Thermal expansion of Cu/carbon nanotube composite wires and the effect of Cu-spatial distribution

Influence of Carbon Nanotube Attributes on Carbon Nanotube/Cu Composite Electrical Performances

“…Carbon nanotube/copper (CNT/Cu) composites are proposed as promising lightweight copper substitutes for next-generation electrical wiring and interconnect applications on account of their rivaling conductivities with superior heat stability, current capacities, and lower densities [1][2][3]. CNT/Cu up to 2/3rd as light as copper have been fabricated in practically applicable forms, such as planar [4,5] and vertical micro-interconnects [6,7], macroscopic wires [8][9][10][11][12][13][14][15], etc. These composites have been observed to show roomtemperature conductivities similar to copper in the range 1.0-4.7 × 10 5 S/cm (20-80% of Cu) [4][5][6][7]12,13,[15][16][17].…”

“…These composites have been observed to show roomtemperature conductivities similar to copper in the range 1.0-4.7 × 10 5 S/cm (20-80% of Cu) [4][5][6][7]12,13,[15][16][17]. The heat stability of conductivity in CNT/Cu is observed as subdued conductivity reduction with temperature rise vs. copper and is quantified as a reduction in temperature coefficients of resistance (TCR) [5,6,8,[11][12][13]15,16,18]. TCR values as low as 10-50% that of Cu are reported due to nanotube participation (with their inherently low TCR) in electron transport.…”

“…Composite fabrication by Cu electrodeposition of CNT templates preserves the nanotube structure during processing. Among electrodeposition methods, the two-step Cu deposition strategy has yielded composites with uniform nanotube-Cu mixing even with high CNT vol % (≈45 vol %) [4][5][6][7][8][9][10][11]. Applying only typical aqueous electrolyte-based Cu electrodeposition on CNT templates leads merely to core-sheath composites consisting of templates coated by Cu with no CNT-Cu mixing in the bulk [8,11].…”

“…Among electrodeposition methods, the two-step Cu deposition strategy has yielded composites with uniform nanotube-Cu mixing even with high CNT vol % (≈45 vol %) [4][5][6][7][8][9][10][11]. Applying only typical aqueous electrolyte-based Cu electrodeposition on CNT templates leads merely to core-sheath composites consisting of templates coated by Cu with no CNT-Cu mixing in the bulk [8,11]. This is because aqueous electrolytes cannot infiltrate hydrophobic nanotube templates.…”

“…This is because aqueous electrolytes cannot infiltrate hydrophobic nanotube templates. In contrast, the two-step strategy [4][5][6][7][8][9][10][11] involves deposition from an organic electrolyte capable of wetting and infiltrating CNT templates that first seeds Cu within CNT templates. This is followed by the second seed-growth step (by aqueous electrodeposition) to obtain the final composites exhibiting uniform CNT-Cu mixing throughout.…”