Li Ruo-Zhou, Hu Anming, Bridges Denzel, Zhang Tong, Oakes Ken D, Peng Rui, Tumuluri Uma, Wu Zili, Feng Zhili
School of Electronic Science and Engineering, Southeast University, Key Laboratory of Micro-Inertial Instrument and Advanced Navigation Technology, Ministry of Education, Nanjing 210096, China.
Nanoscale. 2015 Apr 28;7(16):7368-77. doi: 10.1039/c5nr00312a.
Nanoinks are currently a topic of heightened interest with respect to low temperature bonding processes and printable electronics. We have developed an innovative polyvinylpyrrolidone (PVP)-stabilized Ag nanoplate ink amenable to very strong low temperature packaging, and investigated the relationship between bonding strength and electrical conductivity post-bonding. PVP shell plastic deformations observed in failure microcracks with the formation of PVP nanofibers, revealed bonding strength at low temperatures (<250 °C) was primarily due to adhesive bonding. It is found that, utilizing photonic sintering, ∼ 70 °C reduction of transformation temperature from adhesive to metallic bonding was achieved compared to that of thermal sintering. A numerical simulation was developed to better understand the influences of the light-induced heat generation, which demonstrated near-infrared light can facilitate sintering. Bonding strengths of 27 MPa were achieved at room temperatures, and 29.4 MPa at 210 °C with photonic sintering. Moreover, the anisotropic resistivity was observed with different thermal dependences. These results demonstrate Ag nanoplate inks have potential for low temperature 3D interconnections in lead-free microcircuits, flexible electronic packaging, and diverse sensing applications.
纳米墨水目前是低温键合工艺和可印刷电子产品领域备受关注的一个话题。我们开发了一种创新的、适用于非常强的低温封装的聚乙烯吡咯烷酮（PVP）稳定的银纳米片墨水，并研究了键合强度与键合后电导率之间的关系。在失效微裂纹中观察到PVP壳层发生塑性变形并形成PVP纳米纤维，这表明低温（<250°C）下的键合强度主要归因于粘附键合。研究发现，与热烧结相比，利用光子烧结可使从粘附键合到金属键合的转变温度降低约70°C。开展了数值模拟以更好地理解光致发热的影响，结果表明近红外光可促进烧结。通过光子烧结，室温下的键合强度达到27 MPa，210°C时达到29.4 MPa。此外，还观察到具有不同热依赖性的各向异性电阻率。这些结果表明，银纳米片墨水在无铅微电路的低温3D互连、柔性电子封装及各种传感应用方面具有潜力。
