Yong-Soon Lee

46.1: Invited Paper: Integrated a‐Si:H TFT Gate Driver Circuits on Large Area TFT‐LCDs

Integrated a-Si:H TFT gate driver circuits on large area TFT-LCDs are reviewed. A novel AC-biased holding circuit to stabilize the floating node of the shift register on the gate drivers is proposed to improve the driver reliability. Experimental confirmation validates that the new a-Si:H TFT gate drivers are highly reliable

16.2: Advanced TFT-LCD Data Line Reduction Method

A new multiplexing technique has been developed which eliminates 2/3 of the TFT-LCD data lines and column drivers by rearranging horizontally-placed RGB pixels vertically. The method requires three times the number of gate drivers, which in turn are integrated in α-Si silicon onto the glass substrate. This new method has been successfully tested and verified on a 12.1-inch WXGA TFT-LCD panel using only two data driver ICs.

55.3: Driving Method of Integrated Gate Driver for Large Area LCD-TV

HD and FHD LCD-TV panels have been implemented using integrated gate drivers. By removing external gate driver ICs, the number of driver ICs has been reduced to only 2 for a 32″ HD panel. A 46″ FHD 120Hz LCD-TV panel and a 40″ HD 60Hz panel have also been developed using integrated gate drivers.

Heel cracking induced by the steep conversion of EMC in large QFP

Bonding wire heel crack observed in large QFP was studied. From the analysis, it was found that this type of open failure was caused by heel crack at stitch bond during molding. The mold simulation was conducted for quantitative analysis. The software considers the polymerization kinetics of EMC since the mold flow depends on thermal excursion. According to simulation, it was proven that the EMC near gate shrinks with very steep gradient of conversion rate. At this moment the chemical shrinkage of EMC results in the fracture of Au wire due to the excessive tension. The mold simulation analysis coincides with experimental results. Both wire bonding and molding parameters were optimized to solve the heel crack problem. The heel crack resistance could be improved by using a capillary which makes large cross-sectional area of stitch bond. The other solution to suppress the heel crack was to use EMC having a smaller chemical shrinkage. Also an additional improvement was obtained by decreasing molding temperature from 175/spl deg/C to 168/spl deg/C. Conclusively, the chemical shrinkage of EMC is an important property and needs to be reduced to minimize the transfer molding failures, especially for the large body size packages.