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How Lcd Displays Are Made,COB

October 14, 2024

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.

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