Material PropertiesUltrasonic bond process for polymer-based anisotropic conductive film joints. Part 2: Application in chip-on-FR4 board assemblies

Polymer-based anisotropic conductive film has become widely used in many electronic packaging interconnect applications. The ultrasonic flip chip bond technology for anisotropic conductive film (ACF) joints in Chip-on-Glass (COG) assemblies has been investigated in part 1 of this paper [1]. In Part 2, the ultrasonic flip chip bond process for polymer-based anisotropic conductive film joints in chip-on-FR4 organic rigid board assemblies is discussed. The effects of ultrasonic bond process parameters, including the bonding time, bonding force, substrate temperature and ultrasonic power on the degree of cure and bond strength of ACF joints between chip and FR4 organic rigid board are investigated in detail. The optimized ultrasonic bonding process conditions for the Chip-on-FR4 organic rigid board assemblies are obtained as: (1) the bonding time can be from 2500 ms to 3000 ms; (2) the bonding force should be over 10 N; (3) the substrate temperature should be higher than 70 °C; (4) the optimum ultrasonic power is about 2.80 W.