Development of novel anisotropic conductive film (ACF)

Developments on flip chip connections are ongoing for high density packaging in the electronics industry. Anisotropic conducting adhesive is an interconnecting material for one of the flip chip packaging methods. Electronic Industries Association of Japan (EIAJ) forecasts, in the roadmap of Semiconductor Packaging Technology, that such an adhesive material will be used for connecting bump-less chips and printed circuit boards in a pitch of 0.040 mm in the year 2000. The development on the novel structure of anisotropic conductive film (ACF), started to achieve the ultimate IC-packaging system, in which bump-less chips can be electrically connected and encapsulated on circuit boards through this ACF. Optimizing the structure and material can improve a variety of operational conditions, such as bonding time, pressure and temperature. These improvements can contribute to better throughput, when the ACF connects chips and circuit boards in the assembly process, and allow one to remove the defective chips from the board after connecting chips and boards with the ACF. This development is extended to wafer level packaging from the die level, for more effective IC-packaging. The enlarged ACF successfully and reliably bonds to wafers. This paper is an overview of the novel ACF in the packaging application, including its wafer level handling.