PS (Photo Spacer)

Photo-spacer material is a kind of photoresist used to create small patterns on a color filter with lithography processes. The function of photo-spacer is to keep a constant gap of a specific distance between the two glass substrates and generate the space for the principal material of a TFT-LCD display – liquid crystal.

Many leading TFT-LCD companies have evaluated and introduced the photo-spacer product of Topgiga for their manufacturing of LCD. It is highly appreciated that the photo-spacer product of Topgiga has the following advantages:

1. high transmittance
2. high elastic recovery ratio
3. high VHR value (Voltage Holding Ratio)
4. high resolution
5. high uniformity
6. excellent heat and chemical resistance.

Over Coat

An overcoat is a protection for the color filter, and meanwhile, it is mostly used to minimize the height difference of the surface of a color filter. The height difference between red, green, and blue subpixels are reduced by the application of overcoat on top of them and thereby making the surface of the color filter as flat as possible. The overcoat also plays a role of separating the black matrix and the transparent ITO electrode film and prevents the liquid crystal from contamination.

Generally, an overcoat is mainly composed of either epoxy or acrylic resin.

Product Application

UV type

UV type Overcoat is a UV light-sensitive material. A regular lithography process could define the pattern of an overcoat, and the result is usually determined by the light sensitivity and developability of the overcoat. Other than the application of a full coating, the overcoat could be used for applications, such as insulating bumps or contact holes.

The UV type Overcoat has the following advantages:

  1. Excellent flattening
  2. High resolution
  3. High transmittance
  4. High VHR (Voltage Holding Ratio)
  5. Excellent uniformity
  6. Excellent heat and chemical resistance.

Thermal type

Thermal type Overcoat is a heat-sensitive transparent photoresist material. It requires low investment in the equipment and straightforward manufacturing process.

It has the following advantages:

  1. Good light transmittance
  2. Excellent flatness
  3. High VHR (Voltage Holding Ratio)
  4. High hardness
  5. Low moisture absorption
  6. Excellent heat and chemical resistance.

MVA : Multi-Domain Vertical Alignment

In the MVA (Multi-Domain Vertical Alignment) technique, the Liquid Crystal molecules are angled in more than one direction within a single cell. The behavior of liquid crystal molecules is then controlled by dividing the cell into two or more regions, called domains, and by using protrusions on the glass surfaces to pre-tilt the molecules in the desired direction. By combining areas of molecules oriented in one direction with regions of molecules oriented in the opposite direction, and by making the areas very small, the brightness of the cells can be made to appear uniform over a wide range of viewing angles.

MVA (Multi-Domain Vertical Alignment) is a method of angling the liquid crystals in a TFT display so that the screen remains uniformly bright and the colors stay true over much broader viewing angle X up to 170 degrees, or 85 degrees on either side of center. On the other hand, regular displays have viewing angles merely ranging from 100 to 140 degrees.

Product Application

Another tangible benefit of MVA is a relatively fast refresh rate of 25 milliseconds or less. Slow refresh rates result in smearing when you’re watching videos or playing games.

Negative type MVA surpassing positive type MVA

  • Negative type MVA transcends positive type MVA for the following characteristics:
    1. High transmittance
    2. Better optical performance
    3. Good Chemical & Thermal resistance
    4. Better process yield rate

 Black Matrix

 

TG Resin BM photoresist has advantages of high OD, high resolution, high adhesion, good uniformity, good heat resistance and good chemical resistance for both normal and high ohm series.

Product Application

Generally, the OD value of BM film should be larger than 3.5/um. The higher OD value of BM, the lower BM film thickness is required which can reduce the different thickness between edge and center of RGB layers and even lower Overcoat film thickness. TG is able to provide Resin BM photoresist (OD/um = 3.5~4.5) with different spec requirements for our customers.

TG Resin BM photoresist has advantages of high OD, high resolution, high adhesion, good uniformity, good heat resistance and good chemical resistance for both normal and high ohm series.

 RGB Color Resister

　

The vivid colors revealed by a TFT-LCD display is from the color filter embodied in the device and the filter is made of three types of color photoresists. The major components of the color photoresist are dispersed pigmented or dyed millbases, acrylic resin, photo-initiators. The color filter has highly densely distributed subpixels of red, green, and blue color. By controlling the behavior of liquid crystal which results in the illuminations of different intensities on each of the RGB subpixels simultaneously, the TFT-LCD display, therefore, shows a significant number of wonderful colors.  Most importantly, the quality of the color filter is mainly affected by various characteristics of the color photoresists. And the color photoresist products of Topgiga have the most critical advantages of high transmittance, high color saturation, and good reliabilities, such as heat and chemical resistance.

Product Application

Wide Color Gamut products, which has a CIE 1931 coverage of more than 85% (NTSC) under standard C illumination, could bring higher saturated colors to the filter and empower the TFT-LCD display with richer and more vivid pictures.