In the 1980s, 7 LCD segment screens began to gain widespread market adoption, and were subsequently further subdivided into dot matrix screens, driving the development of data visualization. Early graphic screens primarily used DIP (Dip Insulated Circuit) packaging or TAB (Tape Automated Bonding) processes.
This manufacturing process was bulky, involved numerous pins, and was costly, making it difficult to miniaturize. With the rise in popularity of consumer electronics (watches, calculators, and telephones), demand for low-cost, lightweight, and thin LCD modules emerged.
In the early 1990s, the COB (Chip On Board) process was introduced and began to be used in the LCD module industry. The driver IC is bonded directly to the PCB as a bare die.
The electrodes are then connected via wire bonding, and then protected with adhesive (vinyl encapsulation). This process reduced costs (by eliminating IC packaging costs),
allowed thinner modules to save space, and resulted in a more compact design with improved reliability (by reducing solder joints). At the time, it was primarily used for small-sized segment screens and low-end graphic dot matrix screens.
In the 2000s, the maturity and widespread adoption of COB technology made COB the mainstream process for segmented LCD modules.
It was widely used in home appliance panels (such as air conditioner remote controls, microwave ovens, and washing machine displays), industrial instruments (electricity meters, water meters, and gas meters), and portable devices (blood pressure monitors and calculators).
The black vinyl package was commonly seen, forming the typical identification method of the "black dot IC."
It enabled multi-channel drive and supported complex segment codes.
Due to its low cost, it became the most common LCD packaging solution at the time.
Since 2010, it has been developed in parallel with COG/SMT, offering the lowest cost and suitable for high-volume, low-cost LCD segmented screens. Furthermore, the process is mature and has a high yield rate. However, its size is relatively large (because the IC is packaged on the PCB, which takes up space). This makes it unsuitable for ultra-thin and high-resolution displays. At the same time, the COG (Chip On Glass) process gradually gained popularity: it directly bonds the IC to the glass, resulting in a smaller size and suitable for TFT color screens and high-end segmented screens.
COB technology is still widely used for low-cost and low-information applications. High-end, ultra-thin applications: COG, TAB or SMT packaging is more commonly used.
