Reliability of fine pitch COF: Influence of surface morphology and CuSn intermetallic compound formation

Chip-on-film (COF) reliability with fine Cu metal on the film tape used as inner or outer leads for bonding with Au bump that forms electrical contact in display driver IC (DDI) chip is reported. In COF structure, Cu metal is fabricated by electroplating and its mechanical strength was characterized using bending test. It is found that the reliability of COF relies on the quality of Cu electroplating and interface of bonding joint that was optimized to provide excellent bending test results.