Optimization of Heating Temperature History for Anisotropic Conductive Film Interconnection

Anisotropic conductive film (ACF) interconnection is used for mounting electronic components, because this method can decrease the mounting area and electric connection length, as well as the thermal stress in the connecting area. An ACF comprises thermosetting resin and conductive particles. The resin is heated and its curing rate and viscosity changes complexly with the heating temperature during the process. There are several requirements for the heating temperature history from the industrial viewpoint such as the reliability of adhesion and energy efficiency. These requirements are related to the curing rate and the viscosity of the resin. A global optimization method proposed for nonlinear programming problems is adopted to optimize the values of the curing reaction parameters and the temperature history. First, the values of parameters in the functions determining the curing rate and viscosity are identified, and the curing rate and viscosity calculated using the values of the parameters agree well with the experimental data. Then, several optimization examples clarify features of the optimum heating temperature history. It is possible to increase the final curing rate to ensure adhesion and to control the viscosity in the bubble-removing process. The period in which bubbles are removed can be changed by the setting of the optimization parameters. It is also possible to minimize the heat input and ensure the required final curing rate. These results clarify that the temperature history for ACF interconnection can be determined accurately by the presented global optimization approach.