Kyu-ho Shin

18.3: Implementation of a New Wide Viewing Angle Mode for TFT-LCDs

Compare to the conventional twisted nematic (TN) mode TFT-LCD fabrication process, so far suggested method for the wide viewing angle modes require extra mask-counts. Patterning of the color filter common electrode to achieve the multi-domain vertical alignment (VA) mode costs additional process step. In addition, to avoid improper disclinations, strict alignment margin is necessary. Enhanced vertical alignment (EVA) mode has been developed where the multi-domain cell is formed by the interaction between fringe fields of the pixel electrodes and protrusions on the TFT-array panel. Compared to the TN-mode, since the common electrode is not patterned, EVA mode does not require any additional mask-count. Using the combinations of multi-layer overlap patterns with gate metal, gate dielectrics, passivation nitride, and source/drain metal, protrusions can be formed during the normal TFT-array fabrication process. Viewing angle of the EVA mode can even surpass other wide viewing modes.

Implantable flexible wireless pressure sensor module

A chip embedded flexible packaging scheme has been developed using a thinned silicon chip. Mechanical characteristics of thinned silicon chips are examined by bending test and finite element analysis. Thinned silicon chips (t<50 /spl mu/m) are fabricated by a chemical etching process to avoid possible surface damage. These technologies can be used for an implantable real-time monitoring of blood pressure. Our research targets are developing an implantable blood pressure sensor module and its telemetric measurement. By winding around the coronary arteries, we can measure the blood pressure by capacitance variation of blood vessels.

Chip-On-ACB (Anodized Circuit Board) Package for High Power Light-Emitting Diode

A new light-emitting diode (LED) package module based on anodized circuit board (ACB) is developed in this study. ACB represents the selectively anodized aluminum board, in which the aluminum oxide layer, formed by anodizing process, serves as a dielectric layer and the electric signal lines are formed on it. LED chips can be directly attached to the metal pads on the aluminum core of ACB, which acts as p-electrode and at the same time easily spreads out the heat generated from the chips. The use of ACB in LED packaging has the benefit that ACB provides an excellent heat dissipation path from junction to board. This characteristic cannot be obtained from metal-core printed circuit board (MC-PCB), because it inevitably has a dielectric layer for electrical insulation of signal lines from metal base, which acts as a blocking layer in the heat path. By using the thermal transient method, the thermal resistance of the LED package (from junction to board) is measured to be about 4 °C/W. Also, we have performed...