In this case, the dies will have been sorted prior to the die bonding operation, and will be presented for placement via either waffle packs or tape and reel. In the case of wafer processing, wafers are received after dicing on a film frame. Cassettes of 25 wafers are fed to the machine, and one wafer is indexed into the machine for placement. Frames are stretched to permit optimum mapping and picking. In order to pick a device from the frame, an ejector pin pushes the die off the frame while the pick head of the machine lifts the die.
Substrates vary widely in the industry.
Other materials include rigid board materials, such as FR-4 and BT, ceramics, and polyimide flex circuits. Devices are sometimes placed in metal housings, as in the case of optoelectronic devices. The lighting scheme and camera resolution are critical and application specific. For flex circuit assembly, for example, blue lighting provides superior imaging resolution over the traditional 660nm red light. In the case of co-fired ceramics, the use of polarised light provides a better contrast between the alumina ceramic and the circuit metallurgy.