Chowdhury Rajib, Young Karl, Poche Thomas J, Jang Seonhee
Department of Mechanical Engineering, University of Louisiana at Lafayette, Lafayette, LA 70503, United States of America.
Nanotechnology. 2023 Aug 7;34(42). doi: 10.1088/1361-6528/ace6a5.
The dual sintering of copper (Cu) nanoparticles (NPs) was introduced to produce conductive patterns suitable for flexible electronics applications. In this method, laser irradiation using a Nd:YAG laser with a wavelength of 1064 nm was performed at laser powers of 400, 600 and 800 mJ. The laser irradiation time was 15 and 30 s for each laser power. After laser irradiation, all of the Cu NP patterns were thermally sintered under formic acid vapors. The temperature and time for thermal treatment were selected as 260 °C and 15 min, respectively. The resultant physical, chemical, electrical and mechanical properties were evaluated and compared considering the six different dual sintering conditions. The Cu NP patterns sintered using 800 mJ for 30 s showed increased necking and coalescence compared to the other patterns and featured a microstructure with increased density. Despite being oxidized, the Cu NP patterns sintered with 800 mJ for 30 s showed the lowest electrical resistivity of 11.25Ω cm. The surface of every sintered Cu pattern was oxidized, and mechanical hardness increased with increasing laser power. The Cu NP pattern sintered with 800 mJ for 30 s demonstrated the highest hardness of 48.64 N mm. After sintering using the six different conditions, the Cu NP patterns exhibited a weight loss of 0.02-3.87 wt%, and their roughness varied in the range of 26.15-74.08 nm. This can be attributed to the effective removal of organic residues and the degree of particle agglomeration. After performing folding tests up to 50 cycles, Cu NP patterns showed an upward trend in resistance with increasing laser power and time. The highest and lowest resistance ratios were observed as 3.97 and 17.24 for the patterns sintered at 400 mJ for 15 s and 800 mJ for 30 s, respectively.
引入铜（Cu）纳米颗粒（NPs）的双重烧结工艺来制备适用于柔性电子应用的导电图案。在该方法中，使用波长为1064 nm的Nd:YAG激光，在400、600和800 mJ的激光功率下进行激光辐照。每种激光功率下的激光辐照时间为15 s和30 s。激光辐照后，所有铜纳米颗粒图案在甲酸蒸汽下进行热烧结。热处理的温度和时间分别选择为260°C和15分钟。考虑六种不同的双重烧结条件，对所得的物理、化学、电学和力学性能进行了评估和比较。与其他图案相比，使用800 mJ烧结30 s的铜纳米颗粒图案显示出颈缩和聚结增加，并且具有密度增加的微观结构。尽管被氧化，但使用800 mJ烧结30 s的铜纳米颗粒图案显示出最低的电阻率，为11.25Ω·cm。每个烧结铜图案的表面都被氧化，并且机械硬度随着激光功率的增加而增加。使用800 mJ烧结30 s的铜纳米颗粒图案表现出最高硬度，为48.64 N/mm。在使用六种不同条件烧结后，铜纳米颗粒图案的重量损失为0.02 - 3.87 wt%，其粗糙度在26.15 - 74.08 nm范围内变化。这可归因于有机残留物的有效去除和颗粒团聚程度。在进行高达50次循环的折叠测试后，铜纳米颗粒图案的电阻随着激光功率和时间的增加呈现上升趋势。对于在400 mJ下烧结15 s和800 mJ下烧结30 s的图案，观察到的最高和最低电阻比分别为3.97和17.24。
