Chip Removal by C4 Garroting
Original Publication Date: 1985-Dec-01
Included in the Prior Art Database: 2005-Feb-19
In semiconductor manufacturing of integrated circuits, it is sometimes necessary to selectively remove one or more of the chips from the substrate. The soldered C4 (controlled collapse chip connectors) are severed in various ways which frequently damage the chips. This article proposes a garroting method to remove the chips from the modules, leaving uniform solder heights and doing no mechanical damage. As shown in the figure a wire 1, fine enough to fit between the chip 2 and the substrate can be made to pass through a C4 array 3, severing each C4. A tensile force 4 applied to the wire will cause plastic deformation of the solder so that garroting proceeds to sever the connectors. The rate of plastic deformation can be increased by heating the module so as to shorten the time necessary to complete the task.