A novel flip chip technology using nonconductive resin sheet

The process flow of this new packaging system is as follows. First, epoxy base resin sheet is laminated onto substrate to cover the substrate surface including land electrodes. Bumped chip alignment and attachment was done through the resin sheet, in the second stage with pressure and temperature. The bumps under the chip penetrate with removal of resin sheet material eventually reaching to the metal land of the substrate in this process. Metal connection and curing of the interface resin have been completed in the third stage. This new process has the potential to make flip chip packages simple compared with the current process using liquid resin with dispensing system. The throughput time can be reduced to less than 10 s/unit in actual model case even for large flip chip package which has over 15/spl times/15 (mm) square area IC chips. The other advantages are thermal stability of material in the process, moisture related performance, and warpage control performance. For current underfill process the only choice is to use anhydride type resin system which has many disadvantages. This new process made it possible to introduce moisture and thermally stable epoxy resin with phenol curing system for flip chip packaging. Drastic process ability improvement can be achieved by the new process and material. As a typical improvement of thermal shock performance, it was confirmed that the life of chip damage is over 10 times longer by flip chip bonding parameters which can be controlled only by this new flip chip packaging process.