title: One-Step Preparation of Silver Hexagonal Microsheets as Electrically Conductive Adhesive Fillers for Printed Electronics.
abstract: A facile one-step solution-phase chemical reduction method has been developed to synthesize Ag microsheets at room temperature. The morphology of Ag sheets is a regular hexagon more than 1 μm in size and about 200 nm in thickness. The hexagonal Ag microsheets possess a smoother and straighter surface compared with that of the commercial Ag micrometer-sized flakes prepared by ball milling for electrically conductive adhesives (ECAs). The function of the reagents and the formation mechanism of Ag hexagonal microsheets are also investigated. For the polyvinylpyrrolidone (PVP) and citrate facet-selective capping, the Ag atoms freshly reduced by N2H4 would orientationally grow alone on the {111} facet of Ag seeds, with the synergistically selective etching of irregular and small Ag particles by H2O2, to form Ag hexagonal microsheets. The hexagonal Ag microsheet-filled epoxy adhesives, as electrically conductive materials, can be easily printed on various substrates such as polyethylene terephthalate (PET), epoxy, glass, and flexible papers. The hexagonal Ag microsheet filled ECAs demonstrate lower bulk resistivity (approximately 8 × 10(-5) Ω cm) than that of the traditional Ag micrometer-sized-flake-filled ECAs with the same Ag content of 80 wt % (approximately 1.2 × 10(-4) Ω cm).
authors.affiliation: †Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.|‡Shenzhen High Density Electronic Packaging and Device Assembly Key Laboratory, Shenzhen 518055, China.
authors.forename: Hu-Ming
authors.initials: HM
authors.lastname: Ren
authors.affiliation: †Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.|‡Shenzhen High Density Electronic Packaging and Device Assembly Key Laboratory, Shenzhen 518055, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Guo
authors.affiliation: †Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.|‡Shenzhen High Density Electronic Packaging and Device Assembly Key Laboratory, Shenzhen 518055, China.
authors.forename: Sheng-Yun
authors.initials: SY
authors.lastname: Huang
authors.affiliation: §Department of Mechanical and Aerospace Engineering, Hong Kong University of Science and Technology, Hong Kong, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Zhang
authors.affiliation: §Department of Mechanical and Aerospace Engineering, Hong Kong University of Science and Technology, Hong Kong, China.
authors.forename: Matthew M F
authors.initials: MM
authors.lastname: Yuen
authors.affiliation: †Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.|‡Shenzhen High Density Electronic Packaging and Device Assembly Key Laboratory, Shenzhen 518055, China.
authors.forename: Xian-Zhu
authors.initials: XZ
authors.lastname: Fu
authors.affiliation: †Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.|‡Shenzhen High Density Electronic Packaging and Device Assembly Key Laboratory, Shenzhen 518055, China.
authors.forename: Shuhui
authors.initials: S
authors.lastname: Yu
authors.affiliation: †Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.|‡Shenzhen High Density Electronic Packaging and Device Assembly Key Laboratory, Shenzhen 518055, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Sun
authors.affiliation: ∥Department of Electronics Engineering, The Chinese University of Hong Kong, Hong Kong, China.|⊥School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
authors.forename: Ching-Ping
authors.initials: CP
authors.lastname: Wong
keywords: Ag hexagonal flake; electrically conductive adhesive; facet selective growth; nanoplate; printed electronic