P‐6.5: Cu Erosion of Via Hole within GOA Unit of Super‐large and Ultra‐HD TFT‐LCD of 120Hz Frame Rate

Abstract

Cu erosion of via hole within GOA unit of super‐large and ultra‐HD TFT‐LCD of 120Hz frame rate is an important issue and may cause some line failures. Reliability tests of panel about temperature and humidity are used to accelerate occurrences of the relative failures (Y‐Line). Effects of some critical factors including ITO thickness, tray life and sealant coverage are analyzed for optimal combination of mass production parameters. Furthermore, mechanisms of the Y‐Line failure are dissected by some modern analytical equipment. Deep via hole broken is found to be primary cause of Y‐Line failure of 75inch 4K 120Hz panel in Green127 pattern. The broken is caused by erosion of gate Cu in the via hole. There is initial Cu erosion at chamfer consisting of GI‐Cu‐ITO, caused by photoresist stripping after via hole etch, leading to open the ITO used to connect gate Cu (below GI) and data line (above GI). The ITO open provides possibility for H2O to passing through, and greatly weakens its shielding ability. A channel for H2O diffusion resulting in Cu erosion after “8585” and “THO” tests can be speculated to be interfaces consisting of Sealant‐PVX and Sealant‐ITO.