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Double Cantilever Flip-Chip Resistor

IP.com Disclosure Number: IPCOM000046071D
Original Publication Date: 1983-May-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Aakalu, NG: AUTHOR

Abstract

Described is a resistor chip which is cantilever mounted by attachment in its central portion. An S-shaped resistor film replaces the traditional rectangular shape film between the two electrodes. The electrodes are near the center of the chip, whereas in the traditional design they are at the two ends of the chip. The electrodes can be either solder coated and reflow attached to a substrate or silver epoxied to the substrate. Except for the part of the chip between the two electrodes, the chip is free to expand or contract. Only a third of the length of the chip is constrained, and hence this configuration provides higher thermal cycle life for the solder or epoxy connections.

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Double Cantilever Flip-Chip Resistor

Described is a resistor chip which is cantilever mounted by attachment in its central portion. An S-shaped resistor film replaces the traditional rectangular shape film between the two electrodes. The electrodes are near the center of the chip, whereas in the traditional design they are at the two ends of the chip. The electrodes can be either solder coated and reflow attached to a substrate or silver epoxied to the substrate. Except for the part of the chip between the two electrodes, the chip is free to expand or contract. Only a third of the length of the chip is constrained, and hence this configuration provides higher thermal cycle life for the solder or epoxy connections.

This improvement allows greater freedom in the choice of materials for the chip and the substrate upon which it is to be mounted. For instance, alumina ceramic resistors expand or contract much less than a porcelain-coated steel substrate and hence there would be high thermalexpansion mismatch and lower thermal cycle life with traditional chip resistors mounted on such a substrate. Use of the double cantilevertype would enhance their life.

Fig. 1 shows a traditional flip-chip 1, which has a thick film or a thin film resistor 2 terminated at the two ends with the solder or the silver spoxy-coated electrodes 3. In some cases trimming up by laser or abrasive jet is necessary, as shown at 4. Fig. 2 shows a double cantilever flip-chip 5 which has a thick or...