Chip-off involves heating the device's circuit board until the solder holding the components to the board melts, and then removing the flash memory chip. The memory chip can then be read using commercial tools, resulting in a full physical image. Chip-off techniques, like JTAG, stem from the commercial electronic production process. The process of melting the solder (commonly called reflow or rework) is used to place and remove components from a circuit board, and the readers used to acquire the memory are used to both read and write to memory chips, often in bulk quantities:

Chip-off has the same benefits as JTAG: it does not require the device to be powered on, and can be used to bypass the PIN/password on a locked device. Chip-off is normally considered to be a destructive process. While the memory chip can be replaced on the device, it is a technically demanding process and requires further training. But, as a last resort, chip-off is an excellent alternative for devices that would otherwise be impossible to examine.

Chip-off is significantly more expensive than JTAG, as a specialized rework station and commercial memory reader is required. There are dozens of rework stations available, and they all provide essentially the same functionality. There is also a wide range of memory readers, though we have had great success with this reasonably priced model: http://www.dataman.com/programmers/universal/dataman-48pro2-super-fast-universal-isp-programmer.html. A rework station and reader aren't the only costs associated with chip-off; most readers will also require a specific adapter for each model of chip to be read.