Shenzhen Key Laboratory of Advanced Materials, Shenzhen Graduate School, Harbin Institute of Technology, HIT Campus, Shenzhen University Town, Xili, Nanshan, Shenzhen 518055, PR China.
Shenzhen Key Laboratory of Advanced Materials, Shenzhen Graduate School, Harbin Institute of Technology, HIT Campus, Shenzhen University Town, Xili, Nanshan, Shenzhen 518055, PR China.
Ultrason Sonochem. 2018 Mar;41:375-381. doi: 10.1016/j.ultsonch.2017.10.003. Epub 2017 Oct 4.
Sintering of low-cost Cu nanoparticles (NPs) for interconnection of chips to substrate at low temperature and in atmosphere conditions is difficult because they are prone to oxidation, but dramatically required in semiconductor industry. In the present work, we successfully synthesized Cu@Ag NPs paste, and they were successfully applied for joining Cu/Cu@Ag NPs paste/Cu firstly in air by the ultrasonic-assisted sintering (UAS) at a temperature of as low as 160 °C. Their sintered microstructures featuring with dense and crystallized cells are completely different from the traditional thermo-compression sintering (TCS). The optimized shear strength of the joints reached to 54.27 MPa, exhibiting one order of magnitude higher than TCS at the same temperature (180 °C) under the UAS. This ultra-low sintering temperature and high performance of the sintered joints were ascribed to ultrasonic effects. The ultrasonic vibrations have distinct effects on the metallurgical reactions of the joints, resulting in the contact and growth of Cu core and the stripping and connection of Ag shell, which contributes to the high shear strength. Thus, the UAS of Cu@Ag NPs paste has a great potential to be applied for high-temperature power device packaging.
在大气条件下，低温烧结用于芯片与衬底互连的低成本铜纳米颗粒（NPs）非常困难，因为它们容易氧化，但在半导体行业中却有很大的需求。在本工作中，我们成功合成了 Cu@Ag NPs 糊剂，并通过超声辅助烧结（UAS）在低至 160°C 的温度下首次成功地将它们应用于 Cu/Cu@Ag NPs 糊剂/Cu 的连接。它们的烧结微观结构具有致密和结晶化的晶粒，与传统的热压烧结（TCS）完全不同。优化后的接头剪切强度达到 54.27 MPa，在相同温度（180°C）下，UAS 的剪切强度比 TCS 高一个数量级。这种超低的烧结温度和烧结接头的高性能归因于超声效应。超声波振动对接头的冶金反应有明显的影响，导致 Cu 核的接触和生长以及 Ag 壳的剥落和连接，从而提高了接头的剪切强度。因此，Cu@Ag NPs 糊剂的 UAS 有望应用于高温功率器件封装。
