COB (chip–on-board) assembly service：
COB assembly leverages existing die attach, gold ball and aluminum wedge wire bonding technology. Consequently dies to be used in COB applications generally use a peripheral bond pad arrangement. Post wire-bond, the application of either liquid encapsulation or transfer molding provides protection for the die. The encapsulated device is then marked using inkjet techniques for maximum legibility and performance.
COG (Chip-On-Glass) is the most commonly used for LCM (Liquid Crystal Module) manufacturing process. LCM comprises of LCD panel, connector, control driver IC, PCBA, backlight panel, and frame. For the LCD screen has too many pins with very small pitch, coventional methods of using electroconductive rubber connecting LCD and the driver IC circuit have been very inconvenient to end users. COG has therefore been introduced to bond the driver IC on the LCD panel by ACF (anisotropy glue) thermocompression, then connect the module to external circuit by FPC and its connector.
Flip Chip assembly relies on eutectic solder bumps to make the interconnection between die and substrate. Consequently dies to be used in flip chip applications generally use an array format, resulting in a smaller footprint and optimum electrical performance. Post placement dies are subjected to a reflow process and underfilled to enhance the thermal and mechanical properties of the interconnection. Devices are then encapsulated and marked just as in the COB process.