Failure mechanism of COF based Line Driver IC for Flat Panel Display by contamination

摘要

This study is about the field failure and mechanism of Chip on Film (COF) based Line Driver IC (LDI) for FPD. Due to LDI failure, there is vertical line defect on Flat Panel Display (FPD). Contamination is detected in bumps of LDI which is packaged by Resin. Chemical and physical method has applied for analyzing the elements and the isolation of contamination. The first detected contamination type is Gold (Au). The second contamination type is the mixed material of metal particle and organic material like Aluminum (Al), Iron (Fe), Chrome (Cr). It is found that all contamination is getting in during the Inner Layer Bonding (ILB) process. In case of Au contamination, remained Au particle is getting into the surface of collet (Rubber) which is used for Chip pick-up with collet particle. Fe, Cr, Al contamination is floating dust inside of the equipment and getting into with all kinds of dust. Dust inside is getting energy from temperature, moisture, Bias, catalyst. As a result, each contamination could cause short in bumps in LDI due to Au migration and by changing the characteristic from high resistor to low resistor.