Reliability and thermodynamic studies of an anisotropic conductive adhesive film (ACAF) prepared from epoxy/rubber resins

A thermoset type anisotropic conductive adhesive film (ACAF) comprising epoxy resin, natural butyl rubber (NBR), and micro-encapsulated imidazole as the binder and Ni/Au coated polymer bead as a conductive particle, has been studied. These films have been prepared to respond to requirements such as improved contact resistance, pitch interval of less than 80 μm and reliability. They showed good physical properties after being pressurized and heated to electrically and mechanically bond the ITO glass and the flexible circuit board. The curing conditions for the connection were 40, 20 and 15 s at 150, 170 and 190 °C, respectively. The initial contact resistance and adhesion strength were 0.5 Ω/sq. and 0.4 kg/cm under the condition of 30 kgf/cm2, respectively. After 1000 thermal shock cycling tests between −15 and 100 °C, the contact resistance was maintained below 0.7 Ω/sq. Durability against high temperature (80 °C) and high humidity (85% RH) was also tested to confirm long-term stability (1000 h) of the conduction.