A novel low resistivity copper diffusion joint for REBa2Cu3O7-δ tapes by thermocompression bonding in air

A novel low resistivity copper diffusion joint for REBa2Cu3O7-δ tapes by thermocompression bonding in air

Applications of REBa2Cu3O7-δ tapes require joints with a simple manufacturing process, low resistance and good mechanicalproperties. In the present study, we successfully developed a copper diffusion joint between Cu-stabilized REBa2Cu3O7-δ tapes thatmeets the above requirements without solder simply by applying flux, heat and pressurization. After a 3 min thermocompressionprocess at approximately 150 ℃ and 336 MPa in air, two tapes were directly connected between Cu stabilizers by copper diffusion,which was proven by microstructure analysis. The specific resistivity of the copper diffusion joint reached 5.8 nΩ·cm2(resistanceof 0.4 nΩ for a 306 mm splicing length) at 77 K in the self-field. The axial tensile stress reached 200 N without critical currentdegradation. The results show promise for the preparation of copper diffusion joints to be used in coils, attached tapes, andwire/cable terminals.

Applications of REBa2Cu3O7-δ tapes require joints with a simple manufacturing process, low resistance and good mechanicalproperties. In the present study, we successfully developed a copper diffusion joint between Cu-stabilized REBa2Cu3O7-δ tapes thatmeets the above requirements without solder simply by applying flux, heat and pressurization. After a 3 min thermocompressionprocess at approximately 150 ℃ and 336 MPa in air, two tapes were directly connected between Cu stabilizers by copper diffusion,which was proven by microstructure analysis. The specific resistivity of the copper diffusion joint reached 5.8 nΩ·cm2(resistanceof 0.4 nΩ for a 306 mm splicing length) at 77 K in the self-field. The axial tensile stress reached 200 N without critical currentdegradation. The results show promise for the preparation of copper diffusion joints to be used in coils, attached tapes, andwire/cable terminals.