily be purified and evaporated as thin films (up to 2.5 nm) which enable DNA-like sequences [23,24,26]. Moreover, DNA which has been functionalized by a cationic surfactant reaction became soluble in polar solvents and allowed wet coated thin films.…”

Preparation and performance of Ag-coated Cu flakes filled epoxy as electrically conductive adhesives

“…However, because of the high price of Ag, great attentions and efforts have been made to reduce the costs of ECAs [10,11]. Cu has the most comparable property to Ag but it is easily oxidized and corroded.…”