COB is a popular module construction method for low to medium resolution displays including segmented glass and alphanumeric display modules.
The controller/driver IC is directly bonded to the PCB as a naked die and subsequently wire bonded to the PCB using micro diameter gold or aluminum wires. The entire area of the bonded IC is then encapsulated using a thermo-setting epoxy.
"Because of the low price nearly all LCD drivers and LCD controllers of our custom designed LCD modules are in COB. We do not outsource the bonding process and the testing."
We have experience to assemble custom circuitry on the LCD pcb and we are also capable to make the needed hard- and software for testing. Hence, we can do more than simply to put all the LCD related components such as temp.comp., dig. pot., back-light, drivers etc. on board.
This particular specialty of ours, is one of our strengths. Also the integration of keypad, special connectors or cable assemblies could be part of the overall module design.
We can assemble any kind of LCD - back-light, which is available on the market. Most commonly used are LED back-light assemblies, which are preferred due to the low voltage and non-critical lifetime. LEDs are spot lamps. Depending on the type of module, light could be distributed from side or as a LED matrix directly behind the panel (starry sky).
Modules with sidelight back-light are more flat. Mostly high-efficiency LEDs are used, in order to provide enough luminance for an even surface brightness.
Attention should be paid to the LCD module thickness and outer dimension, when sidelight back-light is the preferred choice. Compared to the LED matrix, this kind of modules are less thick, but sometimes extra space for the LED spot is needed on one side of the module. Especially if high-efficiency LEDs are used, the LED is positioned some millimeters outside the LCD-panel, in order to improve the uniformity and also because of temperature problems.