chip on board (package) (CoB)

Chip on Board (CoB) is a packaged chip design that belongs to the Direct Chip Attach( DCA) technology. In CoB technology, the chip is mounted directly on a printed circuit board or on a ceramic substrate and electrically connected with bond wires. CoB boards are very robust against mechanical and thermal influences. Heat dissipation for the chip is provided by a thermal paste and across the entire CoB board.

For heat dissipation, the chip can be attached to the board with an insulating, conductive adhesive or a heat-conducting paste, which dissipates the heat lost by the chip thanks to its thermal properties. The connections of the chips, LEDs or other integrated components to the printed circuit board, which is designed using microfine conductor technology( MFT), are made by bonding with thin wires with diameters between 10 µm and 50 µm, or with thick wires from 70 µm to 500 µm made of gold, aluminum or copper. Since the chip has relatively short connections to the CoB board, it can be operated at a high clock frequency. Layer techniques, in which several chips are arranged in layers on top of each other, allow relatively compact CoB boards to be developed using CoB technology.

Chip on Board (CoB), photo: m-tek.com

CoB technology is a low-cost, space-saving technique that achieves high packing densities in small areas. In addition to the inflexible CoB boards, there is another variant, Chip on Flex( CoF), which uses flexible base material.