Characterization of silver flake lubricants

There is a thin layer of organic lubricant on commercial silver (Ag) flakes that are widely used as the fillers in electrically conductive adhesives ( ECAs). This lubricant layer highly affects the properties such as conductiv ity of the ECAs. Therefore, understanding the behavior of Ag flake lubrican t layer is essential for developing high performance ECAs. This work is aim ed at studying the chemical nature of the lubricant layer, interaction betw een the lubricant layer and Ag flakes, and thermal behavior of the lubrican ts during heating. A blank Ag powder is ball-milled into Ag flakes with fiv e fatty acids that have different carbon-hydrogen chain length as lubricant s. After lubrication, the Ag flakes are studied using scanning electron mic roscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetr y (TG), and diffuse reflectance infrared Fourier transform spectroscopy (DR IFTS). It is found that (i) Ag flakes lubricated with fatty acids of differ ent chain lengths have exothermic DSC peaks and mass losses at different te mperatures, (ii) the lubricant layer on the lubricated Ag flake surfaces is a salt formed between the acid and Ag, and (iii) exothermic DSC peaks (in air) of a lubricated Ag flake is probably due to the oxidation of lubricant layer on the Ag flake surface.