Assembly and interconnection technology for micromechanical structures using anisotropic conductive film

A bonding method using an anisotropic conductive film (ACF) has been developed for the assembly and interconnection of micromechanical structures. The method provides many advantages such as low temperature, low cost, process simplicity, selective bonding as well as both electrical and mechanical interconnection. These advantages were confirmed by experiment using CP7621. ACF on various materials such as wafers, glasses, thin metal layers, and plastic films. For the experiments, a range of materials were tested including p type, (100) orientation, 100 ohm-cm resistivity, 300 micrometers thickness silicon wafers with/without micromechanical structures, 300 micrometers thick sodalime glass substrates, 1.5 mm thick pyrex glass substrates, and 100 micrometers polyethylene plastic thin film were used to verify the effectiveness of this bonding method. A 2000 angstrom thick sputtered aluminium and chrome layer was also used to confirm the electrical interconnection between conductors. The optimum bonding conditions were achieved at 180 degrees C temperature with 5 kg/cm ² pressure applied for 10 seconds. Cleaning was not over critical for the process and the bond strength was strong on silicon and glass substrates. The process was applied to fabricate a silicon micropump that consists of three wafers, results indicating excellent sealing and stability characteristics both needed for this application.