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Chip Mounting Using Mercury Tension Bands and Alignment Frames

IP.com Disclosure Number: IPCOM000050758D
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Brown, KH: AUTHOR [+2]

Abstract

Microminiaturized alignment frames of solder or polyamide provide lateral retention for chips during periods when liquid metal bonds are in the liquid phase, when only surface tension bonds and the retention frames hold the chips in place.

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Chip Mounting Using Mercury Tension Bands and Alignment Frames

Microminiaturized alignment frames of solder or polyamide provide lateral retention for chips during periods when liquid metal bonds are in the liquid phase, when only surface tension bonds and the retention frames hold the chips in place.

Liquid metal contacts, usually mercury, are known. Below the freezing point of the liquid metal, these contacts also serve to retain the chips, but at room temperature only the surface tension of the liquid metal is available to retain the chips in position. Forces necessary to dislodge chips in a perpendicular direction are large (approx. 5-10 gms) and are not likely to occur since the separation of the chip rom the substrate is small. Impact forces (F=MA) require large acceleration/ deacceleration (approx. 100-200 "G") since the chip mass is so small. However, for liquid mercury contacts, small lateral forces (approx. 2-3 gms), common during assembly of cards, are sufficient to dislodge the chips.

Small alignment frames, approximately 4 mils in height, provide a lateral retention for the chips at their corners, as shown in Figs. 1 and 2.

Alignment frames are patterned solder depositions, passivated by sprayon, exposed/polymerized, and by development of negative photoresist (e.g. , KTFR(Trademark of Estman Kodak Co.) or other conformal polymer (e.g. parylene) . Wholly organic frames (e.g., patterned polyamide) are also usable.

The passivation of the alignment frame...