Browse Prior Art Database

Flip-Chip With Superconducting Contacts

IP.com Disclosure Number: IPCOM000038334D
Original Publication Date: 1987-Jan-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Brady, MJ: AUTHOR [+3]

Abstract

This article relates generally to a method of connecting conductors to superconducting devices and, more particularly, to a method of bonding superconducting contacts on a substrate with those on a superconducting device. Contacts of a superconducting device or chip can be easily and reliably attached to measurement conductors by first forming the conductors and their contact pads on a transparent substrate. A transparent substrate of glass is coated with a thin chromium layer covered by a thicker copper layer. Using photoresist lithography, pads and lines are etched on the substrate to match the contact pads of the superconducting device and to form lines leading to other larger pads beyond the superconducting device area.

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Flip-Chip With Superconducting Contacts

This article relates generally to a method of connecting conductors to superconducting devices and, more particularly, to a method of bonding superconducting contacts on a substrate with those on a superconducting device. Contacts of a superconducting device or chip can be easily and reliably attached to measurement conductors by first forming the conductors and their contact pads on a transparent substrate. A transparent substrate of glass is coated with a thin chromium layer covered by a thicker copper layer. Using photoresist lithography, pads and lines are etched on the substrate to match the contact pads of the superconducting device and to form lines leading to other larger pads beyond the superconducting device area. The transparent, etched substrate is then dipped in a liquid solder flux and eutectic alloy of fluxless solder to coat the delineated chromium-copper pattern, leaving well-defined, uniform solder mounds on the etched pads. The solder, such as 60% tin-40% lead, is superconducting below 7OEK. Using low magnification optics, the substrate is aligned over the superconducting device and pressed into place. Bonding can be completed by either mechanical pressure or thermal reflow.

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