Cu nanoparticles are promising interconnection material due to low cost and superior conductivity while they readily oxidize and need special processing and storing conditions. To solve these problems, a specific in situ reduction-sintering of CuO nanoparticles was developed and oxide free Cu submicron particles suitable for sintering were fabricated. The surfaces of the Cu submicron particles show no obvious oxide structure even after air sintering at 220 °C for 15 min and Cu-Cu joints with high shear strength of 22 MPa were produced. The oxide forms during longer bonding durations had a morphological evolution from stripe into grain and developed different layer structures on Cu particle surface. The micro-fracture mechanism of sintered Cu particles was analyzed and Cu particles were found to deform plastically while the surface oxide show obvious brittle fracture. Variation in shear strength with bonding time was analyzed and simulated based on contact area theory and the degradation of shear strength was correlated to the oxide formation. The proposed method produces similar shear strengths to Cu nanoparticle sintered joints but without the need for pressurized sintering or protective gas atmospheres.

铜纳米颗粒由于低成本和优异的导电性而很有希望成为一种互连材料，同时它们易于氧化并且需要特殊的加工和储存条件。为了解决这些问题，开发了CuO纳米颗粒的特定原位还原烧结，并制造了适合烧结的不含氧化物的Cu亚微米颗粒。即使在220°C空气烧结15分钟后，Cu亚微米颗粒的表面也没有显示出明显的氧化物结构，并制得了具有22 MPa的高剪切强度的Cu-Cu接头。在较长的键合期间，氧化物的形态从条带状演变为晶粒状，并在Cu颗粒表面形成了不同的层结构。分析了烧结Cu颗粒的微观断裂机理，发现Cu颗粒发生塑性变形，而表面氧化物表现出明显的脆性断裂。基于接触面积理论分析和模拟了剪切强度随结合时间的变化，并且剪切强度的下降与氧化物的形成有关。所提出的方法产生与Cu纳米粒子烧结接头相似的剪切强度，但不需要加压烧结或保护性气氛。