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

A low-cost and high performance Ag-coated Cu flakes filled epoxy was prepared as electrically conductive adhesives (ECAs) for light emitting diode (LED) packaging. As-prepared ECAs consisted of bisphenol-F-epoxy resin, micro-sized Ag-coated Cu flakes and other additives. The ECAs with content of 70 wt % Ag-coated Cu flakes pre-modified by silane coupling agent (SCA) exhibited much lower bulk resistivity (8.4∗10-3 Ωcm) than that of ECA filled with 70 wt % Ag-coated Cu flakes without SCA modification (1.6∗10-1 Ωcm). An appropriate content of diluent (below 20 wt %) was beneficial for the flakes' regular dispersion in resin, which enhanced the electrical conductivity (10-4∈~∈-10-5 Ωcm) and mechanical strength (>14 Mpa) of ECAs.