The pinholes on the surface of alignment layer was studied

which formed during the TFT-LCD manufacturing process and caused defects of the products. Herein

a vitally typical defect

black spot

was analyzed via FIB

SEM and OMS. The analysis results of statistical software BO (Business Objects) show that the pinhole is the main cause of the black spot. Based on theoretical analysis and further experimental results

it is found that the hydrodynamic instability of the solution may lead to the pinholes on the alignment layer surface

and the pre-cure time of the alignment film solution is significantly responsible for hydrodynamic instability. It is noteworthy that the instability needs times to grow full enough and then to influence the film structure. Therefore

the pinholes on the alignment layer surface will be reduced or eliminated if the pre-cure time is less than or equal to that time.