FLIP CHIP ON FR-4, CERAMICS AND FLEX

Abstract

This paper discusses flip chip on FR-4, ceramics and flex investigated in our research institution and the industry. The reliability performance of the processes of flip chip on FR-4 and ceramics using gold bumps with anisotropic conductive film or anisotropic conductive paste, and eutectic solder bumps with underfill epoxy was studied. Flip chip on ceramic substrate gives much better reliability than flip chip on FR-4 boards. Most of the samples assembled on ceramic boards using eutectic solder with underfill epoxy survived after 9,500 cycles of the thermal cycling test (-40°C to 125°C). Also, flip chip on FR-4 substrate using eutectic solder with underfill epoxy showed reasonable reliability performance. Flip chip on flex (FCOF) was also studied as FCOF can be the next generation of flex circuit packaging for cheaper and faster speed performance. The FCOF utilized eutectic solder bumps for the chip interconnection. Prototypes of the FCOF were assembled and their reliability was tested with satisfactory results.