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Low Resistance and High Electromigration Lifetime of Cu-To-Cu Joints Using (111)-Oriented Nanotwinned Copper

Jing-Ye Juang; Kai Cheng Shie; Yu Jin Li; K. N. Tu; Chih Chen

Advanced Materials Letters, 2021, Volume 12, Issue 8, Pages 1-4
DOI: 10.5185/amlett.2021.081654

Cu-to-Cu joints of 30 mm in diameter were fabricated using (111)-oriented nanotwinned copper at 300 °C for 20 min in N2 ambient. The joints possess excellent electrical properties. The average resistance and specific contact resistivity are 4.1 mΩ and 3.98 × 10 -8 Ω·cm 2 , respectively for an as-fabricated Cu joint. With a second step annealing at 400 °C, the resistance can be reduced to 3.27 mΩ due to grain growth across the joint interface. There is 50% resistance reduction compared to SnAg solder joints with the same diameter. The electromigration lifetime for Cu-to-Cu joints is at least 750 times longer than solder joints.

Relaxations In Gelatin Hydrogels Probed By Dynamic Light Scattering

Nitin Kumar; Vinay Kumar; Jitendra Sharma

Advanced Materials Letters, 2016, Volume 7, Issue 2, Pages 136-143
DOI: 10.5185/amlett.2016.6012

The relaxation behavior of gelatin aqueous solutions has been investigated by time resolved dynamic light scattering (TRDLS) measurements at different temperatures spanning the entire sol to gel phase transition behavior of the system (i.e. from 5 min to 1440 min after a sudden quench from high temperature sol to low temperature gel state), when the chosen gelatin concentration in water was maintained at 5 % (w/v), well over the overlap threshold. The quantity of interest, structure factor S (q,τ), has been obtained from the experimentally measured autocorrelation function,  g2(τ), allowing appropriate heterodyne contribution. The nonlinear regression analysis of the obtained scattering profiles (variation of structure factor vs. delay time) exhibited good fits to the function S(q,τ) ~A exp(-Dq 2 τ) + B exp(-(τ/τc) β ), up tosystem evolution time of 360 min, whereas the data obtained after 360 min showed appropriate fits to S(q,τ) ~A exp(-Dq 2 τ)+ Cτ -α + B exp(-(τ/τc) β ). The temporal behavior of different fit parameters defining the transient structural network formed in the system has been quantified and analyzed under the purview of well-defined theories. Furthermore, the evolution of particle dynamics from fast to slow and then to almost frozen behavior has been explored through the continuous evaluation of ‘Gelation factor (κ)’ at different stages of system evolution times during the measurements.