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Electrical Connections in Josephson Circuitry

IP.com Disclosure Number: IPCOM000050930D
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Wu, CT: AUTHOR

Abstract

In packaging of circuits using Josephson devices, Pt pins located on circuit chips or boards are inserted into liquid mercury droplets held in cavities in an interconnect board. The Pt pins can be easily contaminated and therefore wettability problems result. In order to solve this problem and in order to protect the Pt pins during formation of the pins, interface metallurgy layers and protect layers are used.

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Electrical Connections in Josephson Circuitry

In packaging of circuits using Josephson devices, Pt pins located on circuit chips or boards are inserted into liquid mercury droplets held in cavities in an interconnect board. The Pt pins can be easily contaminated and therefore wettability problems result. In order to solve this problem and in order to protect the Pt pins during formation of the pins, interface metallurgy layers and protect layers are used.

Phased layers of Pt/Pd can be used for interfacing with liquid Hg to provide improved wettability. The phased layer goes from 100 percent Pt to 100 percent Pd, one component increasing in amount while the other decreases at the same rate. A protection layer of Cu (or Al, etc.) is placed on top of the interface metallurgy layer to protect the thin interface metallurgy layer during pin formation by electrodischarge machining (EDM). The protective layer is removed after EDM to leave a very smooth and uncontaminated surface on the interface metallurgy layer.

The process for forming pins is the following:

- Deposit the interface metallurgy layer comprising a first

layer of Pt, a second layer of phased Pt/Pd, a layer of Pd,

and a top layer of Au on a Pt sheet after sputter cleaning of

the sheet.

- Place a thin layer of protective metal, such as Cu or Al,

on top of the Au layer.

- EDM pin sets.

- Etch the protection layer away.

The rest of the steps for the complete process are the same as those known in the art, invol...