Flip-Chip Bonding Using Superconducting Solder Bump

概要

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Flip-chip bonding using superconducting solder bumps consists of two technologies: acid-free thermosonic compression ball bonding and face-down bonding of the chip on the substrate by means of thermosonic compression at 373 K. A superconducting test chip with 68 bumps formed on Nb/Pd film pads was bonded on a ceramic substrate. The maximum shear strength of a single solder bump for the Nb/Pd films was found to be 26.5 MPa, which was about 3 times higher than that obtained for Nb/Au film pads. The flip-chip module did not undergo catastrophic failures in either prototype design or material combination during 20 thermal cyclings between 4.2 K and 273 K. Electrical check tests at 4.2 K before and after the thermal cyclings suggest that the present superconducting solder bump can be put into practical use for superconducting IC chip connection.
社団法人応用物理学会の論文
1995-08-15