What is COG (Chip on Glass)?
COG is a construction where the display driver IC is bonded directly onto the LCD glass, reducing module size and connection count.
How COG works
In a COG module the driver IC is bonded straight onto an extended ledge of the LCD glass using anisotropic conductive film (ACF). The FPC then connects to the glass with a second bonding step (FOG, film on glass).
COG vs alternatives
Construction | Driver IC location | Typical use |
|---|---|---|
COG | On the glass | Most small and medium TFTs |
COF | On the flex circuit | Narrow-bezel and large panels |
COB | On a PCB behind the display | Older character and graphic LCDs |
Why it matters to you
COG keeps modules thin and cheap and reduces the number of FPC pins. The glass ledge carrying the IC is fragile, however: avoid mechanical stress on it during assembly and design the enclosure so the ledge is not loaded.
COG and FOG bonding lines are core processes in TFT module manufacturing; see factory & quality.
Frequently asked questions
What does COG mean on a display datasheet?
It means the driver IC is mounted directly on the LCD glass (Chip on Glass).
Is COG reliable?
Yes, it is the dominant construction for small and medium TFTs. Avoid mechanical stress on the glass ledge where the IC sits.
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