How Lcd Displays Are Made,COB

LCD Display Manufacturing Process (COB Method)

COB (Chip on Board) technology integrates the LCD panel with other key components in a compact design. Here’s an outline of how LCD displays are made using the COB method:

1. Basic Working Principle of LCD

• Liquid Crystal Technology: Understanding the behavior of liquid crystals and how they modulate light when subjected to an electric field.
• Pixel Formation: Arrangement of liquid crystal cells between two polarizers, with individual control over each pixel using electrodes.
• Backlight System: Ensuring uniform lighting behind the liquid crystals, typically using LED backlights.

2. Materials Required

• Glass Substrate: Transparent glass sheets for the front and rear panels.
• Liquid Crystal Material: Specially formulated liquid crystal compounds.
• Polarizers: Sheets that allow light of a specific polarization to pass through.
• Electrodes: Conductive layers, usually made of ITO (Indium Tin Oxide).
• Backlight Unit: LEDs or other light sources to provide the necessary backlighting.
• Adhesives and Seals: Used to fix components and prevent contamination.

3. Fabricating the Glass Substrate

• Glass Cutting: Large glass substrates are cut into required sizes.
• Cleaning: Clean the substrate to remove dust and particles.
• ITO Coating: A transparent conductive coating (ITO) is applied to the glass for the pixel electrodes.

4. Patterning and Circuit Printing

• Electrode Patterning: Use lithography and etching techniques to create fine electrode patterns on the glass.
• COB Integration: In COB, the display driver IC is directly bonded onto the glass substrate.
  • Bare Chip Mounting: The bare driver chip (without a package) is placed directly onto the PCB or display substrate.
  • Wire Bonding: Tiny gold or aluminum wires are used to bond the chip to the circuit, making electrical connections between the IC and the display.