Transcription solder bump technology using the evaporation method

Abstract

We have developed a new transcription solder bump (TSB) technology using the evaporation method. We use this method in the current production of micro solder area array bump (/spl mu/SAB) formation with 153 /spl mu/m pitch and on chips with over 8000 bumps. In this method, transcription bumps are formed on a dummy wafer by evaporation using a metal mask. Temporary chips are made by dicing the dummy wafer with evaporated bumps, and then the bumps on the temporary chips are transcribed to real chips. This technology has a high accuracy in terms of bump height of less than 2 /spl mu/m, and bumping yield is greater than 99.99999% per bump. Also, we have developed a restoration technique for solder bumps with high yield and low cost.