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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