Browse Prior Art Database

Chip Removal Method

IP.com Disclosure Number: IPCOM000034756D
Original Publication Date: 1989-Apr-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Gruber, HW: AUTHOR [+4]

Abstract

Substrates comprising several chips are repaired by removing defective chips. This can be done in two ways. 1. The chip is severed by simple reciprocal rotational movements. 2. The chip-to-substrate solder interface is preheated across the entire substrate face and then more strongly through the chip by a focusing lamp. After the solder melting point has been reached, the chip is lifted off by a suction means. The disadvantage of these methods is that the sudden chip acceleration causes the molten solder to be spilled over the chip surface, so that it can either not be analyzed or be analyzed only with great difficulty.

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Chip Removal Method

Substrates comprising several chips are repaired by removing defective chips. This can be done in two ways. 1. The chip is severed by simple reciprocal

rotational movements.

2. The chip-to-substrate solder interface is

preheated across the entire substrate face and

then more strongly through the chip by a focusing

lamp. After the solder melting point has been

reached, the chip is lifted off by a suction

means. The disadvantage of these methods is that the sudden chip acceleration causes the molten solder to be spilled over the chip surface, so that it can either not be analyzed or be analyzed only with great difficulty. The method described below uses a mechanical device which permits removing chip 1 from substrate 2 undamaged, so that the chip can be electrically tested for further analysis. In addition, damage to the substrate in the vicinity of the chip to be lifted off is avoided. The device used for this purpose consists of an aluminum bracket 3 which is provided with five Cu tubes 4 such that an arrangement as shown in the plan and cross-sectional views is obtained. Lead tin balls 5 are attached to the bottom ends of tubes 4 by a fluxing agent. A metallization is vapor deposited on chip 1 to be lifted off. Bracket 3 is clipped over chip 1, and the entire arrangement is put in a conventional chip join oven. As the lead tin of solder balls 6 melt, the chips on substrate 2 are loosened. By the capillary effect of the liquid lead tin of ball...