Unpackaged ICs, e.g. made of silicon or other base materials, are glued or soldered to the substrate and connected to the conductive pattern with gold or aluminium wires.
Various COB technologies such as soldering, gluing, gold wire bonding, aluminium wire bonding or potting (Gloptop, Dam & Fill) are used, depending on the requirements. In many cases a combination of these different processes will be the ideal solution. The specific combination depends on the requirements of the desired module.