High performance packaging system for superconducting electronics

• Published in: IEEE transactions on applied superconductivity 1999-06, Vol.9 (2), p.3668-3671
• Main Authors: Gaidarenko, D., Robertazzi, R.
• Format: Article
• Language: English
• Subjects: Applied sciences; Chips; Circuit testing; Electronics; Electronics packaging; Exact sciences and technology; Flux; Heaters; Integrated circuit packaging; Integrated circuit testing; Josephson junctions; Liquid helium; Liquids; Packaging; Probes; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Superconducting devices; Superconducting integrated circuits; Superconducting transition temperature; Superconductivity; System testing
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/77.783824

We demonstrate a packaging system/test probe suitable for testing complex, large scale superconducting integrated circuits with thousands of Josephson junctions. The cryopackage is designed to work with a 1 cm superconducting die, with liquid He immersion cooling using a standard storage dewar. The package has 80 high-speed input-output lines (DC to 20 GHz) which connect the chip to room temperature electronics. The tip of the cryopackage, containing the chip, is shielded from the ambient magnetic field with two mumetal cylinders and contains a built-in coil, which provides in-situ degaussing of the inner shield. To clear flux trapped in the chip being tested, the probe contains a novel gas manifold and a system of heaters. During the defluxing operation, a heater evaporates liquid helium inside the chip enclosure, the expanding vapor purging the liquid from the sample cell and warming the chip above its transition temperature. Once the chip is defluxed, the liquid helium is allowed back into the cell, at a rate slow enough to avoid trapping flux in the chip while it is cooled. The process can be automated and does not require any movement of the probe once inserted in the dewar.