Browse Prior Art Database

Chip Removal Method

IP.com Disclosure Number: IPCOM000034757D
Original Publication Date: 1989-Apr-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Gruber, HW: AUTHOR [+3]

Abstract

The proposed removal method is used for a single, flip-chip mounted semiconductor chip soldered to a multi- or single-chip substrate by solder balls. Chips 1 are removed and lifted off substrate 3 by heating solder pads 2. Instead of being applied from the outside, the heat for melting solder pads 2 is produced in chip 1 to be lifted off. In an additional step, prior to sawing a wafer into chips 1, metallized conductor structures, forming a resistance network 4, are applied to the back of the chips. A current source is connected to resistance network 4 by connectors 5 and contacts 6. The heat produced by the current flow in resistance network 4 can be accurately controlled as a function of the current characteristic, without affecting adjacent chips.

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Chip Removal Method

The proposed removal method is used for a single, flip-chip mounted semiconductor chip soldered to a multi- or single-chip substrate by solder balls. Chips 1 are removed and lifted off substrate 3 by heating solder pads 2. Instead of being applied from the outside, the heat for melting solder pads 2 is produced in chip 1 to be lifted off. In an additional step, prior to sawing a wafer into chips 1, metallized conductor structures, forming a resistance network 4, are applied to the back of the chips. A current source is connected to resistance network 4 by connectors 5 and contacts 6. The heat produced by the current flow in resistance network 4 can be accurately controlled as a function of the current characteristic, without affecting adjacent chips. The chip temperature (melting point of solder pads 2) can be derived from the current/voltage characteristic of resistance network 4, which is determined by its temperature coefficient. As soon as the melting point of the solder pads 2 has been reached, chip 1 is lifted off substrate 3 by a vacuum applied by suction means 7.

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