Uniform Heating of C-4 Solder Balls on a Chip by a Laser Phase Holography
Original Publication Date: 1980-Sep-01
Included in the Prior Art Database: 2005-Feb-13
In order to obtain uniform heating of C-4 solder balls, the heat must be preferentially distributed over the C-4 balls. For instance, a uniform distribution of the heat over a chip can cause a large temperature gradient between the C-4 balls. In individual chip replacement tools, a laser source is used to heat the chip during removal and replacement. The use of a phase hologram makes possible the distribution of the laser energy at the exact chip's footprint, thus resulting in a uniform heating of the C-4 balls. Here, the use of a phase hologram provides selective heat distribution on chips having C-4 balls during individual chip replacement. Individual chip replacement refers to the removal and replacement of a single defective chip that was previously mounted on a large substrate containing arrays of chips.