Chip on board
Chip-on-board technology (short: COB) is a direct chip attach technology, in which chips -chips not enclosed in housings - are glued to a substrate and covered with an encapsulant. Prior to encapsulation, the electrical connection to the board assembly is established through wire bonding or flip-chip soldering. Because of its relatively low cost, this technology is frequently used for high volume products (calculators, watches, etc.). Major draw backs are the facts that the chip cannot be replaced and that a clean room is required for the production.